[daala] Curious about progress of codec

Jean-Marc Valin jmvalin at jmvalin.ca
Wed Apr 27 17:49:37 UTC 2016

On 04/27/2016 01:08 PM, Jarek Duda wrote:
> Regarding using probability distribution from the last I-frame, I have
> meant remembering probability distribution at the end of this I-frame
> (not updated further) - additional buffer which is updated every
> I-frame, P-frames use it as the initial probability distribution.

While it would be technically possible to do that without hurting
robustness to losses too much (what if you lost *part* of the keyframe),
the main problem is that it likely wouldn't actually help either. The
statistics of symbols on a keyframe are very very different from the
statistics of those on a P-frame. Not to mention that keyframes don't
have things like motion vectors which eat up a lot of the bits in P-frames.

You *could* have the keyframe explicitly send initial probabilities for
all subsequent P-frames, but it's a lot of work and it's not clear how
much gain there would be. Not to mention that the statistics again
change depending on how far your P-frame is from your keyframe.



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