I wish to create an audio only flavour to extract an audio only track from a video and audio source. The scenario is that I have multiple language source with 3 or four languages. I was intending to set up a flavour of type AAC and use some extra flags ( -map 0:ID ) where ID is the number of the correct language stream.
I would then create multiple audio flavours extractions, one for each language and then use a late binding audio player to mux the video and newly extracted audio files in the player. We do this already by creating a custom playmanifest which returns the correct flavours based on tags.
I can do the above if I choose mp3 as the container format, but i cant force it to AAC. If i choose mp4 as the container format then the video is assumed.
I know that there was a feature entitled Multistream but it looks immature in the source code and i am not sure it works as intended.