[MPlayer-users] Re: Encoding quality advices

[Rémi Guyomarch]

On Thu, Nov 28, 2002 at 07:24:43PM +0100, Moritz Bunkus wrote:
> Hi everyone.
> 
> Encoding quality - or why automatism is bad.

Very good write !

But may I add another point ? Sure I can :)

Sometimes I found that encoding to y-scaled only DVD qualty (ie 704 x
288 for a 2.85 film) gives better visual quality than a scaled-down
version even if the quantizers are significantly higher than for the
scaled-down version.
Keep in mind that blocs, fuzzy parts and generaly mpeg artefacts in a
704x288 image will be harder to spot in full-screen mode than on a
512x208 image. In fact I've see example where the same movie looks
better compressed to 704x288 with an average weighted quantizer of
~3 than the same movie scaled to 576x240 with an average weighted
quantizer of 2.4.
Btw, a print of the weighted average quantizer would be nice in
countquant.pl :)

Another point in favor of not trying to scale down too much : on hard
scaled-down movies, the MPEG codec will need to compress relatively
high frequencies rather than low frequencies and it doesn't like that
at all. You will see less and less returns while you scale down and
scale down again in desesperate need of some bandwidth :)

In my experience, don't try to go below a width of 576 without closely
watching what's going on.

-- 
Rémi