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

Harald Karner harald.karner
Fri May 25 12:03:06 CEST 2007

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".

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