[Libav-user] Different decoded frame number from ffmpeg commend line and the example demuxing

[Liang Zhang]

Thanks a lot, Sergey! I got it.




On Fri, Jul 26, 2013 at 1:56 PM, Sergey Fedorov <
night.rain.whisper at gmail.com> wrote:

> ‘-r[:stream_specifier] fps (input/output,per-stream)’
>
> Set frame rate (Hz value, fraction or abbreviation).
>
> As an input option, ignore any timestamps stored in the file and
> instead generate timestamps assuming constant frame rate fps.
>
> As an output option, duplicate or drop input frames to achieve
> constant output frame rate fps.
>
>
> 2013/7/23 Liang Zhang <liazhang2000 at gmail.com>:
> > Hello,
> >
> > I'm learning how to use libav to decode the video data into YUV. I try to
> > use ffmpeg commend line and also use the example program "demuxing"
> which is
> > provided in ffmpeg documentation. It surprised me that both resulted in
> > different frame number.
> >
> > I use the following ffmpeg commend line
> >
> > ffmpeg -y -i sample.mp4 -an -r 24 -pix_fmt rgb24 -vcodec tiff
> tif/%06d.tif
> >
> > to decode one video data file and get, e.g., 1460 frames.
> >
> > Then, I used the example program "demuxing"
> >
> > demuxing  sample.mp4  out_video out_audio
> >
> > to decode the same file and I got 1821 frames.
> >
> > Can someone help me explain why the frame number is different with these
> two
> > methods?
> >
> > FYI, I run the program in Ubuntu operating system.
> >
> > Thanks,
> >
> >
> >
> > liang
> >
> > _______________________________________________
> > Libav-user mailing list
> > Libav-user at ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/libav-user
> >
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