Not sure, we want to do this that far down. FFmpeg has that in there for a reason. We decide actively for our users, by interpreting (my focus is on interpreting) the channel layout. FFmpeg just does what the spec says, which I find okay, as that is what I would expect from the down most lib we use.

But doing what we want in our code is a valid interpretation with the goal to please the user's hifi system. The swr_convert looks sane to me. But the other problem "Channel Layout of non ffmpeg sources" is even more important.