[FFmpeg-user] Why does fps == 1 for a webm videos?

Misha Penkov misha.penkov at gmail.com
Thu Mar 21 16:55:21 CET 2013

On 22 March 2013 00:02, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> Misha Penkov <misha.penkov <at> gmail.com> writes:
> > Unfortunately, my use case actually is to output raw video.
> > I'm passing it into an in-house application that that only
> > accepts raw video. The app performs shot segmentation, so
> > it needs to be accurate about frame numbers.
> How does your application deal with variable frame rate /
> how does it know the framerate of your yuv file?

The application is frame-rate agnostic.  It examines adjacent frames to
detect shot boundaries, and keeps track of the shot boundaries using the
frame numbers.  This is why I need frame numbers between the webm and the
YUV to match: if they don't, I won't be able to seek to the shot boundaries
in the webm file accurately.

> > It seems that -vsync 0 fixes the problem of duplicate frames.
> > Could it cause the frame numbers in the YUV and webm files
> > to no longer match up?
> It on the contrary guarantees that every input frame matches one
> output frame (no matter the timestamp).

That's exactly what I needed.  Thank you for your help.


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