The mapping for the input streams and audio channels.
Required. The ``Channel``
that identifies the input that this audio mapping applies
to. If an active input doesn't have an audio mapping, the
primary audio track in the input stream will be selected.
Required. The zero-based index of the track in the input
in the same
must have the same input track.
Required. The zero-based index of the channel
in the input stream.
Required. The zero-based index of the channel in the output
audio stream. Must be consistent with the