[MEncoder-users] Codec-independant objective quality measurement

[Nicolas George]

Le quintidi 15 thermidor, an CCXIV, Matthias Wieser a écrit :
> First: I don't know any good non-psnr tool for linux.

That is too bad :(

> You could use mplayer/TOOLS/psnr-video.sh for this purpose.

Thanks, I did not see this script until now.

As fas as I understand how it works, what it does is:

- call mplayer twice to convert the videos into simple bitmap files in
  temporary directories;

- call pnmpsnr to make the actual evaluation on each pair of images;

- do some postprocessing on the results to combine it in a simple, usable
  result.

Am I right?

I started doing roughly the same thing a few days ago. I use yuv4mpeg and
pipes instead of pnm and temp files, which is a little bit more efficient
(especially because it does not require 60 megaoctets of temporary storage
space for each second of DVD-quality evaluated material :-), but the
principle is exactly the same. I intend to publish the result when it will
be a little bit more polished.


I will also try to find other metrics. What bothers me with PSNR is that I
fear it fails to see some artifacts that I find really annoying.

In particular, with H.264 at ~1 Mbit/s, there are a few 16x16 blocks that
are really blurry, and I believe this blur would be better if it was spread
on all the blocks of the image. If someone knows how to reduce that effect,
I am interested.


Regards,

-- 
  Nicolas George
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