filters.h

/*
 *			GPAC - Multimedia Framework C SDK
 *
 *			Authors: Jean Le Feuvre
 *			Copyright (c) Telecom ParisTech 2017-2024
 *					All rights reserved
 *
 *  This file is part of GPAC / filters sub-project
 *
 *  GPAC is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  GPAC is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#ifndef _GF_FILTERS_H_
#define _GF_FILTERS_H_

#ifdef __cplusplus
extern "C" {
#endif

#include <gpac/tools.h>
#include <gpac/list.h>
#include <gpac/events.h>
#include <gpac/constants.h>
#include <gpac/download.h>
#include <gpac/main.h>

//for offsetof()
#include <stddef.h>

/*!
\file "gpac/filters.h"
\brief Filter management of GPAC.

This file contains all exported functions for filter management of the GPAC framework.
*/

/*!
\addtogroup filters_grp Filter Management
\brief Filter Management of GPAC.

API Documentation of the filter managment system of GPAC.

The filter management in GPAC is built using the following core objects:
- \ref GF_FilterSession in charge of:
 - loading filters from register, managing argument parsing and co
 - resolving filter graphs to handle PID connection(s)
 - tracking data packets and properties exchanged on PIDs
 - scheduling tasks between filters
 - ensuring thread-safe filter state: a filter may be called from any thread in the session (unless explicitly asked not to), but only by a single thread at any time.
- \ref __gf_filter_register static structure describing possible entry points of the filter, possible arguments and input output PID capabilities.
	Each filter share the same API (register definition) regardless of its type: source/sink, mux/demux, encode/decode, raw media processing, encoded media processing, ...
- \ref GF_Filter is an instance of the filter register. A filter implementation typical tasks are:
 - accepting new input PIDs (for non source filters)
 - defining new output PIDs (for non sink filters), applying any property change due to filter processing
 - consuming packets on the input PIDs
 - dispatching packets on the output PIDs
- \ref GF_FilterPid handling the connections between two filters.
	- PID natively supports fan-out (one filter PID connecting to multiple destinations).
	- A PID is in charge of dispatching packets to possible destinations and storing PID properties in sync with dispatched packets.
	- Whenever PID properties change, the next packet sent on that PID is associated with the new state, and the destination filter(s) will be called
	upon fetching the new packet. This is the one of the two reentrant code of a filter, the other one being the \ref GF_FEVT_INFO_UPDATE event.
	- When blocking mode is not disabled at the session filter, a PID is also in charge of managing its occupancy through either a number of packets or the
	cumulated duration of the packets it is holding.
	- Whenever a PID holds too much data, it enters a blocking state. A filter with ALL its output PIDs in a blocked state won't be scheduled
	for processing. This is a semi-blocking design, which imply that if a filter has one of its PIDs in a non blocking state, it will be scheduled for processing. If a PID has multiple destinations and one of the destination consumes faster than the other one, the filter is currently not blocking (this might change in the near future).
	- A PID is in charge of managing the packet references across filters, by performing memory management of allocated data packets
	 (avoid alloc/free at each packet but rather recycle the memory) and tracking shared packets references.
- \ref GF_FilterPacket holding data to dispatch from a filter on a given PID.
	- Packets are always associated to a single output PID, ie it is not possible for a filter to send one packet to multiple PIDs, the data has to be cloned.
	- Packets have default attributes such as timestamps, size, random access status, start/end frame, etc, as well as optional properties.
	- All packets are reference counted.
	- A packet can hold allocated block on the output PID, a pointer to some filter internal data, a data reference to a single input packet, or a frame interface object used for accessing data or OpenGL textures of the emitting filter.
	Packets holding data references rather than copy are notified back to their creators upon destruction.
- \ref __gf_prop_val holding various properties for a PID or a packet
	- Properties can be copied/merged between input and output PIDs, or input and output packets. These properties are reference counted.
	- Two kinds of properties are defined, built-in ones which use a 32 bit identifier (usually a four character code), and user properties identified by a string.
	- PID properties are defined by the filter creating the PID. They can be overridden/added after being set by the filter by specifying fragment properties
	in the filter arguments. For example \code fin=src=myfile.foo:#FEXT=bar \endcode will override the file extension property (FEXT) foo to bar AFTER the PID is being defined.
- \ref __gf_filter_event used to pass various events (play/stop/buffer requirements/...) up and down the filter chain.
	This part of the API will likely change in the future, being merged with the global GF_Event of GPAC.


GPAC comes with a set of built-in filters in libgpac. It is also possible to define external filters in dynamic libraries. GPAC will look for such libraries
 in default module folder and  folders listed in GPAC config file section core, key mod-dirs. The files SHALL be named gf_* and export a function called RegisterFilter
 with the following prototype:


\param fsess is set to NULL unless meta filters are listed, in which case the filter register should list all possible meta filters it supports
\return a GF_FilterRegister structure used for instantiating the filter.
\code const GF_FilterRegister *RegisterFilter(GF_FilterSession *fsess);\endcode

*/

/*! \hideinitializer
A packet byte offset is set to this value when not valid
*/
#define GF_FILTER_NO_BO 0xFFFFFFFFFFFFFFFFUL
/*! \hideinitializer
A packet timestamp (Decoding or Composition) is set to this value when not valid
*/
#define GF_FILTER_NO_TS 0xFFFFFFFFFFFFFFFFUL

/*! \hideinitializer
Filter Session object
 */
typedef struct __gf_filter_session GF_FilterSession;

/*! \hideinitializer
Filter object
 */
typedef struct __gf_filter GF_Filter;
/*! \hideinitializer
Filter PID object
 */
typedef struct __gf_filter_pid GF_FilterPid;

/*! \hideinitializer
Filter Packet object
 */
typedef struct __gf_filter_pck GF_FilterPacket;
/*!
Filter Packet destructor function prototype
 */
typedef void (*gf_fsess_packet_destructor)(GF_Filter *filter, GF_FilterPid *PID, GF_FilterPacket *pck);

/*!
Filter Event object
 */
typedef union __gf_filter_event GF_FilterEvent;

/*!
Filter Session Task object
 */
typedef struct __gf_fs_task GF_FSTask;

/*!
Filter Register object
 */
typedef struct __gf_filter_register GF_FilterRegister;
/*!
Filter Property object
 */
typedef struct __gf_prop_val GF_PropertyValue;

/*!
Filter Property Reference object, used for info query only
 */
typedef struct __gf_prop_entry GF_PropertyEntry;

/*!
\addtogroup fs_grp Filter Session
\ingroup filters_grp
\brief Filter Session

 The GPAC filter session object allows building media pipelines using multiple sources and destinations and arbitrary filter chains.

 Filters are described through a \ref __gf_filter_register structure. A set of built-in filters are available, and user-defined filters can be added or removed at runtime.

 The filter session keeps an internal graph representation of all available filters and their possible input connections, which is used when resolving connections between filters.

 The number of \ref GF_FilterCapability matched between registries defines the weight of the connection.

 Paths from an instantiated filter are enabled/disabled based on the source PID capabilities.

 Paths to destination are recomputed for each destination, based on the instantiated destination filter capabilities.

 The graph edges are then enabled in the possible subgraphs allowed by the destination capabilities, and unused filter registries (without enabled input connections) are removed from the graph.

 The resulting weighted graph is then solved using Dijkstra's algorithm, using filter priority in case of weight equality.

 The filter session works by default in a semi-blocking state. Whenever output PID buffers on a filter are all full, the filter is marked as blocked and not scheduled for processing. Whenever one output PID buffer is not full, the filter unblocks.

 This implies that PID buffers may grow quite large if a filter is consuming data from a PID at a much faster rate than another filter consuming from that same PID.
 *	@{
 */


/*! Filter session scheduler type */
typedef enum
{
	/*! In this mode, the scheduler does not use locks for packet and property queues. Main task list is mutex-protected */
	GF_FS_SCHEDULER_LOCK_FREE=0,
	/*! In this mode, the scheduler uses locks for packet and property queues. Defaults to lock-free if no threads are used. Main task list is mutex-protected */
	GF_FS_SCHEDULER_LOCK,
	/*! In this mode, the scheduler does not use locks for packet and property queues, nor for the main task list */
	GF_FS_SCHEDULER_LOCK_FREE_X,
	/*! In this mode, the scheduler uses locks for packet and property queues even if single-threaded (test mode) */
	GF_FS_SCHEDULER_LOCK_FORCE,
	/*! In this mode, the scheduler uses direct dispatch and no threads, trying to nest task calls within task calls */
	GF_FS_SCHEDULER_DIRECT
} GF_FilterSchedulerType;

/*! Filter session flags */
typedef enum
{
	/*! Flag set to indicate meta filters should be loaded. A meta filter is a filter providing various sub-filters.
	The sub-filters are usually not exposed as filters, only the parent one is.
	When set, all sub-filters are exposed. This should only be set when inspecting filters help*/
	GF_FS_FLAG_LOAD_META = 1<<1,
	/*! Flag set to run session in non-blocking mode. Each call to \ref gf_fs_run will return as soon as there are no more pending tasks on the main thread */
	GF_FS_FLAG_NON_BLOCKING = 1<<2,
	/*! Flag set to disable internal caching of filter graph connections. If disabled, the graph will be recomputed at each link resolution (less memory occupancy but slower)*/
	GF_FS_FLAG_NO_GRAPH_CACHE = 1<<3,
	/*! Flag set to disable session regulation (no sleep)*/
	GF_FS_FLAG_NO_REGULATION = 1<<4,
	/*! Flag set to disable data probe*/
	GF_FS_FLAG_NO_PROBE = 1<<5,
	/*! Flag set to disable source reassignment (e.g. switching from fin to ffdmx) in PID resolution*/
	GF_FS_FLAG_NO_REASSIGN = 1<<6,
	/*! Flag set to print enabled/disabled edges for debug of PID resolution*/
	GF_FS_FLAG_PRINT_CONNECTIONS = 1<<7,
	/*! Flag set to disable argument checking*/
	GF_FS_FLAG_NO_ARG_CHECK = 1<<8,
	/*! Disables reservoir for packets and properties, uses much less memory but much more alloc/free*/
	GF_FS_FLAG_NO_RESERVOIR = 1<<9,
	/*! Throws an error if any PID in the filter graph cannot be linked. The default behavior is to run the session even when some PIDs are not connected*/
	GF_FS_FLAG_FULL_LINK = 1<<10,
	/*! Flag set to disable implicit linking
	 By default the session runs in implicit linking when no link directives are set on any filter: linking aborts after the first successful pid if destination is not a sink, or links only to sinks otherwise.
	 \note This implies that the order in which filters are added to the session matters
	*/
	GF_FS_FLAG_NO_IMPLICIT = 1<<11,
	/*! Flag set to force all filters to require a source ID (same as setting RSID option on all filters). This is typically used when the app sets links on all used filters while declaring more, unused filters.
	*/
	GF_FS_FLAG_REQUIRE_SOURCE_ID = 1<<12,
	/*! Flag set to force all explicitly added filters to be loaded in deferred link state - linking will only happen once  \ref gf_filter_reconnect_output is called on the filter.
	*/
	GF_FS_FLAG_FORCE_DEFER_LINK = 1<<13,
	/*! Flag set to ignore all PLAY events from sinks - use \ref gf_fs_send_deferred_play to start playback
	*/
	GF_FS_FLAG_PREVENT_PLAY = 1<<14
} GF_FilterSessionFlags;

/*! Creates a new filter session. This will also load all available filter registers not blacklisted.
\param nb_threads number of extra threads to allocate. A negative value means all core used by session (eg nb_cores-1 extra threads)
\param type scheduler type
\param flags set of above flags for the session. Modes set by flags cannot be changed at runtime
\param blacklist string containing comma-separated names of filters to disable. If first character is '-', this describes a whitelist, i.e. only filters listed in this string will be allowed
\return the created filter session
*/
GF_FilterSession *gf_fs_new(s32 nb_threads, GF_FilterSchedulerType type, GF_FilterSessionFlags flags, const char *blacklist);

/*! Creates a new filter session, loading parameters from gpac config. This will also load all available filter registers not blacklisted.
\param flags set of flags for the session. Only \ref GF_FS_FLAG_LOAD_META,  \ref GF_FS_FLAG_NON_BLOCKING , \ref GF_FS_FLAG_NO_GRAPH_CACHE and \ref GF_FS_FLAG_PRINT_CONNECTIONS are used, other flags are set from config file or command line
\return the created filter session
*/
GF_FilterSession *gf_fs_new_defaults(GF_FilterSessionFlags flags);

/*! Destructs the filter session
\param session the filter session to destruct
*/
void gf_fs_del(GF_FilterSession *session);
/*! Loads a given filter by its register name. Filter are created using their register name, with options appended as a list of colon-separated Name=Value pairs.
Value can be omitted for boolean, defaulting to true (eg :allt). Using '!' before the name negates the result (eg :!moof_first).
Name can be omitted for enumerations (eg :disp=pbo is equivalent to :pbo), provided that filter developers pay attention to not reuse enum names in one filter.

Options are either options for the target filter class, options to be inherited between the new filter and its implicit source(s) or implici destination(s), or generic filter options.

Generic filter options are:
- FID: filter identifier (string value)
- SID: filter source(s) (string value)
- N=NAME: filter name (string value)
- FS: sub-session identifier (unsigned int value)
- RSID: require sourceID to be present on target filters (no value)
- TAG: filter tag (string value)
- ITAG: filter inherited tag (string value)
- FBT: buffer time in microseconds (unsigned int value)
- FBU: buffer units (unsigned int value)
- FBD: decode buffer time in microseconds (unsigned int value)
- clone: explicitly enable/disable filter cloning flag (no value)
- nomux: enable/disable direct file copy (no value)
- gfreg: preferred filter registry names for link solving (string value)
- gfloc: following options are local to filter declaration, not inherited (no value)
- gfopt: following options are not tracked (no value)
- gpac: argument separator for URLs (no value)
- ccp: filter replacement control (string list value)
- NCID: ID of netcap configuration to use (string)
- DBG: debug missing input PID property (`=pid`), missing input packet property (`=pck`) or both (`=all`)
- DL: enable defer linking of filter (no value) - the filter output pids will not be connected until a call to \ref gf_filter_reconnect_output


\param session filter session
\param name name and arguments of the filter register to instantiate.
\param err_code set to error code if any - may be NULL. If initially set to GF_EOS, disables log messages.
\return created filter or NULL if filter register cannot be found
*/
GF_Filter *gf_fs_load_filter(GF_FilterSession *session, const char *name, GF_Err *err_code);

/*! Checks if a filter register exists by name.
\param session filter session
\param name name of the filter register to check.
\return GF_TRUE if a filter register exists with the given name, GF_FALSE otherwise
*/
Bool gf_fs_filter_exists(GF_FilterSession *session, const char *name);

/*! Runs the session

If the session is non-blocking (created with \ref GF_FS_FLAG_NON_BLOCKING), process all tasks of oldest scheduled filter, process any pending PID connections and returns.
Otherwise (session is blocking), runs until session is over or aborted.

\param session filter session
\return error if any, or GF_EOS. The last errors can be retrieved using \ref gf_fs_get_last_connect_error and \ref gf_fs_get_last_process_error
*/
GF_Err gf_fs_run(GF_FilterSession *session);

/*! The default separator set used*/
#define GF_FS_DEFAULT_SEPS	":=#,!@"

/*! Sets the set of separators to use when parsing args
\param session filter session
\param separator_set filter session.
The first char is used to separate argument names - default is ':'
The second char, if present, is used to separate names and values - default is '='
The third char, if present, is used to separate fragments for PID sources - default is '#'
The fourth char, if present, is used for list separators (sourceIDs, gfreg, ...) - default is ','
The fifth char, if present, is used for boolean negation - default is '!'
The sixth char, if present, is used for LINK directives - default is '@'
\return error if any
*/
GF_Err gf_fs_set_separators(GF_FilterSession *session, const char *separator_set);

/*! Sets the maximum length of a filter chain dynamically loaded to solve connection between two filters
\param session filter session
\param  max_chain_length sets maximum chain length when resolving filter links.
Default value is 6 ([ in -> ] demux -> reframe -> decode -> encode -> reframe -> mux [ -> out ])
(filter chains loaded for adaptation (eg pixel format change, audio resample) are loaded after the link resolution)
Setting the value to 0 disables dynamic link resolution. You will have to specify the entire chain manually
\return error if any
*/
GF_Err gf_fs_set_max_resolution_chain_length(GF_FilterSession *session, u32 max_chain_length);

/*! Sets the maximum sleep time when postponing tasks.
\param session filter session
\param  max_sleep maximum sleep time in milliseconds. 0 means yield only.
\return error if any
*/
GF_Err gf_fs_set_max_sleep_time(GF_FilterSession *session, u32 max_sleep);

/*! gets the maximum filter chain lengtG
\param session filter session
\return maximum chain length when resolving filter links.
*/
u32 gf_fs_get_max_resolution_chain_length(GF_FilterSession *session);

/*! Stops the session, waiting for all additional threads to complete
\param session filter session
\return error if any
*/
GF_Err gf_fs_stop(GF_FilterSession *session);

/*! Gets the number of available filter registries (not blacklisted)
\param session filter session
\return number of filter registries
*/
u32 gf_fs_filters_registers_count(GF_FilterSession *session);

/*! Returns the register at the given index
\param session filter session
\param idx index of register, from 0 to \ref gf_fs_filters_registers_count
\return the register object, or NULL if index is out of bounds
*/
const GF_FilterRegister *gf_fs_get_filter_register(GF_FilterSession *session, u32 idx);

/*! Registers the test filters used for unit tests
\param session filter session
*/
void gf_fs_register_test_filters(GF_FilterSession *session);

/*! Loads a source filter from a URL and arguments
\param session filter session
\param url URL of the source to load. Can be a local file name, a full path (/.., \\...) or a full URL with scheme (eg http://, tcp://)
\param args arguments for the filter, see \ref gf_fs_load_filter - the arguments can also be set in the url, typycally using `:gpac:` option delimiter
\param parent_url parent URL of the source, or NULL if none
\param err if not NULL, is set to error code if any
\return the filter loaded or NULL if error
*/
GF_Filter *gf_fs_load_source(GF_FilterSession *session, const char *url, const char *args, const char *parent_url, GF_Err *err);

/*! Loads a destination filter from a URL and arguments
\param session filter session
\param url URL of the source to load. Can be a local file name, a full path (/.., \\...) or a full URL with scheme (eg http://, tcp://)
\param args arguments for the filter, see \ref gf_fs_load_filter - the arguments can also be set in the url, typycally using `:gpac:` option delimiter
\param parent_url parent URL of the source, or NULL if none
\param err if not NULL, is set to error code if any
\return the filter loaded or NULL if error
*/
GF_Filter *gf_fs_load_destination(GF_FilterSession *session, const char *url, const char *args, const char *parent_url, GF_Err *err);

/*! Returns the last error which happened during a PID connection
\param session filter session
\return the error code if any
*/
GF_Err gf_fs_get_last_connect_error(GF_FilterSession *session);

/*! Returns the last error which happened during a filter process
\param session filter session
\return the error code if any
*/
GF_Err gf_fs_get_last_process_error(GF_FilterSession *session);

/*! Adds a user-defined register to the session - the register is added regardless of the session blacklist
\param session filter session
\param freg filter register to add
*/
void gf_fs_add_filter_register(GF_FilterSession *session, const GF_FilterRegister *freg);

/*! Removes a user-defined register from the session
\param session filter session
\param freg filter register to remove
*/
void gf_fs_remove_filter_register(GF_FilterSession *session, GF_FilterRegister *freg);

/*! Sends PLAY event on all sinks, ignored if GF_FS_FLAG_PREVENT_PLAY flag is not set
\param session filter session
*/
void gf_fs_send_deferred_play(GF_FilterSession *session);

/*! Posts a user task to the session
\param session filter session
\param task_execute the callback function for the task. The callback can return:
 - GF_FALSE to cancel the task
 - GF_TRUE to reschedule the task, in which case the task will be rescheduled immediately or after reschedule_ms.
\param udta_callback callback user data passed back to the task_execute function
\param log_name log name of the task. If NULL, default is "user_task"
\return the error code if any
*/
GF_Err gf_fs_post_user_task(GF_FilterSession *session, Bool (*task_execute) (GF_FilterSession *fsess, void *callback, u32 *reschedule_ms), void *udta_callback, const char *log_name);

/*! Posts a user task to the session main thread only
\param session filter session
\param task_execute the callback function for the task. The callback can return:
 - GF_FALSE to cancel the task
 - GF_TRUE to reschedule the task, in which case the task will be rescheduled immediately or after reschedule_ms.
\param udta_callback callback user data passed back to the task_execute function
\param log_name log name of the task. If NULL, default is "user_task"
\return the error code if any
*/
GF_Err gf_fs_post_user_task_main(GF_FilterSession *session, Bool (*task_execute) (GF_FilterSession *fsess, void *callback, u32 *reschedule_ms), void *udta_callback, const char *log_name);

/*! Session flush types*/
typedef enum
{
	/*! Do not flush session: everything is discarded, potentially breaking output files*/
	GF_FS_FLUSH_NONE=0,
	/*! Flush all pending data before closing sessions:  sources will be forced into end of stream and all emitted packets will be processed*/
	GF_FS_FLUSH_ALL,
	/*! Stop session (resetting buffers) and flush pipeline*/
	GF_FS_FLUSH_FAST
} GF_FSFlushType;

/*! Aborts the session. This can be called within a callback task to stop the session. Do NOT use \ref gf_fs_stop from within a user task callback, this will deadlock the session
\param session filter session
\param flush_type flush method to use
\return the error code if any
*/
GF_Err gf_fs_abort(GF_FilterSession *session, GF_FSFlushType flush_type);
/*! Checks if the session is processing its last task. This can be called within a callback task to check if this is the last task, in order to avoid rescheduling the task
\param session filter session
\return GF_TRUE if no more task, GF_FALSE otherwise
*/
Bool gf_fs_is_last_task(GF_FilterSession *session);

/*! Checks if the session is in its final flush state (shutdown)
\param session filter session
\return GF_TRUE if no session is aborting, GF_FALSE otherwise
*/
Bool gf_fs_in_final_flush(GF_FilterSession *session);

/*! Checks if a given MIME type is supported as input
\param session filter session
\param mime MIME type to query
\return GF_TRUE if MIME is supported
*/
Bool gf_fs_is_supported_mime(GF_FilterSession *session, const char *mime);


/*! Sets UI callback event
\param session filter session
\param ui_event_proc the event proc callback function. Its return value depends on the event type, usually 0
\param cbk_udta pointer passed back to callback
*/
void gf_fs_set_ui_callback(GF_FilterSession *session, Bool (*ui_event_proc)(void *opaque, GF_Event *event), void *cbk_udta);

/*! Prints stats to logs using \code LOG_APP@LOG_INFO \endcode
\param session filter session
*/
void gf_fs_print_stats(GF_FilterSession *session);

/*! Prints connections between loaded filters in the session to logs using \code LOG_APP@LOG_INFO \endcode
\param session filter session
*/
void gf_fs_print_connections(GF_FilterSession *session);

/*! Prints the list of filters not connected using \code LOG_APP@LOG_WARNING \endcode
\param session filter session
*/
void gf_fs_print_non_connected(GF_FilterSession *session);

/*! Prints the list of filters not connected using \code LOG_APP@LOG_WARNING \endcode
\param session filter session
\param ignore_sinks if set, do not warn if some sinks are not connected (mostly used for playback cases)
*/
void gf_fs_print_non_connected_ex(GF_FilterSession *session, Bool ignore_sinks);

/*! Prints the list of arguments specified but not used by the filter session using \code LOG_APP@LOG_WARNING \endcode
 \note This is simply a wrapper to \ref gf_fs_enum_unmapped_options
\param session filter session
\param ignore_args ignore unused arguments if present in this comma-separated list - may be NULL
*/
void gf_fs_print_unused_args(GF_FilterSession *session, const char *ignore_args);

/*! Prints all possible connections between filter registries to logs using \code LOG_APP@LOG_INFO \endcode
\param session filter session
\param filter_name if not null, only prints input connection for this filter register
\param print_fn optional callback function for print, otherwise print to stderr
*/
void gf_fs_print_all_connections(GF_FilterSession *session, char *filter_name, void (*print_fn)(FILE *output, GF_SysPrintArgFlags flags, const char *fmt, ...) );

/*! Checks the presence of an input capability and an output capability in a target register. The caps are matched only if they belong to the same bundle.
\param filter_reg filter register to check
\param in_cap_code capability code (property type) of input capability to check
\param in_cap capabiility value of input capability to check
\param out_cap_code capability code (property type) of output capability to check
\param out_cap capability value of output capability to check
\param exact_match_only if true returns TRUE only if exact match (code and value), otherwise return TRUE if caps code are matched
\return GF_TRUE if filter register has such a match, GF_FALSE otherwise
*/
Bool gf_fs_check_filter_register_cap(const GF_FilterRegister *filter_reg, u32 in_cap_code, GF_PropertyValue *in_cap, u32 out_cap_code, GF_PropertyValue *out_cap, Bool exact_match_only);


/*! Enables or disables filter reporting
\param session filter session
\param reporting_on if GF_TRUE, reporting will be enabled
*/
void gf_fs_enable_reporting(GF_FilterSession *session, Bool reporting_on);

/*! Locks global session mutex - mostly used to query filter reports and avoids concurrent destruction of a filter.
 When adding a filter in an already running session, the session must be locked if set_source is to be used.
\param session filter session
\param do_lock if GF_TRUE, session is locked, otherwise session is unlocked
*/
void gf_fs_lock_filters(GF_FilterSession *session, Bool do_lock);

/*! Gets number of active filters in the session
\param session filter session
\return number of active filters
*/
u32 gf_fs_get_filters_count(GF_FilterSession *session);

/*! Gets a filter by its current index in the session
\param session filter session
\param idx index in the filter session
\return filter, or NULL if none found
*/
GF_Filter *gf_fs_get_filter(GF_FilterSession *session, u32 idx);

/*! Type of filter*/
typedef enum
{
	/*! Generic filter type accepting input(s) and producing output(s)*/
	GF_FS_STATS_FILTER_GENERIC,
	/*! raw input (file, socket, pipe) filter type*/
	GF_FS_STATS_FILTER_RAWIN,
	/*! demultiplexer filter type*/
	GF_FS_STATS_FILTER_DEMUX,
	/*! decoder filter type*/
	GF_FS_STATS_FILTER_DECODE,
	/*! encoder filter type*/
	GF_FS_STATS_FILTER_ENCODE,
	/*! multiplexer filter type*/
	GF_FS_STATS_FILTER_MUX,
	/*! raw output (file, socket, pipe) filter type*/
	GF_FS_STATS_FILTER_RAWOUT,
	/*! media sink (video out, audio out, ...) filter type*/
	GF_FS_STATS_FILTER_MEDIA_SINK,
	/*! media source (capture audio or video ...) filter type*/
	GF_FS_STATS_FILTER_MEDIA_SOURCE,
} GF_FSFilterType;

/*! Filter statistics object*/
typedef struct
{
	/*!filter object*/
	const GF_Filter *filter;
	/*!set if filter is only an alias, in which case all remaining fields of the structure are not set*/
	const GF_Filter *filter_alias;

	/*!number of tasks executed by this filter*/
	u64 nb_tasks_done;
	/*!number of packets processed by this filter*/
	u64 nb_pck_processed;
	/*!number of bytes processed by this filter*/
	u64 nb_bytes_processed;
	/*!number of packets sent by this filter*/
	u64 nb_pck_sent;
	/*!number of hardware frames packets sent by this filter*/
	u64 nb_hw_pck_sent;
	/*!number of processing errors in the lifetime of the filter*/
	u32 nb_errors;

	/*!number of bytes sent by this filter*/
	u64 nb_bytes_sent;
	/*!number of microseconds this filter was active*/
	u64 time_process;
	/*!percentage of data processed (between 0 and 100), otherwise unknown (-1)*/
	s32 percent;
	/*!last status report from filter, null if session reporting is not enabled*/
	const char *status;
	/*!set to GF_TRUE of status or percent changed since last query for this filter, GF_FALSE otherwise*/
	Bool report_updated;
	/*!filter name*/
	const char *name;
	/*!filter register name*/
	const char *reg_name;
	/*!filter register ID*/
	const char *filter_id;
	/*!set to GF_TRUE if filter is done processing*/
	Bool done;
	/*!number of input PIDs*/
	u32 nb_pid_in;
	/*!number of input packets processed*/
	u64 nb_in_pck;
	/*!number of output PIDs*/
	u32 nb_pid_out;
	/*!number of output packets sent*/
	u64 nb_out_pck;
	/*!set to GF_TRUE if filter has seen end of stream*/
	Bool in_eos;
	/*!set to the filter class type*/
	GF_FSFilterType type;
	/*!set to streamtype of output PID if single output, GF_STREAM_UNKNOWN otherwise*/
	u32 stream_type;
	/*!set to codecid of output PID if single output, GF_CODECID_NONE otherwise*/
	u32 codecid;
	/*! timestamp and timescale of last packet emitted on output pids*/
	GF_Fraction64 last_ts_sent;
	/*! timestamp and timescale of last packet dropped on input pids*/
	GF_Fraction64 last_ts_drop;
} GF_FilterStats;

