I need to use ffmpeg to merge 8 mono wav files into one 8 channel file. I have the command to achieve the default channel layouts (l r c lfe ls rs lsd rsd) but I need the last two to be LT RT and not lsd rsd. My 8 mono files going in are 5.1 and 2.0 (not a 7.1). I've searched all over on how to map the channels going in but can't quite hit on one that works. Is this possible with "amerge" and/or -"filter_complex"?