[FFmpeg-devel] [PATCH 5/5] libavcodec/ffv1: Support storing LSB raw

[Michael Niedermayer]

Hi Jerome

On Wed, Oct 16, 2024 at 10:29:18PM +0200, Jerome Martinez wrote:
> Le 16/10/2024 à 21:51, Michael Niedermayer a écrit :
> > did you try qtable 1 ? strangely it performed better for the file i used compression wise
> 
> Updated with latest code (in practice, no change in previous values):
> 0,037x    0,471    No patch
> 0,051x    0,491    bitfield
> 0,046x    0,489    rangecoder
> 0,046x    0,486    rangecoder qtable=1
> 
> qtable=1 helps but still not enough for being interesting compared to the
> bitfield version.
> 
> > also i cleaned the code up a bit and reposted, some of the code was
> > not exactly optimized
> > 
> > here the old "bitfield"
> > real	0m5.545s
> > real	0m5.655s
> > real	0m5.643s
> > 
> > vs. just now posted:
> > real	0m5.407s
> > real	0m5.393s
> > real	0m5.404s
> 
> Even more interesting to keep the bitfield version rather than the range
> coder!

what are you testing?
the new code is faster than the old code.
There is something not right here, the range coder based implementation
i posted now is 5% faster then the range coder based one i posted earlier today
thats overall speed meassured with "time ./ffmpeg"
if you see no difference there is something fishy

i simply tested this:
./ffmpeg -i rawsamples/16/01.dpx -threads 1  -c:v ffv1 -context 1 -coder 1 -strict -2 -level 4 -rawlsb 4   -y /tmp/speedtest4.nut

It uses 1 thread as the speed with more threads was very unstable between runs
and we want to know how fast ffv1 is not how multithreading behaves


> 
> FYI I test on 2 different sets of 2 seconds of real content, on SSD, 1 min
> of encoding each so result is stable, unfortunately I don't have more
> content but I try to have more.

can this content be downloaded somewhere ?

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Modern terrorism, a quick summary: Need oil, start war with country that
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