/*! Gets statistics for a given filter index in the session
\param session filter session
\param idx index of filter to query
\param stats statistics for filter
\return error code if any
*/
GF_Err gf_fs_get_filter_stats(GF_FilterSession *session, u32 idx, GF_FilterStats *stats);


/*! Enumerates filter and meta-filter arguments not matched in the session. All output parameters may be NULL.
\param session filter session
\param idx index of argument to query, 0 being first argument; this value is automatically incremented
\param argname set to argument name
\param argtype set to argument type: 0 was a filter param (eg :arg=val), 1 was a global arg (eg --arg=val) and 2 was a global meta arg (eg -+arg=val)
\param meta_name set to meta filter name if any (for local filter args only)
\param meta_opt set to meta filter suboption name if any (for local filter args only)
\return GF_TRUE if success, GF_FALSE if nothing more to enumerate
*/
Bool gf_fs_enum_unmapped_options(GF_FilterSession *session, u32 *idx, const char **argname, u32 *argtype, const char **meta_name, const char **meta_opt);



/*! Flags for argument update event*/
typedef enum
{
	/*! the update event can be sent down the source chain*/
	GF_FILTER_UPDATE_DOWNSTREAM = 1,
	/*! the update event can be sent up the filter chain*/
	GF_FILTER_UPDATE_UPSTREAM = 1<<1,
} GF_EventPropagateType;

/*! Enumerates filter and meta-filter arguments not matched in the session
\param session filter session
\param fid ID of filter on which to send the update, NULL if filter is set
\param filter filter on which to send the update, NULL if fid is set
\param name name of filter option to update
\param val value of filter option to update
\param propagate_mask propagation flags - 0 means no propagation
*/
void gf_fs_send_update(GF_FilterSession *session, const char *fid, GF_Filter *filter, const char *name, const char *val, GF_EventPropagateType propagate_mask);


/*! Loads JS script for filter session
\param session filter session
\param jsfile path to local JS script file to use
\return error if any
*/
GF_Err gf_fs_load_script(GF_FilterSession *session, const char *jsfile);

/*! get max download rate allowed by download manager
\param session filter session
\return max rate in bps
*/
u32 gf_fs_get_http_max_rate(GF_FilterSession *session);

/*! set max download rate allowed by download manager
\param session filter session
\param rate max rate in bps
\return error if any
*/
GF_Err gf_fs_set_http_max_rate(GF_FilterSession *session, u32 rate);


/*! get current download rate  of download manager, all active resources together
\param session filter session
\return current rate in bps
*/
u32 gf_fs_get_http_rate(GF_FilterSession *session);

/*! check if a URL is likely to be supported
\param session filter session
\param url the URL to test
\param parent_url  the parent URL
\return GF_TRUE if a filter for such a source could be loaded
*/
Bool gf_fs_is_supported_source(GF_FilterSession *session, const char *url, const char *parent_url);

/*! callback functions for external monitoring of filter creation or destruction
\param udta user data passed back to callback
\param filter created or destroyed filter
\param is_destroy if GF_TRUE, the filter is being destroyed, otherwise it is being created
 */
typedef	void (*gf_fs_on_filter_creation)(void *udta, GF_Filter *filter, Bool is_destroy);

/*! assign callbacks for filter creation and destruction monitoring
\param session filter session
\param on_create_destroy filter creation/destruction callback, may be NULL
\param udta user data for callbacks, may be NULL
\param force_sync execute tasks involving filter creation/setup and user tasks on main thread
\return error if any
 */
GF_Err gf_fs_set_filter_creation_callback(GF_FilterSession *session, gf_fs_on_filter_creation on_create_destroy, void *udta, Bool force_sync);

/*! returns RT user data passed in  \ref gf_fs_set_filter_creation_callback
\param session filter session
\return  udta user data, NULL if error or none
 */
void *gf_fs_get_rt_udta(GF_FilterSession *session);

/*! Checks if a filter is still valid - typically used when not monitoring filter destruction at session level using \ref gf_fs_set_filter_creation_callback
\param session filter session
\param filter filter to check
\return GF_TRUE if filter is still valid until the next call to \ref gf_fs_run, GF_FALSE otherwise
*/
Bool gf_fs_check_filter(GF_FilterSession *session, GF_Filter *filter);

/*! Fires an event on filter
\param session filter session
\param filter target filter - if NULL, event will be executed on all filters. Otherwise, the event will be executed directly if its type is \ref GF_FEVT_USER, and fired otherwise
\param evt event to fire
\param upstream if true, send event toward sinks, otherwise towards sources
\return GF_TRUE if event was sent, GF_FALSE otherwise
 */
Bool gf_fs_fire_event(GF_FilterSession *session, GF_Filter *filter, GF_FilterEvent *evt, Bool upstream);

/*! callback functions for external monitoring of filter creation or destruction
\param udta user data passed back to callback
\param do_activate if true context must be activated for calling thread, otherwise context is no longer used
\return error if any
 */
typedef	GF_Err (*gf_fs_gl_activate)(void *udta, Bool do_activate);

/*! assign callbacks for filter creation and destruction monitoring
\param session filter session
\param on_gl_activate openGL context activation callback, must not be NULL
\param udta user data for callbacks, may be NULL
\return error if any
 */
GF_Err gf_fs_set_external_gl_provider(GF_FilterSession *session, gf_fs_gl_activate on_gl_activate, void *udta);


/*! Flags for debug info*/
typedef enum
{
	/*! print filter graph*/
	GF_FS_DEBUG_GRAPH = 1,
	/*! print filter stats*/
	GF_FS_DEBUG_STATS = 1<<1,
	/*! print tasks present in scheduler*/
	GF_FS_DEBUG_TASKS = 1<<2,
	/*! print filter status and task scheduled on filter*/
	GF_FS_DEBUG_FILTERS = 1<<3,
	/*! print all info*/
	GF_FS_DEBUG_ALL = 0x00FFFFFF,
	/*! enable continuous reporting*/
	GF_FS_DEBUG_CONTINUOUS = 0x80000000,
} GF_SessionDebugFlag;

/*! prints session debug info on stderr

 To turn on (resp.off) continous reporting, set (resp. unset) the flag GF_FS_DEBUG_CONTINUOUS. Continuous reporting is done in the main thread using the last flags provided

\param session filter session
\param dbg_flags set of flags indicating what to print
 */
void gf_fs_print_debug_info(GF_FilterSession *session, GF_SessionDebugFlag dbg_flags);


/*! @} */




/*!
\addtogroup fs_props Filter Properties
\ingroup filters_grp
\brief PID and filter properties

Documents the property object used for PID and packets.
@{
 */

/*! Property types*/

//DO NOT MODIFY WITHOUT APPLYNG SIMILAR CHANGE TO share/python/libgpac.py
//DO NOT CHANGE A VALUE ASSIGNMENT WITHOUT CHANGING GF_GSF_VERSION

typedef enum
{
	/*! not allowed*/
	GF_PROP_FORBIDDEN	=	0,
	/*! signed 32 bit integer*/
	GF_PROP_SINT		=	1,
	/*! unsigned 32 bit integer*/
	GF_PROP_UINT		=	2,
	/*! signed 64 bit integer*/
	GF_PROP_LSINT		=	3,
	/*! unsigned 64 bit integer*/
	GF_PROP_LUINT		=	4,
	/*! boolean*/
	GF_PROP_BOOL		=	5,
	/*! 32 bit / 32 bit fraction*/
	GF_PROP_FRACTION	=	6,
	/*! 64 bit / 64 bit fraction*/
	GF_PROP_FRACTION64	=	7,
	/*! float (Fixed) number*/
	GF_PROP_FLOAT		=	8,
	/*! double number*/
	GF_PROP_DOUBLE		=	9,
	/*! 2D signed integer vector*/
	GF_PROP_VEC2I		=	10,
	/*! 2D double number vector*/
	GF_PROP_VEC2		=	11,
	/*! 3D signed integer vector*/
	GF_PROP_VEC3I		=	12,
	/*! 4D signed integer vector*/
	GF_PROP_VEC4I		=	13,
	/*! string property, memory is duplicated when setting the property and managed internally*/
	GF_PROP_STRING		=	14,
	/*! string property, memory is NOT duplicated when setting the property but is then managed (and free) internally.
	Only used when setting a property, the type then defaults to GF_PROP_STRING
	DO NOT USE the associate string field upon return from setting the property, it might have been destroyed*/
	GF_PROP_STRING_NO_COPY=	15,
	/*! data property, memory is duplicated when setting the property and managed internally*/
	GF_PROP_DATA		=	16,
	/*! const string property, memory is NOT duplicated when setting the property, stays user-managed*/
	GF_PROP_NAME		=	17,
	/*! data property, memory is NOT duplicated when setting the property but is then managed (and free) internally.
	Only used when setting a property, the type then defaults to GF_PROP_DATA
	DO NOT USE the associate data field upon return from setting the property, it might have been destroyed*/
	GF_PROP_DATA_NO_COPY=	18,
	/*! const data property, memory is NOT duplicated when setting the property, stays user-managed*/
	GF_PROP_CONST_DATA	=	19,
	/*! user-managed pointer*/
	GF_PROP_POINTER		=	20,
	/*! string list, memory is NOT duplicated when setting the property, the passed array is directly assigned to the new property and will be and managed internally (freed by the filter session)
	DO NOT USE the associate string array field upon return from setting the property, it might have been destroyed*/
	GF_PROP_STRING_LIST	=	21,
	/*! unsigned 32 bit integer list, memory is ALWAYS duplicated when setting the property*/
	GF_PROP_UINT_LIST	=	22,
	/*! signed 32 bit integer list, memory is ALWAYS duplicated when setting the property*/
	GF_PROP_SINT_LIST	=	23,
	/*! 2D signed integer vector list, memory is ALWAYS duplicated when setting the property*/
	GF_PROP_VEC2I_LIST	=	24,
	/*! 4CC on unsigned 32 bit integer*/
	GF_PROP_4CC			=	25,
	/*! 4CC list on unsigned 32 bit integer, memory is ALWAYS duplicated when setting the property*/
	GF_PROP_4CC_LIST	=	26,
	/*! string list, memory is duplicated when setting the property - to use only with property assignment functions*/
	GF_PROP_STRING_LIST_COPY = 27,
	
	/*! last non-enum property*/
	GF_PROP_LAST_NON_ENUM,

	/*! All constants are defined after this - constants are stored as  u32*/
	GF_PROP_FIRST_ENUM	=	40, //GSF will code prop type using vlen, try to keep all values between 1 and 127 to only use 1 byte

	/*! Video Pixel format*/
	GF_PROP_PIXFMT			=	GF_PROP_FIRST_ENUM,
	/*! Audio PCM format*/
	GF_PROP_PCMFMT			=	GF_PROP_FIRST_ENUM+1,
	/*! CICP Color Primaries*/
	GF_PROP_CICP_COL_PRIM	=	GF_PROP_FIRST_ENUM+2,
	/*! CICP Color Transfer Characteristics*/
	GF_PROP_CICP_COL_TFC	=	GF_PROP_FIRST_ENUM+3,
	/*! CICP Color Matrix*/
	GF_PROP_CICP_COL_MX		=	GF_PROP_FIRST_ENUM+4,
	/*! CICP Layout*/
	GF_PROP_CICP_LAYOUT		=	GF_PROP_FIRST_ENUM+5,
	/*! not allowed*/
	GF_PROP_LAST_DEFINED
} GF_PropType;

/*! GSF version (coded on 8 bits in gsf format) */
#define GF_GSF_VERSION	2

/*! Data property*/
typedef struct
{
	/*! data pointer */
	u8 *ptr;
	/*! data size */
	u32 size;
} GF_PropData;

/*! 2D signed integer vector property*/
typedef struct
{
	/*! x coord */
	s32 x;
	/*! y coord */
	s32 y;
} GF_PropVec2i;


/*! 2D double number vector property*/
typedef struct
{
	/*! x coord */
	Double x;
	/*! y coord */
	Double y;
} GF_PropVec2;

/*! 3D signed integer vector property*/
typedef struct
{
	/*! x coord */
	s32 x;
	/*! y coord */
	s32 y;
	/*! z coord */
	s32 z;
} GF_PropVec3i;

/*! 4D signed integer vector property*/
typedef struct
{
	/*! x coord */
	s32 x;
	/*! y coord */
	s32 y;
	/*! z coord */
	s32 z;
	/*! w coord */
	s32 w;
} GF_PropVec4i;


/*! List of strings property - do not change field order !*/
typedef struct
{
	/*! array of unsigned integers */
	char **vals;
	/*! number of items in array */
	u32 nb_items;
} GF_PropStringList;

/*! List of unsigned int property - do not change field order !*/
typedef struct
{
	/*! array of unsigned integers */
	u32 *vals;
	/*! number of items in array */
	u32 nb_items;
} GF_PropUIntList;

/*! List of signed int property - do not change field order !*/
typedef struct
{
	/*! array of signed integers */
	s32 *vals;
	/*! number of items in array */
	u32 nb_items;
} GF_PropIntList;

/*! List of unsigned int property*/
typedef struct
{
	/*! array of vec2i  */
	GF_PropVec2i *vals;
	/*! number of items in array */
	u32 nb_items;
} GF_PropVec2iList;

/*! Property value used by PIDs and packets*/
struct __gf_prop_val
{
	/*! type of the property */
	GF_PropType type;
	/*! union of all possible property data types */
	union {
		/*! 64 bit unsigned integer value of property */
		u64 longuint;
		/*! 64 bit signed integer value of property */
		s64 longsint;
		/*! 32 bit signed integer value of property */
		s32 sint;
		/*! 32 bit unsigned integer value of property */
		u32 uint;
		/*! boolean value of property */
		Bool boolean;
		/*! fraction (32/32 bits) value of property */
		GF_Fraction frac;
		/*! fraction (64/64 bits) value of property */
		GF_Fraction64 lfrac;
		/*! fixed number (float or 32 bit depending on compilation settings) value of property */
		Fixed fnumber;
		/*! double value of property */
		Double number;
		/*! 2D signed integer vector value of property */
		GF_PropVec2i vec2i;
		/*! 2D double vector value of property */
		GF_PropVec2 vec2;
		/*! 3D signed integer vector value of property */
		GF_PropVec3i vec3i;
		/*! 4D signed integer vector value of property */
		GF_PropVec4i vec4i;
		/*! data value of property. For non const data type, the memory is freed by filter session.
		Otherwise caller is responsible to free it at end of filter/session*/
		GF_PropData data;
		/*! string value of property. For non const string / names, the memory is freed by filter session, otherwise handled as const char *. */
		char *string;
		/*! pointer value of property */
		void *ptr;
		/*! string list value of property - memory is handled by filter session (always copy)*/
		GF_PropStringList string_list;
		/*! unsigned integer list value of property - memory is handled by filter session (always copy)*/
		GF_PropUIntList uint_list;
		/*! signed integer list value of property - memory is handled by filter session (always copy)*/
		GF_PropIntList sint_list;
		/*! vec2i list value of property - memory is handled by filter session (always copy)*/
		GF_PropVec2iList v2i_list;
	} value;
};

/*! Playback mode type supported on PID*/
typedef enum
{
	/*! simplest playback mode, can play from 0 at speed=1 only*/
	GF_PLAYBACK_MODE_NONE=0,
	/*! seek playback mode, can play from any position at speed=1 only*/
	GF_PLAYBACK_MODE_SEEK,
	/*! fast forward playback mode, can play from any position at speed=N only, with N>=0*/
	GF_PLAYBACK_MODE_FASTFORWARD,
	/*! rewind playback mode, can play from any position at speed=N, N positive or negative*/
	GF_PLAYBACK_MODE_REWIND
} GF_FilterPidPlaybackMode;

/*! Built-in property types
See gpac help (gpac -h props) for codes, types, formats and and meaning
	\hideinitializer
*/
enum
{
	GF_PROP_PID_ID = GF_4CC('P','I','D','I'),
	GF_PROP_PID_ESID = GF_4CC('E','S','I','D'),
	GF_PROP_PID_ITEM_ID = GF_4CC('I','T','I','D'),
	GF_PROP_PID_ITEM_NUM = GF_4CC('I','T','I','X'),
	GF_PROP_PID_TRACK_NUM = GF_4CC('P','I','D','X'),
	GF_PROP_PID_SERVICE_ID = GF_4CC('P','S','I','D'),
	GF_PROP_PID_CLOCK_ID = GF_4CC('C','K','I','D'),
	GF_PROP_PID_DEPENDENCY_ID = GF_4CC('D','P','I','D'),
	GF_PROP_PID_SUBLAYER = GF_4CC('D','P','S','L'),
	GF_PROP_PID_PLAYBACK_MODE = GF_4CC('P','B','K','M'),
	GF_PROP_PID_SCALABLE = GF_4CC('S','C','A','L'),
	GF_PROP_PID_TILE_BASE = GF_4CC('S','A','B','T'),
	GF_PROP_PID_TILE_ID = GF_4CC('P','T','I','D'),
	GF_PROP_PID_LANGUAGE = GF_4CC('L','A','N','G'),
	GF_PROP_PID_SERVICE_NAME = GF_4CC('S','N','A','M'),
	GF_PROP_PID_SERVICE_PROVIDER = GF_4CC('S','P','R','O'),
	GF_PROP_PID_STREAM_TYPE = GF_4CC('P','M','S','T'),
	GF_PROP_PID_SUBTYPE = GF_4CC('P','S','S','T'),
	GF_PROP_PID_ISOM_SUBTYPE = GF_4CC('P','I','S','T'),
	GF_PROP_PID_ORIG_STREAM_TYPE = GF_4CC('P','O','S','T'),
	GF_PROP_PID_CODECID = GF_4CC('P','O','T','I'),
	GF_PROP_PID_IN_IOD = GF_4CC('P','I','O','D'),
	GF_PROP_PID_UNFRAMED = GF_4CC('P','F','R','M'),
	GF_PROP_PID_UNFRAMED_FULL_AU = GF_4CC('P','F','R','F'),
	GF_PROP_PID_DURATION = GF_4CC('P','D','U','R'),
	GF_PROP_PID_NB_FRAMES = GF_4CC('N','F','R','M'),
	GF_PROP_PID_FRAME_OFFSET = GF_4CC('F','R','M','O'),
	GF_PROP_PID_FRAME_SIZE = GF_4CC('C','F','R','S'),
	GF_PROP_PID_TIMESHIFT_DEPTH = GF_4CC('P','T','S','D'),
	GF_PROP_PID_TIMESHIFT_TIME = GF_4CC('P','T','S','T'),
	GF_PROP_PID_TIMESHIFT_STATE = GF_4CC('P','T','S','S'),
	GF_PROP_PID_TIMESCALE = GF_4CC('T','I','M','S'),
	GF_PROP_PID_PROFILE_LEVEL = GF_4CC('P','R','P','L'),
	GF_PROP_PID_DECODER_CONFIG = GF_4CC('D','C','F','G'),
	GF_PROP_PID_DECODER_CONFIG_ENHANCEMENT = GF_4CC('E','C','F','G'),
	GF_PROP_PID_DSI_SUPERSET = GF_4CC('D','C','F','S'),
	GF_PROP_PID_CONFIG_IDX =  GF_4CC('I','C','F','G'),
	GF_PROP_PID_SAMPLE_RATE = GF_4CC('A','U','S','R'),
	GF_PROP_PID_SAMPLES_PER_FRAME = GF_4CC('F','R','M','S'),
	GF_PROP_PID_NUM_CHANNELS = GF_4CC('C','H','N','B'),
	GF_PROP_PID_AUDIO_BPS = GF_4CC('A','B','P','S'),
	GF_PROP_PID_CHANNEL_LAYOUT = GF_4CC('C','H','L','O'),
	GF_PROP_PID_AUDIO_FORMAT = GF_4CC('A','F','M','T'),
	GF_PROP_PID_AUDIO_SPEED = GF_4CC('A','S','P','D'),
	GF_PROP_PID_UNFRAMED_LATM = GF_4CC('L','A','T','M'),
	GF_PROP_PID_DELAY = GF_4CC('M','D','L','Y'),
	GF_PROP_PID_CTS_SHIFT = GF_4CC('M','D','T','S'),
	GF_PROP_PID_NO_PRIMING = GF_4CC('A','S','K','P'),
	GF_PROP_PID_WIDTH = GF_4CC('W','I','D','T'),
	GF_PROP_PID_HEIGHT = GF_4CC('H','E','I','G'),
	GF_PROP_PID_PIXFMT = GF_4CC('P','F','M','T'),
	GF_PROP_PID_PIXFMT_WRAPPED = GF_4CC('P','F','M','W'),
	GF_PROP_PID_STRIDE = GF_4CC('V','S','T','Y'),
	GF_PROP_PID_STRIDE_UV = GF_4CC('V','S','T','C'),
	GF_PROP_PID_BIT_DEPTH_Y = GF_4CC('Y','B','P','S'),
	GF_PROP_PID_BIT_DEPTH_UV = GF_4CC('C','B','P','S'),
	GF_PROP_PID_FPS = GF_4CC('V','F','P','F'),
	GF_PROP_PID_INTERLACED = GF_4CC('V','I','L','C'),
	GF_PROP_PID_SAR = GF_4CC('P','S','A','R'),
	GF_PROP_PID_WIDTH_MAX = GF_4CC('M', 'W','I','D'),
	GF_PROP_PID_HEIGHT_MAX = GF_4CC('M', 'H','E','I'),
	GF_PROP_PID_ZORDER = GF_4CC('V', 'Z','I','X'),
	GF_PROP_PID_TRANS_X = GF_4CC('V','T','R','X'),
	GF_PROP_PID_TRANS_Y = GF_4CC('V','T','R','Y'),
	GF_PROP_PID_TRANS_X_INV = GF_4CC('V','T','R','x'),
	GF_PROP_PID_TRANS_Y_INV = GF_4CC('V','T','R','y'),
	GF_PROP_PID_HIDDEN = GF_4CC('H','I','D','E'),
	GF_PROP_PID_CROP_POS = GF_4CC('V','C','X','Y'),
	GF_PROP_PID_ORIG_SIZE = GF_4CC('V','O','W','H'),
	GF_PROP_PID_SRD = GF_4CC('S','R','D',' '),
	GF_PROP_PID_SRD_REF = GF_4CC('S','R','D','R'),
	GF_PROP_PID_SRD_MAP = GF_4CC('S','R','D','M'),
	GF_PROP_PID_ALPHA = GF_4CC('V','A','L','P'),
	GF_PROP_PID_MIRROR = GF_4CC('V','M','I','R'),
	GF_PROP_PID_ROTATE = GF_4CC('V','R','O','T'),
	GF_PROP_PID_CLAP_W = GF_4CC('C','L','P','W'),
	GF_PROP_PID_CLAP_H = GF_4CC('C','L','P','H'),
	GF_PROP_PID_CLAP_X = GF_4CC('C','L','P','X'),
	GF_PROP_PID_CLAP_Y = GF_4CC('C','L','P','Y'),
	GF_PROP_PID_NUM_VIEWS = GF_4CC('P','N','B','V'),
	GF_PROP_PID_DOLBY_VISION = GF_4CC('D','O','V','I'),
	GF_PROP_PID_BITRATE = GF_4CC('R','A','T','E'),
	GF_PROP_PID_MAXRATE = GF_4CC('M','R','A','T'),
	GF_PROP_PID_TARGET_RATE = GF_4CC('T','B','R','T'),
	GF_PROP_PID_DBSIZE = GF_4CC('D','B','S','Z'),
	GF_PROP_PID_MEDIA_DATA_SIZE = GF_4CC('M','D','S','Z'),
	GF_PROP_PID_CAN_DATAREF = GF_4CC('D','R','E','F'),
	GF_PROP_PID_URL = GF_4CC('F','U','R','L'),
	GF_PROP_PID_REMOTE_URL = GF_4CC('R','U','R','L'),
	GF_PROP_PID_REDIRECT_URL = GF_4CC('R','E','L','O'),
	GF_PROP_PID_FILEPATH = GF_4CC('F','S','R','C'),
	GF_PROP_PID_MIME = GF_4CC('M','I','M','E'),
	GF_PROP_PID_FILE_EXT = GF_4CC('F','E','X','T'),
	GF_PROP_PID_OUTPATH = GF_4CC('F','D','S','T'),
	GF_PROP_PID_FILE_CACHED = GF_4CC('C','A','C','H'),
	GF_PROP_PID_DOWN_RATE = GF_4CC('D','L','B','W'),
	GF_PROP_PID_DOWN_SIZE = GF_4CC('D','L','S','Z'),
	GF_PROP_PID_DOWN_BYTES = GF_4CC('D','L','B','D'),
	GF_PROP_PID_FILE_RANGE = GF_4CC('F','B','R','A'),
	GF_PROP_PID_DISABLE_PROGRESSIVE = GF_4CC('N','P','R','G'),
	GF_PROP_PID_ISOM_BRANDS = GF_4CC('A','B','R','D'),
	GF_PROP_PID_ISOM_MBRAND = GF_4CC('M','B','R','D'),
	GF_PROP_PID_ISOM_MOVIE_TIME = GF_4CC('M','H','T','S'),
	GF_PROP_PID_HAS_SYNC = GF_4CC('P','S','Y','N'),
	GF_PROP_SERVICE_WIDTH = GF_4CC('D','W','D','T'),
	GF_PROP_SERVICE_HEIGHT = GF_4CC('D','H','G','T'),
	GF_PROP_PID_IS_DEFAULT = GF_4CC('P','D','E','F'),
	GF_PROP_PID_CAROUSEL_RATE = GF_4CC('C','A','R','A'),
	GF_PROP_PID_AUDIO_VOLUME = GF_4CC('A','V','O','L'),
	GF_PROP_PID_AUDIO_PAN = GF_4CC('A','P','A','N'),
	GF_PROP_PID_AUDIO_PRIORITY = GF_4CC('A','P','R','I'),
	GF_PROP_PID_PROTECTION_SCHEME_TYPE = GF_4CC('S','C','H','T'),
	GF_PROP_PID_PROTECTION_SCHEME_VERSION = GF_4CC('S','C','H','V'),
	GF_PROP_PID_PROTECTION_SCHEME_URI = GF_4CC('S','C','H','U'),
	GF_PROP_PID_PROTECTION_KMS_URI = GF_4CC('K','M','S','U'),
	GF_PROP_PID_ISMA_SELECTIVE_ENC = GF_4CC('I','S','S','E'),
	GF_PROP_PID_ISMA_IV_LENGTH = GF_4CC('I','S','I','V'),
	GF_PROP_PID_ISMA_KI_LENGTH = GF_4CC('I','S','K','I'),
	GF_PROP_PID_ISMA_KI = GF_4CC('I','K','E','Y'),
	GF_PROP_PID_OMA_CRYPT_TYPE = GF_4CC('O','M','C','T'),
	GF_PROP_PID_OMA_CID = GF_4CC('O','M','I','D'),
	GF_PROP_PID_OMA_TXT_HDR = GF_4CC('O','M','T','H'),
	GF_PROP_PID_OMA_CLEAR_LEN = GF_4CC('O','M','P','T'),
	GF_PROP_PID_CRYPT_INFO = GF_4CC('E','C','R','I'),
	GF_PROP_PID_DECRYPT_INFO = GF_4CC('E','D','R','I'),
	GF_PROP_PCK_SENDER_NTP = GF_4CC('N','T','P','S'),
	GF_PROP_PCK_RECEIVER_NTP = GF_4CC('N','T','P','R'),
	GF_PROP_PID_ADOBE_CRYPT_META = GF_4CC('A','M','E','T'),
	GF_PROP_PID_ENCRYPTED = GF_4CC('E','P','C','K'),
	GF_PROP_PID_OMA_PREVIEW_RANGE = GF_4CC('O','D','P','R'),
	GF_PROP_PID_CENC_PSSH = GF_4CC('P','S','S','H'),
	GF_PROP_PCK_CENC_SAI = GF_4CC('S','A','I','S'),
	GF_PROP_PID_CENC_KEY_INFO = GF_4CC('C','B','I','V'),
	GF_PROP_PID_CENC_PATTERN = GF_4CC('C','P','T','R'),
	GF_PROP_PID_CENC_STORE = GF_4CC('C','S','T','R'),
	GF_PROP_PID_CENC_STSD_MODE = GF_4CC('C','S','T','M'),
	GF_PROP_PID_CENC_HAS_ROLL = GF_4CC('C','R','O','L'),
	GF_PROP_PID_AMR_MODE_SET = GF_4CC('A','M','S','T'),
	GF_PROP_PCK_SUBS = GF_4CC('S','U','B','S'),
	GF_PROP_PID_MAX_NALU_SIZE = GF_4CC('N','A','L','S'),
	GF_PROP_PCK_FILENUM = GF_4CC('F','N','U','M'),
	GF_PROP_PCK_FILENAME = GF_4CC('F','N','A','M'),
	GF_PROP_PCK_IDXFILENAME = GF_4CC('I','N','A','M'),
	GF_PROP_PCK_FILESUF = GF_4CC('F','S','U','F'),
	GF_PROP_PCK_EODS = GF_4CC('E','O','D','S'),
	GF_PROP_PCK_CUE_START = GF_4CC('P','C','U','S'),
	GF_PROP_PCK_UTC_TIME = GF_4CC('U','T','C','D'),
	GF_PROP_PCK_MEDIA_TIME = GF_4CC('M','T','I','M'),
	GF_PROP_PCK_MPD_SEGSTART = GF_4CC('F','M','S','S'),

