[libav-bugs] [Bug 643] New: Rewrapping MTS into MKV results in wrong framerate (90000.90 fps instead of 25 fps)

bugzilla at libav.org bugzilla at libav.org
Sun Feb 23 21:34:13 CET 2014


https://bugzilla.libav.org/show_bug.cgi?id=643

           Summary: Rewrapping MTS into MKV results in wrong framerate
                    (90000.90 fps instead of 25 fps)
           Product: Libav
           Version: 0.8
          Platform: All
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: Normal
         Component: general
        AssignedTo: bugzilla at libav.org
        ReportedBy: dfnsonfsduifb at gmx.de


Hi,

this is a bug that I've previously found affected ffmpeg roughly one year ago:
https://www.mail-archive.com/kdenlive-devel@lists.sourceforge.net/msg04363.html
Back then I switched to the latest ffmpeg version and the bug was gone. Now I'm
switching to avconv and the bug reappeared again.

I'm on Linux Mint x86_64 using

avconv version 0.8.10-6:0.8.10-0ubuntu0.13.10.1, Copyright (c) 2000-2013 the
Libav developers
  built on Feb  6 2014 20:53:28 with gcc 4.8.1
avconv 0.8.10-6:0.8.10-0ubuntu0.13.10.1
libavutil    51. 22. 2 / 51. 22. 2
libavcodec   53. 35. 0 / 53. 35. 0
libavformat  53. 21. 1 / 53. 21. 1
libavdevice  53.  2. 0 / 53.  2. 0
libavfilter   2. 15. 0 /  2. 15. 0
libswscale    2.  1. 0 /  2.  1. 0
libpostproc  52.  0. 0 / 52.  0. 0

for comparison, here's the ffmpeg version that is installed on my system:

ffmpeg version 0.8.10-6:0.8.10-0ubuntu0.13.10.1, Copyright (c) 2000-2013 the
Libav developers
  built on Feb  6 2014 20:53:28 with gcc 4.8.1
*** THIS PROGRAM IS DEPRECATED ***
This program is only provided for compatibility and will be removed in a future
release. Please use avconv instead.
ffmpeg 0.8.10-6:0.8.10-0ubuntu0.13.10.1
libavutil    51. 22. 2 / 51. 22. 2
libavcodec   53. 35. 0 / 53. 35. 0
libavformat  53. 21. 1 / 53. 21. 1
libavdevice  53.  2. 0 / 53.  2. 0
libavfilter   2. 15. 0 /  2. 15. 0
libswscale    2.  1. 0 /  2.  1. 0
libpostproc  52.  0. 0 / 52.  0. 0

The problem occurs when I rewrap a MTS file that comes from a camcorder into
MKV:

$ avconv -i in.mts -vcodec copy -acodec copy -sn out.mkv

When I do this with ffmpeg instead of avconv, I get a video that is perfectly
fine:

$ avconv -i out_ffmpeg.mkv 
avconv version 0.8.10-6:0.8.10-0ubuntu0.13.10.1, Copyright (c) 2000-2013 the
Libav developers
  built on Feb  6 2014 20:53:28 with gcc 4.8.1
[matroska,webm @ 0x6ab1e0] Estimating duration from bitrate, this may be
inaccurate
Input #0, matroska,webm, from 'out_ffmpeg.mkv':
  Metadata:
    ENCODER         : Lavf53.21.1
  Duration: 00:00:02.44, start: 0.000000, bitrate: 256 kb/s
    Stream #0.0: Video: h264 (High), yuv420p, 1920x1080 [PAR 1:1 DAR 16:9], 25
fps, 50 tbr, 1k tbn, 50 tbc (default)
    Stream #0.1: Audio: ac3, 48000 Hz, stereo, s16, 256 kb/s (default)
At least one output file must be specified

When I use avconv to do the same conversion, I get a broken video that
indicates 90000.90 fps:

$ avconv -i out_avconv.mkv 
avconv version 0.8.10-6:0.8.10-0ubuntu0.13.10.1, Copyright (c) 2000-2013 the
Libav developers
  built on Feb  6 2014 20:53:28 with gcc 4.8.1
[matroska,webm @ 0x25401e0] Estimating duration from bitrate, this may be
inaccurate
Input #0, matroska,webm, from 'out_avconv.mkv':
  Metadata:
    ENCODER         : Lavf53.21.1
  Duration: 00:00:02.44, start: 0.000000, bitrate: 256 kb/s
    Stream #0.0: Video: h264 (High), yuv420p, 1920x1080 [PAR 1:1 DAR 16:9],
90000.90 fps, 50 tbr, 1k tbn, 50 tbc (default)
    Stream #0.1: Audio: ac3, 48000 Hz, stereo, s16, 256 kb/s (default)
At least one output file must be specified

This wrong framerate messes up kdenlive and effectively makes it unusable.

I'll upload a source MTS file to the avconv FTP server with which the problem
can be reproduced. Really hope this can be fixed so I can ditch ffmpeg
altogether :-)

Best regards,
Johannes

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