[FFmpeg-trac] #8070(avformat:new): mov demuxer is broken on fragmented MP4 files with multiple trun boxes per sidx entry

[FFmpeg]

#8070: mov demuxer is broken on fragmented MP4 files with multiple trun boxes per
sidx entry
-------------------------------------+-------------------------------------
               Reporter:  dbuitenh   |                  Owner:
                   Type:  defect     |                 Status:  new
               Priority:  normal     |              Component:  avformat
                Version:  git-       |               Keywords:  mov dash
  master                             |  mp4 fmp4
             Blocked By:             |               Blocking:
Reproduced by developer:  0          |  Analyzed by developer:  0
-------------------------------------+-------------------------------------
 Summary of the bug:

 FFmpeg makes the assumption that fragmented MP4 files will have exactly
 one 'trun' box per entry in the 'sidx' box (see here:
 http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavformat/mov.c;h=24de5429d1d546473c27e7d7291f477ea3fa79d5;hb=HEAD#l4747).
 This is not the case and the spec explicitly allows multiple 'trun' boxes
 (chunks) per sidx entry. Other players, browsers, and demuxers handle this
 corectly. FFmpeg ends up resetting the PTS and DTS at each new trun box,
 resulting in repeated timestamps.

 Sample with multiple trun per sidx (broken): http://chromashift.org/vd.mp4
 Sample with single trun per sidx (works): http://chromashift.org/vd2.mp4

 How to reproduce:

 FFmpeg example:
 {{{
 % ffmpeg -i vd.mp4 -f null -
 ffmpeg version N-94258-g10f3793823 Copyright (c) 2000-2019 the FFmpeg
 developers
   built with gcc 8 (Debian 8.3.0-19)
   configuration: --enable-static --disable-shared
   libavutil      56. 30.100 / 56. 30.100
   libavcodec     58. 53.101 / 58. 53.101
   libavformat    58. 28.101 / 58. 28.101
   libavdevice    58.  7.100 / 58.  7.100
   libavfilter     7. 56.101 /  7. 56.101
   libswscale      5.  4.101 /  5.  4.101
   libswresample   3.  4.100 /  3.  4.100
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '../chopshop/vd.mp4':
   Metadata:
     major_brand     : dash
     minor_version   : 0
     compatible_brands: dashmp42mp41iso6
     creation_time   : 2019-08-09T15:55:03.000000Z
   Duration: 00:01:58.66, start: 0.000000, bitrate: 301 kb/s
     Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv,
 smpte170m), 426x240, 15 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 48k tbc
 (default)
     Metadata:
       creation_time   : 2019-08-09T15:55:03.000000Z
       handler_name    : L-SMASH Video Handler
       encoder         : AVC Coding
 Stream mapping:
   Stream #0:0 -> #0:0 (h264 (native) -> wrapped_avframe (native))
 Press [q] to stop, [?] for help
 Output #0, null, to 'pipe:':
   Metadata:
     major_brand     : dash
     minor_version   : 0
     compatible_brands: dashmp42mp41iso6
     encoder         : Lavf58.28.101
     Stream #0:0(und): Video: wrapped_avframe, yuv420p, 426x240, q=2-31,
 200 kb/s, 23.98 fps, 23.98 tbn, 23.98 tbc (default)
     Metadata:
       creation_time   : 2019-08-09T15:55:03.000000Z
       handler_name    : L-SMASH Video Handler
       encoder         : Lavc58.53.101 wrapped_avframe
 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x563629252700] DTS -2002 < 9009 out of order

 }}}

 FFprobe example:

 {{{
 % ffprobe -show_packets vd.mp4 | grep 'dts='
 dts=-2002
 dts=-1001
 dts=0
 dts=1001
 dts=2002
 dts=3003
 dts=4004
 dts=5005
 dts=6006
 dts=7007
 dts=8008
 dts=9009
 dts=-2002
 dts=-1001
 dts=0
 dts=1001
 dts=2002
 dts=3003
 dts=4004
 dts=5005
 dts=6006
 dts=7007
 dts=8008
 dts=9009
 dts=-2002
 dts=-1001
 dts=0
 dts=1001
 dts=2002
 dts=3003
 dts=4004
 dts=5005
 dts=6006
 dts=7007
 dts=8008
 dts=9009
 dts=-2002
 dts=-1001

 [... snip ...]
 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/8070>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker