[FFmpeg-trac] #3558(undetermined:new): "-fflags +igndts" generates wrong dts when rewrapping some ts files to mp4

[FFmpeg]

#3558: "-fflags +igndts" generates wrong dts when rewrapping some ts files to mp4
-------------------------------------+-------------------------------------
             Reporter:  wim_arbor    |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  wish         |                Component:
              Version:  git-master   |  undetermined
             Keywords:  mov          |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
-------------------------------------+-------------------------------------

Comment (by wim_arbor):

 Replying to [comment:4 cehoyos]:
 > Replying to [comment:3 wim_arbor]:
 > > Replying to [comment:2 cehoyos]:
 > > > Replying to [ticket:3558 wim_arbor]:
 > > > > Without {{{-fflags +igndts}}} a proper output is created.
 > > >
 > > > I don't understand: Why do you add this option if it breaks
 remuxing?
 > >
 > > I also have files which require this option to be able to remux or
 transcode.
 >
 > Could you add such a sample for completeness?


 I have attached such a sample. Here is the diagnostics I performed on that
 file;

 Starting with the first I-Frame, attachment:dts_error_refbframe.ts
 contains the following values for PTS/DTS (PID 481/video):

 754: PTS: 5562850426 DTS: 5562846826
 821: PTS: 5562864826 DTS: 5562850426
 859: PTS: 5562857626
 866: PTS: 5562854026
 875: PTS: 5562861226
 879: PTS: 5562879226 DTS: 5562864826
 891: PTS: 5562872026
 902: PTS: 5562868426
 905: PTS: 5562875626
 908: PTS: 5562893626 DTS: 5562879226

 It looks like the B-Frame with PTS=5562857626 is used as a reference
 frame. So this stream is correctly in decoding order, as that frame must
 be decoded before the frame with PTS=5562854026. But it needs a different
 (lower) DTS. So this file is no valid stream. (to be clear, it is not
 generated with ffmpeg).

 Remuxing with ffmpeg without {{{-fflags +igndts}}} fails:
 {{{
 arbor at debian7:~$ bin/ffmpeg -y -i dts_error_refbframe.ts -f mov -c:a copy
 -c:v copy -bsf:a aac_adtstoasc out.mp4
 ffmpeg version N-62439-g5e379cd Copyright (c) 2000-2014 the FFmpeg
 developers
   built on Apr 14 2014 13:41:14 with gcc 4.7 (Debian 4.7.2-5)
 ...
 [mpegts @ 0x30549c0] DTS 5562792826 < 5562796426 out of order
 ...
 Press [q] to stop, [?] for help
 [mov @ 0x21cc440] Non-monotonous DTS in output stream 0:0; previous:
 130560, current: 130560; changing to 130561. This may result in incorrect
 timestamps in the output file.
 [mov @ 0x21cc440] pts (126960) < dts (130561) in stream 0
 av_interleaved_write_frame(): Invalid argument
 frame=    4 fps=0.0 q=-1.0 Lsize=      33kB time=00:00:01.45 bitrate=
 186.1kbits/s
 video:17kB audio:15kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 2.363399%
 }}}
 No problem that this fails, the DTS is wrong in the input file.

 But with {{{-fflags +igndts}}} it succeeds;
 {{{
 arbor at debian7:~$ bin/ffmpeg -y -fflags +igndts -i dts_error_refbframe.ts
 -f mov -c:a copy -c:v copy -bsf:a aac_adtstoasc out.mp4
 ffmpeg version N-62439-g5e379cd Copyright (c) 2000-2014 the FFmpeg
 developers
   built on Apr 14 2014 13:41:14 with gcc 4.7 (Debian 4.7.2-5)
 ...
 [mpegts @ 0x20e3a20] DTS 5562792826 < 5562796426 out of order
 ...
 Input #0, mpegts, from 'dts_error_refbframe.ts':
   Duration: 00:00:11.37, start: 61808.078511, bitrate: 1322 kb/s
   Program 1
     Stream #0:0[0x1e1]: Video: h264 (Main) ([27][0][0][0] / 0x001B),
 yuv420p(tv), 720x576 [SAR 64:45 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
     Stream #0:1[0x1e2]: Audio: aac ([15][0][0][0] / 0x000F), 48000 Hz,
 stereo, fltp, 127 kb/s
 Output #0, mov, to 'out.mp4':
   Metadata:
     encoder         : Lavf55.37.100
     Stream #0:0: Video: h264 (avc1 / 0x31637661), yuv420p, 720x576 [SAR
 64:45 DAR 16:9], q=2-31, 25 fps, 90k tbn, 90k tbc
     Stream #0:1: Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, 127
 kb/s
 Stream mapping:
   Stream #0:0 -> #0:0 (copy)
   Stream #0:1 -> #0:1 (copy)
 Press [q] to stop, [?] for help
 frame=  251 fps=0.0 q=-1.0 Lsize=    1405kB time=00:00:11.29
 bitrate=1019.4kbits/s
 video:1229kB audio:167kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 0.648900%
 }}}
 There are other errors in the output because the file was not cut at an
 I-Frame.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/3558#comment:6>
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