[FFmpeg-user] ffmpeg compand knobs problem

[Beeblebrox]

I neglected to mention in this thread that I had combined several video
slices into one file with cat ($ cat 1.mpg 2.mpg > out.mpg). I also have
other "non concatenated" videos, and I ran the normal command on one of
those files (ffmpeg -i dim_sum.mpg -c:a libfdk_aac -af 'volume=2,
compand=.05|.2:.05|.2:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-60:.1' -c:v
libx264 -preset slow -crf 32 -f mp4 test.mp4). The result was exactly what
I wanted (clean and balanced audio).

As alternative, I tried the libfaac encoder on a pre-concatenated file (
ffmpeg -i day7.mpg -c:a libfaac -af 'volume=2,
compand=.05|.2:.05|.2:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-60:.1' -c:v
libx264 -preset slow -crf 32 -f mp4 day7.mp4). Audio was once again
corrupted by the transformation, although not as bad (but still
unacceptable).

I suspect that the initial cat command for this video set is what is
causing the problems. As future reference, maybe it should be suggested
that the process should be "transform first, then concatenate"?

Per Oliver's suggestion, the terminal output for ffmpeg does complain of
certain issues - I don't know what they mean, or how to correct:
Press [q] to stop, [?] for help
[ac3 @ 0x80d05d620] frame CRC mismatch
[ac3 @ 0x80d05d620] frame sync error
Error while decoding stream #0:0: Invalid data found when processing input
[mpeg2video @ 0x80d05ef20] 00 motion_type at 2 29
[mpeg2video @ 0x80d05ef20] 00 motion_type at 26 30
[mpeg2video @ 0x80d05ef20] 00 motion_type at 35 31
[mpeg2video @ 0x80d05ef20] 00 motion_type at 23 27
[mpeg2video @ 0x80d05ef20] invalid mb type in B Frame at 3 32
[mpeg2video @ 0x80d05ef20] 00 motion_type at 1 23
[mpeg2video @ 0x80d05ef20] 00 motion_type at 12 33
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 0 24
[mpeg2video @ 0x80d05ef20] invalid mb type in B Frame at 16 34
[mpeg2video @ 0x80d05ef20] mb incr damaged
[mpeg2video @ 0x80d05ef20] 00 motion_type at 34 35
[mpeg2video @ 0x80d05ef20] 00 motion_type at 26 26
[mpeg2video @ 0x80d05ef20] 00 motion_type at 4 27
[mpeg2video @ 0x80d05ef20] 00 motion_type at 13 28
[mpeg2video @ 0x80d05ef20] Warning MVs not available
[mpeg2video @ 0x80d05ef20] concealing 585 DC, 585 AC, 585 MV errors in B
frame
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 3 29
[mpeg2video @ 0x80d05ef20] 00 motion_type at 4 30
[mpeg2video @ 0x80d05ef20] 00 motion_type at 2 31
[mpeg2video @ 0x80d05ef20] 00 motion_type at 2 32
[mpeg2video @ 0x80d05ef20] 00 motion_type at 12 33
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 12 14
[mpeg2video @ 0x80d05ef20] 00 motion_type at 1 15
[mpeg2video @ 0x80d05ef20] 00 motion_type at 8 16
[mpeg2video @ 0x80d05ef20] 00 motion_type at 18 17
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 5 18
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 1 7
[mpeg2video @ 0x80d05ef20] 00 motion_type at 3 19
[mpeg2video @ 0x80d05ef20] invalid mb type in P Frame at 3 22
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 38 34
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 0 35
[mpeg2video @ 0x80d05ef20] 00 motion_type at 23 23
[mpeg2video @ 0x80d05ef20] 00 motion_type at 9 20
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 9 24
[mpeg2video @ 0x80d05ef20] 00 motion_type at 14 8
[mpeg2video @ 0x80d05ef20] 00 motion_type at 21 4
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 1 21
[mpeg2video @ 0x80d05ef20] 00 motion_type at 31 25
[mpeg2video @ 0x80d05ef20] 00 motion_type at 2 9
[mpeg2video @ 0x80d05ef20] 00 motion_type at 15 26
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 17 27
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 11 28
[mpeg2video @ 0x80d05ef20] 00 motion_type at 35 10
[mpeg2video @ 0x80d05ef20] 00 motion_type at 2 11
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 24 13
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 0 13
[mpeg2video @ 0x80d05ef20] 00 motion_type at 18 3
[mpeg2video @ 0x80d05ef20] ac-tex damaged at 1 4
[mpeg2video @ 0x80d05ef20] slice mismatch
[mpeg2video @ 0x80d05ef20] 00 motion_type at 4 6
[mpeg2video @ 0x80d05ef20] Warning MVs not available