Working with Media

The Concept

Media objects are objects that are capable to process media. There are several type of media objects supported in pjsua:

• call, obviously, to transmit and receive media from remote person.
• WAV file player to play WAV file
• WAV file recorder to record audio to a WAV file
• WAV playlist, to playback multiple WAV files sequentially.

More media objects may be added in the future.

In pjsua Python module and in ​PJSUA API in general, all media objects are terminated in the central conference bridge so that they are easier to manipulate. When objects are plugged-in to the conference bridge, they will be given a slot number that identifies the objects in the bridge.

The conference bridge provides a simple but yet powerful API to manage audio routing between the audio objects. The principle is very simple, that is you connect audio source to audio destination, and that's it. If more than one sources are transmitting to the same destination, then the audio will be mixed. If one source is transmitting to more than one destinations, the bridge will take care of duplicating the audio from the source to the multiple destinations.

Lets see a diagram of a conference bridge with several media objects.