[FFmpeg-trac] #6350(ffmpeg:open): n3.3 corrupts when remuxing mp4->mp4 or mp4->mkv

FFmpeg trac at avcodec.org
Tue Apr 25 07:30:00 EEST 2017


#6350: n3.3 corrupts when remuxing mp4->mp4 or mp4->mkv
----------------------------------------+----------------------------------
             Reporter:  carstenmattner  |                    Owner:
                 Type:  defect          |                   Status:  open
             Priority:  important       |                Component:  ffmpeg
              Version:  git-master      |               Resolution:
             Keywords:                  |               Blocked By:
             Blocking:                  |  Reproduced by developer:  1
Analyzed by developer:  0               |
----------------------------------------+----------------------------------
Changes (by jamrial):

 * status:  new => open
 * version:  unspecified => git-master
 * reproduced:  0 => 1


Comment:

 Regression since af1761f7b5b1b72197dc40934953b775c2d951cc. A bunch of
 frames at the beginning are not being copied to the output file.

 {{{
 $ youtube-dl -f 18 --restrict-filenames
 https://www.youtube.com/watch?v=jNQXAC9IVRw

 $ ./ffmpeg -i Me_at_the_zoo-jNQXAC9IVRw.mp4 -vframes 9 -c:v copy -an -f
 framecrc -
 #extradata 0:       37, 0xd9bf0acd
 #software: Lavf57.72.101
 #tb 0: 1/15
 #media_type 0: video
 #codec_id 0: h264
 #dimensions 0: 320x240
 #sar 0: 1/1
 0,          0,          0,        1,    12783, 0xdea0e2ed
 0,          1,          1,        1,      758, 0x464e901e, F=0x0
 0,          2,          2,        1,     1333, 0xed209cf2, F=0x0
 0,          3,          3,        1,     1578, 0xe3d6363c, F=0x0
 0,          4,          4,        1,     1056, 0xd32e2f83, F=0x0
 0,          5,          5,        1,     1855, 0xf37fc03e, F=0x0
 0,          6,          6,        1,     1773, 0xfe439ac6, F=0x0
 0,          7,          7,        1,     1806, 0x8da5a08c, F=0x0
 0,          8,          8,        1,     2306, 0xdd7e8f1a, F=0x0

 $ ./ffmpeg -i Me_at_the_zoo-jNQXAC9IVRw.mp4 -c:a aac -c:v copy out.mp4

 $ ./ffmpeg -i out.mp4 -vframes 2 -c:v copy -an -f framecrc -
 #extradata 0:       37, 0xd9bf0acd
 #software: Lavf57.72.101
 #tb 0: 1/15360
 #media_type 0: video
 #codec_id 0: h264
 #dimensions 0: 320x240
 #sar 0: 1/1
 0,          0,          0,     8192,    12783, 0xdea0e2ed
 0,       8192,       8192,     1024,     2306, 0xdd7e8f1a, F=0x0

 $ ./ffmpeg_ref -i Me_at_the_zoo-jNQXAC9IVRw.mp4 -c:a aac -c:v copy
 out_ref.mp4

 $ ./ffmpeg -i out_ref.mp4 -vframes 9 -c:v copy -an -f framecrc -
 #extradata 0:       37, 0xd9bf0acd
 #software: Lavf57.72.101
 #tb 0: 1/15360
 #media_type 0: video
 #codec_id 0: h264
 #dimensions 0: 320x240
 #sar 0: 1/1
 0,          0,          0,     1024,    12783, 0xdea0e2ed
 0,       1024,       1024,     1024,      758, 0x464e901e, F=0x0
 0,       2048,       2048,     1024,     1333, 0xed209cf2, F=0x0
 0,       3072,       3072,     1024,     1578, 0xe3d6363c, F=0x0
 0,       4096,       4096,     1024,     1056, 0xd32e2f83, F=0x0
 0,       5120,       5120,     1024,     1855, 0xf37fc03e, F=0x0
 0,       6144,       6144,     1024,     1773, 0xfe439ac6, F=0x0
 0,       7168,       7168,     1024,     1806, 0x8da5a08c, F=0x0
 0,       8192,       8192,     1024,     2306, 0xdd7e8f1a, F=0x0
 }}}

 Replying to [comment:2 carstenmattner]:
 > I would consider this bug critical since it silently corrupts and
 doesn't noticeably crash, but I didn't know if you consider this critical
 as well so important is what I chose as severity.
 "critical" is reserved for data loss, AKA, ffmpeg overwriting input files,
 configure script deleting things outside the build directory, etc.

 Regressions in transcoding and such are "important".

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6350#comment:4>
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