fixed filter session bugs

- graph probing returning chains rejected by regular graph resolver
- possible extra cloning of filters when relinking an already connected PID

include/gpac/filters.h

@@ -3311,8 +3311,8 @@ GF_Err gf_filter_probe_link(GF_Filter *filter, u32 opid_idx, const char *fname,
 /*! 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
-\return error if any
+\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 chain
 */
 GF_Err gf_filter_get_possible_destinations(GF_Filter *filter, s32 opid_idx, char **result_list);
 

src/filter_core/filter_pid.c

@@ -3847,6 +3847,7 @@ u32 gf_filter_pid_resolve_link_length(GF_FilterPid *pid, GF_Filter *dst)
 	return chain_len;
 }
 
+static Bool gf_filter_pid_needs_explicit_resolution(GF_FilterPid *pid, GF_Filter *dst);
 
 GF_List *gf_filter_pid_compute_link(GF_FilterPid *pid, GF_Filter *dst)
 {
@@ -3857,6 +3858,8 @@ GF_List *gf_filter_pid_compute_link(GF_FilterPid *pid, GF_Filter *dst)
 
 	if (!fsess->max_resolve_chain_len) return NULL;
 	if (!dst) return NULL;
+	if (gf_filter_pid_needs_explicit_resolution(pid, dst))
+		return NULL;
 
 	filter_chain = gf_list_new();
 
@@ -4672,7 +4675,13 @@ static void gf_filter_pid_init_task(GF_FSTask *task)
 			s32 ours = gf_list_find(pid->filter->destination_filters, filter_dst);
 			if (ours<0) {
 				ours = num_pass ? gf_list_del_item(pid->filter->destination_links, filter_dst) : -1;
-				if (!filter_dst->source_ids && (ours<0)) {
+				if ((ours<0) && (
+					//no source ID on filter, exclude
+					!filter_dst->source_ids
+					//dst is already linked and cannot accept more inputs, don't try to connect (this would trigger a clone)
+					//this is typically needed with defer linking when we reconnect outputs of a filter already connected
+					|| (filter_dst->num_input_pids && !filter_dst->max_extra_pids)
+				)) {
 					GF_LOG(GF_LOG_DEBUG, GF_LOG_FILTER, ("PID %s has destination filters, filter %s not one of them\n", pid->name, filter_dst->name));
 					continue;
 				}