You must attach an output to a context before attaching the input. An output is specified by naming a URL. The acceptable URL format depends on the output type, which can be an audio device, video device, or file. For video outputs, the URL string can configure settings of the output window.
A context can have multiple outputs; for instance, when playing video files, you can attach both a video device and an audio device as outputs by making separate calls to mmr_output_attach(). Individual outputs can be detached with mmr_output_detach().
With mmr_output_parameters(), you can set the volume for any audio output. For those outputs that use the Audio Manager service, you can also specify audio stream characteristics. Note that the Screen API, not the mm-renderer API, should be used for manipulating properties of video output. There are no output parameters for file outputs.