[FFmpeg-trac] #6335(undetermined:closed): ffmpeg silently ignores first 50 frames when decoding h264

[FFmpeg]

#6335: ffmpeg silently ignores first 50 frames when decoding h264
-------------------------------------+-------------------------------------
             Reporter:  zhukov       |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  important    |                Component:
              Version:  git-master   |  undetermined
             Keywords:  regression   |               Resolution:  duplicate
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  1
-------------------------------------+-------------------------------------
Changes (by cehoyos):

 * keywords:   => regression
 * priority:  normal => important
 * status:  new => closed
 * resolution:   => duplicate
 * reproduced:  0 => 1


Comment:

 Replying to [comment:6 zhukov]:
 > Replying to [comment:5 cehoyos]:
 > > Am I correct that for the Telestream file, no frames are missing?
 > >
 > > I don't know what you are trying to do but you cannot generally cut
 files with {{{-vcodec copy}}} and for the first file you uploaded, the
 reference decoder produces the same output as FFmpeg (meaning any software
 that outputs different frames has a bug).
 > > Work-around is to use {{{-flags2 +showall}}} which makes decoding
 (possibly) non-compliant.
 >
 > So you are saying the fact that safari, firefox, vlc and quicktime play
 all frames of this file is a bug in all of them?

 I am saying that the H.264 reference decoder does not show the first 50
 frames for the sample you uploaded, just as FFmpeg does.

 The issue that af1761f7 broke remuxing in certain cases is a duplicate of
 several other tickets, for example #6227 (and possibly #6275).
 {{{
 $ ffmpeg -i telestream_first2mb_ticket6335.mp4 -vcodec copy out.mp4
 ffmpeg version N-85646-g550a9c5 Copyright (c) 2000-2017 the FFmpeg
 developers
   built with gcc 6.3.0 (GCC)
   configuration: --enable-gpl
   libavutil      55. 61.100 / 55. 61.100
   libavcodec     57. 93.100 / 57. 93.100
   libavformat    57. 72.101 / 57. 72.101
   libavdevice    57.  7.100 / 57.  7.100
   libavfilter     6. 87.100 /  6. 87.100
   libswscale      4.  7.101 /  4.  7.101
   libswresample   2.  8.100 /  2.  8.100
   libpostproc    54.  6.100 / 54.  6.100
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from
 'telestream_first2mb_ticket6335.mp4':
   Metadata:
     major_brand     : mp42
     minor_version   : 0
     compatible_brands: mp42isom
     creation_time   : 2016-01-11T11:30:54.000000Z
   Duration: 00:21:22.70, start: 0.000000, bitrate: 13 kb/s
     Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p,
 640x360 [SAR 1:1 DAR 16:9], 914 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 47.95
 tbc (default)
     Metadata:
       handler_name    : Telestream Inc. Dib Library - ReleaseEnterprise
 2014.61.142792
       encoder         : AVC
     Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz,
 stereo, fltp, 93 kb/s (default)
     Metadata:
       handler_name    : Telestream Inc. Dib Library - ReleaseEnterprise
 2014.61.142792
 Stream mapping:
   Stream #0:0 -> #0:0 (copy)
   Stream #0:1 -> #0:1 (aac (native) -> aac (native))
 Press [q] to stop, [?] for help
 Output #0, mp4, to 'out.mp4':
   Metadata:
     major_brand     : mp42
     minor_version   : 0
     compatible_brands: mp42isom
     encoder         : Lavf57.72.101
     Stream #0:0(und): Video: h264 (Main) ([33][0][0][0] / 0x0021),
 yuv420p, 640x360 [SAR 1:1 DAR 16:9], q=2-31, 914 kb/s, 23.98 fps, 23.98
 tbr, 24k tbn, 24k tbc (default)
     Metadata:
       handler_name    : Telestream Inc. Dib Library - ReleaseEnterprise
 2014.61.142792
       encoder         : AVC
     Stream #0:1(eng): Audio: aac (LC) ([64][0][0][0] / 0x0040), 48000 Hz,
 stereo, fltp, 128 kb/s (default)
     Metadata:
       handler_name    : Telestream Inc. Dib Library - ReleaseEnterprise
 2014.61.142792
       encoder         : Lavc57.93.100 aac
 frame=  196 fps=0.0 q=-1.0 Lsize=    1137kB time=00:00:09.00
 bitrate=1034.2kbits/s speed=29.6x
 video:984kB audio:147kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 0.545792%
 [aac @ 0x2c4a760] Qavg: 2458.570
 }}}
 Output file shows less frames than input with FFmpeg (and the reference
 decoder), not reproducible with {{{-an}}} and {{{-acodec copy}}}.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6335#comment:9>
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