Re[2]: [XviD-devel] API 3.0

skal xvid-devel@xvid.org
10 Sep 2002 17:35:13 +0200


On Tue, 2002-09-10 at 17:08, Radoslaw Czyz wrote:

> BTW, do you know a way to compute PSNR of my second pass? I'd like to
> compare hinted me search vs. full me search, but I have no idea how ;)
> A simple program to compute PSNR between 2 avi's would be the best,
> and I have a strange feeling that I've read about it somewhere - on a
> forum of sort - but search at Doom9's didn't give me any effect.

	Something close to what you want is the 'sum' returned
	by quant_inter() in MbTransQuantInter(). It's the SAV
	(yeh! a new acronym. no? ok, Sum of Absolute Values) of the
	inter coeffs. Would it be the SSV (ok ok. Sum of Squared
	Values), Parceval theorem would tell it's the PNSR of
	interblocks (the ones you're interested in for ME).
	Anyhow, this SAV is not so far from PSNR as a quality
	measure...
	This reminds me that collecting this PSNR-like stat in
	xvid (with a special compile flag, since it slows down 
	the encoding a little) is just few lines... 

		Skal