	GF_PROP_PID_MAX_FRAME_SIZE = GF_4CC('M','F','R','S'),
	GF_PROP_PID_AVG_FRAME_SIZE = GF_4CC('A','F','R','S'),
	GF_PROP_PID_MAX_TS_DELTA = GF_4CC('M','T','S','D'),
	GF_PROP_PID_MAX_CTS_OFFSET = GF_4CC('M','C','T','O'),
	GF_PROP_PID_CONSTANT_DURATION = GF_4CC('S','C','T','D'),
	GF_PROP_PID_ISOM_TRACK_TEMPLATE = GF_4CC('I','T','K','T'),
	GF_PROP_PID_ISOM_TREX_TEMPLATE = GF_4CC('I','T','X','T'),
	GF_PROP_PID_ISOM_STSD_TEMPLATE = GF_4CC('I','S','T','D'),
	GF_PROP_PID_ISOM_STSD_TEMPLATE_IDX = GF_4CC('I','S','T','I'),
	GF_PROP_PID_ISOM_STSD_ALL_TEMPLATES = GF_4CC('I','S','T','A'),
	GF_PROP_PID_ISOM_UDTA = GF_4CC('I','M','U','D'),
	GF_PROP_PID_ISOM_HANDLER = GF_4CC('I','H','D','L'),
	GF_PROP_PID_ISOM_TRACK_FLAGS = GF_4CC('I','T','K','F'),
	GF_PROP_PID_ISOM_TRACK_MATRIX = GF_4CC('I','T','K','M'),
	GF_PROP_PID_ISOM_ALT_GROUP = GF_4CC('I','A','L','G'),
	GF_PROP_PID_ISOM_FORCE_NEGCTTS = GF_4CC('I','F','N','C'),
	GF_PROP_PID_DISABLED = GF_4CC('I','T','K','D'),
	GF_PROP_PID_PERIOD_ID = GF_4CC('P','E','I','D'),
	GF_PROP_PID_PERIOD_START = GF_4CC('P','E','S','T'),
	GF_PROP_PID_PERIOD_DUR = GF_4CC('P','E','D','U'),
	GF_PROP_PID_REP_ID = GF_4CC('D','R','I','D'),
	GF_PROP_PID_AS_ID = GF_4CC('D','A','I','D'),
	GF_PROP_PID_MUX_SRC = GF_4CC('M','S','R','C'),
	GF_PROP_PID_DASH_MODE = GF_4CC('D','M','O','D'),
	GF_PROP_PID_FORCE_SEG_SYNC = GF_4CC('D','F','S','S'),
	GF_PROP_PID_DASH_DUR = GF_4CC('D','D','U','R'),
	GF_PROP_PID_DASH_MULTI_PID = GF_4CC('D','M','S','D'),
	GF_PROP_PID_DASH_MULTI_PID_IDX = GF_4CC('D','M','S','I'),
	GF_PROP_PID_DASH_MULTI_TRACK = GF_4CC('D','M','T','K'),
	GF_PROP_PID_ROLE = GF_4CC('R','O','L','E'),
	GF_PROP_PID_PERIOD_DESC = GF_4CC('P','D','E','S'),
	GF_PROP_PID_AS_COND_DESC = GF_4CC('A','C','D','S'),
	GF_PROP_PID_AS_ANY_DESC = GF_4CC('A','A','D','S'),
	GF_PROP_PID_REP_DESC = GF_4CC('R','D','E','S'),
	GF_PROP_PID_BASE_URL = GF_4CC('B','U','R','L'),
	GF_PROP_PID_TEMPLATE = GF_4CC('D','T','P','L'),
	GF_PROP_PID_START_NUMBER = GF_4CC('D','R','S','N'),
	GF_PROP_PID_XLINK = GF_4CC('X','L','N','K'),
	GF_PROP_PID_CLAMP_DUR = GF_4CC('D','C','M','D'),
	GF_PROP_PID_HLS_PLAYLIST = GF_4CC('H','L','V','P'),
	GF_PROP_PID_HLS_GROUPID = GF_4CC('H','L','G','I'),
	GF_PROP_PID_HLS_FORCE_INF = GF_4CC('H','L','F','I'),
	GF_PROP_PID_HLS_EXT_MASTER = GF_4CC('H','L','M','X'),
	GF_PROP_PID_HLS_EXT_VARIANT = GF_4CC('H','L','V','X'),
	GF_PROP_PID_DASH_CUE = GF_4CC('D','C','U','E'),
	GF_PROP_PID_DASH_SEGMENTS = GF_4CC('D','C','N','S'),
	GF_PROP_PID_CODEC = GF_4CC('C','O','D','S'),
	GF_PROP_PID_SINGLE_SCALE = GF_4CC('D','S','T','S'),
	GF_PROP_PID_UDP = GF_4CC('P','U','D','P'),

	GF_PROP_PID_PRIMARY_ITEM = GF_4CC('P','I','T','M'),

	GF_PROP_PID_PLAY_BUFFER = GF_4CC('P','B','P','L'),
	GF_PROP_PID_MAX_BUFFER = GF_4CC('P','B','M','X'),
	GF_PROP_PID_RE_BUFFER = GF_4CC('P','B','R','E'),
	GF_PROP_PID_VIEW_IDX = GF_4CC('V','I','D','X'),

	GF_PROP_PID_COLR_PRIMARIES = GF_4CC('C','P','R','M'),
	GF_PROP_PID_COLR_TRANSFER = GF_4CC('C','T','R','C'),
	GF_PROP_PID_COLR_MX = GF_4CC('C','M','X','C'),
	GF_PROP_PID_COLR_RANGE = GF_4CC('C','F','R','A'),
	GF_PROP_PID_COLR_CHROMAFMT = GF_4CC('C','F','M','T'),
	GF_PROP_PID_COLR_CHROMALOC = GF_4CC('C','L','O','C'),
	GF_PROP_PID_CONTENT_LIGHT_LEVEL = GF_4CC('C','L','L','I'),
	GF_PROP_PID_MASTER_DISPLAY_COLOUR = GF_4CC('M','D','C','V'),
	GF_PROP_PID_ICC_PROFILE = GF_4CC('I','C','C','P'),
	GF_PROP_PID_SRC_MAGIC = GF_4CC('P','S','M','G'),
	GF_PROP_PID_MUX_INDEX = GF_4CC('T','I','D','X'),
	GF_PROP_NO_TS_LOOP = GF_4CC('N','T','S','L'),
	GF_PROP_PID_MHA_COMPATIBLE_PROFILES = GF_4CC('M','H','C','P'),
	GF_PROP_PCK_FRAG_START = GF_4CC('P','F','R','B'),
	GF_PROP_PCK_FRAG_RANGE = GF_4CC('P','F','R','R'),
	GF_PROP_PCK_FRAG_TFDT = GF_4CC('P','F','R','T'),
	GF_PROP_PCK_SIDX_RANGE = GF_4CC('P','F','S','R'),
	GF_PROP_PCK_MOOF_TEMPLATE = GF_4CC('M','F','T','P'),
	GF_PROP_PCK_INIT = GF_4CC('P','C','K','I'),
	GF_PROP_PID_RAWGRAB = GF_4CC('P','G','R','B'),
	GF_PROP_PID_KEEP_AFTER_EOS = GF_4CC('P','K','A','E'),
	GF_PROP_PID_COVER_ART = GF_4CC('P','C','O','V'),
	GF_PROP_PID_ORIG_FRAG_URL = GF_4CC('O','F','R','A'),

	GF_PROP_PID_ROUTE_IP = GF_4CC('R','S','I','P'),
	GF_PROP_PID_ROUTE_PORT = GF_4CC('R','S','P','N'),
	GF_PROP_PID_ROUTE_NAME = GF_4CC('R','S','F','N'),
	GF_PROP_PID_ROUTE_CAROUSEL = GF_4CC('R','S','C','R'),
	GF_PROP_PID_ROUTE_SENDTIME = GF_4CC('R','S','S','T'),

	GF_PROP_PID_STEREO_TYPE = GF_4CC('P','S','T','T'),
	GF_PROP_PID_PROJECTION_TYPE = GF_4CC('P','P','J','T'),
	GF_PROP_PID_VR_POSE = GF_4CC('P','P','O','S'),
	GF_PROP_PID_CUBE_MAP_PAD = GF_4CC('P','C','M','P'),
	GF_PROP_PID_EQR_CLAMP = GF_4CC('P','E','Q','C'),
	GF_PROP_PID_SPARSE = GF_4CC('P','S','P','A'),
	GF_PROP_PID_CHARSET = GF_4CC('P','C','H','S'),
	GF_PROP_PID_FORCED_SUB = GF_4CC('P','F','C','S'),

	GF_PROP_PID_SCENE_NODE = GF_4CC('P','S','N','D'),
	GF_PROP_PID_ORIG_CRYPT_SCHEME = GF_4CC('P','O','C','S'),
	GF_PROP_PID_TIMESHIFT_SEGS = GF_4CC('P','T','S','N'),

	GF_PROP_PID_CHAP_TIMES = GF_4CC('C','H','P','T'),
	GF_PROP_PID_CHAP_NAMES = GF_4CC('C','H','P','N'),
	GF_PROP_PID_IS_CHAP = GF_4CC('P','C','H','P'),
	//internal prop indicating the (main) streamtype of a PID before mux, only used for route setup
	GF_PROP_PID_PREMUX_STREAM_TYPE = GF_4CC('P','P','S','T'),

	GF_PROP_PID_CODEC_MERGEABLE = GF_4CC('P','C','M','B'),
	GF_PROP_PID_FILE_REL = GF_4CC('F','N','R','L'),


	//internal for HLS playlist reference, gives a unique ID identifying media mux, and indicated in packets carrying child playlists
	GF_PROP_PCK_HLS_REF = GF_4CC('H','P','L','R'),
	//internal for HLS low latency
	GF_PROP_PID_LLHLS = GF_4CC('H','L','S','L'),
	GF_PROP_PCK_HLS_FRAG_NUM = GF_4CC('H','L','S','N'),
	//we also use this property on PID to signal sample-accurate seek info is present
	GF_PROP_PCK_SKIP_BEGIN = GF_4CC('P','C','K','S'),
	GF_PROP_PCK_SKIP_PRES = GF_4CC('P','C','K','D'),
	//internal for DASH forward mode
	GF_PROP_PID_DASH_FWD = GF_4CC('D','F','W','D'),
	GF_PROP_PCK_DASH_MANIFEST = GF_4CC('D','M','P','D'),
	GF_PROP_PCK_HLS_VARIANT = GF_4CC('D','H','L','V'),
	GF_PROP_PID_DASH_PERIOD_START = GF_4CC('D','P','S','T'),
	GF_PROP_PCK_HLS_VARIANT_NAME = GF_4CC('D','H','L','N'),
	GF_PROP_PID_HLS_KMS = GF_4CC('H','L','S','K'),
	GF_PROP_PID_HLS_IV = GF_4CC('H','L','S','I'),
	GF_PROP_PID_CLEARKEY_URI = GF_4CC('C','C','K','U'),
	//internal
	GF_PROP_PID_CLEARKEY_KID = GF_4CC('C','C','K','I'),
	//internal, indicate DASH segments are generated in sparse mode (from context)
	GF_PROP_PID_DASH_SPARSE = GF_4CC('D','S','S','G'),
	//internal, indicate DASH dependency group
	GF_PROP_PID_DASH_DEP_GROUP = GF_4CC('D','G','D','I'),

	//internal property indicating pointer to associated GF_DownloadSession
	GF_PROP_PID_DOWNLOAD_SESSION = GF_4CC('G','H','T','T'),

	//PID has temi information
	GF_PROP_PID_HAS_TEMI = GF_4CC('P','T','E','M'),
	//PID has no init segment associated (file forward mode of dasher)
	GF_PROP_PID_NO_INIT = GF_4CC('P','N','I','N'),

	//PID carries a manifest
	GF_PROP_PID_IS_MANIFEST = GF_4CC('P','H','S','M'),

	GF_PROP_PCK_XPS_MASK = GF_4CC('P','X','P','M'),
	GF_PROP_PCK_END_RANGE = GF_4CC('P','C','E','R'),

	//internal, force creation of rewriter filter (only used for forcing reparse of NALU-based codecs)
	GF_PROP_PID_FORCE_UNFRAME = GF_4CC('P','F','U','F'),

	GF_PROP_PCK_SPLIT_START = GF_4CC('P','S','P','S'),
	GF_PROP_PCK_SPLIT_END = GF_4CC('P','S','P','E'),


	/*! Internal property used for meta demuxers ( FFMPEG, ...) codec ID

	Property can be:
	- pointer to codec context: only for ffdmx with old ffmpeg versions)
	- uint: AVCODEC_ID_*  ffdmx with newer versions or ffenc output
	*/
	GF_PROP_PID_META_DEMUX_CODEC_ID = GF_4CC('M','D','C','I'),

	/*! Internal property used for meta demuxers ( FFMPEG, ...) codec name*/
	GF_PROP_PID_META_DEMUX_CODEC_NAME = GF_4CC('M','D','C','N'),

	/*! Internal property used for meta demuxers ( FFMPEG, ...) codec opaque data, u32*/
	GF_PROP_PID_META_DEMUX_OPAQUE = GF_4CC('M','D','O','P'),
};

/*! Block patching requirements for FILE pids, as signaled by GF_PROP_PID_DISABLE_PROGRESSIVE
 	\hideinitializer
*/
enum
{
	GF_PID_FILE_PATCH_NONE = 0,
	GF_PID_FILE_PATCH_REPLACE = 1,
	GF_PID_FILE_PATCH_INSERT = 2,
};

/*! Gets readable name of built-in property
\param prop_4cc property built-in 4cc
\return readable name
*/
const char *gf_props_4cc_get_name(u32 prop_4cc);

/*! Gets property type of built-in property
\param prop_4cc property built-in 4cc
\return property name
*/
u32 gf_props_4cc_get_type(u32 prop_4cc);

/*! Checks if two properties are equal
\param p1 first property to compare - shall not be NULL
\param p2 second property to compare - shall not be NULL
\return GF_TRUE if properties are equal, GF_FALSE otherwise
*/
Bool gf_props_equal(const GF_PropertyValue *p1, const GF_PropertyValue *p2);

/*! Same as \ref gf_props_equal but do not match string with value "*"  to string with value different from "*"
\param p1 first property to compare - shall not be NULL
\param p2 second property to compare - shall not be NULL
\return GF_TRUE if properties are equal, GF_FALSE otherwise
*/
Bool gf_props_equal_strict(const GF_PropertyValue *p1, const GF_PropertyValue *p2);

/*! Gets the readable name for a property type
\param type property type
\return readable name
*/
const char *gf_props_get_type_name(GF_PropType type);

/*! Gets the description for a property type
\param type property type
\return description
*/
const char *gf_props_get_type_desc(GF_PropType type);

/*! Gets the description type for a given property type name
\param name property type name
\return property type or GF_PROP_FORBIDDEN
*/
GF_PropType gf_props_parse_type(const char *name);

/*! Check if a property type is an enum type
\param type  property type
\return GF_TRUE if constant, GF_FALSE otherwise
*/
Bool gf_props_type_is_enum(GF_PropType type);

/*! Parse a enum type property string
\param type  property type
\param value value to parse
\return value, 0xFFFFFFFF if error
*/
u32 gf_props_parse_enum(u32 type, const char *value);

/*! Get the name of a constant type property value
\param type  property type
\param value value of constant
\return value, 0xFFFFFFFF if error
*/
const char *gf_props_enum_name(u32 type, u32 value);

/*! Get the possible names of an enum type property
\param type  property type
\return comma-separated list of possible values
*/
const char *gf_props_enum_all_names(u32 type);

/*! Get the base type of a property type. Properties with same base type can be safely type-casted
\param type  property type
\return base property type
*/
u32 gf_props_get_base_type(u32 type);


/*! Parses a property value from string
\param type property type to parse
\param name property name to parse (for logs)
\param value string containing the value to parse
\param enum_values string containig enum_values, or NULL. enum_values are used for unsigned int properties, take the form "a|b|c" and resolve to 0|1|2.
\param list_sep_char value of the list separator character to use
\return the parsed property value
*/
GF_PropertyValue gf_props_parse_value(u32 type, const char *name, const char *value, const char *enum_values, char list_sep_char);

/*! Maximum string size to use when dumping a property*/
#define GF_PROP_DUMP_ARG_SIZE	100

/*! Data property dump mode*/
typedef enum
{
	/*! do not dump data*/
	GF_PROP_DUMP_DATA_NONE=0,
	/*! dump data if less than 40 bytes, otherwise dump ptr address and CRC*/
	GF_PROP_DUMP_DATA_INFO,
	/*! dump data to parsable property, as ADDRESS+'@'+POINTER*/
	GF_PROP_DUMP_DATA_PTR,
	/*! do not reduce fractions when dumping*/
	GF_PROP_DUMP_NO_REDUCE = 1<<16,
} GF_PropDumpDataMode;

/*! Dumps a property value to string
\param att property value
\param dump buffer holding the resulting value for types requiring string conversions (integers, ...)
\param dump_data_flags data dump mode and flags
\param min_max_enum optional, gives the min/max or enum string when the property is a filter argument
\return string
*/
const char *gf_props_dump_val(const GF_PropertyValue *att, char dump[GF_PROP_DUMP_ARG_SIZE], GF_PropDumpDataMode dump_data_flags, const char *min_max_enum);

/*! Dumps a property value to string, resolving any built-in types (pix formats, codec id, ...)
\param p4cc property 4CC
\param att property value
\param dump buffer holding the resulting value for types requiring string conversions (integers, ...)
\param dump_data_mode data dump mode
\return string
*/
const char *gf_props_dump(u32 p4cc, const GF_PropertyValue *att, char dump[GF_PROP_DUMP_ARG_SIZE], GF_PropDumpDataMode dump_data_mode);

/*! Resets a property value, freeing allocated data or strings depending on the property type
\param prop property 4CC
*/
void gf_props_reset_single(GF_PropertyValue *prop);

/*! Property aplies only to packets */
#define GF_PROP_FLAG_PCK 1
/*! Property is optional for GPAC GSF serialization (not transmitted over network when property removal is enabled) */
#define GF_PROP_FLAG_GSF_REM 1<<1

/*! Structure describing a built-in property in GPAC*/
typedef struct {
	/*! identifier (4CC) */
	u32 type;
	/*! name */
	const char *name;
#ifndef GPAC_DISABLE_DOC
	/*! description */
	const char *description;
#endif
	/*! data type  (uint, float, etc ..) */
	u8 data_type;
	/*! flags for the property */
	u8 flags;
} GF_BuiltInProperty;

/*! Gets property description
\param prop_idx built-in property index, starting from 0
\return associated property description or NULL if property was not found
*/
const GF_BuiltInProperty *gf_props_get_description(u32 prop_idx);

/*! Gets built-in property 4CC from name
\param name built-in property name
\return built-in property 4CC or 0 if not found
*/
u32 gf_props_get_id(const char *name);

/*! Gets flags of built-in property
\param prop_4cc built-in property 4CC
\return built-in property flags, 0 if not found
*/
u8 gf_props_4cc_get_flags(u32 prop_4cc);


/*! Helper macro to set signed int property */
#define PROP_SINT(_val) (GF_PropertyValue){.type=GF_PROP_SINT, .value.sint = _val}
/*! Helper macro to set unsigned int property */
#define PROP_UINT(_val) (GF_PropertyValue){.type=GF_PROP_UINT, .value.uint = _val}
/*! Helper macro to set an enum  property */
#define PROP_ENUM(_val, _type) (GF_PropertyValue){.type=_type, .value.uint = _val}
/*! Helper macro to set 4CC unsigned int property */
#define PROP_4CC(_val) (GF_PropertyValue){.type=GF_PROP_4CC, .value.uint = _val}
/*! Helper macro to set long signed int property */
#define PROP_LONGSINT(_val) (GF_PropertyValue){.type=GF_PROP_LSINT, .value.longsint = _val}
/*! Helper macro to set long unsigned int property */
#define PROP_LONGUINT(_val) (GF_PropertyValue){.type=GF_PROP_LUINT, .value.longuint = _val}
/*! Helper macro to set boolean property */
#define PROP_BOOL(_val) (GF_PropertyValue){.type=GF_PROP_BOOL, .value.boolean = _val}
/*! Helper macro to set fixed-point number property */
#define PROP_FIXED(_val) (GF_PropertyValue){.type=GF_PROP_FLOAT, .value.fnumber = _val}
/*! Helper macro to set float property */
#define PROP_FLOAT(_val) (GF_PropertyValue){.type=GF_PROP_FLOAT, .value.fnumber = FLT2FIX(_val)}
/*! Helper macro to set 32-bit fraction property from integers*/
#define PROP_FRAC_INT(_num, _den) (GF_PropertyValue){.type=GF_PROP_FRACTION, .value.frac.num = _num, .value.frac.den = _den}
/*! Helper macro to set 32-bit fraction property*/
#define PROP_FRAC(_val) (GF_PropertyValue){.type=GF_PROP_FRACTION, .value.frac = _val }
/*! Helper macro to set 64-bit fraction property from integers*/
#define PROP_FRAC64(_val) (GF_PropertyValue){.type=GF_PROP_FRACTION64, .value.lfrac = _val}
/*! Helper macro to set 64-bit fraction property*/
#define PROP_FRAC64_INT(_num, _den) (GF_PropertyValue){.type=GF_PROP_FRACTION64, .value.lfrac.num = _num, .value.lfrac.den = _den}
/*! Helper macro to set double property */
#define PROP_DOUBLE(_val) (GF_PropertyValue){.type=GF_PROP_DOUBLE, .value.number = _val}
/*! Helper macro to set string property */
#define PROP_STRING(_val) (GF_PropertyValue){.type=GF_PROP_STRING, .value.string = (char *) _val}
/*! Helper macro to set string property without string copy (string memory is owned by filter) */
#define PROP_STRING_NO_COPY(_val) (GF_PropertyValue){.type=GF_PROP_STRING_NO_COPY, .value.string = _val}
/*! Helper macro to set name property */
#define PROP_NAME(_val) (GF_PropertyValue){.type=GF_PROP_NAME, .value.string = _val}
/*! Helper macro to set data property */
#define PROP_DATA(_val, _len) (GF_PropertyValue){.type=GF_PROP_DATA, .value.data.ptr = _val, .value.data.size=_len}
/*! Helper macro to set data property without data copy ( memory is owned by filter) */
#define PROP_DATA_NO_COPY(_val, _len) (GF_PropertyValue){.type=GF_PROP_DATA_NO_COPY, .value.data.ptr = _val, .value.data.size =_len}
/*! Helper macro to set const data property */
#define PROP_CONST_DATA(_val, _len) (GF_PropertyValue){.type=GF_PROP_CONST_DATA, .value.data.ptr = _val, .value.data.size = _len}
/*! Helper macro to set 2D float vector property */
#define PROP_VEC2(_val) (GF_PropertyValue){.type=GF_PROP_VEC2, .value.vec2 = _val}
/*! Helper macro to set 2D integer vector property */
#define PROP_VEC2I(_val) (GF_PropertyValue){.type=GF_PROP_VEC2I, .value.vec2i = _val}
/*! Helper macro to set 2D integer vector property from integers*/
#define PROP_VEC2I_INT(_x, _y) (GF_PropertyValue){.type=GF_PROP_VEC2I, .value.vec2i.x = _x, .value.vec2i.y = _y}
/*! Helper macro to set 3D integer vector property */
#define PROP_VEC3I(_val) (GF_PropertyValue){.type=GF_PROP_VEC3I, .value.vec3i = _val}
/*! Helper macro to set 3D integer vector property from integers*/
#define PROP_VEC3I_INT(_x, _y, _z) (GF_PropertyValue){.type=GF_PROP_VEC3I, .value.vec3i.x = _x, .value.vec3i.y = _y, .value.vec3i.z = _z}
/*! Helper macro to set 4D integer vector property */
#define PROP_VEC4I(_val) (GF_PropertyValue){.type=GF_PROP_VEC4I, .value.vec4i = _val}
/*! Helper macro to set 4D integer vector property from integers */
#define PROP_VEC4I_INT(_x, _y, _z, _w) (GF_PropertyValue){.type=GF_PROP_VEC4I, .value.vec4i.x = _x, .value.vec4i.y = _y, .value.vec4i.z = _z, .value.vec4i.w = _w}
/*! Helper macro to set pointer property */
#define PROP_POINTER(_val) (GF_PropertyValue){.type=GF_PROP_POINTER, .value.ptr = (void*)_val}


/*! @} */




/*!
\addtogroup fs_evt Filter Events
\ingroup filters_grp
\brief Filter Events

PIDs may receive commands and may emit messages using an event system.

Events may flow downwards (towards the source), in which case they are commands, or upwards (towards the sink), in which case they are informative event.

A filter not implementing a process_event will result in the event being forwarded down to all input PIDs or up to all output PIDs.

A filter may decide to cancel an event, in which case the event is no longer forwarded down/up the chain.

GF_FEVT_PLAY, GF_FEVT_STOP and GF_FEVT_SOURCE_SEEK events will trigger a reset of PID buffers.

A GF_FEVT_PLAY event on a PID already playing is discarded.

A GF_FEVT_STOP event on a PID already stopped is discarded.

GF_FEVT_PLAY and GF_FEVT_SET_SPEED events will trigger larger (abs(speed)>1) or smaller (abs(speed)<1) PID buffer limit in blocking mode.

GF_FEVT_STOP and GF_FEVT_SOURCE_SEEK events are filtered to reset the PID buffers.

The following events may be used globally on a filter, e.g. without a  PID associated to the event:

GF_FEVT_FILE_DELETE: used for source and sinks, indicata a file deletion

GF_FEVT_SOURCE_SWITCH: used for source filters only, indicate URL switching

GF_FEVT_QUALITY_SWITCH: globally change quality of of the filters for all pids (typically used in scalable contexts)

GF_FEVT_USER:

The filter session does not maintain a notion of paused or resume streams, it is up to the consummer to stop processing the data wgile paused.
The GF_FEVT_PAUSE and GF_FEVT_RESUME events are only used to trigger pause and resume on interactive channels such as an RTSP session, i.e. to tell the remote peer to stop and resume.

