Regression: mkv encoder DTS discontinuity

[mbat]

Summary of the bug:
How to reproduce:

Download sample from here:
​https://www.datafilehost.com/d/v5QV9Y2BBg

Input file has no errors. Frames are every 40ms (25fps).
DTS progression is linear: 0 - 40 - 80 - 120 - 160 - 200 - 240 - ...

Run this command line:

ffmpeg -i test.mp4 -c copy test.mkv

Output file has DTS discontinuities at 0, 141 and 160ms.
DTS progression is: 0 - 61 - 101 - 141 - 160 - 221 - ...

DTS timings are in milliseconds.

My test configuration was Windows 7 64 bit.
I'm using Zeranoe build of 2016-08-17 (bba6a03).

Zeranoe build of 2015-02-03 has no issues.

Thanks,
MB

[cehoyos]

Please provide the command line that allows to reproduce the issue together with the complete, uncut console output to make this a valid ticket and please explain how the reproduce the "dts discontinuities".

[mbat]

Step by step instructions to reproduce DTS errors:

1. Download attached sample (test.mp4);
2. Run ffmpeg -i test.mp4 -c copy test.mkv;
3. Output:

   ffmpeg version N-81378-gbba6a03 Copyright (c) 2000-2016 the FFmpeg developers
     built with gcc 5.4.0 (GCC)
     configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-libebur128 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
     libavutil      55. 28.100 / 55. 28.100
     libavcodec     57. 53.100 / 57. 53.100
     libavformat    57. 47.101 / 57. 47.101
     libavdevice    57.  0.102 / 57.  0.102
     libavfilter     6. 52.100 /  6. 52.100
     libswscale      4.  1.100 /  4.  1.100
     libswresample   2.  1.100 /  2.  1.100
     libpostproc    54.  0.100 / 54.  0.100
   Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
     Metadata:
       major_brand     : isom
       minor_version   : 512
       compatible_brands: isomiso2avc1mp41
       encoder         : Lavf57.47.101
     Duration: 00:00:10.02, start: 0.000000, bitrate: 1287 kb/s
       Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x576 [SAR 64:45 DAR 16:9], 1201 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
       Metadata:
         handler_name    : VideoHandler
       Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 81 kb/s (default)
       Metadata:
         handler_name    : SoundHandler
   [matroska @ 023fba20] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
       Last message repeated 1 times
   Output #0, matroska, to 'test.mkv':
     Metadata:
       major_brand     : isom
       minor_version   : 512
       compatible_brands: isomiso2avc1mp41
       encoder         : Lavf57.47.101
       Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x576 [SAR 64:45 DAR 16:9], q=2-31, 1201 kb/s, 25 fps, 25 tbr, 1k tbn, 12800 tbc (default)
       Metadata:
         handler_name    : VideoHandler
       Stream #0:1(und): Audio: aac (LC) ([255][0][0][0] / 0x00FF), 48000 Hz, stereo, 81 kb/s (default)
       Metadata:
         handler_name    : SoundHandler
   Stream mapping:
     Stream #0:0 -> #0:0 (copy)
     Stream #0:1 -> #0:1 (copy)
   Press [q] to stop, [?] for help
   frame=  250 fps=0.0 q=-1.0 Lsize=    1572kB time=00:00:10.00 bitrate=1287.0kbits/s speed= 592x    
   video:1466kB audio:100kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.370809%
   
   

4. Since video track has been copied (-c copy) PTS, DTS and all timecodes of video track must be the same (timebase apart);
5. But...this is not what I've found;
6. Run ffprobe -show_frames test.mkv > mkv.txt and ffprobe -show_frames test.mp4 > mp4.txt;
7. Open the .txt files previously generated;
8. Extract pkt_dts_time fields of video track;
9. For mp4.txt you'll find (diffs in ms on side):

   pkt_dts_time=0.000000
   pkt_dts_time=0.040000   40
   pkt_dts_time=0.080000   40
   pkt_dts_time=0.120000   40
   pkt_dts_time=0.160000   40
   pkt_dts_time=0.200000   40
   ...
   

10. For mkv.txt you'll find (diffs in ms on side):

    pkt_dts_time=0.000000   
    pkt_dts_time=0.061000   61
    pkt_dts_time=0.101000   40
    pkt_dts_time=0.141000   40
    pkt_dts_time=0.160000   19
    pkt_dts_time=0.221000   61
    ...
    

As you can see, DTS in .mkv is not regular like in .mp4. With old ffmpeg builds (2015-02-03 i.e.), it was.

Thanks,
MB

[cehoyos]

Behaviour has changed several times:
Before 9d4fdfe24c731d1880797dee65365154b41c1dea (related to #4487): 0.080000, 0.120000, 0.160000, 0.200000, 0.240000
Before 65efcaeb8467f5aff25eaf02b20dae43d5ca9dc7 (related to #2324, #2325): 0.021000, 0.061000, 0.101000, 0.141000, 0.181000

[isasi]

This file has the same behavior even before the edit list patch ​http://git.videolan.org/?p=ffmpeg.git;a=commit;h=ca6cae73db207f17a0d5507609de12842d8f0ca3 . Something wrong in matroska muxer.