[FFmpeg-devel] [PATCH] Bugfix H.263+ encoder frame header corruption

Michael Niedermayer michaelni
Fri May 25 14:30:27 CEST 2007


On Fri, May 25, 2007 at 12:03:06PM +0200, Harald Karner wrote:
> In libavcodec's h263p encoder under certain circumstances the picture 
> header gets corrupted:
> Due to wrong parameter order for an call to the "av_clip" function, the 
> value for the  "clock divisor" in the "CPCFC" (Custom Picture Code 
> Frequency Code) field of the H.263 header does not get clipped, which 
> causes the preceeding fields in the header to be corrupted (namely the 
> "Picture Height Indication" in case of custom picture format).
> The problem seems only to appear at low framerates, since only this 
> leads to large values of the "clock divisor".
> E.g. encoding a 1024x768 video with 0.5 fps lead to a resolution of 
> 1024x824 wrongly written to the frame header.
> The patch corrects the parameter order for the call to "av_clip".

patch ok

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
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