[XviD-devel] HUGE ME regressions between beta1 and beta2

Radek Czyz radoslaw at syskin.cjb.net
Sat Nov 26 13:42:09 CET 2005


Now you see how strange it is :)

It would appear that we've got an impressive quality boost from your 
patch. Initially you only saw that with higher quants, however *if* I 
make all tables linear (same formula for low and high quants) then 
there's a detectable gain in lower quants too.

I tweaked 8x8 lambda multiplier a bit and got some more.

If we keep this, I'll be happy to sacrifice some speed.

What I said above is true for no bframes.
Example I just did, quant 3, defaults, no bframes:
old code, size 43,010,048, psnr 44.1543, time 2:03
new code, size 42,905,600, psnr 44.1544, time 2:07

Funny, heh? It searches more and actually finds more. I'm happy with that.

With bframes, I get this:

old code: size 35,866,624, psnr 43.1332, time 2:01
new code: size 35,934,208, psnr 43.1822, time 1:52

So new and old are equivalent for psnr (more or less) with a rather 
major slowdown. Whatever new p-frames got us, b-frames wasted.

I'll continue working on it now.

If I "fix" bframes, then I will highly recommend a simple patch that 
changes 16x16 table to be linear. It looks like an unexpected win.

Radek


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