rsked

rsked, short for radio scheduler, is a Linux application that plays any of various audio sources at specific times on a weekly schedule, without any requirement for human interaction. Sources include locally stored recordings (ogg, mp3, mp4, flac), internet streams, and FM broadcasts (via inexpensive SDR hardware). It is intended to be run as an embedded application on an inexpensive low power microsystem (e.g. Raspberry Pi 3, RPi). However it can run on x86 desktop computers as well, and likely on any Linux computer with a sound card.

rsked was originally developed for people who, due to disability, are physically unable to operate conventional audio equipment. It satisfies a desire to have a variety of audio programming without reliance on others to control the equipment. It can work in an environment where internet connectivity is absent or unreliable. It could be used in any situation where it is inconvenient or undesirable to require human interaction to schedule audio programming.

Features

• Weekly program schedule defined in a simple JSON file
• Web-based schedule editor and log viewer
• Play MP3, MP4, FLAC, or Ogg-Vorbis files, directories, or playlists
• Play internet streams
• Play FM broadcast stations, including HD
• Audio "message of the day" at scheduled times
• Audio source failure detected, with reversion to defined backup sources
• Runs on Raspberry Pi-3 or x86_64, no screen required
• Snooze button to pause or resume play (optional, GPIO)
• Status LEDs (optional, GPIO)
• Control of active cooling (optional, GPIO)
• Logging of operations for remote monitoring
• Bluetooth status monitoring and setup (optional)

See CHANGES for a summary of important changes that have occurred over versions of rsked.

Usage Overview

The overall system consists of several applications compiled from this repository, and a selection of external audio players that you must install separately. The choice of external players depends on the sources desired for the intended application.

A typical embedded application will:

1. Compile and install the rsked software and external audio players
2. Adjust configuration parameters to select the desired features
3. Install any desired recorded music files
4. Configure a schedule that references local and remote music sources
5. Set rsked to start automatically when the embedded device boots.

Recorded Music

Recorded music may be played with any of these external applications available as packages on most Linux distributions:

• mpd
• ogg123
• mpg321
• vlc

The ogg123 player plays Ogg-Vorbis recordings, and is required to play announcements in rsked. The music player daemon mpd plays a wide range of audio files and has been extensively tested with rsked. Vlc is similarly versatile. The lightweight mpg321 player is suitable for MP3 files. All of these programs can play both individual files and playlists.

Streaming

All of the above mentioned applications also handle streaming sources, such as internet radio stations. Streaming connections occasionally break for reasons outside of one's control. rsked can detect and respond to such problems. No player I've tested handles the full range of failures encountered in the field, but mpd seems most robust. ogg123 can support ogg vorbis streams, although these have not been tested in rsked.

FM Radio

Over-the-air FM broadcasts may be scheduled using Software Defined Radio (SDR). Attach an inexpensive USB SDR radio dongle such as RTL-2832U, then configure the desired frequencies in the schedule. rsked uses either of:

• gqrx, a modified fork
• nrsc5, an HD-FM receiver compatible with RTL-SDR dongles.

rsked application

The rsked application reads a configuration file and a weekly schedule. It then orchestrates external players to deliver the requested audio content at the correct times. rsked should be started after the target system boots. This job may be performed by the cooling application described below. rsked is the sole mandatory application in the system.

cooling application

The cooling application is a supervisor for rsked. cooling should be started after the target system boots. It is not essential, but is recommended for embedded applications. It can be configured to:

• start or stop a cooling fan based on CPU temperature
• start rsked with desired options
• restart rsked if it stops for any reason
• signal rsked that a button has been pressed
• control external LEDs to indicate status

RPi systems may need active cooling (fan) if the SDR player is used extensively. SDR is very compute intensive and will make an RPi run too hot for passive cooling alone in some enclosures. See README-RPi for more details about hardware, wiring, and configuration.

VUmonitor application

vumonitor is an optional application that may be started by rsked. It continuously monitors the audio output level delivered to the Linux sound system. If this is dead quiet for an extended period, it signals rsked; it signals again when audio output resumes. This allows rsked to detect when a source has failed "silently". This condition can occur with internet streams and broadcast radio stations.

check_inet.sh application

check_inet.sh is an optional application that periodically verifies that an internet connection usable for streaming is available. rsked uses this datum to determine whether it is feasible to use an internet streaming source.

Compilation and Installation

For installation instructions see: INSTALLATION

We hope to provide occasional binary releases; check the releases link. Compilation from source should be straightforward.

For a reference to the configuration files and command line options for rsked and cooling, see: CONFIGURATION

README-RPi covers instructions particular to the Raspberry Pi platform.

Known problems and limitations

Limitation: rsked only runs under Linux.

rsked is experimental software.

License

rsked sources are covered by the Apache 2.0 License. See: LICENSE External components referenced by rsked are covered by their own licenses.