@{
 */

/*! Filter event types */
typedef enum
{
	/*! PID control, usually triggered by sink - see \ref GF_FilterPidPlaybackMode*/
	GF_FEVT_PLAY = 1,
	/*! PID speed control, usually triggered by sink - see \ref GF_FilterPidPlaybackMode*/
	GF_FEVT_SET_SPEED,
	/*! PID control, usually triggered by sink - see \ref GF_FilterPidPlaybackMode*/
	GF_FEVT_STOP,
	/*! PID pause, usually triggered by sink - see \ref GF_FilterPidPlaybackMode*/
	GF_FEVT_PAUSE,
	/*! PID resume, usually triggered by sink - see \ref GF_FilterPidPlaybackMode*/
	GF_FEVT_RESUME,
	/*! PID byte-seek of source, allows seeking in bytes the source - typically used by demuxer to convert time ranges to byte ranges*/
	GF_FEVT_SOURCE_SEEK,
	/*! PID source switch, allows a source filter to switch its source URL for the same protocol*/
	GF_FEVT_SOURCE_SWITCH,
	/*! DASH segment size info, sent down from muxers to manifest generators*/
	GF_FEVT_SEGMENT_SIZE,
	/*! Scene attach event, sent down from compositor to filters (BIFS/OD/timedtext/any scene-related) to share the scene (resources and node graph)*/
	GF_FEVT_ATTACH_SCENE,
	/*! Scene reset event, sent down from compositor to filters (BIFS/OD/timedtext/any scene-related) to indicate scene reset (resources and node graph). This is a direct filter call, only sent processed by filters running on the main thread*/
	GF_FEVT_RESET_SCENE,
	/*! quality switching request event, helps filters decide how to adapt their processing*/
	GF_FEVT_QUALITY_SWITCH,
	/*! visibility hint event, helps filters decide how to adapt their processing*/
	GF_FEVT_VISIBILITY_HINT,
	/*! special event type sent to a filter whenever the PID info properties have been modified. No cancel because no forward - cf \ref gf_filter_pid_set_info. A filter returning GF_TRUE on this event will prevent info update notification on the destination filters*/
	GF_FEVT_INFO_UPDATE,
	/*! buffer requirement event. This event is NOT sent to filters, it is internaly processed by the filter session. Filters may however send this
	event to indicate their buffereing preference (real-time sinks mostly)*/
	GF_FEVT_BUFFER_REQ,
	/*! filter session capability change, sent whenever global capabilities (max width, max height, ... ) are changed*/
	GF_FEVT_CAPS_CHANGE,
	/*! inidicates the PID could not be connected - the PID passed is an output PID of the filter, no specific event structure is associated*/
	GF_FEVT_CONNECT_FAIL,
	/*! user event, sent from compositor/vout down to filters*/
	GF_FEVT_USER,
	/*! PLAY hint event, used to signal if block dispatch is needed or not for the source*/
	GF_FEVT_PLAY_HINT,
	/*! file delete event, sent upstream by dasher to notify file deletion, downstream by flist to ask for file deletion. The associated file processing (reading, writing) MUST be done when firing this event*/
	GF_FEVT_FILE_DELETE,

	/*! DASH fragment (cmaf chunk) size info, sent down from muxers to manifest generators*/
	GF_FEVT_FRAGMENT_SIZE,

	/*! Encoder hints*/
	GF_FEVT_ENCODE_HINTS,
	/*! NTP source clock send by other services (eg from TS to dash using TEMI) */
	GF_FEVT_NTP_REF,
} GF_FEventType;

/*! type: the type of the event*/
/*! on_pid: PID to which the event is targeted. If NULL the event is targeted at the whole filter */
#define FILTER_EVENT_BASE \
	GF_FEventType type; \
	GF_FilterPid *on_pid; \
	\


/*! Macro helper for event structure initializing*/
#define GF_FEVT_INIT(_a, _type, _on_pid)	{ memset(&_a, 0, sizeof(GF_FilterEvent)); _a.base.type = _type; _a.base.on_pid = _on_pid; }

/*! Base type of events. All events start with the fields defined in \ref FILTER_EVENT_BASE*/
typedef struct
{
	FILTER_EVENT_BASE
} GF_FEVT_Base;

/*! Event structure for GF_FEVT_PLAY, GF_FEVT_SET_SPEED, GF_FEVT_PLAY_HINT, GF_FEVT_STOP*/
typedef struct
{
	FILTER_EVENT_BASE

	/*!GF_FEVT_PLAY only, play range in sec - if range is <0, it means end of file (eg [2, -1] with speed>0 means 2 +oo) */
	Double start_range;
	/*!GF_FEVT_PLAY only, send range in sec - if range is less than start, ignored*/
	Double end_range;
	/*! params for GF_FEVT_PLAY and GF_FEVT_SET_SPEED*/
	Double speed;

	/*! GF_FEVT_PLAY only, indicates playback should start from given packet number - used by dasher and GHI when reloading sources*/
	u32 from_pck;

	/*! GF_FEVT_PLAY only, set when PLAY event is sent upstream to audio out, indicates HW buffer reset*/
	u8 hw_buffer_reset;
	/*!
		1: indicates this is the first PLAY on an element inserted from broadcast/live (GF_FEVT_PLAY only)
		2: indicates this is a PLAY preceeding a STOP or a STOP for a PID being disconnected (GF_FEVT_PLAY and GF_FEVT_STOP)
	*/
	u8 initial_broadcast_play;
	/*! params for GF_FEVT_PLAY only
		0: range is in media time
		1: range is in timesatmps
		2: range is in media time but timestamps should not be shifted (hybrid dash only for now)
	*/
	u8 timestamp_based;
	/*! GF_FEVT_PLAY only, indicates the consumer only cares for the full file, not packets*/
	u8 full_file_only;
	/*!
	 for GF_FEVT_PLAY: indicates any current download should be aborted
	 for GF_FEVT_PLAY_HINT if upstream event: indicates a HAS segment switch has occured (used by tileagg to flush reassembly buffers)
	 for GF_FEVT_STOP: indicates the source filter has already received stop/play events and cancel event just before source
	*/
	u8 forced_dash_segment_switch;
	/*! GF_FEVT_PLAY only, indicates non ref frames should be drawn for faster processing*/
	u8 drop_non_ref;
	/*! GF_FEVT_PLAY only, indicates  that a demuxer must not forward this event as a source seek because seek has already been done
	(typically this play request is a segment play and byte range access within the file has already been performed by DASH client)*/
	u8 no_byterange_forward;

	/*! GF_FEVT_PLAY only, indicates playback should stop from given packet number - used by GHI when loading sources*/
	u32 to_pck;
	/*! GF_FEVT_PLAY only, indicates orginal delay applied to dts - used by GHI when loading sources*/
	u32 orig_delay;
	/*! GF_FEVT_PLAY only, hint DTS of first sample at ot just after start offset, in media timescale*/
	u64 hint_first_dts;
	/*! GF_FEVT_PLAY only, start offset in source - used by GHI when loading sources*/
	u64 hint_start_offset;
	/*! GF_FEVT_PLAY only, end offset in source - used by GHI when loading sources*/
	u64 hint_end_offset;

} GF_FEVT_Play;

/*! Event structure for GF_FEVT_SOURCE_SEEK and GF_FEVT_SOURCE_SWITCH*/
typedef struct
{
	FILTER_EVENT_BASE

	/*! start offset in source*/
	u64 start_offset;
	/*! end offset in source*/
	u64 end_offset;
	/*! GF_FEVT_SOURCE_SWITCH only, new path to switch to*/
	const char *source_switch;
	/*!GF_FEVT_SOURCE_SWITCH only, indicates  source is a DASH init segment and should be kept in memory cache*/
	u8 is_init_segment;
	/*!GF_FEVT_SOURCE_SWITCH only, ignore cache expiration directive for HTTP*/
	u8 skip_cache_expiration;
	/*! GF_FEVT_SOURCE_SEEK only,  hint block size for source, might not be respected*/
	u32 hint_block_size;
} GF_FEVT_SourceSeek;

/*! Event structure for GF_FEVT_SEGMENT_SIZE*/
typedef struct
{
	FILTER_EVENT_BASE
	/*! URL of segment this info is for, or NULL if single file*/
	const char *seg_url;
	/*! media start range in segment file*/
	u64 media_range_start;
	/*! media end range in segment file*/
	u64 media_range_end;
	/*! index start range in segment file*/
	u64 idx_range_start;
	/*! index end range in segment file*/
	u64 idx_range_end;
	/*! global sidx is signaled using is_init=1 and range in idx range*/
	u8 is_init;
	/*! if global sidx, indicates if this is is an insertion and that byte range previously received should be shifted*/
	u8 is_shift;
} GF_FEVT_SegmentSize;

/*! Event structure for  GF_FEVT_FRAGMENT_SIZE*/
typedef struct
{
	FILTER_EVENT_BASE
	/*! set to TRUE if last fragment in segment*/
	Bool is_last;
	/*! media start range in segment file*/
	u64 offset;
	/*! media end range in segment file*/
	u64 size;
	/*! media duration of fragment*/
	GF_Fraction64 duration;
	/*! fragment contains an IDR*/
	Bool independent;
} GF_FEVT_FragmentSize;

/*! Event structure for GF_FEVT_ATTACH_SCENE and GF_FEVT_RESET_SCENE
For GF_FEVT_RESET_SCENE, THIS IS A DIRECT FILTER CALL NOT THREADSAFE, filters processing this event SHALL run on the main thread*/
typedef struct
{
	FILTER_EVENT_BASE
	/*! Pointer to a GF_ObjectManager structure for this PID*/
	void *object_manager;
	/*! Pointer to a GF_Node structure for this PID if node decoder pid*/
	void *node;
} GF_FEVT_AttachScene;

/*! Event structure for GF_FEVT_QUALITY_SWITCH*/
typedef struct
{
	FILTER_EVENT_BASE

	/*! switch quality up or down */
	Bool up;
	/*! 0: current group, otherwise index of the depending_on group */
	u32 dependent_group_index;
	/*! index of the quality to switch, as indicated in "has:qualities" property. If < 0, sets to automatic quality switching*/
	s32 q_idx;
	/*! 1+tile mode adaptation (does not change other selections) */
	u32 set_tile_mode_plus_one;
	/*! quality degradation hint, between 0 (full quality) and 100 (lowest quality, stream not currently rendered)*/
	u32 quality_degradation;
} GF_FEVT_QualitySwitch;

/*! Event structure for GF_FEVT_USER*/
typedef struct
{
	FILTER_EVENT_BASE
	/*! GF_Event structure*/
	GF_Event event;
} GF_FEVT_Event;

/*! Event structure for GF_FEVT_FILE_DELETE*/
typedef struct
{
	FILTER_EVENT_BASE
	/*! URL to delete, or "__gpac_self__" when asking source filter to delete file */
	const char *url;
} GF_FEVT_FileDelete;

/*! Event structure for GF_FEVT_VISIBILITY_HINT*/
typedef struct
{
	FILTER_EVENT_BASE
	/*! gives minimun and maximum coordinates of the visible rectangle associated with channels. min_x may be greater than max_x in case of 360 videos */
	u32 min_x, max_x, min_y, max_y;
	/*! if set, only min_x, min_y are used and indicate the gaze direction in pixels in the visual with/height frame (0,0) being top-left*/
	Bool is_gaze;
} GF_FEVT_VisibilityHint;


/*! Event structure for GF_FEVT_BUFFER_REQ*/
typedef struct
{
	FILTER_EVENT_BASE
	/*! indicates the max buffer to set on PID - the buffer is only activated on PIDs connected to decoders*/
	u32 max_buffer_us;
	/*! indicates the max playout buffer to set on PID (buffer level triggering playback)
		\note This is not used internally by the blocking mechanisms, but may be needed by other filters to take decisions
	*/
	u32 max_playout_us;
	/*! indicates the min playout buffer to set on PID (buffer level triggering rebuffering)
		\note This is not used internally by the blocking mechanisms, but may be needed by other filters to take decisions
	*/
	u32 min_playout_us;
	/*! if set, only the PID target of the event will have the buffer req set; otherwise, the buffer requirement event is passed down the chain until a raw media PID is found or a decoder is found. Used for muxers*/
	Bool pid_only;
} GF_FEVT_BufferRequirement;


/*! Event structure for GF_FEVT_ENCODE_HINT*/
typedef struct
{
	FILTER_EVENT_BASE

	/*! duration of intra (IDR, closed GOP) as expected by the dasher */
	GF_Fraction intra_period;
	/*! if TRUE codec should only generate DSI (possibly no input frame, and all output packets will be discarded) */
	Bool gen_dsi_only;
} GF_FEVT_EncodeHints;


/*! Event structure for GF_FEVT_NTP_REF*/
typedef struct
{
	FILTER_EVENT_BASE

	/*! 64 bit NTP timestamp */
	u64 ntp;

} GF_FEVT_NTPRef;

/*!
Filter Event object
 */
union __gf_filter_event
{
	GF_FEVT_Base base;
	GF_FEVT_Play play;
	GF_FEVT_SourceSeek seek;
	GF_FEVT_AttachScene attach_scene;
	GF_FEVT_Event user_event;
	GF_FEVT_QualitySwitch quality_switch;
	GF_FEVT_VisibilityHint visibility_hint;
	GF_FEVT_BufferRequirement buffer_req;
	GF_FEVT_SegmentSize seg_size;
	GF_FEVT_FragmentSize frag_size;
	GF_FEVT_FileDelete file_del;
	GF_FEVT_EncodeHints encode_hints;
	GF_FEVT_NTPRef ntp;
};

/*! Gets readable name for event type
\param type type of the event
\return readable name of the event
*/
const char *gf_filter_event_name(GF_FEventType type);

/*! @} */


/*!
\addtogroup fs_filter Filter
\ingroup filters_grp
\brief Filter


The API for filters documents declaration of filters, their creation and functions available to interact with the filter session.
The gf_filter_* functions shall only be called from within a given filter, this filter being the target of the function. This is not checked at runtime.

Calling these functions on other filters will result in unpredictable behavior, very likely crashes in multi-threading conditions.

A filter is instanciated through a filter register. The register holds entry points to a filter, arguments of a filter (basically property values) and capabilities.

Capabilities are used to check if a filter can be connected to a given input PID, or if two filters can be directly connected (capability match).

Capabilities are organized in so-called bundles, gathering the caps that shall be present or not present in the PID / connecting filter. Typically a capability bundle
will contain a stream type for input a stream type for output, a codec id for input and a codec id for output.

Several capability bundles can be used if needed. A good example is the writegen filter in GPAC, which simply transforms a sequence of media frames into a raw file, hence converts
stream_type/codecID to file extension and MIME type - cf gpac/src/filters/write_generic.c

When resolving a chain, PID properties are checked against these capabilities. If a property of the same type exists in the PID than in the capability,
it must match the capability requirement (equal, excluded). If no property exists for a given non-optional capability type,
 the bundle is marked as not matching and the ext capability bundle in the filter is checked.
 A PID property not listed in any capability of the filter does not impact the matching.

The GF_PROP_PID_FILE_EXT and GF_PROP_PID_MIME are handled as alternate to each other, this allows matching a PID if either its MIME or extension map and avoids failing if the pid has no MIME or extension set.
@{
 */


/*! Structure holding arguments for a filter*/
typedef enum
{
	/*! used for GUI config: regular argument type */
	GF_FS_ARG_HINT_NORMAL = 0,
	/*! used for GUI config: advanced argument type */
	GF_FS_ARG_HINT_ADVANCED = 1<<1,
	/*! used for GUI config: expert argument type */
	GF_FS_ARG_HINT_EXPERT = 1<<2,
	/*! used for GUI config: hidden argument type */
	GF_FS_ARG_HINT_HIDE = 1<<3,
	/*! if set indicates that the argument is updatable. If so, the value will be changed if offset_in_private is valid, and the update_args function will be called if not NULL*/
	GF_FS_ARG_UPDATE = 1<<4,
	/*! used by meta filters (ffmpeg & co) to indicate the parsing is handled by the filter in which case the type is overloaded to string and passed to the update_args function*/
	GF_FS_ARG_META = 1<<5,
	/*! internal flag used by meta filters (ffmpeg & co) to indicate the description of the argument is a dynamic allocated memory*/
	GF_FS_ARG_META_ALLOC = 1<<6,
	/*! internal flag used by filters acting as sinks (gsfmx in file mode) to allow retrieving dst url but avoid being used as direct sinks*/
	GF_FS_ARG_SINK_ALIAS = 1<<7,
	/*! if set indicates that the argument is updatable only as a direct synchronous call (typically used for shared data).
		If so, the value will only be updated if the update directly targets the filter, and the global filter mutex will be locked before calling update_arg.
		It is however recommended for the calling app to lock the target filter whenever shared data is modified (see vout filter overlay argument  for example)
		The filter should lock itself whenever appropriate using \ref gf_filter_lock
	*/
	GF_FS_ARG_UPDATE_SYNC = 1<<8,
	/*! internal flag used by meta filters (ffmpeg & co) to indicate the argument is an array of the indicated type*/
	GF_FS_ARG_META_ARRAY = 1<<9,
} GF_FSArgumentFlags;

/*! Structure holding arguments for a filter*/
typedef struct
{
	/*! argument name. Naming conventions:
		- only use lowercase
		- keep short and avoid '_'
	*/
	const char *arg_name;
	/*! offset of the argument in the structure, -1 means not exposed/stored in structure, in which case it is notified through the update_arg function.
	The offset is casted into the corresponding property value of the argument type*/
	s32 offset_in_private;
	/*! description of argument. Format conventions:
		- first letter is lowercase except if it is an acronym (eg, 'IP').
		- description does not end with a '.'; multiple sentences are however allowed with '.' separators.
		- description does not end with a new line CR or LF; multiple sentences are however allowed with '.' separators.
		- keep it short. If too long, use " - see filter help" and put description in filter help.
		- only use markdown '`' and '*', except for enumeration lists which shall use "- ".
		- do not use CR/LF in description except to start enum types description.
		- use infinitive (eg \"set foo to bar\" and not \"sets foo to bar\").
		- Enumerations should be described as:
		 		sentence(s)'\n' (no '.' nor ':' at end)
		 		- name1: val'\n' (no '.' at end)
		 		- nameN: val (no '.' nor '\n' at end of last value description)
			and enum value description order shall match enum order
		- links are allowed, see GF_FilterRegister doc
	*/
	const char *arg_desc;
	/*! type of argument - this is a property type*/
	GF_PropType arg_type;
	/*! default value of argument, can be NULL (for number types, value 0 for each dimension of the type is assumed)*/
	const char *arg_default_val;
	/*! string describing an enum (unsigned integer type) or a min/max value.
		For min/max, the syntax is "min,max", with -I = -infinity and +I = +infinity
		For enum, the syntax is "a|b|...", resoling in a=0, b=1,... To skip a value insert '|' eg "|a|b" resolves to a=1, b=2, "a||b" resolves to a=0, b=2

		Naming conventions for enumeration:
			- use single word
			- use lowercase escept for single/double characters name (eg 'A', 'V').
	*/
	const char *min_max_enum;
	/*! set of argument flags*/
	GF_FSArgumentFlags flags;
} GF_FilterArgs;

/*! Shortcut macro to assign singed integer capability type*/
#define CAP_SINT(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_SINT, .value.sint = _b}, .flags=(_f) }
/*! Shortcut macro to assign unsigned integer capability type*/
#define CAP_UINT(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_UINT, .value.uint = _b}, .flags=(_f) }
/*! Shortcut macro to assign unsigned integer capability type*/
#define CAP_4CC(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_4CC, .value.uint = _b}, .flags=(_f) }
/*! Shortcut macro to assign signed long integer capability type*/
#define CAP_LSINT(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_LSINT, .value.longsint = _b}, .flags=(_f) }
/*! Shortcut macro to assign unsigned long integer capability type*/
#define CAP_LUINT(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_LUINT, .value.longuint = _b}, .flags=(_f) }
/*! Shortcut macro to assign boolean capability type*/
#define CAP_BOOL(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_BOOL, .value.boolean = _b}, .flags=(_f) }
/*! Shortcut macro to assign fixed-point number capability type*/
#define CAP_FIXED(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_FLOAT, .value.fnumber = _b}, .flags=(_f) }
/*! Shortcut macro to assign float capability type*/
#define CAP_FLOAT(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_FLOAT, .value.fnumber = FLT2FIX(_b)}, .flags=(_f) }
/*! Shortcut macro to assign 32-bit fraction capability type*/
#define CAP_FRAC_INT(_f, _a, _b, _c) { .code=_a, .val={.type=GF_PROP_FRACTION, .value.frac.num = _b, .value.frac.den = _c}, .flags=(_f) }
/*! Shortcut macro to assign 32-bit fraction capability type from integers*/
#define CAP_FRAC(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_FRACTION, .value.frac = _b}, .flags=(_f) }
/*! Shortcut macro to assign double capability type*/
#define CAP_DOUBLE(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_DOUBLE, .value.number = _b}, .flags=(_f) }
/*! Shortcut macro to assign name (const string) capability type*/
#define CAP_NAME(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_NAME, .value.string = _b}, .flags=(_f) }
/*! Shortcut macro to assign string capability type*/
#define CAP_STRING(_f, _a, _b) { .code=_a, .val={.type=GF_PROP_STRING, .value.string = _b}, .flags=(_f) }
/*! Shortcut macro to assign unsigned integer capability type with capability priority*/
#define CAP_UINT_PRIORITY(_f, _a, _b, _p) { .code=_a, .val={.type=GF_PROP_UINT, .value.uint = _b}, .flags=(_f), .priority=_p}

/*! Flags for filter capabilities*/
enum
{
	/*! when not set, indicates the start of a new set of capabilities. Set by default by the generic GF_CAPS_* */
	GF_CAPFLAG_IN_BUNDLE = 1,
	/*!  if set this is an input capability of the bundle*/
	GF_CAPFLAG_INPUT = 1<<1,
	/*!  if set this is an output capability of the bundle. A capability can be declared both as input and output. For example stream type is usually the same on both inputs and outputs*/
	GF_CAPFLAG_OUTPUT = 1<<2,
	/*!  when set, the capability is valid if the value does not match. If an excluded capability is not found in the destination PID, it is assumed to match*/
	GF_CAPFLAG_EXCLUDED = 1<<3,
	/*! when set, the capability is validated only for filter loaded for this destination filter*/
	GF_CAPFLAG_LOADED_FILTER = 1<<4,
	/*! indicates that this capability (input or output) applies to all following bundles. This avoids repeating capabilities common to all bundles by setting them only in the first*/
	GF_CAPFLAG_STATIC = 1<<5,
	/*! Only used for input capabilities, indicates that this capability is optional in the input PID */
	GF_CAPFLAG_OPTIONAL = 1<<6,
};

/*! Shortcut macro to set for input capability flags*/
#define GF_CAPS_INPUT	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_INPUT)
/*! Shortcut macro to set for optional input capability flags*/
#define GF_CAPS_INPUT_OPT	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_INPUT|GF_CAPFLAG_OPTIONAL)
/*! Shortcut macro to set for static input capability flags*/
#define GF_CAPS_INPUT_STATIC	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_INPUT|GF_CAPFLAG_STATIC)
/*! Shortcut macro to set for static optional input capability flags*/
#define GF_CAPS_INPUT_STATIC_OPT	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_INPUT|GF_CAPFLAG_STATIC|GF_CAPFLAG_OPTIONAL)
/*! Shortcut macro to set for excluded input capability flags*/
#define GF_CAPS_INPUT_EXCLUDED	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_INPUT|GF_CAPFLAG_EXCLUDED)
/*! Shortcut macro to set for input for loaded filter only capability flags*/
#define GF_CAPS_INPUT_LOADED_FILTER	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_INPUT|GF_CAPFLAG_LOADED_FILTER)
/*! Shortcut macro to set for output capability flags*/
#define GF_CAPS_OUTPUT	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_OUTPUT)
/*! Shortcut macro to set for output for loaded filter only capability flags*/
#define GF_CAPS_OUTPUT_LOADED_FILTER	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_OUTPUT|GF_CAPFLAG_LOADED_FILTER)
/*! Shortcut macro to set for excluded output capability flags*/
#define GF_CAPS_OUTPUT_EXCLUDED	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_OUTPUT|GF_CAPFLAG_EXCLUDED)
/*! Shortcut macro to set for static output capability flags*/
#define GF_CAPS_OUTPUT_STATIC	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_OUTPUT|GF_CAPFLAG_STATIC)
/*! Shortcut macro to set for excluded static output capability flags*/
#define GF_CAPS_OUTPUT_STATIC_EXCLUDED	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_OUTPUT|GF_CAPFLAG_EXCLUDED|GF_CAPFLAG_STATIC)
/*! Shortcut macro to set for input and output capability flags*/
#define GF_CAPS_INPUT_OUTPUT	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_INPUT|GF_CAPFLAG_OUTPUT)
/*! Shortcut macro to set for optional input and output capability flags*/
#define GF_CAPS_INPUT_OUTPUT_OPT	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_INPUT|GF_CAPFLAG_OUTPUT|GF_CAPFLAG_OPTIONAL)
/*! Shortcut macro to set for excluded input capability flags*/
#define GF_CAPS_IN_OUT_EXCLUDED	(GF_CAPFLAG_IN_BUNDLE|GF_CAPFLAG_INPUT|GF_CAPFLAG_OUTPUT|GF_CAPFLAG_EXCLUDED)

/*! Filter capability description*/
typedef struct
{
	/*! 4cc of the capability listed. This shall be 0 or the type of a built-in property */
	u32 code;
	/*! default type and value of the capability listed*/
	GF_PropertyValue val;
	/*! name of the capability listed, NULL if code is set. The special value * is used to indicate that the capability is solved at runtime (the filter must be loaded)*/
	const char *name;
	/*! Flags of the capability*/
	u32 flags;
	/*! overrides the filter register priority for this capability. Usually 0*/
	u8 priority;
} GF_FilterCapability;

/*! Filter session capability structure*/
typedef struct
{
	u32 max_screen_width;
	u32 max_screen_height;
	u32 max_screen_bpp;
	u32 max_screen_fps;
	u32 max_screen_nb_views;
	u32 max_audio_channels;
	u32 max_audio_sample_rate;
	u32 max_audio_bit_depth;
} GF_FilterSessionCaps;

/*! Gets filter session capability
\param filter source of the query - avoids fetching the filter session object
\param caps pointer filled with caps
*/
void gf_filter_get_session_caps(GF_Filter *filter, GF_FilterSessionCaps *caps);

/*! Sets filter session capability
\param filter source of the query - avoids fetching the filter session object
\param caps session capability new values - completely replace the old ones
*/
void gf_filter_set_session_caps(GF_Filter *filter, GF_FilterSessionCaps *caps);

/*! Check if the filter is an instance of a  filter register
\param filter filter to test
\param freg  filter register to test
\return GF_TRUE if filter is an instance of this register, GF_FALSE otehrwise
*/
Bool gf_filter_is_instance_of(GF_Filter *filter, const GF_FilterRegister *freg);


/*! Aborts a filter, discarding and stopping all input PIDs and sending EOS on all output PIDs
\param filter filter to abort
*/
void gf_filter_abort(GF_Filter *filter);


/*! Locks a filter. A filter should only lock itself when using updatable arguments of type GF_FS_ARG_UPDATE_SYNC
\param filter filter to lock
\param do_lock if GF_TRUE, locks the filter global mutex, otherwise unlocks it
*/
void gf_filter_lock(GF_Filter *filter, Bool do_lock);



/*! Lock global filter session. This is needed when assigning source IDs after a connect source or destination to the loaded source to connect in an async way
\param filter target filter
\param do_lock if GF_TRUE, locks the filter session global mutex, otherwise unlocks it
*/
void gf_filter_lock_all(GF_Filter *filter, Bool do_lock);

/*! Force all output pids created for this filter to require a source ID for linking.

 This is used by filters loading subchains to enforce that filters from these subchain only connect to each other or the target filter but not other filters outside this chain.
 Filters using this function must setup source IDs on filters of the sunchain(s) they load.

