FilmCraft reorders AAC configurations 3 to 6, 11 and 12 to WAVE/SMPTE order
and leaves configuration 7 and program config elements as coded, so the
channel count alone can't say which order arrives: ffmpeg writes 7.1 as
configuration 7 (C L R first) and 6.1 as a PCE it fills in its own order
(L R C LFE Cs Ls Rs), while FilmCraft's encoder writes a centre-first PCE.
The order is now read from an MP4/MOV's AudioSpecificConfig when the source
opens; other containers keep a channel-count guess.
The ffmpeg oracle test gains configuration 12 (ffmpeg's 7.1 relabelled) and
skips PCE files ffmpeg 4.2 marks as stereo, which FilmCraft reads as two
channels.