[FFmpeg-user] Filter video using libavfilter is longer than input video

Stefano Sabatini stefano.sabatini-lala at poste.it
Sun Apr 17 21:06:06 CEST 2011

On date Sunday 2011-04-17 20:38:43 +0200, Roger Pau Monné encoded:
> Hello,
> I'm trying to develop a new filter using the avfilter API, but it
> seems to add some frames at the beginning of the video, so input and
> output videos don't have the same duration (for example if I use an
> input video of duration 00:01:41.60 the output video has a duration of
> 00:01:41.64). I don't know if there is a problem with my filter, I
> don't think I'm adding any frames, but it's the first time I use it,
> so I'm attaching the filter I'm working on to see if anyone knows what
> the problem might be.
> Thanks, Roger.

from some quick tests it looks a problem related to transcoding, so
not necessarily libavfilter-specific.

BTW if you want to integrate the filter into FFmpeg you're welcome to
post it on ffmpeg-devel, I see there are some simplifications which
can be done.
ffmpeg-user random tip #11
One minute of video silence with ffmpeg:
ffmpeg -t 60 -s qcif -f rawvideo -pix_fmt rgb24 -r 25 -i /dev/zero \
    -y silence.mpeg

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