[FFmpeg-devel] inverse weighitng tables for DV seems to be wrong

Roman V. Shaposhnik rvs
Fri Feb 27 02:54:15 CET 2009

Hi Michael,

thanks for replying!

On Thu, 2009-02-26 at 22:36 +0100, Michael Niedermayer wrote:
> > As you can see -- almost all of the errors are now in 1 range. 
> > 
> > But! Is there a way we can do better?
> > 
> > My division-foo is weak today, so any kind of suggestions will be appreciated.
> the best table is not neccessarily the one that is closest to the inverse
> but the one that generates the best PSNR at a specific bitrate

I guess I'd be really glad if you can elaborate on this point. For DV,
at least, if there's no quantization involved than decoding is a 100%
inverse of the encoding weighting. If there's quantization things can
get a little bit less straightforward, but still.

> our tiny_psnr tool prints the PSNR and dv is constant bitrate so it should not
> be hard to find a good table by +-1 of one coeff and trial and error

tiny_psnr assumes that there's an image. What would your recommend? 
workman? rotozoom? something else?


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