[FFmpeg-devel] [PATCH] Make VP3/Theora Decoder Much Faster

Mike Melanson mike
Mon Dec 7 16:43:23 CET 2009

Loren Merritt wrote:
> H264 does it this way because it has to keep track of num_coefs anyway. 
> But you're creating this variable, so you can check 
> index_of_highest_nonzero_coef == 0 instead.

I'm a little surprised to realize that this functionality doesn't 
already exist (been a long time since I wrote the decoder). The original 
VP3 decoder had IDCTs for 1- and 3-element fragments in addition to the 
full flavor IDCT. I think perhaps I tried to bring them over but someone 
convinced me that those other cases don't occur often enough to make it 
worthwhile. Have you found a lot of fragments with 1-3 non-zero coeffs?

     -Mike Melanson

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