[FFmpeg-user] Alter YUV values of AVFrames

Carl Eugen Hoyos cehoyos at ag.or.at
Wed Feb 1 11:31:40 CET 2012

killkenny64 <kennethjjgibson <at> gmail.com> writes:

> I tried just altering the first frame of a video stream. I decoded the
> frame, added 100 to each Y value in the AVFrame->data[0], encoded the frame
> again and saved it into the video.
> However when I play the video back, it is not only the first frame that has
> been altered, but the first 30 frames.

Sounds as if the codec the original video was encoded with used a gop-size 
of 30.

Try rawvideo or an intra-only codec (or try forcing a gop-size of 1).

Carl Eugen

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