[Ffmpeg-devel] Partial frame decode in avcodec?

Matt Schuckmann mschuck
Wed May 10 23:52:16 CEST 2006


Ok I checked and it looks the old codec holds on to the uncompressed I
Frames and the region that has been decoded and if a dependent block hasn't
been decoded it decodes it. 

Matt S. 

-----Original Message-----
From: ffmpeg-devel-bounces at mplayerhq.hu
[mailto:ffmpeg-devel-bounces at mplayerhq.hu] On Behalf Of Matt Schuckmann
Sent: Wednesday, May 10, 2006 2:34 PM
To: 'FFMpeg development discussions and patches'
Subject: RE: [Ffmpeg-devel] Partial frame decode in avcodec?

> What happens if a predicted block depends on pixels outside the
> region?  Are you sure your old decoder didn't simply decode the full
> frame and crop it for you?

I don't know about the predictive block question I haven't looked into it to
closely. I'm kind of new to video compression but maybe the fact that the
old codec doesn't use P frames has something to do with it or maybe it goes
back and decodes just those blocks in needs. 

I'm certain the old codec only decodes the specified region (or something
close to it) because testing shows that if I have it decode only 1/4 of the
frame the processing time drops by about 75%. 

Thanks
Matt S. 

-- 
M?ns Rullg?rd
mru at inprovide.com

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