I'm creating audio tracks from movies that can be played on Apple TV and iOS devices. Handbrake could downmix 5.1 audio to stereo with Pro Logic II matrix encoding. How can I do that with ffmpeg?
I found this link on ffmpeg Trac mentioning that I could do matrix encoding with
libswresample, but further searching doesn't show how to actually use this in command line.
ffmpeg -i test.mkv -map 0:1 -c libfdk_aac -ac 2 -af aresample -matrix_encoding dplii out.aac
where the only audio track in the source file
test.mkv is a 5.1ch DTS HD MA, but the generated AAC audio does not seem to be matrix encoded.