 Note: This has the same effect as setting the `:RSID` option on the filter

\param filter target filter
*/
void gf_filter_require_source_id(GF_Filter *filter);

/*! Sets opaque runtime data for filter - used by bindings
\param filter target filter
\param udta data to set
\return error if any
*/
GF_Err gf_filter_set_rt_udta(GF_Filter *filter, void *udta);
/*! Gets opaque runtime data for filter - used by bindings
\param filter target filter
\return associated data or NULL
*/
void *gf_filter_get_rt_udta(GF_Filter *filter);


/*! Filter probe score, used when probing a URL/MIME or when probing formats from data*/
typedef enum
{
	/*! (de)mux format is not supported*/
	GF_FPROBE_NOT_SUPPORTED = 0,
	/*!
		For demux: format is maybe a match but garbage data was found at the start
		For mux: protocol is supported but format is not - if :ext=foo is set on sink URL, probe_url will be recall with URL=test.foo
	*/
	GF_FPROBE_MAYBE_NOT_SUPPORTED,
	/*!
		- for demux: format is maybe a match and can maybe be demuxed
		- for mux:  format is supported with potentially missing features
	*/
	GF_FPROBE_MAYBE_SUPPORTED,
	/*! (de)mux format is supported*/
	GF_FPROBE_SUPPORTED,
	/*! demux format should be handled by this filter*/
	GF_FPROBE_FORCE,
	/*! used by demux formats not supporting data prober*/
	GF_FPROBE_EXT_MATCH,
} GF_FilterProbeScore;

/*! Quick macro for assigning the capability arrays to the register structure*/
#define SETCAPS( __struct ) .caps = __struct, .nb_caps=sizeof(__struct)/sizeof(GF_FilterCapability)

#ifndef GPAC_DISABLE_DOC
/*! Macro for assigning filter register description*/
#define GF_FS_SET_DESCRIPTION(_desc) .description = _desc,
/*! Macro for assigning filter register author*/
#define GF_FS_SET_AUTHOR(_author) .author = _author,
/*! Macro for assigning filter register help*/
#define GF_FS_SET_HELP(_help) .help = _help,
/*! Macro for assigning filter register argument types and description*/
#define GF_FS_DEF_ARG(_name, _offset, _desc, _type, _default, _enum, _flags) { _name, _offset, _desc, _type, _default, _enum, _flags }
#else
#define GF_FS_SET_DESCRIPTION(_desc)
#define GF_FS_SET_AUTHOR(_author)
#define GF_FS_SET_HELP(_help)
#define GF_FS_SET_ARGHELP(_help)
#define GF_FS_DEF_ARG(_name, _offset, _desc, _type, _default, _enum, _flags) {_name, _offset, _type, _default, _enum, _flags}
#endif

/*! Filter register flags*/
typedef enum
{
	/*! when set indicates all calls shall take place in the main thread (running GL output) - to be refined*/
	GF_FS_REG_MAIN_THREAD = 1<<1,
	/*! when set indicates the initial call to configure_pid will happen in the main thread. This is typically called by decoders requiring
	a GL context (currently only in main thread) upon init, but not requiring it for the decode. Such decoders get their GL frames mapped
	(through get_gl_texture callback) in the main GL thread*/
	GF_FS_REG_CONFIGURE_MAIN_THREAD = 1<<2,
	/*! when set indicates the filter does not take part of dynamic filter chain resolution and can only be used by explicitly loading the filter*/
	GF_FS_REG_EXPLICIT_ONLY = 1<<3,
	/*! when set ignores the filter weight during link resolution - this is typically needed by decoders requiring a specific reframing so that the weight of the reframer+decoder is the same as the weight of other decoders*/
	GF_FS_REG_HIDE_WEIGHT = 1<<4,
	/*! Usually set for filters acting as sources but without exposing an src argument. This prevents throwing warnings on arguments not handled by the filter*/
	GF_FS_REG_ACT_AS_SOURCE = 1<<5,
	/*! Indicates the filter can connect to another instance of the same class (avoids cyclic detection in linker graph)
	Filters of the same class can only connect directly to each other if the destination filter is explictly loaded */
	GF_FS_REG_ALLOW_CYCLIC = 1<<6,
	/*! Indicates the filter PIDs may be dynamically added during process (e.g.M2TS, GSF, etc).
	This will prevent deactivating a filter when none of its output PIDs are connected*/
	GF_FS_REG_DYNAMIC_PIDS = 1<<7,
	/*! Indicates the filter is a script-based filter. The registry is not valid until the script is loaded*/
	GF_FS_REG_SCRIPT = 1<<8,
	/*! Indicates the filter is a meta filter, wrapping various underlying filters (e.g. FFmpeg)*/
	GF_FS_REG_META = 1<<9,
	/*! Indicates that this filter, when dynamically loaded, allows the link resolver to redirect PID connection to this filter rather than to its next explicitly loaded filter in the chain.
		This is typically used by mux filters
	*/
	GF_FS_REG_DYNAMIC_REDIRECT = 1<<10,
	/*! Indicates the filter requires graph resolver (typically because it creates new destinations/sinks at run time)*/
	GF_FS_REG_REQUIRES_RESOLVER = 1<<11,
	/*!
		For sink filters, indicates the filter forces remux of input PIDs of type GF_STREAM_FILE (prevents direct file copy)
		For source filters, indicates the PIDs should be remuxed to a destination filter with force remux set
	*/
	GF_FS_REG_FORCE_REMUX = 1<<12,
	/*! Indicates the filter must always be run by the same thread, except for the initialize and finalize methods*/
	GF_FS_REG_SINGLE_THREAD = 1<<13,
	/*! Indicates the filter needs to be initialized even if temporary - see \ref gf_filter_is_temporary. Always enabled if GF_FS_REG_META is set */
	GF_FS_REG_TEMP_INIT = 1<<14,
	/*! Indicates the filter uses libc sync file read - only needed for emscripten multithreaded support for now, translated into GF_FS_REG_MAIN_THREAD */
	GF_FS_REG_USE_SYNC_READ = 1<<15,
	/*! Indicates the filter may block the main thread (configure, process) - only needed for emscripten multithreaded support*/
	GF_FS_REG_BLOCK_MAIN = 1<<16,
	/*! Indicates the filter uses async tools (JS promises & co) blocking the calling thread until resolved - only needed for emscripten multithreaded support*/
	GF_FS_REG_ASYNC_BLOCK = 1<<17,
	/*! Indicates a dynamic instance of the filter can be reused in resolver even if the source PID already has a possible link to an explicit non-sink filter
		This is typically required by PID merger filters allowing implicit loading (tileagg, hevcmerge, etc)
	*/
	GF_FS_REG_DYNAMIC_REUSE = 1<<18,


	/*! flag dynamically set at runtime for custom filters*/
	GF_FS_REG_CUSTOM = 0x40000000,
} GF_FSRegisterFlags;

/*! The filter register. Registries are loaded once at the start of the session and shall never be modified after that.
If capabilities need to be changed for a specific filter, use \ref gf_filter_override_caps*/
struct __gf_filter_register
{
	/*! mandatory - name of the filter as used when setting up filters. Naming conventions:
		- shall not contain any space (breaks filter lookup)
		- should use lowercase
		- should not use '_'
	*/
	const char *name;
	/*! optional - size of private stack structure. The structure is allocated by the framework and arguments are setup before calling any of the filter functions*/
	u32 private_size;
	/*! indicates the max number of additional input PIDs - muxers and scalable filters typically set this to (u32) -1. A value of 0 implies the filter can only handle one PID*/
	u32 max_extra_pids;
	/*! set of register flags*/
	GF_FSRegisterFlags flags;

	/*! list of PID capabilities*/
	const GF_FilterCapability *caps;
	/*! number of PID capabilities*/
	u32 nb_caps;

	/*! optional - filter arguments if any*/
	const GF_FilterArgs *args;

	/*! mandatory - callback for filter processing

	This function is called whenever packets are available on the input PID and buffer space is available on the output.
	The session will by default monitor a filter for errors, and throw en error if a filter is not consuming nor producing packets for a given amount of process calls.
	In some cases, it might be needed to not consume nor produce a packet for a given time (for example, waiting for a packet drop before reconfiguring a filter).
	A filter must signal this using \ref gf_filter_ask_rt_reschedule, possibly with no timeout.

	A filter may return GF_EOS to indicate no more data is expected to be produced by this filter

	A filter may return GF_PROFILE_NOT_SUPPORTED to indicate that the filter is not supported (when unable to detect this at configure) and trigger a relink of the filter graph unless disabled at session level.
	*/
	GF_Err (*process)(GF_Filter *filter);

	/*! optional for sources, mandatory for filters and sinks (any filter with an input cap set) - callback for PID update may be called several times
	on the same PID if PID config is changed.
	Since discontinuities may happen at any time, and a filter may fetch packets in burst,
	this function may be called while the filter is calling \ref gf_filter_pid_get_packet (this is the only reentrant call for filters).
	If an error is returned, the PID object shall no longer be used by the filter.

	\param filter the target filter
	\param PID the input PID to configure
	\param is_remove indicates the input PID is removed
	\return error if any.
	- a return error of GF_REQUIRES_NEW_INSTANCE indicates the PID cannot be processed in this instance but could be in a clone of the filter.
	- a return error of GF_FILTER_NOT_SUPPORTED indicates the PID cannot be processed and no alternate chain resolution would help
	- a return error of GF_EOS silently discard the input pid (same as GF_FILTER_NOT_SUPPORTED but does not throw error)
	- a return error of GF_BAD_PARAM, GF_SERVICE_ERROR or GF_REMOTE_SERVICE_ERROR indicates the PID cannot be processed and no alternate chain resolution would help, and throws a log error message
	- any other return error will trigger a reconfigure of the chain to find another filter unless disabled at session level.

	If an error is returned when (re)configuring a pid, the function is called again with is_remove set to GF_TRUE
	*/
	GF_Err (*configure_pid)(GF_Filter *filter, GF_FilterPid *PID, Bool is_remove);

	/*! optional - callback for filter initialization -  private stack of filter is allocated by framework)
	\param filter the target filter
	\return error if any. A filter may return GF_EOS to indicate the filter session shall not be run, but that no error should be thrown (used by dasher in realtime regulation mode)
	*/
	GF_Err (*initialize)(GF_Filter *filter);

	/*! optional - callback for filter destruction -  private stack of filter is freed by framework
	\param filter the target filter
	*/
	void (*finalize)(GF_Filter *filter);

	/*! optional - callback for arguments update. If GF_OK is returned, the filter private stack is updated accordingly.
	If function is NULL, all updatable arguments will be changed in the filter private stack without the filter being notified.
	If argument is a meta argument, it is the filter responsibility to handle the update, as meta arguments do not live on the filter private stack.
	If the filter is a meta filter and argument is not declared in the argument list, the function is always called.

	\param filter the target filter
	\param arg_name the name of the argument being set
	\param new_val the value of the argument being set
	\return error if any, GF_NOT_FOUND to silently disable argument value change.
	*/
	GF_Err (*update_arg)(GF_Filter *filter, const char *arg_name, const GF_PropertyValue *new_val);

	/*! optional - process a given event. Returns TRUE if the event has to be canceled, FALSE otherwise
		- If a downstream (towards source) event is not canceled, it will be forwarded to each input PID of the filter.
		- If you need to forward the event only to one input pid, send a copy of the event to the desired input and cancel the event.
	\param filter the target filter
	\param evt the event to process
	\return GF_TRUE if the event should be canceled, GF_FALSE otherwise
	*/
	Bool (*process_event)(GF_Filter *filter, const GF_FilterEvent *evt);

	/*! optional - Called whenever an output PID needs format renegotiation. If not set, a filter chain will be loaded to solve the negotiation

	\param filter the target filter
	\param PID the filter output PID being reconfigured
	\return error code if any
	*/
	GF_Err (*reconfigure_output)(GF_Filter *filter, GF_FilterPid *PID);

	/*! optional, mostly used for source filters and destination filters - probe the given URL, returning a score.
	This function is called before opening the source (no data received yet)

	\param url the url of the source to probe, never NULL.
	\param mime the MIME type of the source to probe. Can be NULL if mime not available at probe type
	\return probe score
	*/
	GF_FilterProbeScore (*probe_url)(const char *url, const char *mime);

	/*! optional, usually set by demuxers. This function probes the mime type of a data chunk, usually located at the start of the file.
	This function is called once the source is open, but is never called on an instanciated filter. The returned mime type (if any) is then used instead of the file extension
	for solving filter graph.
	\note Demux filters should always exposed 2 input caps bundle, one for specifying input cap by file extension and one for specifying input cap by mime type.
	\param data data to probe
	\param size size of the data to probe
	\param score set to the probe score. Initially set to \ref GF_FPROBE_NOT_SUPPORTED before calling the function. If you are certain of the data type, use \ref GF_FPROBE_SUPPORTED, if unsure use \ref GF_FPROBE_MAYBE_SUPPORTED. If the format cannot be probed (bad design), set it to \ref GF_FPROBE_EXT_MATCH
	\return mime type of content, list of known extensions for the format if score is set to GF_FPROBE_EXT_MATCH, or NULL if not detected.
	*/
	const char * (*probe_data)(const u8 *data, u32 size, GF_FilterProbeScore *score);

	/*! for filters having the same match of input capabilities for a PID, the filter with priority at the lowest value will be used
	\note Scalable decoders should use high values, so that they are only selected when enhancement layers are present*/
	u8 priority;

	/*! optional for dynamic filter registries. Dynamic registries may declare any number of registries. The register_free function will be called to cleanup any allocated memory

	\param session the filter session
	\param freg the filter register to destroy
	*/
	void (*register_free)(GF_FilterSession *session, struct __gf_filter_register *freg);
	/*! user data of register loader, not inspected/modified by filter session*/
	void *udta;

	/*! optional. Used by sink filters offering multiple sink support
		GPAC instantiates filter chains based on filter capabilities and arguments of source and destination. When a sink/destination filter can handle
		multiple file inputs of various formats/types, temporary filters called alias are needed to instantiate the proper chain.
		If the return value is true, an alias filter of the same type as this filter will be created with the proper arguments and initialized (in order to modify the
		 alias filter capabilities if needed), and finalized when no longer needed. All other callbacks will however be made on the main filter, not the alias.

		A good example is HTTP output of a DASH session:
		- the first PID will be a FILE stream for the manifest (MPD, M3U8), and the http output capabilities will be set to accept the manifest file extension.mime
		- the other PIDs will be media PIDs (mp4, ts, mkv ...) and won't match the filter instance, creating a new instance which we don't want

		By creating filter alias, a temprary HTTP output (alias) will be created, holding the arguments for the chain (including destination type). Overloading the alias filter capabilities
		with the desired file extension or MIME will trigger the proper chain resolution. The alias will be switched to the final filter upon connecting the PIDs

		To access original arguments of the chain, see \ref gf_filter_pid_get_alias_udta
		To check if an initialize callback targets the main filter or the temporary one, see \ref gf_filter_is_alias
	\param filter the target filter
	\param url the url of the target destination, never NULL.
	\param mime the MIME type of the target destination. Can be NULL if mime not available
	\return GF_TRUE if this filter instance should be used to handle the given URL, in which case an alias filter will be created
	*/
	Bool (*use_alias)(GF_Filter *filter, const char *url, const char *mime);


	/*! version of the filter, usually only for external libs
		\note If this strings starts with "! " it indicates an error message at load time of the registry. This should only be set when \code gf_opts_get_bool("temp", "gendoc"); \endcode returns true, indicating the filter session is only loaded for documentation purposes (man/md generation and command line help).
	*/
	const char *version;
#ifndef GPAC_DISABLE_DOC
	/*! short description of the filter. Conventions:
		- should be small (used to generate UI / documentation)
		- Should be Capitalized
		- shall not use markdown
		- shall be single line
	*/
	const char *description;
	/*! author of the filter. Conventions:
		- shall not use markdown
		- first line if present is author name and should be normally capitalized
		- second line if present is comma-separated list of contact info (eg http://foo.bar,mailto:foo@bar.com)

		If first character is a `-`, this field is interpreted as a configuration info (typically for meta filters such as ffmpeg).
	*/
	const char *author;
	/*! help of the filter. Conventions:
		- describe any non-obvious behavior of the filter here
		- markdown is allowed. Use '`' for code, "__" for italic, "**" for bold and  "~~" for strikethrough.
		- mardown top-level sections shall use '#', second level '##', and so on
		- mardown bullet lists shall use "- ", " - " etc...
		- notes shall be identifed as a line starting with "Note: "
		- warnings shall be identifed as a line starting with "Warning: "
		- examples shall be identifed as a line starting with "EX "
		- the sequence "[-" is reserved for option links. It is formatted as:
		 		- "[-OPT]()": link to self page for option OPT
		 		- "[-OPT](LINK)": link to other page for option OPT.
			LINK can be:
				- GPAC: resolves to general GPAC help
				- CORE: resolves to general CORE help
				- LOG: resolves to general LOG help
				- ANY: resolves to filter with register name 'ANY'

			Note that [text](ANY) with ANY a filter register name will link to that filter help page
	*/
	const char *help;
#endif
};


/*! Gets filter private stack - the stack is allocated and freed by the filter session, as are any arguments. The rest is up to the filter to delete it
\param filter target filter
\return filter private stack if any, NULL otherwise
*/
void *gf_filter_get_udta(GF_Filter *filter);

/*! Sets filter name - mostly used for logging purposes
\param filter target filter
\param name new name to assign. If NULL, name is reset to register name
*/
void gf_filter_set_name(GF_Filter *filter, const char *name);

/*! Checks is a filter is temporary, ie only loaded to solve caps but will not be used.

 Only filter classes setting the GF_FS_REG_TEMP_INIT or GF_FS_REG_META need to check this, and only during the initialize call.

if filter is temprary, it is loaded only to probe for a filter chain setup and will be finalized immediately after.
This implies that most filter resources (sockets, file handles, etc) must not be created in this case.

A temporary filter will be finalized as any other filter.

\param filter target filter
\return GF_TRUE if filter is temporary
*/
Bool gf_filter_is_temporary(GF_Filter *filter);

/*! Gets filter name
\param filter target filter
\return name of the filter
*/
const char *gf_filter_get_name(GF_Filter *filter);

/*! Makes the filter sticky. A sticky filter is not removed when all its input PIDs are disconnected. Typically used by the player
\param filter target filter
*/
void gf_filter_make_sticky(GF_Filter *filter);

/*! Return the number of queued events on the filter. Events are not aggregated, some filter may want to wait until all events are processed before taking actions. The function recursively goes up the filter chain and count queued events.
\param filter target filter
\return number of queued events
*/
u32 gf_filter_get_num_events_queued(GF_Filter *filter);

/*! Returns the single instance of GPAC download manager. DO NOT DESTROY IT!!
\param filter target filter
\return the GPAC download manager
*/
GF_DownloadManager *gf_filter_get_download_manager(GF_Filter *filter);

/*! Returns the single instance of GPAC font manager. DO NOT DESTROY IT!!
\param filter target filter
\return the GPAC font manager
*/
struct _gf_ft_mgr *gf_filter_get_font_manager(GF_Filter *filter);

/*! Asks task reschedule for a given delay. There is no guarantee that the task will be recalled at exactly the desired delay

 The function can be called several times while in process, the smallest reschedule time will be kept.
 
\param filter target filter
\param us_until_next number of microseconds to wait before recalling this task
*/
void gf_filter_ask_rt_reschedule(GF_Filter *filter, u32 us_until_next);

/*! Posts a filter process task to the parent session. This is needed for some filters not having any input packets to process but still needing to work
such as decoder flushes, servers, etc... The filter session will ignore this call if the filter is already scheduled for processing
\param filter target filter
*/
void gf_filter_post_process_task(GF_Filter *filter);

/*! Posts a task to the session scheduler. This task is not a process task but the filter will still be called by a single thread at any time (ie, might delay process)
\param filter target filter
\param task_execute the callback function for the task. The callback can return GF_TRUE to reschedule the task, in which case the task will be rescheduled
immediately or after reschedule_ms.
\param udta user data passed back to the task function
\param task_name name of the task for logging purposes
\return error code if failure
*/
GF_Err gf_filter_post_task(GF_Filter *filter, Bool (*task_execute) (GF_Filter *filter, void *callback, u32 *reschedule_ms), void *udta, const char *task_name);


/*! Sets callback function on source filter setup failure
\param filter target filter
\param source_filter the source filter to monitor
\param on_setup_error callback function to call upon source  setup error - the callback can return GF_TRUE to cancel error reporting
\param udta user data passed back to the task function
*/
void gf_filter_set_setup_failure_callback(GF_Filter *filter, GF_Filter *source_filter, Bool (*on_setup_error)(GF_Filter *f, void *on_setup_error_udta, GF_Err e), void *udta);

/*! Notify a filter setup error. This is typically called when a source filter or a filter having accepted input PIDs detects an issue.
For a source filter (no input PID), the failure callback will be called if any, and the filter will be removed.
For a connected filter, all input PIDs od the filter will be disconnected and the filter removed.
\param filter target filter
\param reason the failure reason code
*/
void gf_filter_setup_failure(GF_Filter *filter, GF_Err reason);

/*! Notify a filter fatal error but not a connection error. Typically, a 404 in HTTP.
\param filter target filter
\param reason the failure reason code
\param force_disconnect indicates if the filter chain should be disconnected or not
*/
void gf_filter_notification_failure(GF_Filter *filter, GF_Err reason, Bool force_disconnect);

/*! Disconnects a source filter chain between two filters
\param filter the calling filter. This filter is NOT disconnected
\param src_filter the source filter point of the chain to disconnect.
*/
void gf_filter_remove_src(GF_Filter *filter, GF_Filter *src_filter);

/*! Disconnects a filter from fthe chain
\param filter the filter to remove
*/
void gf_filter_remove(GF_Filter *filter);

/*! Sets the number of additional input PID a filter can accept. This overrides the default value of the filter register
\param filter the target filter
\param max_extra_pids the number of additional PIDs this filter can accept
*/
void gf_filter_set_max_extra_input_pids(GF_Filter *filter, u32 max_extra_pids);

/*! Gets the number of additional input PID a filter can accept. This overrides the default value of the filter register
\param filter the target filter
\return max_extra_pids the number of additional PIDs this filter can accept
*/
u32 gf_filter_get_max_extra_input_pids(GF_Filter *filter);


/*! Queries if blocking mode is enabled for the filter
\param filter the target filter
\return GF_TRUE if blocking mode is enabled, GF_FALSE otherwise
*/
Bool gf_filter_block_enabled(GF_Filter *filter);

/*! Indicates the EOS status on input PIDs of this filter shall not be checked when probing for end of stream in the chain
\param filter the target filter
\param do_block if GF_TRUE, prevents EOS checking on input stream, otherwise enables it (default is FALSE upon creation)
*/
void gf_filter_block_eos(GF_Filter *filter, Bool do_block);


/*! Connects a source to this filter.
\note Any filter loaded between the source and the calling filter will not use argument inheritance from the caller.

\param filter the target filter
\param url url of source to connect to, with optional arguments.
\param parent_url url of parent if any
\param inherit_args if GF_TRUE, the source to connect will inherit arguments of the target filter's destination
\param err return code - can be NULL
\return the new source filter instance or NULL if error
*/
GF_Filter *gf_filter_connect_source(GF_Filter *filter, const char *url, const char *parent_url, Bool inherit_args, GF_Err *err);

/*! Connects a destination to this filter
\param filter the target filter
\param url url of destination to connect to, with optional arguments.
\param err return code - can be NULL
\return the new destination filter instance or NULL if error
*/
GF_Filter *gf_filter_connect_destination(GF_Filter *filter, const char *url, GF_Err *err);


/*! Loads a new filter in the session - see \ref gf_fs_load_filter
\param filter the target filter
\param name name and arguments of the filter register to instantiate.
\param err_code error code if any
\return created filter or NULL if filter register cannot be found
*/
GF_Filter *gf_filter_load_filter(GF_Filter *filter, const char *name, GF_Err *err_code);

/*! Checks if a source filter can handle the given URL. The source filter is not loaded.

\param filter the target filter
\param url url of source to connect to, with optional arguments.
\param parent_url url of parent if any
\return GF_TRUE if a source filter can be found for this URL, GF_FALSE otherwise
*/
Bool gf_filter_is_supported_source(GF_Filter *filter, const char *url, const char *parent_url);

/*! Checks if a URL describes a filter

\param filter the target filter
\param url filter description chain, with optional arguments.
\param act_as_source set to GF_TRUE if filter described acts as a source - may be NULL.
\return GF_TRUE if a filter is described by this url, GF_FALSE otherwise
*/
Bool gf_filter_url_is_filter(GF_Filter *filter, const char *url, Bool *act_as_source);

/*! Gets the number of input PIDs connected to a filter
\param filter the target filter
\return number of input PIDs
*/
u32 gf_filter_get_ipid_count(GF_Filter *filter);

/*! Gets an input PIDs connected to a filter
\param filter the target filter
\param idx index of the input PID to retrieve, between 0 and \ref gf_filter_get_ipid_count
\return the input PID, or NULL if not found
*/
GF_FilterPid *gf_filter_get_ipid(GF_Filter *filter, u32 idx);

/*! Gets the number of output PIDs connected to a filter
\param filter the target filter
\return number of output PIDs
*/
u32 gf_filter_get_opid_count(GF_Filter *filter);

/*! Gets an output PIDs connected to a filter
\param filter the target filter
\param idx index of the output PID to retrieve, between 0 and \ref gf_filter_get_opid_count
\return the output PID, or NULL if not found
*/
GF_FilterPid *gf_filter_get_opid(GF_Filter *filter, u32 idx);

/*! Queries buffer max limits on a filter. This is the max of buffer limits on all its connected outputs
\param filter the target filter
\param max_buf will be set to the maximum buffer duration in microseconds - may be NULL
\param max_playout_buf will be set to the maximum playout buffer (the one triggering play) duration in microseconds - may be NULL
*/
void gf_filter_get_output_buffer_max(GF_Filter *filter, u32 *max_buf, u32 *max_playout_buf);

/*! Sets a clock state at session level indicating the time / timestamp of the last rendered frame. This is used by basic audio output
\param filter the target filter
\param time_in_us the system time in us, see \ref gf_sys_clock_high_res
\param media_timestamp the media timestamp associated with this time.
*/
void gf_filter_hint_single_clock(GF_Filter *filter, u64 time_in_us, GF_Fraction64 media_timestamp);

/*! Retrieves the clock state at session level, as set by \ref gf_filter_hint_single_clock
\param filter the target filter
\param time_in_us will be set to the system time in us, see \ref gf_sys_clock_high_res - may be NULL
\param media_timestamp will be set to the media timestamp associated with this time - may be NULL.
*/
void gf_filter_get_clock_hint(GF_Filter *filter, u64 *time_in_us, GF_Fraction64 *media_timestamp);

/*! Explicitly assigns a source ID to a filter. This shall be called before connecting the link_from filter
If no ID is assigned to the linked filter, a dynamic one in the form of _%08X_ (using the filter mem address) will be used

\warning In multithreaded sessions, the session must be locked before the filter creation step and unlocked after calling this function, otherwise graph resolution might happen before \ref gf_filter_set_source is called

\param filter the target filter
\param link_from the filter to link from
\param link_ext any link extensions allowed in link syntax:
\c \#PIDNAME: accepts only PID(s) with name PIDNAME
\c \#TYPE: accepts only PIDs of matching media type. TYPE can be 'audio' 'video' 'scene' 'text' 'font'
\c \#TYPEN: accepts only Nth PID of matching type from source
\c \#P4CC=VAL: accepts only PIDs with property matching VAL.
\c \#PName=VAL: same as above, using the built-in name corresponding to the property.
\c \#P4CC-VAL: accepts only PIDs with property strictly less than VAL (only for 1-dimension number properties).
\c \#P4CC+VAL: accepts only PIDs with property strictly greater than VAL (only for 1-dimension number properties).
\return error code if any
*/
GF_Err gf_filter_set_source(GF_Filter *filter, GF_Filter *link_from, const char *link_ext);

/*! Similar to \ref gf_filter_set_source
 This should be used on source filters when the calling filter is expected to have more possible sources added in the future, thereby dynamically changing its source IDs.
 Typically the compositor running the GUI is one such filter. This variant will make sure the sourceID used in the adaptation chain is always the ID of the source and not the source ID of the calling filter
\param filter the target filter
\param link_from the filter to link from
\param link_ext any link extensions allowed in link syntax:
\return error code if any
*/
GF_Err gf_filter_set_source_restricted(GF_Filter *filter, GF_Filter *link_from, const char *link_ext);

/*! Explicitly reset sourceID of a filter. This shall be called before connecting the filter (eg creating PIDs).

 This is mostly used to reset a source ID of a filter created from a destination (e.g. dasher creating muxers from the MPD URL) where the destination arguments could have sourceIDs specified/

\param filter the target filter
*/
void gf_filter_reset_source(GF_Filter *filter);

/*! Explicitly assigns an ID to a filter. This shall be called before running the session, and cannot be called on a filter with ID assign
\param filter the target filter
\param filter_id the ID to assign. If NULL, a dynmic ID is generated
\return error code if any
*/
GF_Err gf_filter_assign_id(GF_Filter *filter, const char *filter_id);

/*! Gets the ID of a filter
\param filter the target filter
\return ID of the filter, NULL if not defined
*/
const char *gf_filter_get_id(GF_Filter *filter);

/*! Indicates the filter is a likely to block for a long time (typically, network IO).
In multithread mode, this prevents the filter to be scheduled on the main thread, blocking video or audio output.
By default, all filters are created as non-blocking.

\param filter the target filter
\param is_blocking if GF_TRUE, indicates the filter is likely to block
*/
void gf_filter_set_blocking(GF_Filter *filter, Bool is_blocking);

/*! Overrides the filter caps with new caps for this instance. Typically used when an option of the filter changes the capabilities

The new caps are only taken into account for future graph resolutions, any current link from/to the target filter will not be re-solved when calling this function.

\param filter the target filter
\param caps the new set of capabilities to use for the filter. These are NOT copied and shall be valid for the lifetime of the filter
\param nb_caps number of capabilities set
\return error code if any
*/
GF_Err gf_filter_override_caps(GF_Filter *filter, const GF_FilterCapability *caps, u32 nb_caps );

/*! Indicates this filter acts as a sink and will be used as such in graph resolution. Such filters must provide a use_alias function in their registry.
\param filter the target filter
\return error code if any
*/
GF_Err gf_filter_act_as_sink(GF_Filter *filter);

/*! Filter session separator set query*/
typedef enum
{
	/*! queries the character code used to separate between filter arguments*/
	GF_FS_SEP_ARGS=0,
	/*! queries the character code used to separate between argument name and value*/
	GF_FS_SEP_NAME,
	/*! queries the character code used to indicate fragment identifiers (source PIDs, PID properties)*/
	GF_FS_SEP_FRAG,
	/*! queries the character code used to separate items in a list*/
	GF_FS_SEP_LIST,
	/*! queries the character code used to negate values*/
	GF_FS_SEP_NEG,
} GF_FilterSessionSepType;

/*! Queries the character code used as a given separator type in argument names. Used for formatting arguments when loading sources and destinations from inside a filter
\param filter the target filter
\param sep_type the separator type to query
\return character code of the separator
*/
u8 gf_filter_get_sep(GF_Filter *filter, GF_FilterSessionSepType sep_type);

/*! Queries the arguments of the destination arguments. The first output PID connected to a filter with non NULL args will be used (this is a recursive check until end of chain)
\param filter the target filter
\return the argument string of the destination args
*/
const char *gf_filter_get_dst_args(GF_Filter *filter);

/*! Queries the destination name. The first output PID connected to a filter with non NULL args will be used (this is a recursive check until end of chain)
\param filter the target filter
\return the argument string of the destination (SHALL be freed by caller), NULL if none found
*/
char *gf_filter_get_dst_name(GF_Filter *filter);

/*! Get the filter arguments.
\param filter the target filter
\return the argument string of the filter
*/
const char *gf_filter_get_src_args(GF_Filter *filter);

/*! Sends an event on all input PIDs (downstream) or on all output PIDs (upstream)
\param filter the target filter
\param evt the event to send
\param upstream send the even upstream
*/
void gf_filter_send_event(GF_Filter *filter, GF_FilterEvent *evt, Bool upstream);

/*! Trigger reconnection of output PIDs of a filter. This is needed when inserting a filter in the chain while the session is running
\param filter the target filter
\param for_pid reconnects only the given output PID - if NULL, reconnect all output PIDs
\return error if any, GF_EOS if no output pids available
*/
GF_Err gf_filter_reconnect_output(GF_Filter *filter, GF_FilterPid *for_pid);


/*! Indicates that the filter accept and can process events coming from outside the filter chain, typically used by application firing events.
 The event is sent on the process_event function with no associated PID.
\param filter the target filter
\param enable_events if GF_TRUE, the filter is considered an event target
\return error if any
*/
GF_Err gf_filter_set_event_target(GF_Filter *filter, Bool enable_events);

/*! Looks for a built-in property value marked as informative on a filter on all PIDs (inputs and output)
This is a recursive call on both input and output chain.
There is no guarantee that a queried property will still be valid at the setter side upon returning the call, the setter could have
already reassigned it to NULL. To avoids random behavior, the property returned is reference counted so that it is not
destroyed by the setter while the caller uses it.

