[FFmpeg-devel] Why does vp56_init() sets avctx->width and avctx->height to 0?
Sat Aug 30 17:44:52 CEST 2008
On date Saturday 2008-08-30 16:55:57 +0200, Aurelien Jacobs encoded:
> Stefano Sabatini wrote:
> > Hi,
> > this causes a bug both in ffprobe (prints widht=size=0) and causes
> > a division by 0 exception in libavfilter/vf_scale when it tryies
> > to set the parameters for the filter.
> > What's the point into setting those values to 0?
> The point is that the actual frame width and height are not known
> at this point. They only get known after parsing the header of the
> first key frame.
> And also don't forget that those value may change at every key frame.
> The width/height is not an intrinsic property of a video stream, it's
> a property of each individual frame.
Thanks, it makes sense.
I wonder if this is a property of some some codecs, and if it would be
useful to mark somewhere this capability (for example
And for what regards libavfilter: for what I understood, the
capabilities negotiation between the filters happens during the
initialization of the filters graph, is libavfilter supposed to manage
cases when the video frame size may change after the initialization?
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