[MPlayer-users] MPlayer-1.0pre4 bug with divx4 multipass filter

Vladimir Mosgalin mosgalin at VM10124.spb.edu
Sat Sep 11 10:26:52 CEST 2004

On Fri, 10 Sep 2004, D Richard Felker III wrote:

DRFI>> Try xvid. It's much better than both of them on high bitrate. I'm
DRFI>> pretty
DRFI>false. lavc is the best, just try comparing psnr or double-blind.

I learned this a long time ago - never ever compare psnr, it's quite
meaningless. Large difference in psnr values can easily be seen, and
small differences can't be trusted at all.

DRFI>perhaps you're just using dumb options.

You just haven't tried right xvid options or saw only very old xvid
versions, that's why you are saying so.  I encoded a lot with lavc
before, and now I can say for sure: lavc sucks a lot comparing with
xvid. lavc _can_ be sometimes better than xvid: when you need realtime
encode, or when you are encoding to low or average bitrate and aim for
postprocessing with pp or spp filters.

But when making high-quality dvd-rips, you can't even compare lavc and
xvid. With postprocessing, hq rips look bad - all the details are
blurred away. So I always make rips that do not need postprocessing
(1700-2500kbit/s depending on material is enough to make very hq rip
with the right settings). Sadly, on most types on content it's nearly
impossible with lavc. Scenes with qp=2 look extremly bad (and I don't
want to discuss my monitor, gamma, brightness and eyes - they are
perfectly well). In a lot of scenes, you can see blocks everywhere!
With xvid, qp=2 will lead to perfect result. The bitrate will be
~1.3-1.5 times higher than with lavc, though; but with qp=3, the result
is still much better than lavc's and bitrate is smaller.

That's where b-frames kick in and improve quality a lot. With the
"regular" xvid settings for the first pass, i/p frames with qp=2 and 2
b-frames with qp=4, the quality almost always is very good.  On the
second pass, bitrate can be reduced by 20-30% without visible quality
loss. At the same bitrate, lavc produces only low-quality video that can
either be watched with postprocessing (thus with washed out details), or
with a lot of blocking.

With xvid, it's extremly hard to find the content that will lead to
blocks at the same bitrate. The still frames everywhere, even on fast
motion scenes look exactly like original ones.  When switching between
two, eye can't tell the difference. With lavc, it is only possible with
qp=1 and insanely high bitrates (higher than original ones).



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