[Ffmpeg-devel] lossless video codec comparison

Loren Merritt lorenm
Mon Mar 19 15:32:14 CET 2007


On Mon, 19 Mar 2007, Kostya wrote:
> On Mon, Mar 19, 2007 at 01:11:26AM -0600, Loren Merritt wrote:
>>
>> imho the most interesting part is the arithcoder. Unlike
>> ffv1/snow/h264/vp*/jpeg2k which use binary arithcoders, lagarith stores a
>> whole coefficient in one symbol. End result is apparently that it's only
>> a few % slower than vlc.
>
> Isn't that a normal operating mode for traditional arithmetic coding
> (and range coding too)?

Yes, but I haven't seen it successfully used in a real codec before. 
Probably because there's no fast way to make it adapt to the observed
probabilities, you have to explicitely record a probability table.

--Loren Merritt




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