[Ffmpeg-devel] [Bad news]: MPEG Seek has failed to work in FFmpeg SVN

Måns Rullgård mru
Thu Oct 26 12:12:26 CEST 2006

Steve Lhomme said:
> M?ns Rullg?rd wrote:
>> Steve Lhomme said:
>>> QuickTime wrote:
>>>> Dear:
>>> Hi Quicktime,
>>>> FFmpeg fails to decode video(avcodec_decode_video() never return
>>>> picture) after perform SEEK on mpeg file format
>>>> It seems that the seek&decode abiliity for mpeg files have been broken
>>>> for 2 months(ealier than August )
>>>> ffmpeg  -ss 00:00:10 -i test.mpg  -r 25 test.mp4
>>>> .....
>>>> Input #0, mpeg, from 'test.mpg':
>>>>  Duration: 00:00:24.0, start: 0.346711, bitrate: 2314 kb/s
>>>>  Stream #0.0[0x1e0]: Video: mpeg1video, yuv420p, 352x288, 2000 kb/s,
>>>> 25.00 fps(r)
>>>>  Stream #0.1[0x1c0]: Audio: mp2, 44100 Hz, stereo, 192 kb/s
>>>> Output #0, mp4, to 'test.mp4':
>>>>  Stream #0.0: Video: mpeg4, yuv420p, 352x288, q=2-31, 200 kb/s, 25.00
>>>> fps(c)
>>>>  Stream #0.1: Audio: aac, 44100 Hz, stereo, 64 kb/s
>>>> Stream mapping:
>>>>  Stream #0.0 -> #0.0
>>>>  Stream #0.1 -> #0.1
>>>> frame=    0 q=0.0 Lsize=     120kB time=14.8 bitrate=  66.1kbits/s
>>>> video:0kB audio:114kB global headers:0kB muxing overhead 4.833664%
>>>> .....
>>> I've had similar problems (actually crashes) with some MPEG2 samples
>>> (from DVDs) for a long time. Maybe if you can provide a sample and say
>>> what platform you use, it could help.
>> Yeah, if Steve hadn't refused to provide samples, maybe this had been fixed
>> already.
> Look at the message "Re: [Ffmpeg-devel] MPEG2 decoding problems" from
> 2006-03-02 there is a chems1.vob sample. The URL should still work.

I have a copy of the file.

> It was not fixed because you need to seek at a specific place in the
> file to crash. Maybe you can manage to do that by doing a
> forward/backward seek in ffplay during a specific fraction of second
> during playback. I proposed to modify ffplay to test it but it was
> rejected...

We do not support modified versions of ffmpeg.  If this is really a bug in
our code (and caused by your mods), it should be possible to trigger it by
cutting that file of yours in the right spot.  Find this spot, and we'll
look into it.  You can't expect us to do all the work.

M?ns Rullg?rd
mru at inprovide.com

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