[Ffmpeg-devel] Partial frame decode in avcodec?

Matt Schuckmann mschuck
Wed May 10 19:59:31 CEST 2006

I've been experimenting with the avcodec library for a couple of months now
as a replacement for an old implementation of the MPEG4 codec. So far
avcodec is working great and totally blows the old codec away in all


The one thing I haven't been able to find in avcodec that I kind of need is
the ability to decode only a part of a frame. 

The old codec supported this via a SetView() function that took a height and
width and upper left corner of the region of interest. I primarily used this
to reduce the decode processing time since often the user is only looking a
small part of a very large frame and large processing time savings could be
had by decoding only the visible part of the frame. 


Can anybody tell me if avcodec supports this type of feature for MPEG4? Or
for any other codec?

I was led to believe that this feature/capability is a part of the MPEG4
standard, does anybody know if this is true?


If this is not in avcodec are there any hooks in place to put it in or can
anybody recommend a good starting place to look at implementing it.


Any feedback is much appreciated. 



Matt Schuckmann

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