[Libav-user] Problems with ffvhuff and huvvyuv

James Board jpboard2 at yahoo.com
Wed Oct 16 18:29:56 CEST 2013


>> I don't know that codec. I just knew it was lossless. So I guess (unless there's a bug) the rule has an exception. Maybe the 'adaptive tables' that google says it has adapt every 24 or so frames. Don't have the source in front of me right now. 
>> 
>> But it's an FOSS project - anyone look at the code and see what's going on. 

>I can't pick it out of the code, and the codec info says it is intra-frame only... but this paper seems to indicate that >ffvhuff isn't always intra-frame only:

>"FFv1 [16] was also developed by the FFmpeg project and is derived from HuffYUV. The main difference is that the intra->frame coding model is limited to the median model as described above"

Okay, but that's ffv1.  It's true that ffv1 uses inter-frame compression.  But ffv1 is 
different from ffvhuff.  I'm using ffvhuff, not ffv1.  As far as I know, ffvhuff is intra-frame
only.
 
Yes, libAV is FOSS and I'm looking at the source now.  But there's a huge learning curve.
It would be nice if someone told me beforehand whether or not this is a problem
that can be fixed.  If I want to decode a single isolated frame with ffvhuff, does the
ffvhuff algorithm require me to decode multiple frames after N?  Or is that merely a
fixable problem with the way libav implements ffvhuff.  If this is fixable, where in the
source would I look?
 
Is there any documentation on how codecs are implemented in libav?
 
Also, how can I build the doxygen HTML pages for the source code?
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