[FFmpeg-devel] [PATCH] adpcm: Store trellis nodes in a heap structure

[Martin Storsjö]

On Fri, 12 Nov 2010, Michael Niedermayer wrote:

> On Fri, Nov 12, 2010 at 12:41:24PM +0200, Martin Storsj? wrote:
> > On Thu, 11 Nov 2010, Reimar D?ffinger wrote:
> > 
> > > On Thu, Nov 11, 2010 at 01:08:41AM +0200, Martin Storsj? wrote:
> > > > > In that case, do you feel like finding some setting that with all 
> > > > > patches is about the same speed as without patches and compare the 
> > > > > quality? IMO that would possibly be the most interesting comparison.
> > > > 
> > > > If reading the graphs at 
> > > > http://albin.abo.fi/~mstorsjo/adpcm-graphs/music1/, I find the following 
> > > > test runs quite similar:
> > > > Original code, -trellis 6: 26.7 seconds, stddev 87.67, PSNR 57.47
> > > > Fully patched, -trellis 8: 22.8 seconds, stddev 85.08, PSNR 57.73
> > > > 
> > > > Thus, with all the patches, you get better quality at comparable run 
> > > > times. Or just roughly similar quality at very much shorter run time. :-)
> > > 
> > > My question was rather: how does the "maximum" quality change, i.e.
> > > at the highest reasonable setting.
> > > I'd expect it to rather improve, but I think you so far only tested really
> > > fast settings (22 seconds is not a long encoding time in any way,
> > > even the original 1 minute something is still "acceptable", I remember
> > > when MP3-encoding was done at I think 1/8th real-time...)
> > 
> > Well, then I guess it's all up to how much patience you have when defining 
> > the "maximum" quality. If we consider 1/8th to 1/10th of realtime as 
> > "maximum", we get these numbers:
> > Original code, -trellis 8: 245.8 seconds, stddev 83.65, PSNR 57.88
> > Fully patched, -trellis 11: 189.7 seconds, stddev 83.26, PSNR 57.92
> > 
> > However, if checking the runtime_psnr graphs at 
> > http://albin.abo.fi/~mstorsjo/adpcm-graphs/, one notices that the original 
> > (and patch #1 and patch #3) will get better PSNR/runtime if extending the 
> > benchmark to even larger trellis sizes. For the music1 sample, this 
> > happens around sometimes after ~1/15 of realtime, for the other samples it 
> > happens even later than that.
> 
> so id say #1-#3 are ok to commit while #4 needs more work

Applied #1-3. I'll think more about #4 later to see if I can make a better 
compromise between quality and runtime.

I don't think I had any code in the G.722 trellis encoder similar to the 
one I'm removing in #4, so I guess I can try to update the G.722 trellis 
patch with these improvments.

Thanks for the persistence on making graphs - the log(time) vs PSNR graph 
really is a valuable tool for making these comparisons.

// Martin