[XviD-devel] low-bitrate patch

[Michael Militzer]

Hi,

oops. The attachment got stripped by the mailing list. So here are the
graphs:

http://www.xvid.org/images/carphone.png
http://www.xvid.org/images/highway.png
http://www.xvid.org/images/mother.png
http://www.xvid.org/images/paris.png
http://www.xvid.org/images/tempete.png

bye,
Michael


Quoting Michael Militzer <michael at xvid.org>:

> Hi all,
> 
> I've committed a patch to cvs that improves XVID's performance at low-
> bitrates by using better lambda values for R-D vector search. By this also
> mode decision (SAD-based) is improved at low-bitrates. At mid/higher
> bitrates
> there's no change in performance, so only people who aim at really low
> bitrate (and quality) encodes will benefit from this patch.
> 
> I've attached some R-D graphs that compare the behavior of patched and 
> unpatched XVID for various sequences and different bit-rates. Note that I've
> used a logarithmic scale, so that the differences at low bitrates can be
> better perceived. As can be clearly noticed, the compression performance is
> enhanced significantly at very low bitrates (up to 2-3 dB PSNR).
> 
> Well, it's another question how useful this patch actually is because such
> extremely low bit-rates are barely used. But for completeness, XVID should
> perform equally great at all bitrates...
> 
> bye,
> Michael
>