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Old 22nd April 2008, 21:19   #10  |  Link
Dark Shikari
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Join Date: Sep 2005
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Quote:
Originally Posted by ToS_Maverick View Post
now that you created another mysteriously patch, would you please explain how it is supposed to work? i'm very interested, and can only trust a patch if i know what it does
RDO normally uses sum of squared differences as its metric. That is, it rewards modes which approximate the source the most accurately according to that metric, and which don't cost too many bits.

FGO uses NSSD instead. NSSD consists of two components:

1) SSD as before.

2) abs( Noise(Reference Block) - Noise(Coded Block) ) * Weight, where "weight" is the --fgo parameter (this parameter also controls a few other things in FGO).

The resulting score is SSD + ND (Noise Difference).

Noise is measured as follows:

If X(i,j) is a pixel in a block, the noise score for that pixel is abs(X(i,j) - X(i+1,j) - X(i,j+1) + X(i+1,j+1)). This is summed up over all pixels in the block.

In other words, NSSD rewards modes which have a similar amount of noise and approximate the source reasonably well. This noise need not be exactly like the source's noise; it merely needs to be good enough.

Quote:
Originally Posted by Blue_MiSfit View Post
I was under the impression that FGM had to be supported decoder side as well?
This isn't FGM, its FGO.
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