mm-control configuration file

The mm-control configuration file lets you define a default set of outputs and zones. This data is specified in JSON format, which provides a compact way of expressing lists of available playback destinations. At startup, mm-control reads the configuration file and stores its information in internal data structures.

Defining an initial set of outputs and zones ensures media applications such as Media Player have default destinations for outputting media content during playback.

QNX CAR systems include an mm-control configuration file, whose full path is: /etc/mm-control.cfg. You can change the initial set of outputs and zones either by modifying the included configuration file or by creating another configuration file. When using a different file, you must direct mm-control to that file by using the -c command option, as explained in the mm-control command line section.

The full contents of the included file look like this:

{
    "outputs":[
        {
            "cabin":{
                "url":"audio:default",
                "type":"audio"    
            }
        },
        {
            "rear":{
                "url":"snd:pcmPreferredpb",
                "type":"audio"    
            }
        },
        {
            "output2":{
                "url":"screen:?dstx=320&dsty=85&zorder=100\
                               &dstw=460&dsth=259",
                "type":"video"
            }
        }
    ],
    "zones":[
        {
            "audio":[
                "cabin"
            ]
        },
        {
            "video":[
                "cabin",
                "output2"
            ]
        }
    ]
}

This configuration defines separate audio outputs for the front and rear speakers of the car, and a video output with the specified screen location and dimensions. Separate zones for outputting audio content and video content are also defined. Although the rear speakers aren't used in any of the default zones, you could use them as a destination in media playback.