[MPlayer-dev-eng] [PATCH] Avoid scaling for tiny aspect ratio differences

[Kurt Garloff]

Ivan,

On Sat, Mar 29, 2008 at 07:16:59PM +0200, Ivan Kalvachev wrote:
> On Fri, Mar 28, 2008 at 2:51 PM, Kurt Garloff <kurt at garloff.de> wrote:
> >  I would rather send this out and see whether people think it's
> >  worthwhile ...
> 
> So, you  deliberately encode sample with small aspect change and then
> you want to bloat mplayer with another useless option to fix what you
> have done.

Life is not always perfect.

So you have this screen that does 1366x768 (1.7786) but your graphics 
driver only handles 1360x768 (1.7708). You want the HD material to
look as good as possible on your effective 1360 screen, so you would
encode with 1360x765 (1.7778) if you can afford three black lines --
but it will result in 1360x766 as you can't handle an uneven number of
lines obviously with YUV420. Or you do 1360x768.

In neither case I want the mpeg decoder to do prescaling. I can
live with an aspect ratio that's off by less than 1%, but not with
images that are less sharp than they need be due to needless prescaling.

> -noaspect would ignore the input file aspect info and assume 1:1
> pixels of the decoded material.
> Some of the encoders do :autoaspect: calculations, some reqiuare it as
> separate option, but there is aways :aspect=1: override available.

OK, so that would be a manual workaround.
I want something that does the right thing automatically for most 
people.
 
> Also why did you pick up 766 instead of 768, don't you know all codecs
> like multiples of 16 ?

I can live with that performance impact. I wanted to be as close to 16:9
as possible ...

Cheers,
-- 
Kurt Garloff                   <kurt at garloff.de>             [Koeln, DE]
Physics:Plasma modeling <garloff at plasimo.phys.tue.nl> [TU Eindhoven, NL]
Linux: VP PM OPS               <garloff at suse.de>            [Novell Inc]
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