[MEncoder-users] new doom9 codec comparission

Corey Hickey bugfood-ml at fatooh.org
Thu Dec 8 02:55:16 CET 2005

Matthias Wieser wrote:
>>Unfortunately, the quality drop from using threads=2 is, in my opinion,
>>unacceptable. The quality is a little bit worse than when not using any
> Do you mean "quality" or psnr?

I mean "quality" by my perception of how accurately the original frame
is represented. Most of the different options are too subtle to see
except by a frame-by-frame comparison. I play the two videos
simultaneously, scaling them with -xy 2 so I can see the differences
more easily, and place them one above the other. Then I seek both videos
to several positions I know look bad, and use framestep to compare
several frames at each position.

Mostly, the quality difference I see corresponds to the difference in PSNR.

> Maybe the low psnr was caused by the psnr-threads-bug?

Actually, the PSNR for threads=2 was being reported as much too high:
44.09 vs. what was really something less than 42.66. I haven't repeated
the test since Michael fixed that bug, but I may do so later for posterity.

See the response I wrote to Rich a few minutes ago for some encouraging
results with qpel:threads=2.

> This might be of interest:
> http://forum.doom9.org/showthread.php?s=&threadid=61128

That is indeed interesting. I skimmed the thread, and also found some
pictures and numbers:


Is there any implementation that works on Linux?

> Regards,
>   Matthias
> p.s.: Keep up the good work!

You're welcome. :)


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