Properties retrieved shall be released using \ref gf_filter_release_property. Failure to do so will cause memory leaks in the program.

If the propentry pointer references a non-null value, this value will be released using \ref gf_filter_release_property,
so make sure to initialize the pointer to a NULL value on the first call.
This avoids calling  \ref gf_filter_release_property after each get_info in the calling code:

\code{.c}
GF_PropertyEntry *pe=NULL;
const GF_PropertyValue *p;
p = gf_filter_get_info(filter, FOO, &pe);
if (p) { }
p = gf_filter_get_info_str(filter, "BAR", &pe);
if (p) { }
p = gf_filter_pid_get_info(PID, ABCD, &pe);
if (p) { }
p = gf_filter_pid_get_info_str(PID, "MyProp", &pe);
if (p) { }
gf_filter_release_property(pe);
\endcode



\param filter the target filter
\param prop_4cc the code of the built-in property to fetch
\param propentry the property reference object for later release. SHALL not be NULL
\return the property if found NULL otherwise.
*/
const GF_PropertyValue *gf_filter_get_info(GF_Filter *filter, u32 prop_4cc, GF_PropertyEntry **propentry);

/*! Looks for a property value on a filter on all PIDs (inputs and output).
This is a recursive call on both input and output chain
Properties retrieved shall be released using \ref gf_filter_release_property. See \ref gf_filter_pid_get_info for more details.
\param filter the target filter
\param prop_name the name of the property to fetch
\param propentry the property reference object for later release. See \ref gf_filter_pid_get_info for more details.
\return the property if found NULL otherwise
*/
const GF_PropertyValue *gf_filter_get_info_str(GF_Filter *filter, const char *prop_name, GF_PropertyEntry **propentry);

/*! Release a property previously queried, only used for []_get_info_[] functions.
This is a recursive call on both input and output chain
\param propentry the property reference object to be released
*/
void gf_filter_release_property(GF_PropertyEntry *propentry);

/*! Sends a filter argument update
\param filter the target filter
\param target_filter_id if set, the target filter will be changed to the filter with this id if any. otherwise the target filter is the one specified
\param arg_name argument name
\param arg_val argument value
\param propagate_mask propagation flags - 0 means no propagation
*/
void gf_filter_send_update(GF_Filter *filter, const char *target_filter_id, const char *arg_name, const char *arg_val, GF_EventPropagateType propagate_mask);



/*! Filters may request listening on global events.\n
\warning This is not thread safe, the callback will be called directly upon event firing, your filter has to take care of this

API of event filter is likely to change any time soon - used for backward compatibility with some old modules
*/
typedef struct
{
	/*! user data of the listener */
	void *udta;
	/*! callback called when an event should be filtered.
	\param udta user data of the listener
	\param evt the event to be processed
	\param consumed_by_compositor indicates the event was already used by the compositor
	\return GF_TRUE if the event is to be cancelled, GF_FALSE otherwise
	*/
	Bool (*on_event)(void *udta, GF_Event *evt, Bool consumed_by_compositor);
} GF_FSEventListener;

/*! Adds an event listener to the session
\param filter filter object
\param el the event listener to add
\return the error code if any
*/
GF_Err gf_filter_add_event_listener(GF_Filter *filter, GF_FSEventListener *el);

/*! Removes an event listener from the session
\param filter filter object
\param el the event listener to add
\return the error code if any
*/
GF_Err gf_filter_remove_event_listener(GF_Filter *filter, GF_FSEventListener *el);

/*! Forwards an event to the filter session
\param filter filter object
\param evt the event forwarded
\param consumed if set, indicates the event was already consumed/processed before forwarding
\param skip_user if set, indicates the event should only be dispatched to event listeners.
Otherwise, if a user is assigned to the session, the event is forwarded to the user
\return the error code if any
*/
Bool gf_filter_forward_gf_event(GF_Filter *filter, GF_Event *evt, Bool consumed, Bool skip_user);

/*! Forwards an event to the filter session. This is a shortcut for gf_filter_forward_gf_event(session, evt, GF_FALSE, GF_FALSE);
\param filter filter object
\param evt the event forwarded
\return the error code if any
*/
Bool gf_filter_send_gf_event(GF_Filter *filter, GF_Event *evt);

/*! Checks if all sink filters in the session have seen end of stream.
\param filter filter object
\return GF_TRUE if all sinks are in end of stream, GF_FALSE otherwise
*/
Bool gf_filter_all_sinks_done(GF_Filter *filter);

/*! Gets a filter argument value as string for a given argument name..
\param filter filter object
\param arg_name name of the filter argument
\param dump buffer in which any formatting of argument value will take place
\return the string value of the argument, or NULL if argument is not found or is invalid
*/
const char *gf_filter_get_arg_str(GF_Filter *filter, const char *arg_name, char dump[GF_PROP_DUMP_ARG_SIZE]);

/*! Gets a filter argument value for a given argument name..
\param filter filter object
\param arg_name name of the filter argument
\param prop filled with the arguments value, do NOT modify
\return GF_TURE if success, GF_FALSE otherwise (argument is not found or is invalid)
*/
Bool gf_filter_get_arg(GF_Filter *filter, const char *arg_name, GF_PropertyValue *prop);


/*! Checks if a given mime type is supported as input in the parent session
\param filter querying filter
\param mime mime type to query
\return GF_TRUE if mime is supported
*/
Bool gf_filter_is_supported_mime(GF_Filter *filter, const char *mime);


/*! Sends UI event from video output into the session. For now only direct callback to global event handler is used, event is not forwarded down the chain
\param filter triggering filter
\param uievt event to send
\return GF_TRUE if event has been cancelled, FALSE otherwise
*/
Bool gf_filter_ui_event(GF_Filter *filter, GF_Event *uievt);


/*! Registers filter as an OpenGL provider. This is only used by sink filters creating a OpenGL context, to avoid creating another context. Filters registered as OpenGL providers will run on the main thread.
\param filter filter providing OpenGL context
\param do_register if TRUE the filter carries a valid gl context, if FALSE the filter no longer carries a valid GL context
*/
void gf_filter_register_opengl_provider(GF_Filter *filter, Bool do_register);

/*! Requests OpenGL support for this filter. If no OpenGL providers exist, a default provider will be created (GL context creation on hidden window). Filters requiring OpenGL will run on the main thread.

\note Filters using OpenGL should not assume any persistent GL state among calls. Other filters using OpenGL might change the OpenGL context state (depth test, viewport, alpha blending, culling, etc...).

\param filter filter providing OpenGL context
\return error code if any
*/
GF_Err gf_filter_request_opengl(GF_Filter *filter);

/*! Sets OpenGL context active for this filter.
\note There may be several OpenGL context created in the filter session, depending on activated filters. A filter using OpenGL must call this function before issuing any OpenGL calls

\param filter filter asking for OpenGL context activation
\param do_activate if true, context must be activated for the calling thread, otherwise context is being released
\return error code if any
*/
GF_Err gf_filter_set_active_opengl_context(GF_Filter *filter, Bool do_activate);


/*! Count the number of source filters for the given filter matching the given protocol type.
\param filter filter to inspect
\param protocol_scheme scheme of the protocol to test, without ://, eg "http", "rtp", "https"
\param expand_proto if set to GF_TRUE, any source protocol with a name beginning like protocol_scheme will be matched. For example, use this with "http" to match all http and https schemes.
\param enum_pids user function to enumerate PIDs against which the source should be checked . If not set, all source filters will be checked.
\param udta user data for the callback function
\return the number of source filters matched by protocols
*/
u32 gf_filter_count_source_by_protocol(GF_Filter *filter, const char *protocol_scheme, Bool expand_proto, GF_FilterPid * (*enum_pids)(void *udta, u32 *idx), void *udta);

/*! Disables data probing on the given filter. Typically used by filters loading source filters.
\param filter target filter
*/
void gf_filter_disable_probe(GF_Filter *filter);

/*! Disables input connection on the filter. This is used by filters acting both as true sources or demux/processing filters depending on their options.
\param filter target filter
*/
void gf_filter_disable_inputs(GF_Filter *filter);

/*! Checks if some PIDs are still not connected in the graph originating at filter. This is typically used by filters dynamically loading source filters to make sure all PIDs from the source are connected.

\note This does not guarantee that no other PID remove or configure will happen later on, this depends on the source type and is unknown by GPAC's filter architecture.
\param filter target filter
\param stop_at_filter check connections until this filter. If NULL, connections are checked until upper (sink) end of graph
\return GF_TRUE if any filter in the path has pending PID connections
*/
Bool gf_filter_has_pid_connection_pending(GF_Filter *filter, GF_Filter *stop_at_filter);

/*! checks if the some PID connection tasks are still pending at the session level

This can be needed by some filters needing to make sure all their inputs are known before starting producing packets.

\param filter target filter
\return GF_TRUE if some connection tasks are pending, GF_FALSE otherwise
*/
Bool gf_filter_connections_pending(GF_Filter *filter);

/*! Disables blocking check for a given filter

This can be needed by some filters internally managing their blocking state because one of their output is not managed by the filter session.

\param filter target filter
\param prevent_blocking_enabled if GF_TRUE, filter will still be called even if one of its output is in blocking mode
\return error if any
*/
GF_Err gf_filter_prevent_blocking(GF_Filter *filter, Bool prevent_blocking_enabled);

/*! Checks if filter was loaded as part of a link resolution or explicitly loaded by application
\param filter target filter
\return GF_TRUE if filter was loaded for link resolution, GF_FALSE if filter was explicitly loaded by the application
*/
Bool gf_filter_is_dynamic(GF_Filter *filter);

/*! Checks if reporting is turned on at session level.
\param filter target filter
\return GF_TRUE if reporting is enabled, GF_FALSE otherwise
*/
Bool gf_filter_reporting_enabled(GF_Filter *filter);

/*! Updates filter status string and progress. Should not be called if reporting is turned off at session level.
This allows gathering stats from filter in realtime. The status string can be anything but shall not contain '\n' and
should not contain any source or destination URL except for sources and sinks.
\param filter target filter
\param percent percentage (from 0 to 10000) of operation status. If more than 10000 ignored
\param szStatus string giving a status of the filter
\return error code if any
*/
GF_Err gf_filter_update_status(GF_Filter *filter, u32 percent, char *szStatus);

/*! check if session has been scheduled for destruction
\param filter target filter
\return GF_TRUE if session is about to be destroyed
*/
Bool gf_filter_end_of_session(GF_Filter *filter);

/*! used by meta-filters (ffmpeg and co) to report used/unused options. This is needed since these filters might not
know the set of available options at initialize() time.
\param filter target filter
\param arg name of the argument not used/found
\param was_found indicate if option was found ot not
\param sub_opt_name indicate sub-option name, or NULL for regular options. This is used to track unused values in multiple-values options
*/
void gf_filter_report_meta_option(GF_Filter *filter, const char *arg, Bool was_found, const char *sub_opt_name);

/*! used by script to set a per-instance description
\param filter target filter
\param new_desc the new description to set
\return error if any
*/
GF_Err gf_filter_set_description(GF_Filter *filter, const char *new_desc);

/*! get a per-instance description
\param filter target filter
\return the filter instance description, NULL otherwise
*/
const char *gf_filter_get_description(GF_Filter *filter);

/*! used by script to set a per-instance version
\param filter target filter
\param new_version the new version to set
\return error if any
*/
GF_Err gf_filter_set_version(GF_Filter *filter, const char *new_version);

/*! get a per-instance version
\param filter target filter
\return the filter instance version, NULL otherwise
*/
const char *gf_filter_get_version(GF_Filter *filter);

/*! used by script to set a per-instance author
\param filter target filter
\param new_author the new author to set
\return error if any
*/
GF_Err gf_filter_set_author(GF_Filter *filter, const char *new_author);

/*! get a per-instance author
\param filter target filter
\return the filter instance author, NULL otherwise
*/
const char *gf_filter_get_author(GF_Filter *filter);

/*! used by script to set a per-instance help
\param filter target filter
\param new_help the new help to set
\return error if any
*/
GF_Err gf_filter_set_help(GF_Filter *filter, const char *new_help);

/*! get a per-instance help
\param filter target filter
\return the filter instance help, NULL otherwise
*/
const char *gf_filter_get_help(GF_Filter *filter);


/*! used by script to set a per-instance arguments. The passed array shall have a 0 argument at the end and shall be valid
for the lifetime of the filter (not locally copied)
\param filter target filter
\param new_args the new args to set
\return error if any
*/
GF_Err gf_filter_define_args(GF_Filter *filter, GF_FilterArgs *new_args);

/*! get per-instance args
\param filter target filter
\return the filter instance args if any, NULL otherwise
*/
GF_FilterArgs *gf_filter_get_args(GF_Filter *filter);

/*! get per-instance caps
\param filter target filter
\param nb_caps set to the number of caps
\return the filter instance caps if any, NULL otherwise
*/
const GF_FilterCapability *gf_filter_get_caps(GF_Filter *filter, u32 *nb_caps);

/*! probes mime type of a given block of data (should be beginning of file )
\param filter target filter
\param data buffer to probe
\param size size of buffer
\param score ste to the probing score, may be NULL
\return the mime type probed, or NULL if not recognized
*/
const char *gf_filter_probe_data(GF_Filter *filter, u8 *data, u32 size, GF_FilterProbeScore *score);

/*! checks if the given filter is an alias filter created by a multiple sink filter
\param filter target filter
\return GF_TRUE if this is an alias  filter created by a multiple sink filter, GF_FALSE otherwise
*/
Bool gf_filter_is_alias(GF_Filter *filter);

/*! checks if the given filter is in the chain ending up at parent
\param parent end of filter chain to check
\param filter target filter to check
\return GF_TRUE if filter is present in the parent chain, GF_FALSE otherwise
*/
Bool gf_filter_in_parent_chain(GF_Filter *parent, GF_Filter *filter);


/*! Gets statistics for filter
\param filter filter session
\param stats statistics for filter
\return error code if any
*/
GF_Err gf_filter_get_stats(GF_Filter *filter, GF_FilterStats *stats);


/*! Enumerates default arguments of a filter
\param filter filter session
\param idx the 0-based index of the argument to query
\return the argument definition, or NULL if error
*/
const GF_FilterArgs *gf_filter_enumerate_args(GF_Filter *filter, u32 idx);


/*! Reslves URL against locales settings
\param filter filter
\param service_url URL of service to relocate
\param parent_url parent URL of service
\param out_relocated_url - must be GF_MAX_PATH size
\param out_localized_url - must be GF_MAX_PATH size
\return GF_TRUE if success
*/
Bool gf_filter_relocate_url(GF_Filter *filter, const char *service_url, const char *parent_url, char *out_relocated_url, char *out_localized_url);


/*! Probes for link resolution towards a given filter description
\param filter target filter
\param opid_idx output pid index of target filter
\param fname textual description of filter - If a source is used, returns an error. Destination can be identified using dst=URL pattern
\param result_chain resulting chain as comma-separated list, or NULL if error. MUST be freed by caller
\return error if any
*/
GF_Err gf_filter_probe_link(GF_Filter *filter, u32 opid_idx, const char *fname, char **result_chain);

/*! Probes for possible link resolution towards a given filter description. Same as \ref gf_filter_probe_link but tests multiple links

The syntax for each chain is `D;P,filters` with:
- `D`: distance between the source and target, as seen by the graph resolver (some filters may hide their distance)
- `P`: priority of the chain
- `filters`: comma-separated list of filters

\param filter target filter
\param opid_idx output pid index of target filter
\param fname textual description of filter - If a source is used, returns an error. Destination can be identified using dst=URL pattern
\param result_chain resulting chains separated by a pipe character ('|') or NULL if error. MUST be freed by caller
\return error if any
*/
GF_Err gf_filter_probe_links(GF_Filter *filter, u32 opid_idx, const char *fname, char **result_chain);

/*! Gets list of possible destinations for this filter
\param filter target filter
\param opid_idx output pid index of target filter. If negative, will check destinations for any of the output pids
\param result_list resulting list as comma-separated list, or NULL if error. MUST be freed by caller. An empty chain means direct connection is possible
\return error if any, GF_FILTER_NOT_FOUND if no available destinations
*/
GF_Err gf_filter_get_possible_destinations(GF_Filter *filter, s32 opid_idx, char **result_list);

/*! Returns the register of a given filter
\param filter target filter
\return the register object, or NULL if error
*/
const GF_FilterRegister *gf_filter_get_register(GF_Filter *filter);

/*! Prints all possible connections between filter registries for a loaded filter using \code LOG_APP@LOG_INFO \endcode
\param filter filter object
\param print_fn optional callback function for print, otherwise print to stderr
*/
void gf_filter_print_all_connections(GF_Filter *filter, void (*print_fn)(FILE *output, GF_SysPrintArgFlags flags, const char *fmt, ...) );

/*! Force a filter to run on main thread.

\param filter filter object
\param do_tag if GF_TRUE, tags filter to run on main thread, otherwise untags filters

\warning There shall be at most as many with do_tag=GF_FALSE as there were calls with do_tag=GF_TRUE
*/
void gf_filter_force_main_thread(GF_Filter *filter, Bool do_tag);

/*! Check if a filter is a sink, i.e. it has no output capabilities.
 \note a filter may have no outputs but still not be a sink due to dynamic nature of filter linking
\param filter target filter
\return GF_TRUE if filter is a sink, GF_FALSE otherwise
*/
Bool gf_filter_is_sink(GF_Filter *filter);

/*! Check if a filter is a source, i.e. it has no input capabilities
 \note a filter may have no inputs but still not be a source, typically the case for some custom filters loading their sources dynamically
\param filter target filter
\return GF_TRUE if filter is a source, GF_FALSE otherwise
*/
Bool gf_filter_is_source(GF_Filter *filter);

/*! Tags a filter in a given subsession, ignored in non-implicit mode.

If  sourceIDs are used on destination filter, subsession and source IDs are ignored.
If filters do not have the same subsession ID, they cannot link to each
If filters do not have the same sourceID, they cannot link to each other except if destination is a sink

Function does nothing if the filter is allready assigned to a subsession

\note In non-implicit mode, subsession tagging must be done through filter option :FS=

\param filter target filter
\param subsession_id subsession identifier
\param source_id subsession identifier
\return error if any, GF_OK or the value of the already assigned subsession ID
*/
GF_Err gf_filter_tag_subsession(GF_Filter *filter, u32 subsession_id, u32 source_id);

/*! Check if connect errors happened in the filter parent session
\param filter target filter
\return GF_TRUE if parent session has seen connection errors, GF_FALSE otherwise
*/
Bool gf_filter_has_connect_errors(GF_Filter *filter);

/*! Get ID of netcap configuration associated with filter, if any
\param filter target filter
\return netcap ID if set, NULL otherwise
*/
const char *gf_filter_get_netcap_id(GF_Filter *filter);


/*! Sets names of sub-instances involved in a meta-filter instance
\param filter target filter
\param instance_names_list space-separated names of meta filter instances, without meta registry name. eg "negate" for ffavf::f=negate
*/
void gf_filter_meta_set_instances(GF_Filter *filter, const char *instance_names_list);

/*! Gets names of sub-instances involved in a meta-filter instance
\param filter target filter
\return NULL or space-separated names of meta filter instances, without meta registry name. eg "negate" for ffavf::f=negate
*/
const char *gf_filter_meta_get_instances(GF_Filter *filter);


/*! Locates start of gpac option separator in a url path
\param filter target filter
\param path path to analyze
\return NULL or first option found (including option separator)
*/
const char *gf_filter_path_escape_colon(GF_Filter *filter, const char *path);

/*! @} */


/*!
\addtogroup fs_pid Filter PID
\ingroup filters_grp
\brief Filter Interconnection


A PID is a connection between two filters, holding packets to process. Internally, a PID created by a filter (output PID) is different from an input PID to a filter (configure_pid)
but the API has been designed to hide this, so that most PID functions can be called regardless of the input/output nature of the PID.

All setters functions (gf_filter_pid_set*) will fail on an input PID.

The generic design of the architecture is that each filter is free to decide how it handle PIDs and their packets. This implies that the filter session has no clue how
an output PID relates to an input PID (same goes for packets).
Developpers must therefore manually copy PID properties that seem relevant, or more practically copy all properties from input PID to output PID and
reassign output PID properties changed by the filter.

PIDs can be reconfigured multiple times, even potentially changing caps on the fly. The current architecture does not check for capability matching during reconfigure, it is up to
the filter to do so.

It is also up to filters to decide how to handle a an input PID removal: remove the output PID immediately, keep it open to flush internal data or keep generating data on the output.
The usual practice is to remove the output as soon as the input is removed.

Once an input PID has been notified to be removed, it shall no longer be used by the filter, as it may be discarded/freed (PID are NOT reference counted).

@{
 */



/*! Creates a new output PID for the filter. If the filter has a single input PID already connected, the PID properties are copied by default
\param filter the target filter
\return the new output PID
*/
GF_FilterPid *gf_filter_pid_new(GF_Filter *filter);

/*! Removes an output PID from the filter. This will trigger removal of the PID upward in the chain
\param PID the target filter PID to remove
*/
void gf_filter_pid_remove(GF_FilterPid *PID);

/*! Creates an output PID for a raw input filter (file, sockets, pipe, etc). This will assign file name, local name, mime and extension properties to the created PID
\param filter the target filter
\param url URL of the source, SHALL be set
\param local_file path on local host, can be NULL
\param mime_type mime type of the content. If none provided and propbe_data is not null, the data will be probed for mime type resolution
\param fext file extension of the content. If NULL, will be extracted from URL
\param probe_data data of the stream to probe in order to solve its mime type
\param probe_size size of the probe data
\param trust_mime if set and mime_type is set, disables data probing
\param out_pid the output PID to create or update. If no referer PID, a new PID will be created otherwise the PID will be updated
\return error code if any
*/
GF_Err gf_filter_pid_raw_new(GF_Filter *filter, const char *url, const char *local_file, const char *mime_type, const char *fext, const u8 *probe_data, u32 probe_size, Bool trust_mime, GF_FilterPid **out_pid);

/*! Sets a new property on an output PID for built-in property names.
Setting a new property will trigger a PID reconfigure at the consumption point of the next dispatched packet.
Previous properties (ones set before last packet dispatch) will still be valid. You can remove any of them using \ref gf_filter_pid_set_property with NULL property, or reset the properties with \ref gf_filter_pid_reset_properties.
There cannot be two instances of a property a given type/name:
- If a property with same type/name exists and has the same value, assignment will be skipped: this avoids triggering PID reconfiguration when not needed. In that case, if the property contains memory to be passed to the filter session, this memory will be destroyed (eg GF_PROP_STRING_NO_COPY, GF_PROP_DATA_NO_COPY, GF_PROP_STRING_LIST).
- If the values differ, the property will be reassigned. There cannot be tow instances of a proerty value with a given type/name.

Warning: changing a property at the final end of stream (i.e. if no more packets are sent) will have no effect. You must use \ref gf_filter_pid_set_info and  \ref gf_filter_pid_get_info for this.

\param PID the target filter PID
\param prop_4cc the built-in property code to modify
\param value the new value to assign, or NULL if the property is to be removed
\return error code if any
*/
GF_Err gf_filter_pid_set_property(GF_FilterPid *PID, u32 prop_4cc, const GF_PropertyValue *value);

/*! Sets a new property on an output PID - see \ref gf_filter_pid_set_property.
\param PID the target filter PID
\param name the name of the property to modify
\param value the new value to assign, or NULL if the property is to be removed
\return error code if any
*/
GF_Err gf_filter_pid_set_property_str(GF_FilterPid *PID, const char *name, const GF_PropertyValue *value);

/*! Sets a new property on an output PID - see \ref gf_filter_pid_set_property.
\param PID the target filter PID
\param name the name of the property to modify. The name will be copied to the property, and memory destruction performed by the filter session
\param value the new value to assign, or NULL if the property is to be removed
\return error code if any
*/
GF_Err gf_filter_pid_set_property_dyn(GF_FilterPid *PID, char *name, const GF_PropertyValue *value);

/*! Sets a new info property on an output PID for built-in property names.
Similar to \ref gf_filter_pid_set_property, but infos are not copied up the chain and to not trigger PID reconfiguration.
First packet dispatched after calling this function will be marked, and its fetching by the consuming filter will trigger a process_event notification.
If the consuming filter copies properties from source packet to output packet, the flag will be passed to such new output packet.

If an info property with same type/name exists and has the same value, assignment will be skipped. In that case, if the property contains memory to be passed to the filter session, this memory will be destroyed (eg GF_PROP_STRING_NO_COPY, GF_PROP_DATA_NO_COPY, GF_PROP_STRING_LIST).


