sön 2019-02-10 klockan 22:18 +0000 skrev Matthew Fearnley: > > On Thu, 31 Jan 2019 at 15:00, Tomas Härdin <tjop...@acc.umu.se> wrote: > > > > > > 1. The entropy calculation in block_cmp() omits the score of histogram[0] > > > from the final sum. > > > It's tempting to do this to bias the scores in favour of 0-bytes, but in > > > reality, blocks with a majority of 0 (or any other byte) will already be > > > naturally favoured by the entropy score anyway, and this bias will fail > > > > to > > > penalise blocks with an "average" (i.e. high entropy) number of 0's in > > > > them. > > > The exact implications are difficult to ponder, but in practical terms > > > > this > > > error does tend to produce worse results in the video compression. Not > > > massively so, but it's still noticeable. > > > > Did you try combining the statistics of the current MV with the > > statistics of the previous block, to bias the choice in favor of > > similar bytes? Could work like a cheap order-1 entropy model. > > > > I've had a go at this, but sadly, it seemed to adversely affect > compression, producing larger files. > Maybe it can be improved with some tweaking, or maybe there's a bug > somewhere. > But it feels to me like this approach on its own isn't enough to improve > scoring. Maybe as part of something larger though.. > Anyway, you can see the results of my efforts here: > https://github.com/countingpine/FFmpeg/commit/prev_histogram.
Darn. Interesting result at least /Tomas _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel