[MPlayer-dev-eng] XMAME petition

[D Richard Felker III]

On Thu, Jun 06, 2002 at 04:38:59PM +0200, Colin Leroy wrote:
> On Thu, 6 Jun 2002 10:25:01 -0400 D Richard Felker III <dalias at aerifal.cx>
> wrote:
> 
> > you get scaling
> > at no cost, but you have to convert colorspace from RGB to YUV.
> 
> By the way,
> would it be possible to do something like a "-low-quality" flag in
> mplayer, which would have as effect to get 1/4 of the video data (ie,
> grouping blocks 4 by 4), in order to have fast decoding in the biggest
> files ?

You mean for faster colorspace conversion? Or just less copying across
the bus? You'd have to do really crappy sample-one, skip-three
scaling; actual proper scaling with averaging would be slower than not
scaling down at all.

Also, 4x4 blocks seems a bit drastic. Do you really want 180x120 dvds?
Scaling to half-size would make more sense.

Alternatively it might be good to just do vertical scaling, i.e.
skipping every other scanline. This would be stupid without hardware
scaling to get back the original size, so it wouldn't make sense to do
it to avoid colorspace conversion, but it could cut down on the volume
of data copied. Anyone else have comments as to whether this would
perform well? I would think with the codec exporting the image and the
'lowquality' filter direct rendering to vo, it could help a lot. If
mga_vid/vidix are fixed to handle multiple calls to config() properly,
the filter could even swap back and forth between 'lowquality' based
on cpuload, ala -autoq.

Rich