\param PID the target filter PID
\param prop_4cc the built-in property code to modify
\param value the new value to assign, or NULL if the property is to be removed
\return error code if any
*/
GF_Err gf_filter_pid_set_info(GF_FilterPid *PID, u32 prop_4cc, const GF_PropertyValue *value);

/*! Sets a new info property on an output PID - see \ref gf_filter_pid_set_info
See  \ref gf_filter_pid_set_info
\param PID the target filter PID
\param name the name of the property to modify
\param value the new value to assign, or NULL if the property is to be removed
\return error code if any
*/
GF_Err gf_filter_pid_set_info_str(GF_FilterPid *PID, const char *name, const GF_PropertyValue *value);

/*! Sets a new property on an output PID.
See \ref gf_filter_pid_set_info
\param PID the target filter PID
\param name the name of the property to modify. The name will be copied to the property, and memory destruction performed by the filter session
\param value the new value to assign, or NULL if the property is to be removed
\return error code if any
*/
GF_Err gf_filter_pid_set_info_dyn(GF_FilterPid *PID, char *name, const GF_PropertyValue *value);

/*! Sets user data pointer for a PID - see \ref gf_filter_pid_set_info
\param PID the target filter PID
\param udta user data pointer
*/
void gf_filter_pid_set_udta(GF_FilterPid *PID, void *udta);

/*! Gets user data pointer for a PID
\param PID the target filter PID
\return udta user data pointer
*/
void *gf_filter_pid_get_udta(GF_FilterPid *PID);

/*! get user 32-bits flags
\param PID the target filter PID
\return flags
*/
u32 gf_filter_pid_get_udta_flags(GF_FilterPid *PID);

/*! set user 32-bits flags
\param PID the target filter PID
\param flags the flags (replaces the entire flags))
\return error if any
*/
GF_Err gf_filter_pid_set_udta_flags(GF_FilterPid *PID, u32 flags);

/*! Gets PID name. Mostly used for logging purposes
\param PID the target filter PID
\param name the new PID name. function ignored if NULL.
*/
void gf_filter_pid_set_name(GF_FilterPid *PID, const char *name);

/*! Gets PID name
\param PID the target filter PID
\return PID name
*/
const char *gf_filter_pid_get_name(GF_FilterPid *PID);

/*! Gets filter name of input PID
\param PID the target filter PID
\return name of the filter owning this input PID
*/
const char *gf_filter_pid_get_filter_name(GF_FilterPid *PID);

/*! Gets the source arguments of the PID, walking down the chain until the source filter
\param PID the target filter PID
\param for_unicity if GF_TRUE, will return the arguments of the first filter responsible for a fan-out leading to this PID
\return argument of the source filter
*/
const char *gf_filter_pid_orig_src_args(GF_FilterPid *PID, Bool for_unicity);

/*! Gets the source filter name or class name for the PID, walking down the chain until the source filter (only the first input PID of each filter is used).
\param PID the target filter PID
\return argument of the source filter
*/
const char *gf_filter_pid_get_source_filter_name(GF_FilterPid *PID);

/*! Gets the arguments for the filter
\param PID the target filter PID
\return arguments of the source filter
*/
const char *gf_filter_pid_get_args(GF_FilterPid *PID);

/*! Sets max buffer requirement of an output PID. Typically used by audio to make sure several packets can be dispatched on a PID
that would otherwise block after one packet
\param PID the target filter PID
\param total_duration_us buffer max occupancy in us
*/
void gf_filter_pid_set_max_buffer(GF_FilterPid *PID, u32 total_duration_us);

/*! Returns max buffer requirement of a PID.
\param PID the target filter PID
\return buffer max in us
*/
u32 gf_filter_pid_get_max_buffer(GF_FilterPid *PID);

/*! Checks if a given filter is in the PID parent chain. This is used to identify sources (rather than checking URL/...)
\param PID the target filter PID
\param filter the source filter to check
\return GF_TRUE if filter is a source for that PID, GF_FALSE otherwise
*/
Bool gf_filter_pid_is_filter_in_parents(GF_FilterPid *PID, GF_Filter *filter);

/*! Checks if a given PID has a common filter with another PID in the parent graph
\param PID the target filter PID
\param other_pid the other PID to check
\return GF_TRUE if a filter is found that is outputing these two PIDs, GF_FALSE otherwise
*/
Bool gf_filter_pid_share_origin(GF_FilterPid *PID, GF_FilterPid *other_pid);

/*! Gets current buffer levels of the PID
\param PID the target filter PID
\param max_units maximum number of packets allowed - can be 0 if buffer is measured in time
\param nb_pck number of packets in PID
\param max_duration maximum buffer duration allowed in us - can be 0 if buffer is measured in units
\param duration buffer duration in us
\return GF_TRUE if normal buffer query, GF_FALSE if final session flush, in which case buffer might never complete
*/
Bool gf_filter_pid_get_buffer_occupancy(GF_FilterPid *PID, u32 *max_units, u32 *nb_pck, u32 *max_duration, u32 *duration);

/*! Sets loose connect for a PID, avoiding to throw an error if connection of the PID fails. Used by the compositor filter which acts as both sink and filter.
\param PID the target filter PID
*/
void gf_filter_pid_set_loose_connect(GF_FilterPid *PID);

/*! Adds PID properties from textual description - this does not reset the PID properties
\param PID the target filter PID
\param args one or more serialized properties to set, as documented in gpac -h doc
\param direct_merge if true, next packet to be sent will not trigger a property change
\param use_default_seps if GF_TRUE, the serialized properties are using the default separator set, otherwise they are using the current separator set of the session
\return Error if any
*/
GF_Err gf_filter_pid_push_properties(GF_FilterPid *PID, char *args, Bool direct_merge, Bool use_default_seps);


/*! Negotiate a given property on an input PID for built-in properties
Filters may accept some PID connection but may need an adaptation chain to be able to process packets, eg change pixel format or sample rate
This function will trigger a reconfiguration of the filter chain to try to adapt this. If failing, the filter chain will disconnect
This process is asynchronous, the filter asking for a PID negotiation will see the notification through a pid_reconfigure if success.
\param PID the target filter PID - this MUST be an input PID
\param prop_4cc the built-in property code to negotiate
\param value the new value to negotiate, SHALL NOT be NULL
\return error code if any
*/
GF_Err gf_filter_pid_negotiate_property(GF_FilterPid *PID, u32 prop_4cc, const GF_PropertyValue *value);

/*! Negotiate a given property on an input PID for regular properties
see \ref gf_filter_pid_negotiate_property
\param PID the target filter PID - this MUST be an input PID
\param name name of the property to negotiate
\param value the new value to negotiate, SHALL NOT be NULL
\return error code if any
*/
GF_Err gf_filter_pid_negotiate_property_str(GF_FilterPid *PID, const char *name, const GF_PropertyValue *value);

/*! Negotiate a given property on an input PID for regular properties
see \ref gf_filter_pid_negotiate_property
\param PID the target filter PID - this MUST be an input PID
\param name the name of the property to modify. The name will be copied to the property, and memory destruction performed by the filter session
\param value the new value to negotiate, SHALL NOT be NULL
\return error code if any
*/
GF_Err gf_filter_pid_negotiate_property_dyn(GF_FilterPid *PID, char *name, const GF_PropertyValue *value);

/*! Queries a negotiated built-in capability on an output PID
Filters may check if a property negotiation was done on an output PID, and check the property value.
This can be done on an output PID in a filter->reconfigure_output if the filter accepts caps negotiation
This can be done on an input PID in a generic reconfigure_pid

\param PID the target filter PID
\param prop_4cc the built-in property code to negotiate
\return the negotiated property value
*/
const GF_PropertyValue *gf_filter_pid_caps_query(GF_FilterPid *PID, u32 prop_4cc);

/*! Queries a negotiated capability on an output PID - see \ref gf_filter_pid_caps_query
\param PID the target filter PID
\param prop_name the property name to negotiate
\return the negotiated property value
*/
const GF_PropertyValue *gf_filter_pid_caps_query_str(GF_FilterPid *PID, const char *prop_name);

/*! Statistics for PID*/
typedef struct
{
	/*! if set, indicates the PID is disconnected and stats are not valid*/
	u32 disconnected;
	/*! average process rate on that PID in bits per seconds*/
	u32 average_process_rate;
	/*! max process rate on that PID in bits per seconds*/
	u32 max_process_rate;
	/*! average bitrate for that PID*/
	u32 average_bitrate;
	/*! max bitrate for that PID*/
	u32 max_bitrate;
	/*! number of packets processed on that PID*/
	u32 nb_processed;
	/*! max packet process time of the filter in us*/
	u32 max_process_time;
	/*! total process time of the filter in us*/
	u64 total_process_time;
	/*! process time of first packet of the filter in us*/
	u64 first_process_time;
	/*! process time of the last packet on that PID in us*/
	u64 last_process_time;
	/*! minimum frame duration on that PID in us*/
	u32 min_frame_dur;
	/*! number of saps 1/2/3 on that PID*/
	u32 nb_saps;
	/*! max process time of SAP packets on that PID in us*/
	u32 max_sap_process_time;
	/*! total process time of SAP packets on that PID in us*/
	u64 total_sap_process_time;

	/*! max buffer time in us - only set when querying decoder stats*/
	u64 max_buffer_time;
	/*! max playout buffer time in us - only set when querying decoder stats*/
	u64 max_playout_time;
	/*! min playout buffer time in us - only set when querying decoder stats*/
	u64 min_playout_time;
	/*! current buffer time in us - only set when querying decoder stats*/
	u64 buffer_time;
	/*! number of units in input buffer of the filter - only set when querying decoder stats*/
	u32 nb_buffer_units;

	/*! last RT info update time in microsec (cf \ref gf_sys_clock_high_res)  - input pid only */
	u64 last_rt_report;
	/*! estimated round-trip time in ms - input pid only */
	u32 rtt;
	/*! estimated interarrival jitter in microseconds - input pid only */
	u32 jitter;
	/*! loss rate in per-thousand - input pid only */
	u32 loss_rate;

	/*! timestamp and timescale of last packet droped
		- For input PID, set to last packet dropped
		- For output PID, set to maximum TS value of last packet dropped on all PID destinations
	*/
	GF_Fraction64 last_ts_drop;
	/*! timestamp and timescale of last packet send on PID (for output PID) or on parent PID (for input PID)	*/
	GF_Fraction64 last_ts_sent;
} GF_FilterPidStatistics;

/*! Direction for stats querying*/
typedef enum
{
	/*! statistics are fetched on the current PID's parent filter. If the PID is an output PID, the statistics are fetched on all the destinations for that PID*/
	GF_STATS_LOCAL = 0,
	/*! statistics are fetched on the current PID's parent filter. The statistics are fetched on all input of the parent filter
	If the pid is an output pid, this is equivalent to GF_STATS_LOCAL*/
	GF_STATS_LOCAL_INPUTS,
	/*! statistics are fetched on all inputs of the next decoder filter up the chain (towards the sink)*/
	GF_STATS_DECODER_SINK,
	/*! statistics are fetched on all inputs of the previous decoder filter down the chain (towards the source)*/
	GF_STATS_DECODER_SOURCE,
	/*! statistics are fetched on all inputs of the next encoder filter up the chain (towards the sink)*/
	GF_STATS_ENCODER_SINK,
	/*! statistics are fetched on all inputs of the previous encoder filter down the chain (towards the source)*/
	GF_STATS_ENCODER_SOURCE,
	/*! statistics are fetched on all inputs of the next sink filter of the chain*/
	GF_STATS_SINK
} GF_FilterPidStatsLocation;

/*! Gets statistics for the PID
\param PID the target filter PID
\param stats the retrieved statistics
\param location indicates where to locate the filter to query stats on it.
\return error code if any
*/
GF_Err gf_filter_pid_get_statistics(GF_FilterPid *PID, GF_FilterPidStatistics *stats, GF_FilterPidStatsLocation location);

/*! Resets current properties of the PID
\param PID the target filter PID
\return error code if any
*/
GF_Err gf_filter_pid_reset_properties(GF_FilterPid *PID);


/*! Function protoype for filtering properties.
\param cbk callback data
\param prop_4cc the built-in property code
\param prop_name property name
\param src_prop the property value in the source packet
\return GF_TRUE if the property shall be merged, GF_FALSE otherwise
*/
typedef Bool (*gf_filter_prop_filter)(void *cbk, u32 prop_4cc, const char *prop_name, const GF_PropertyValue *src_prop);

/*! Push a new set of properties on destination PID using all properties from source PID. Old properties in destination will be lost (i.e. reset properties is always performed during copy properties)
\param dst_pid the destination filter PID
\param src_pid the source filter PID
\return error code if any
*/
GF_Err gf_filter_pid_copy_properties(GF_FilterPid *dst_pid, GF_FilterPid *src_pid);

/*! Push a new set of properties on destination PID, using all properties from source PID, potentially filtering them. Currently defined properties are not reseted.
\param dst_pid the destination filter PID
\param src_pid the source filter PID
\param filter_prop callback filtering function
\param cbk callback data passed to the callback function
\return error code if any
*/
GF_Err gf_filter_pid_merge_properties(GF_FilterPid *dst_pid, GF_FilterPid *src_pid, gf_filter_prop_filter filter_prop, void *cbk );

/*! Gets a built-in property of the PID
Warning: properties are only valid until the next configure_pid is called. Attempting to use a property
value (either the pointer or one of the value) queried before the current configure_pid will result in
 unpredictable behavior, potentially crashes.
\param PID the target filter PID
\param prop_4cc the code of the built-in property to retrieve
\return the property if found or NULL otherwise
*/
const GF_PropertyValue *gf_filter_pid_get_property(GF_FilterPid *PID, u32 prop_4cc);

/*! Gets a property of the PID - see \ref gf_filter_pid_get_property
\param PID the target filter PID
\param prop_name the name of the property to retrieve
\return the property if found or NULL otherwise
*/
const GF_PropertyValue *gf_filter_pid_get_property_str(GF_FilterPid *PID, const char *prop_name);

/*! Enumerates properties of a PID - see \ref gf_filter_pid_get_property
\param PID the target filter PID
\param idx input/output index of the current property. 0 means first. Incremented by 1 upon success
\param prop_4cc set to the built-in code of the property if built-in
\param prop_name set to the name of the property if not built-in
\return the property if found or NULL otherwise (end of enumeration)
*/
const GF_PropertyValue *gf_filter_pid_enum_properties(GF_FilterPid *PID, u32 *idx, u32 *prop_4cc, const char **prop_name);

/*! Enumerates info of a PID
\param PID the target filter PID
\param idx input/output index of the current info. 0 means first. Incremented by 1 upon success
\param prop_4cc set to the built-in code of the info if built-in
\param prop_name set to the name of the info if not built-in
\return the property if found or NULL otherwise (end of enumeration)
*/
const GF_PropertyValue *gf_filter_pid_enum_info(GF_FilterPid *PID, u32 *idx, u32 *prop_4cc, const char **prop_name);

/*! Sets PID framing mode. filters can consume packets as they arrive, or may want to only process full frames/files
\param PID the target filter PID
\param requires_full_blocks if GF_TRUE, the packets on the PID will be reaggregated to form complete frame/files.
\return error code if any
*/
GF_Err gf_filter_pid_set_framing_mode(GF_FilterPid *PID, Bool requires_full_blocks);

/*! Gets cumulated buffer duration of PID (recursive until source)
\param PID the target filter PID
\param check_pid_full if GF_TRUE, returns 0 if the PID buffer is not yet full, or GF_FILTER_NO_TS if pid buffer is full
\return the duration in us, or -1 if session is in final flush
*/
u64 gf_filter_pid_query_buffer_duration(GF_FilterPid *PID, Bool check_pid_full);

/*! Try to force a synchronous flush of the filter chain downwards this PID. If refetching a packet returns NULL, this failed.
\param PID the target filter PID
*/
void gf_filter_pid_try_pull(GF_FilterPid *PID);


/*! Looks for a built-in property value on a  PIDs. This is a recursive call on input chain
Info query is NOT threadsafe in gpac, you
Properties retrieved shall be released using \ref gf_filter_release_property. See \ref gf_filter_pid_get_info for more details.
\param PID the target filter PID to query
\param prop_4cc the code of the built-in property to fetch
\param propentry the property reference object for later release. See \ref gf_filter_pid_get_info for more details.
\return the property if found NULL otherwise
*/
const GF_PropertyValue *gf_filter_pid_get_info(GF_FilterPid *PID, u32 prop_4cc, GF_PropertyEntry **propentry);

/*! Looks for a property value on a  PIDs. This is a recursive call on both input and output chain
Properties retrieved shall be released using \ref gf_filter_release_property. See \ref gf_filter_pid_get_info for more details.
\param PID the target filter PID to query
\param prop_name the name of the property to fetch
\param propentry the property reference object for later release. See \ref gf_filter_pid_get_info for more details.
\return the property if found NULL otherwise
*/
const GF_PropertyValue *gf_filter_pid_get_info_str(GF_FilterPid *PID, const char *prop_name, GF_PropertyEntry **propentry);


/*! Signals end of stream on a PID. Each filter needs to call this when EOS is reached on a given stream since there is no explicit link between input PIDs and output PIDs
\param PID the target filter PID
*/
void gf_filter_pid_set_eos(GF_FilterPid *PID);

/*! Signals end of stream on a PID but force stream to be kept alive - used by source filters triggering a pipeline flush, the source filter will remain active after this call
 The flush signal sets all receiving PIDs into end of stream mode
\param PID the target filter PID
*/
void gf_filter_pid_send_flush(GF_FilterPid *PID);

/*! Checks for end of stream has been signaled a PID input chain.
This is a recursive call on input chain. The function is typically used to abort buffering or synchronisation init in muxers.
\param PID the target filter PID
\return GF_TRUE if end of stream was signaled on the input chain
*/
Bool gf_filter_pid_has_seen_eos(GF_FilterPid *PID);

/*! Checks for end of stream has been signaled a PID. Contrary to \ref gf_filter_pid_has_seen_eos this is not a recursive call and only checks the given pid.
\param PID the target filter PID
\return GF_TRUE if end of stream was signaled for that pid (there may be pending packets in queue)
*/
Bool gf_filter_pid_eos_received(GF_FilterPid *PID);

/*! Checks for end of stream signaling on a PID.
\param PID the target filter PID
\return GF_TRUE if end of stream is set on that PID (no more packet in queue)
*/
Bool gf_filter_pid_is_eos(GF_FilterPid *PID);

/*! Checks for flush-only end of stream signaling on a PID. Some filters may request a flush of the pipeline but will send further packets later on. This is signaled by a flush end of stream state
 Only filters storing the state of the pids internally should need to check this state.

\param PID the target filter PID
\return GF_TRUE if end of stream is temporary set on that PID (no more packet in queue)
*/
Bool gf_filter_pid_is_flush_eos(GF_FilterPid *PID);

/*! Checks if there is a packet ready on an input PID.
\param PID the target filter PID
\return GF_TRUE if no packet in buffers
*/
Bool gf_filter_pid_first_packet_is_empty(GF_FilterPid *PID);

/*! Checks if the first packet on an input PID is a blocking ref.
\param PID the target filter PID
\return GF_TRUE if  packet is valid and blocking, GF_FALSE otherwise
*/
Bool gf_filter_pid_first_packet_is_blocking_ref(GF_FilterPid *PID);

/*! Gets the first packet in the input PID buffer.
This may trigger a reconfigure signal on the filter. If reconfigure is not OK, returns NULL and the PID passed to the filter NO LONGER EXISTS (implicit remove)
The packet is still present in the PID buffer until explicitly removed by \ref gf_filter_pid_drop_packet

The returned packet is only valid for the current filter execution (process callback, task, ...), and may be discarded in-between calls, typically when the session is aborted.
If a filter needs to keep a packet across calls, it must use \ref gf_filter_pck_ref and \ref gf_filter_pck_unref

If no packet is returned, the pid may be empty, in end of stream (cf \ref gf_filter_pid_is_eos) or in flush (cf \ref gf_filter_pid_is_flush_eos).

The first time this function is called on a PID at a flush point, it will return NULL even if some packets are pending. This allows the calling filter to detect if a flush point is reached and take appropriate actions.
Subsequent calls will return the pending packet if any.

\param PID the target filter PID
\return packet or NULL of empty or reconfigure error
*/
GF_FilterPacket * gf_filter_pid_get_packet(GF_FilterPid *PID);

/*! Fetches the CTS of the first packet in the input PID buffer.
\param PID the target filter PID
\param cts set to the composition time of the first packet, in PID timescale
\return GF_TRUE if cts was fetched, GF_FALSE otherwise
*/
Bool gf_filter_pid_get_first_packet_cts(GF_FilterPid *PID, u64 *cts);

/*! Drops the first packet in the input PID buffer.
\param PID the target filter PID
*/
void gf_filter_pid_drop_packet(GF_FilterPid *PID);

/*! Gets the number of packets in input PID buffer.
\param PID the target filter PID
\return the number of packets
*/
u32 gf_filter_pid_get_packet_count(GF_FilterPid *PID);

/*! Checks the capability of the input PID match its destination filter.
\param PID the target filter PID
\return GF_TRUE if match , GF_FALSE otherwise
*/
Bool gf_filter_pid_check_caps(GF_FilterPid *PID);

/*! Checks if the PID would enter a blocking state if a new packet is sent.
This function should be called by eg demuxers to regulate the rate at which they send packets

\note PIDs are never fully blocking in GPAC, a filter requesting an output packet should usually get one unless something goes wrong
\param PID the target filter PID
\return GF_TRUE if PID would enter blocking state , GF_FALSE otherwise
*/
Bool gf_filter_pid_would_block(GF_FilterPid *PID);

/*! Checks if the PID is sparse. A sparse PID may have holes in its timeline.

A sparse PID is always considered blocking for the regulation, even if \ref gf_filter_pid_would_block for this PID can return FALSE (buffers not full).
This avoids unblocking a filter when only its sparse output PIDs are not full (typically text streams).

A PID is sparse if:
- it has the property GF_PROP_PID_SPARSE set to true
- or it does not have the property GF_PROP_PID_SPARSE defined and it is not an audio, video or file stream.

\param PID the target filter PID
\return GF_TRUE if PID is sparse , GF_FALSE otherwise
*/
Bool gf_filter_pid_is_sparse(GF_FilterPid *PID);

/*! Shortcut to access the timescale of the PID - faster than get property as the timescale is locally cached for buffer management
\param PID the target filter PID
\return the PID timescale
*/
u32 gf_filter_pid_get_timescale(GF_FilterPid *PID);

/*! Clears the end of stream flag on a PID.
\note The end of stream is automatically cleared when a new packet is dispatched; This function is used to clear it asap, before next packet dispacth (period switch in dash for example).
\param PID the target filter PID
\param all_pids if sets, clear end oof stream for all PIDs coming from the same filter as the target PID
*/
void gf_filter_pid_clear_eos(GF_FilterPid *PID, Bool all_pids);

/*! Indicates how clock references (PCR of MPEG-2) should be handled.
By default these references are passed from input packets to output packets by the filter session (this assumes the filter doesn't modify composition timestamps).
This default can be changed with this function.
\param PID the target filter PID
\param filter_in_charge if set to GF_TRUE, clock references are not forwarded by the filter session and the filter is in charge of handling them
*/
void gf_filter_pid_set_clock_mode(GF_FilterPid *PID, Bool filter_in_charge);

/*! Resolves file template using PID properties and file index. Templates follow the DASH mechanism:

- $KEYWORD$ or $KEYWORD%0nd$ are replaced in the template with the resolved value,

- $$ is an escape for $

Supported KEYWORD (case insensitive):
- num: replaced by file_number (usually matches GF_PROP_PCK_FILENUM, but this property is not used in the solving mechanism)
- PID: ID of the source PID
- URL: URL of source file
- File: path on disk for source file - if resolved value contains a URL scheme (e.g. foo://), it is ignored
- p4cc=ABCD: uses PID property with 4CC ABCD
- pname=VAL: uses PID property with name VAL (either built-in prop name or other peroperty name)

\param PID the target filter PID
\param szTemplate source template to solve
\param szFinalName buffer for final name
\param file_number number of file to use
\param file_suffix if not null, will be appended after the value of the §File$ keyword if present
\return error if any
*/
GF_Err gf_filter_pid_resolve_file_template(GF_FilterPid *PID, const char szTemplate[GF_MAX_PATH], char szFinalName[GF_MAX_PATH], u32 file_number, const char *file_suffix);


/*! Same as \ref  gf_filter_pid_resolve_file_template but overrides file name with given name
\param PID the target filter PID
\param szTemplate source template to solve
\param szFinalName buffer for final name
\param file_number number of file to use
\param file_suffix if not null, will be appended after the value of the §File$ keyword if present
\param file_name if not null, will be used instead of PID URL or local path
\return error if any
*/
GF_Err gf_filter_pid_resolve_file_template_ex(GF_FilterPid *PID, const char szTemplate[GF_MAX_PATH], char szFinalName[GF_MAX_PATH], u32 file_number, const char *file_suffix, const char *file_name);


/*! Sets discard mode on or off on an input PID. When discard is on, all input packets for this PID are no longer dispatched.

This only affect the current PID, not the source filter(s) for that PID.

PID reconfigurations are still forwarded to the filter, so that a filter may decide to re-enable regular mode. Packets sent after a PID reconfiguration are kept until the PID is reconfigured, and discarded if the PID is still in discard mode.

This is typically needed for filters that stop consuming data for a while (dash forced period duration for example) but may resume
consumption later on (stream moving from period 1 to period 2 for example).

\param PID the target filter PID
\param discard_on enables/disables discard
\return error if any
*/
GF_Err gf_filter_pid_set_discard(GF_FilterPid *PID, Bool discard_on);

/*! Discard blocking mode for PID on end of stream. The filter is blocked when all output PIDs are in end of stream, this function unblocks the filter.
This can be needed for playlist type filters dispatching end of stream at the end of each file but setting up next file in
the following process() call.

\param PID the target filter PID
*/
void gf_filter_pid_discard_block(GF_FilterPid *PID);

/*! Gets URL argument of first destination of PID if any - memory shall be freed by caller.
\param PID the target filter PID
\return destination URL string or NULL if error
*/
char *gf_filter_pid_get_destination(GF_FilterPid *PID);

/*! Gets URL  argument of first source of PID if any - memory shall be freed by caller.
\param PID the target filter PID
\return source URL string or NULL if error
*/
char *gf_filter_pid_get_source(GF_FilterPid *PID);

/*! Indicates that this output PID requires a sourceID on the destination filter to be present. This prevents trying to link to other filters with no source IDs but
accepting the PID
\param PID the target filter PID
\return error code if any
*/
GF_Err gf_filter_pid_require_source_id(GF_FilterPid *PID);

/*! Enables decoding time reconstruction on PID for packets with DTS not set. If not enabled (default), dts not set implies dts = cts
\param PID the target filter PID
\param do_recompute if set, dts will be recomputed when not set
*/
void gf_filter_pid_recompute_dts(GF_FilterPid *PID, Bool do_recompute);

/*! Queries minimum packet duration as computed from DTS/CTS info on the PID
\param PID the target filter PID
\return minimum packet duration computed
*/
u32 gf_filter_pid_get_min_pck_duration(GF_FilterPid *PID);


/*! Sends an event down the filter chain for input PID, or up the filter chain for output PIDs.
\param PID the target filter PID
\param evt the event to send
*/
void gf_filter_pid_send_event(GF_FilterPid *PID, GF_FilterEvent *evt);


/*! Helper function to init play events, that checks the PID \ref GF_FilterPidPlaybackMode and adjust start/speed accordingly. This does not send the event.
\param PID the target filter PID
\param evt the event to initialize
\param start playback start time of request
\param speed playback speed time of request
\param log_name name used for logs in case of capability mismatched
*/
void gf_filter_pid_init_play_event(GF_FilterPid *PID, GF_FilterEvent *evt, Double start, Double speed, const char *log_name);

/*! Check if the given PID is marked as playing or not.
\param PID the target filter PID
\return GF_TRUE if PID is currently playing, GF_FALSE otherwise
*/
Bool gf_filter_pid_is_playing(GF_FilterPid *PID);

/*! Enables direct dispatch of packets to connected filters. This mode is useful when a filter may send a very large number of packets
in one process() call; this is for example the case of the isobmff muxer in interleave mode. Using this mode avoids overloading
the PID buffer with packets.
If the session is multi-threaded, this parameter has no effect.
\param PID the target filter PID
\return GF_TRUE if PID is currently playing, GF_FALSE otherwise
*/
GF_Err gf_filter_pid_allow_direct_dispatch(GF_FilterPid *PID);

/*! Gets the private stack of the alias filter associated with an input PID, if any

 \note The filter type of the alias is always the type of the filter holding the input PID connection.
\param PID the target filter PID
\return the temporary alias filter private stack, NULL otherwise
*/
void *gf_filter_pid_get_alias_udta(GF_FilterPid *PID);

/*! Gets the filter owning the  input PID
\param PID the target filter PID
\return the filter owning the PID or NULL if error
*/
GF_Filter *gf_filter_pid_get_source_filter(GF_FilterPid *PID);

/*! Enumerates the destination filters of an output PID
\param PID the target filter PID
\param idx  the target destination index
\return the destination filter for the given index, or NULL if error
*/
GF_Filter *gf_filter_pid_enum_destinations(GF_FilterPid *PID, u32 idx);

/*! Ignore this PID in blocking mode estimations.

This is typically used when a filter consumes N pids, with some at very low frequency for which an empty queue should not imply unblocking the filter to refill the queue.

\param PID the target filter PID
\param do_ignore if GF_TRUE, the PID will not be considered when trying to unblock the filter
\return error if any
*/
GF_Err gf_filter_pid_ignore_blocking(GF_FilterPid *PID, Bool do_ignore);

/*! Gets next estimated time on  this PID, ie last_pck(DTS+dur) or last_pck(CTS+dur)

\param PID the target filter PID
\return GF_FILTER_NO_TS or estimated time
*/
u64 gf_filter_pid_get_next_ts(GF_FilterPid *PID);

/*! Checks if a decoder is present in parent chain of this pid.
This is a recursive call on input chain. The function is typically used when setting up buffer levels on raw media pids.
\param PID the target filter PID
\return GF_TRUE if a decoder is present in input chain, GF_FALSE otherwise
*/
Bool gf_filter_pid_has_decoder(GF_FilterPid *PID);


/*! Sets real-time stats on PID (input PID only for now)

\param PID the target filter PID
\param rtt_ms estimated round-trip time in ms
\param jitter_us estimated packet inter-arrival jitter in us
\param loss_rate loss rate in per-thousand
\return error if any
*/
GF_Err gf_filter_pid_set_rt_stats(GF_FilterPid *PID, u32 rtt_ms, u32 jitter_us, u32 loss_rate);


/*! Returns RFC6381 "codec" string of a PID

\param PID the target filter PID
\param szCodec string to be written, must be RFC6381_CODEC_NAME_SIZE_MAX at least
\param force_inband forces inband signaling for avc/hevc/etc
\param force_sbr forces SBR signaling for AAC
\param tile_base_dcd decoder config of tiled base track if known, may be NULL otherwise
\param out_inband_forced set to 1 if inband is to be forced (dasher only) - may be NULL
\return error if any
*/
GF_Err gf_filter_pid_get_rfc_6381_codec_string(GF_FilterPid *PID, char *szCodec, Bool force_inband, Bool force_sbr, const GF_PropertyValue *tile_base_dcd, u32 *out_inband_forced);

/*! @} */


/*!
\addtogroup fs_pck Filter Packet
\ingroup filters_grp
\brief Filter data exchange

 Packets consist in block of data or reference to such blocks, passed from the source to the sink only.
Internally, a packet created by a filter (output packet) is different from an input packet to a filter (\ref gf_filter_pid_get_packet)
but the API has been designed to hide this, so that most packet functions can be called regardless of the input/output nature of the PID.

Packets have native attributes (timing, sap state, ...) but may also have any number of properties associated to them.

The generic design of the architecture is that each filter is free to decide how it handle PIDs and their packets. This implies that the filter session has no clue how
an output packet relates to an input packet.
Developpers must therefore manually copy packet properties that seem relevant, or more practically copy all properties from input packet to output packet and
reassign output packet properties changed by the filter.

In order to handle reordering of packets, it is possible to keep references to either packets (may block the filter chain), or packet properties.

Packets shall always be dispatched in their processing order (decode order). If reordering upon reception is needed, or AU interleaving is used, a filter SHALL do the reordering.
However, packets do not have to be send in their creation order: a created packet is not assigned to PID buffers until it is sent.

