How about AAC 5.1 to AC3 5.1?
Thread resurrection!
I know PopcornMKV can covert AAC 5.1 to AC3 5.1. My receiver can't handle AAC, so my setup box just passes along some stereo mix of the AAC 5.1 track.
So...what Mac (or Linux) software can convert AAC 5.1 to AC3 5.1? I'm plenty comfortable extracting tracks from files using ffmpeg, remixing with mkvtoolnix, etc, if there's a way to do it using ffmpeg.
Thanks!