[Ffmpeg-devel] wrong framerate in mpeg4 file?

Luca Ognibene luogni
Sun Sep 18 14:54:55 CEST 2005


hi!
I have a problem with some mpeg4 files.
ffmpeg reports that they have a framerate of 3000fps. You can find a
small video with this problem in the bug:
http://bugzilla.gnome.org/show_bug.cgi?id=313970
I've tried with current cvs and with the cvs of a month ago and the
output is:

luogni at bucefalo:/mnt/stor/Multimedia/Examples
$ /home/luogni/Temp/ffmpeg/ffmpeg -i ffmpeg3000fps.avi
ffmpeg version CVS, build 3276800, Copyright (c) 2000-2004 Fabrice
Bellard
  configuration:  --disable-encoders
  built on Sep 17 2005 14:08:36, gcc: 4.0.2 20050808 (prerelease)
(Ubuntu 4.0.1-4ubuntu8)

Seems that stream 0 comes from film source: 30000.00 (30000/1) -> 29.97
(30000/1001)
Input #0, avi, from 'ffmpeg3000fps.avi':
  Duration: 00:20:18.1, start: 0.000000, bitrate: 5 kb/s
  Stream #0.0: Video: mpeg4, yuv420p, 352x256, 30000.00 fps

So if i have undertood correctly ffmpeg.c code the demuxer tells that
the video is 29.97fps but the decoder tells that the video is 3000fps.
I've tried with ffmpeg of 20050427 and it works fine:

Input #0, avi, from 'ffmpeg3000fps.avi':
  Duration: 00:20:18.1, start: 0.000000, bitrate: 5 kb/s
  Stream #0.0: Video: mpeg4, yuv420p, 352x256, 29.97 fps

is this a bug in libavcodec? Or should i always use the framerate
reported by the demuxer? 

btw, thanks for your work on ffmpeg!

ciao
Luca





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