@{
 */


/*! Keeps a reference to the given input packet. The packet shall be released at some point using \ref gf_filter_pck_unref

 Filters keeping reference to packets should check if the packet is a blocking reference using gf_filter_pck_is_blocking_ref. If this is the case, the input chain will likely be blocked until the packet reference is released.
\param pck the target input packet
\return error if any
*/
GF_Err gf_filter_pck_ref(GF_FilterPacket **pck);

/*! Same as \ref gf_filter_pck_ref but doesn't use pointer to packet
\param pck the target input packet
\return the new reference to the packet
*/
GF_FilterPacket *gf_filter_pck_ref_ex(GF_FilterPacket *pck);

/*! Remove a reference to the given input packet. The packet might be destroyed after that call.
\param pck the target input packet
*/
void gf_filter_pck_unref(GF_FilterPacket *pck);

/*! Creates a reference to the packet properties, but not to the data.
This is mostly useful for encoders/decoders/filters with delay, where the input packet needs to be released before getting the corresponding output (frame reordering & co).
This allows merging back packet properties after some delay without blocking the filter chain.
\param pck the target input packet
\return error if any
*/
GF_Err gf_filter_pck_ref_props(GF_FilterPacket **pck);


/*! Allocates a new packet on the output PID with associated allocated data.
The packet has by default no DTS, no CTS, no duration framing set to full frame (start=end=1) and all other flags set to 0 (including SAP type).
\param PID the target output PID
\param data_size the desired size of the packet - can be changed later
\param data set to the writable buffer of the created packet
\return new packet or NULL if allocation error or not an output PID
*/
GF_FilterPacket *gf_filter_pck_new_alloc(GF_FilterPid *PID, u32 data_size, u8 **data);


/*! Allocates a new packet on the output PID referencing internal data.
The packet has by default no DTS, no CTS, no duration framing set to full frame (start=end=1) and all other flags set to 0 (including SAP type).
\param PID the target output PID
\param data the data block to dispatch
\param data_size the size of the data block to dispatch
\param destruct the callback function used to destroy the packet when no longer used - may be NULL
\return new packet or NULL if allocation error or not an output PID
*/
GF_FilterPacket *gf_filter_pck_new_shared(GF_FilterPid *PID, const u8 *data, u32 data_size, gf_fsess_packet_destructor destruct);

/*! Allocates a new packet on the output PID referencing data of some input packet.
The packet has by default no DTS, no CTS, no duration framing set to full frame (start=end=1) and all other flags set to 0 (including SAP type).
\param PID the target output PID
\param data_offset offset in the source data block
\param data_size the size of the data block to dispatch - if 0, the entire data of the source packet beginning at offset is used
\param source_packet the source packet this data belongs to (at least from the filter point of view).
\return new packet or NULL if allocation error or not an output PID
*/
GF_FilterPacket *gf_filter_pck_new_ref(GF_FilterPid *PID, u32 data_offset, u32 data_size, GF_FilterPacket *source_packet);

/*! Same as  \ref gf_filter_pck_new_ref with packet destructor callbacl

\param PID the target output PID
\param data_offset offset in the source data block
\param data_size the size of the data block to dispatch - if 0, the entire data of the source packet beginning at offset is used
\param source_packet the source packet this data belongs to (at least from the filter point of view).
\param destruct the callback function used to destroy the packet when no longer used - may be NULL
\return new packet or NULL if allocation error or not an output PID
*/
GF_FilterPacket *gf_filter_pck_new_ref_destructor(GF_FilterPid *PID, u32 data_offset, u32 data_size, GF_FilterPacket *source_packet, gf_fsess_packet_destructor destruct);

/*! Allocates a new packet on the output PID with associated allocated data.
The packet has by default no DTS, no CTS, no duration framing set to full frame (start=end=1) and all other flags set to 0 (including SAP type).
\param PID the target output PID
\param data_size the desired size of the packet - can be changed later
\param data set to the writable buffer of the created packet
\param destruct the callback function used to destroy the packet when no longer used - may be NULL
\return new packet or NULL if allocation error or not an output PID
*/
GF_FilterPacket *gf_filter_pck_new_alloc_destructor(GF_FilterPid *PID, u32 data_size, u8 **data, gf_fsess_packet_destructor destruct);

/*! Clones a new packet from a source packet and copy all source properties to output.
If the source packet uses a frame interface object or has no associated data, returns a copy of the packet.
If the source packet is referenced more than once (ie more than just the caller), a new packet on the output PID is allocated with source data copied.
Otherwise, the source data is assigned to the output packet.
 This is typically called by filter wishing to perform in-place processing of input data.
\param PID the target output PID
\param pck_source the desired source packet to clone
\param data set to the writable buffer of the created packet
\return new packet or NULL if allocation error or not an output PID
*/
GF_FilterPacket *gf_filter_pck_new_clone(GF_FilterPid *PID, GF_FilterPacket *pck_source, u8 **data);

/*! Copies a new packet from a source packet and copy all source properties to output.
\param PID the target output PID
\param pck_source the desired source packet to clone
\param data set to the writable buffer of the created packet
\return new packet or NULL if allocation error or not an output PID
*/
GF_FilterPacket *gf_filter_pck_new_copy(GF_FilterPid *PID, GF_FilterPacket *pck_source, u8 **data);

/*! Creates a read-only detached copy of a packet from a source packet and copy all source properties to output.

If the source packet uses a frame interface object or has no associated data, returns a copy of the packet.
If the source packet is referenced more than once (ie more than just the caller), a new packet on the output PID is allocated with source data copied.
Otherwise, the source data is assigned to the output packet.

This is typically called by filters requiring read access to data for packets using frame interfaces
\warning The cloned packet will not have any dynamic properties set.

\param pck_source the target source packet
\param cached_pck if not NULL, will try to reuse this packet if possible (if not possible, this packet will be destroyed)
\return new packet or NULL if allocation error or not an output PID
*/
GF_FilterPacket *gf_filter_pck_dangling_copy(GF_FilterPacket *pck_source, GF_FilterPacket *cached_pck);

/*! Marks memory of a shared packet as non-writable. By default \ref gf_filter_pck_new_shared and \ref gf_filter_pck_new_ref allow
write access to internal memory in case the packet can be cloned (single reference used). If your filter relies on the content of the shared
memory for its internal state, packet must be marked as read-only to avoid later state corruption.
Note that packets created with \ref gf_filter_pck_new_frame_interface are always treated as read-only packets
\param pck the target output packet to send
\return error if any
*/
GF_Err gf_filter_pck_set_readonly(GF_FilterPacket *pck);


/*! Checks if packet data has been reallocated

There are cases where memory allocated by \ref gf_filter_pck_new_ref allow needs to be reallocated without using \ref gf_filter_pck_expand .
This function allows checking if the data has changed, and if so reassign the new block to the packet.
If the data pointer was not changed, the packet data size is updated to the new size (acts as gf_filter_pck_truncate).
The data shall have been reallocated with \ref gf_realloc.

\param pck the target  packet to send
\param data the reallocated data pointer
\param size the reallocated data size
*/
void gf_filter_pck_check_realloc(GF_FilterPacket *pck, u8 *data, u32 size);

/*! Sends the packet on its output PID. Packets SHALL be sent in processing order (eg, decoding order for video).
However, packets don't have to be sent in their allocation order.
\param pck the target output packet to send
\return error if any
*/
GF_Err gf_filter_pck_send(GF_FilterPacket *pck);

/*! Destructs a packet allocated but that cannot be sent. Shall not be used on packet references.
\param pck the target output packet to send
*/
void gf_filter_pck_discard(GF_FilterPacket *pck);

/*! Destructs a packet allocated but that cannot be sent. Shall not be used on packet references.
This is a shortcut to \ref gf_filter_pck_new_ref + \ref gf_filter_pck_merge_properties + \ref gf_filter_pck_send
\param reference the input packet to forward
\param PID the output PID to forward to
\return error code if any
*/
GF_Err gf_filter_pck_forward(GF_FilterPacket *reference, GF_FilterPid *PID);

/*! Gets data associated with the packet.
\param pck the target packet
\param size set to the packet data size
\return packet data if any, NULL if empty or if the packet uses a frame interface object. See \ref gf_filter_pck_get_frame_interface
*/
const u8 *gf_filter_pck_get_data(GF_FilterPacket *pck, u32 *size);

/*! Sets a built-in property of a packet
\param pck the target packet
\param prop_4cc the code of the built-in property to set
\param value the property value to set
\return error code if any
*/
GF_Err gf_filter_pck_set_property(GF_FilterPacket *pck, u32 prop_4cc, const GF_PropertyValue *value);

/*! Sets a property of a packet
\param pck the target packet
\param name the name of the property to set
\param value the property value to set
\return error code if any
*/
GF_Err gf_filter_pck_set_property_str(GF_FilterPacket *pck, const char *name, const GF_PropertyValue *value);

/*! Sets a property of a packet
\param pck the target packet
\param name the code of the property to set. The name will be copied to the property, and memory destruction performed by the filter session
\param value the property value to set
\return error code if any
*/
GF_Err gf_filter_pck_set_property_dyn(GF_FilterPacket *pck, char *name, const GF_PropertyValue *value);

/*! Checks if a packet has properties other than packet built-in ones

 This is typically needed to decide whether a packet with no data should be forwarded or not

\param pck the target packet
\return GF_TRUE if packet has properties, GF_FALSE otherwise
*/
Bool gf_filter_pck_has_properties(GF_FilterPacket *pck);

/*! Merge properties of source packet into destination packet but does NOT reset destination packet properties
\param pck_src source packet
\param pck_dst destination packet
\return error code if any
*/
GF_Err gf_filter_pck_merge_properties(GF_FilterPacket *pck_src, GF_FilterPacket *pck_dst);

/*! Same as \ref gf_filter_pck_merge_properties but uses a filter callback to select properties to merge
\param pck_src source packet
\param pck_dst destination packet
\param filter_prop callback filtering function
\param cbk callback data passed to the callback function
\return error code if any
*/
GF_Err gf_filter_pck_merge_properties_filter(GF_FilterPacket *pck_src, GF_FilterPacket *pck_dst, gf_filter_prop_filter filter_prop, void *cbk);

/*! Gets built-in property of packet.
\param pck target packet
\param prop_4cc the code of the built-in property
\return the property if found, NULL otherwise
*/
const GF_PropertyValue *gf_filter_pck_get_property(GF_FilterPacket *pck, u32 prop_4cc);

/*! Gets property of packet.
\param pck target packet
\param prop_name the name of the property
\return the property if found, NULL otherwise
*/
const GF_PropertyValue *gf_filter_pck_get_property_str(GF_FilterPacket *pck, const char *prop_name);

/*! Enumerates properties on packets.
\param pck target packet
\param idx input/output index of the current property. 0 means first. Incremented by 1 upon success
\param prop_4cc set to the code of the built-in property
\param prop_name set to the name of the property
\return the property if found, NULL otherwise
*/
const GF_PropertyValue *gf_filter_pck_enum_properties(GF_FilterPacket *pck, u32 *idx, u32 *prop_4cc, const char **prop_name);


/*! Sets packet framing info. A full frame is a complete entity for the stream type, ie an access unit for media streams and a complete file for file streams
\param pck target packet
\param is_start packet is start of the frame
\param is_end packet is end of the frame
\return error code if any
*/
GF_Err gf_filter_pck_set_framing(GF_FilterPacket *pck, Bool is_start, Bool is_end);

/*! Gets packet framing info. A full frame is a complete entity for the stream type, ie an access unit for media streams and a complete file for file streams
\param pck target packet
\param is_start set to GF_TRUE if packet is start of the frame, to GF_FALSE otherwise
\param is_end set to GF_TRUE if packet is end of the frame, to GF_FALSE otherwise
\return error code if any
*/
GF_Err gf_filter_pck_get_framing(GF_FilterPacket *pck, Bool *is_start, Bool *is_end);

/*! Sets Decoding Timestamp (DTS) of the packet. Do not set if unknown - automatic packet duration is based on DTS diff if DTS is present, otherwise in CTS diff.
\param pck target packet
\param dts decoding timestamp of packet, in PID timescale units
\return error code if any
*/
GF_Err gf_filter_pck_set_dts(GF_FilterPacket *pck, u64 dts);

/*! Gets Decoding Timestamp (DTS) of the packet.
\param pck target packet
\return dts decoding timestamp of packet, in PID timescale units
*/
u64 gf_filter_pck_get_dts(GF_FilterPacket *pck);

/*! Sets Composition Timestamp (CTS) of the packet. Do not set if unknown - automatic packet duration is based on DTS diff if DTS is present, otherwise in CTS diff.
\param pck target packet
\param cts composition timestamp of packet, in PID timescale units
\return error code if any
*/
GF_Err gf_filter_pck_set_cts(GF_FilterPacket *pck, u64 cts);

/*! Gets Composition Timestamp (CTS) of the packet.
\param pck target packet
\return cts composition timestamp of packet, in PID timescale units
*/
u64 gf_filter_pck_get_cts(GF_FilterPacket *pck);

/*! Returns packet timescale (same as PID timescale)
\param pck target packet
\return packet timescale
*/
u32 gf_filter_pck_get_timescale(GF_FilterPacket *pck);

/*! Sets packet duration
\param pck target packet
\param duration duration of packet, in PID timescale units
\return error code if any
*/
GF_Err gf_filter_pck_set_duration(GF_FilterPacket *pck, u32 duration);

/*! Gets packet duration
\param pck target packet
\return duration duration of packet, in PID timescale units
*/
u32 gf_filter_pck_get_duration(GF_FilterPacket *pck);

/*! reallocates packet not yet sent. Returns data start and new range of data. This will reset byte offset information to not available.
\param pck target packet
\param nb_bytes_to_add bytes to add to packet
\param data_start realloc pointer of packet data start - may be NULL if new_range_start is set
\param new_range_start pointer to new (apppended space) data - may be NULL if data_start is set
\param new_size full size of allocated block. - may be be NULL
\return error code if any
*/
GF_Err gf_filter_pck_expand(GF_FilterPacket *pck, u32 nb_bytes_to_add, u8 **data_start, u8 **new_range_start, u32 *new_size);

/*! Truncates packet not yet sent to given size
\param pck target packet
\param size new size to truncate to
\return error code if any
*/
GF_Err gf_filter_pck_truncate(GF_FilterPacket *pck, u32 size);

/*! SAP types as defined in annex I of ISOBMFF */
typedef enum
{
	/*! no SAP */
	GF_FILTER_SAP_NONE = 0,
	/*! closed gop no leading */
	GF_FILTER_SAP_1,
	/*! closed gop leading */
	GF_FILTER_SAP_2,
	/*! open gop */
	GF_FILTER_SAP_3,
	/*! roll period (GDR or audio roll) - roll distance must be indicated in packet */
	GF_FILTER_SAP_4,
	/*! Audio preroll period - roll distance must be indicated in packet */
	GF_FILTER_SAP_4_PROL
} GF_FilterSAPType;

/*! Sets packet SAP type
\param pck target packet
\param sap_type SAP type of the packet
\return error code if any
*/
GF_Err gf_filter_pck_set_sap(GF_FilterPacket *pck, GF_FilterSAPType sap_type);

/*! Sets packet SAP type
\param pck target packet
\return sap_type SAP type of the packet
*/
GF_FilterSAPType gf_filter_pck_get_sap(GF_FilterPacket *pck);


/*! Sets packet video interlacing flag
\param pck target packet
\param is_interlaced set to
	0:  not interlaced
	1:  top field first or contains only top field if packet not full frame
	2:  bottom field first or contains only bottom field.
\return error code if any
*/
GF_Err gf_filter_pck_set_interlaced(GF_FilterPacket *pck, u32 is_interlaced);

/*! Gets packet video interlacing flag
\param pck target packet
\return interlaced flag, see \ref gf_filter_pck_set_interlaced
*/
u32 gf_filter_pck_get_interlaced(GF_FilterPacket *pck);

/*! Sets packet corrupted data flag
\param pck target packet
\param is_corrupted indicates if data in packet is corrupted
\return error code if any
*/
GF_Err gf_filter_pck_set_corrupted(GF_FilterPacket *pck, Bool is_corrupted);

/*! Gets packet corrupted data flag
\param pck target packet
\return GF_TRUE if data in packet is corrupted
*/
Bool gf_filter_pck_get_corrupted(GF_FilterPacket *pck);

/*! Sets seek flag of packet.
For PIDs of stream type FILE with GF_PROP_PID_DISABLE_PROGRESSIVE set, the seek flag set to GF_TRUE indicates
that the packet is a PATCH packet, replacing bytes located at gf_filter_pck_get_byte_offset in file if the interlaced flag of the packet is not set, or
inserting bytes located at gf_filter_pck_get_byte_offset in file if the interlaced flag of the packet is set.
If the corrupted flag is set, this indicates the data will be replaced later on.
A seek packet is not meant to be displayed but is needed for decoding.
\note If a packet is partially skipped but completely decoded, it shall not be marked as seek but have the property "SkipBegin" set.
\note Raw audio packets MUST be split at the proper boundary
\param pck target packet
\param is_seek indicates packet is seek frame
\return error code if any
*/
GF_Err gf_filter_pck_set_seek_flag(GF_FilterPacket *pck, Bool is_seek);

/*! Gets packet seek data flag
\param pck target packet
\return GF_TRUE if packet is a seek packet
*/
Bool gf_filter_pck_get_seek_flag(GF_FilterPacket *pck);

/*! Sets packet byte offset in source.
byte offset should only be set if the data in the packet is exactly the same as the one at the given byte offset
\param pck target packet
\param byte_offset indicates the byte offset in the source. By default packets are created with no byte offset
\return error code if any
*/
GF_Err gf_filter_pck_set_byte_offset(GF_FilterPacket *pck, u64 byte_offset);

/*! Sets packet byte offset in source
\param pck target packet
\return  byte offset in the source
*/
u64 gf_filter_pck_get_byte_offset(GF_FilterPacket *pck);

/*! Sets packet roll info (number of packets to rewind/forward and decode to get a clean access point).
\param pck target packet
\param roll_count indicates the roll distance of this packet - only used for SAP 4 for now
\return error code if any
*/
GF_Err gf_filter_pck_set_roll_info(GF_FilterPacket *pck, s16 roll_count);

/*! Gets packet roll info.
\param pck target packet
\return roll distance of this packet
\return error code if any
*/
s16 gf_filter_pck_get_roll_info(GF_FilterPacket *pck);

/*! Crypt flags for packet */
#define GF_FILTER_PCK_CRYPT 1

/*! Sets packet crypt flags
\param pck target packet
\param crypt_flag packet crypt flag
\return error code if any
*/
GF_Err gf_filter_pck_set_crypt_flags(GF_FilterPacket *pck, u8 crypt_flag);

/*! Gets packet crypt flags
\param pck target packet
\return packet crypt flag
*/
u8 gf_filter_pck_get_crypt_flags(GF_FilterPacket *pck);

/*! Packet clock reference types - used for MPEG-2 TS*/
typedef enum
{
	/*! packet is not a clock reference */
	GF_FILTER_CLOCK_NONE=0,
	/*! packet is a PCR clock reference, expressed in PID timescale */
	GF_FILTER_CLOCK_PCR,
	/*! packet is a PCR clock discontinuity, expressed in PID timescale */
	GF_FILTER_CLOCK_PCR_DISC,
} GF_FilterClockType;

/*! Sets packet clock type
\param pck target packet
\param ctype packet clock flag
\return error code if any
*/
GF_Err gf_filter_pck_set_clock_type(GF_FilterPacket *pck, GF_FilterClockType ctype);

/*! Gets last clock type and clock value on PID. Always returns 0 if the source filter manages clock references internally cd \ref gf_filter_pid_set_clock_mode.
\param PID target PID to query for clock
\param clock_val last clock reference found
\param timescale last clock reference timescale
\return ctype packet clock flag
*/
GF_FilterClockType gf_filter_pid_get_clock_info(GF_FilterPid *PID, u64 *clock_val, u32 *timescale);

/*! Gets clock type of packet. Always returns 0 if the source filter does NOT manages clock references internally cd \ref gf_filter_pid_set_clock_mode.
\param pck target packet
\return ctype packet clock flag
*/
GF_FilterClockType gf_filter_pck_get_clock_type(GF_FilterPacket *pck);

/*! Sets packet carousel info
\param pck target packet
\param version_number carousel version number associated with this data chunk
\return error code if any
*/
GF_Err gf_filter_pck_set_carousel_version(GF_FilterPacket *pck, u8 version_number);

/*! Gets packet carousel info
\param pck target packet
\return version_number carousel version number associated with this data chunk
*/
u8 gf_filter_pck_get_carousel_version(GF_FilterPacket *pck);

/*! Sets packet sample dependency flags.

Sample dependency flags have the same semantics as ISOBMFF:\n
bit(2)is_leading bit(2)sample_depends_on (2)sample_is_depended_on (2)sample_has_redundancy\n
\n
is_leading takes one of the following four values:\n
0: the leading nature of this sample is unknown;\n
1: this sample is a leading sample that has a dependency before the referenced I-picture (and is therefore not decodable);\n
2: this sample is not a leading sample;\n
3: this sample is a leading sample that has no dependency before the referenced I-picture (and is therefore decodable);\n
sample_depends_on takes one of the following four values:\n
0: the dependency of this sample is unknown;\n
1: this sample does depend on others (not an I picture);\n
2: this sample does not depend on others (I picture);\n
3: reserved\n
sample_is_depended_on takes one of the following four values:\n
0: the dependency of other samples on this sample is unknown;\n
1: other samples may depend on this one (not disposable);\n
2: no other sample depends on this one (disposable);\n
3: reserved\n
sample_has_redundancy takes one of the following four values:\n
0: it is unknown whether there is redundant coding in this sample;\n
1: there is redundant coding in this sample;\n
2: there is no redundant coding in this sample;\n
3: reserved\n

\param pck target packet
\param dep_flags sample dependency flags
\return error code if any
*/
GF_Err gf_filter_pck_set_dependency_flags(GF_FilterPacket *pck, u8 dep_flags);

/*! Gets packet sample dependency flags.
\param pck target packet
\return dep_flags sample dependency flags - see \ref gf_filter_pck_set_dependency_flags for syntax.
*/
u8 gf_filter_pck_get_dependency_flags(GF_FilterPacket *pck);


/*! Sets packet sequence number. Shall only be used when a filter handles a PLAY request based on packet sequence number
\param pck target packet
\param seq_num sequence number of packet
\return error code if any
*/
GF_Err gf_filter_pck_set_seq_num(GF_FilterPacket *pck, u32 seq_num);

/*! Gets packet sequence number info
\param pck target packet
\return sequence number associated with this packet
*/
u32 gf_filter_pck_get_seq_num(GF_FilterPacket *pck);

/*! Redefinition of GF_Matrix but without the maths.h include which breaks VideoToolBox on OSX/iOS */
typedef struct __matrix GF_Matrix_unexposed;

/*! frame interface flags*/
enum
{
	/*! When set , indicates that the emitting filter will block until this frame is released.
	Consumers of such a packet shall drop the packet as soon as possible, since it blocks the emiting filter.*/
	GF_FRAME_IFCE_BLOCKING = 1,
	/*! When set , indicates that the associated framebuffer is the main GL framebuffer.*/
	GF_FRAME_IFCE_MAIN_GLFB = 1<<1
};

/*! Frame interface object

The frame interface object can be used to expose an interface between the packet generated by a filter and its consumers, when dispatching a regular data block is not possible.
This is typically used by decoders exposing the output image planes or by OpenGL filters outputing textures.
Currently only video frames use this interface object.
*/
typedef struct _gf_filter_frame_interface
{
	/*! get video frame plane
	\param frame interface object for the video frame
	\param plane_idx plane index, 0: Y or full plane, 1: U or UV plane, 2: V plane
	\param outPlane address of target color plane
	\param outStride stride in bytes of target color plane
	\return error code if any
	*/
	GF_Err (*get_plane)(struct _gf_filter_frame_interface *frame, u32 plane_idx, const u8 **outPlane, u32 *outStride);

	/*! get video frame plane texture
	\param frame interface object for the video frame
	\param plane_idx plane index, 0: Y or full plane, 1: U or UV plane, 2: V plane
	\param gl_tex_format GL texture format used
	\param gl_tex_id GL texture ID used
	\param texcoordmatrix texture transform to fill. The texture is expected to be layed out as an image (first pixel is top-first). If not the case, add a vertical flip (eg dispatching an OpenGL FBO). 	\return error code if any
	*/
	GF_Err (*get_gl_texture)(struct _gf_filter_frame_interface *frame, u32 plane_idx, u32 *gl_tex_format, u32 *gl_tex_id, GF_Matrix_unexposed * texcoordmatrix);

	/*! Flags for this frame interface.*/
	u32 flags;

	/*! private space for the emitting filter, consumers shall not modify this*/
	void *user_data;
} GF_FilterFrameInterface;


/*! Allocates a new packet holding a reference to a frame interface object.
The packet has by default no DTS, no CTS, no duration framing set to full frame (start=end=1) and all other flags set to 0 (including SAP type).
\param PID the target output PID
\param frame_ifce the associated frame interface object
\param destruct the destructor to be called upon packet release
\return new packet
*/
GF_FilterPacket *gf_filter_pck_new_frame_interface(GF_FilterPid *PID, GF_FilterFrameInterface *frame_ifce, gf_fsess_packet_destructor destruct);

/*! Gets a frame interface associated with a packet if any.

Consumers will typically first check if the packet has associated data using \ref gf_filter_pck_get_data.

\param pck the target packet
\return the associated frame interface object if any, or NULL otherwise
*/
GF_FilterFrameInterface *gf_filter_pck_get_frame_interface(GF_FilterPacket *pck);


/*! Checks if the packet is a blocking reference, i.e. a parent filter in the chain is waiting for its destruction to emit a new packet.
This is typically used by sink filters to decide if they can hold references to input packets without blocking the chain.
\param pck the target packet
\return GF_TRUE if the packet is blocking or is a reference to a blocking packet, GF_FALSE otherwise
*/
Bool gf_filter_pck_is_blocking_ref(GF_FilterPacket *pck);

/*! @} */


/*!
\addtogroup filters__cust_grp Custom Filter
\ingroup filters_grp

\brief Custom Filter

Custom filters are filters created by the app with no associated registry.
The app is responsible for assigning capabilities to the filter, and setting callback functions.
Each callback is optional, but a custom filter should at least have a process callback, and a configure_pid callback if not a source filter.

Custom filters do not have any arguments exposed, and cannot be selected for sink or source filters.
If your app requires custom I/Os for source or sinks, use \ref GF_FileIO.
@{
 */

/*! Loads custom filter
\param session filter session
\param name name of filter to use - optional, may be NULL
\param flags flags for filter registry, currently only GF_FS_REG_MAIN_THREAD is used
\param e set to the error code if any - optional, may be NULL
\return filter or NULL if error
*/
GF_Filter *gf_fs_new_filter(GF_FilterSession *session, const char *name, u32 flags, GF_Err *e);

/*! Push a new capability for a custom filter
\param filter the target filter
\param code the capability code - cf \ref GF_FilterCapability
\param value the capability value - cf \ref GF_FilterCapability
\param name the capability name - cf \ref GF_FilterCapability
\param flags the capability flags - cf \ref GF_FilterCapability
\param priority the capability priority - cf \ref GF_FilterCapability
\return error if any
 */
GF_Err gf_filter_push_caps(GF_Filter *filter, u32 code, GF_PropertyValue *value, const char *name, u32 flags, u8 priority);

/*! Set the process function for  a custom filter
\param filter the target filter
\param process_cbk the process callback, may be NULL -  cf process in  \ref __gf_filter_register
\return error if any
 */
GF_Err gf_filter_set_process_ckb(GF_Filter *filter, GF_Err (*process_cbk)(GF_Filter *filter) );

/*! Set the PID configuration function for  a custom filter
\param filter the target filter
\param configure_cbk the configure callback, may be NULL -  cf configure_pid in \ref __gf_filter_register
\return error if any
 */
GF_Err gf_filter_set_configure_ckb(GF_Filter *filter, GF_Err (*configure_cbk)(GF_Filter *filter, GF_FilterPid *PID, Bool is_remove) );

/*! Set the process event function for  a custom filter
\param filter the target filter
\param process_event_cbk the process event callback, may be NULL -  cf process_event in \ref __gf_filter_register
\return error if any
 */
GF_Err gf_filter_set_process_event_ckb(GF_Filter *filter, Bool (*process_event_cbk)(GF_Filter *filter, const GF_FilterEvent *evt) );

/*! Set the reconfigure output function for  a custom filter
\param filter the target filter
\param reconfigure_output_cbk the reconfigure callback, may be NULL -  cf reconfigure_output_cbk in \ref __gf_filter_register
\return error if any
 */
GF_Err gf_filter_set_reconfigure_output_ckb(GF_Filter *filter, GF_Err (*reconfigure_output_cbk)(GF_Filter *filter, GF_FilterPid *PID) );

/*! Set the data prober function for  a custom filter
\param filter the target filter
\param probe_data_cbk the data prober callback , may be NULL-  cf probe_data in \ref __gf_filter_register
\return error if any
 */
GF_Err gf_filter_set_probe_data_cbk(GF_Filter *filter, const char * (*probe_data_cbk)(const u8 *data, u32 size, GF_FilterProbeScore *score) );


/*! @} */

#ifdef __cplusplus
}
#endif

#endif	//_GF_FILTERS_H_