Sets whether to transmux the media items' audio tracks.
The default value is false.
If the Composition contains one MediaItem, the value set is ignored. The audio track will only be transcoded if necessary.
If the input Composition contains multiple media items, all the audio tracks are transcoded by default. They are all transmuxed if transmuxAudio is true. Transmuxed tracks must be compatible (typically, all the MediaItem instances containing the track to transmux are concatenated in a single EditedMediaItemSequence and have the same sample format for that track).
Requesting audio transmuxing and forcing an audio track are not allowed together because generating silence requires transcoding.