mm-control components

The mm-control service exposes several media-management features in one collection of PPS commands. Applications specify commands by stating the operation name followed by the data needed for the operation.

The operation name consists of multiple words: the first word is the command category and the remaining words refer to the specific action to perform. The command category determines which mm-control object type the command affects. Separate subsystems process commands targetted to each of the following object types:

• outputs: outputs provide destinations for media playback; destinations can be audio or video devices
• zones: zones group outputs together for convenience; for example, you could define one zone for outputting video content and another zone for outputting audio content
• tracksessions: tracksessions manage ordered track collections that you can provide to a player; each tracksession stores a start index and an end index as well as the URLs to the source files of its tracks
• players: players control media flows from an input to one or many outputs; each player operates independently of the others, meaning the playback commands sent to it affect only its own media flow

All information on outputs and zones is maintained in internal data structures, so the commands that configure these types of objects don't entail communicating with other multimedia services. But the commands affecting tracksessions and players do require communicating with mm-trkmgr, mm-renderer, and possibly other multimedia services (depending on the device type). When processing commands in either of these last two categories, mm-control uses either PPS objects or API calls to invoke the multimedia services necessary to carry out the command.

See the /pps/services/mm-control/control entry in the PPS Objects Reference for full details on the command message format and the commands supported by each of the mm-control components.