[MPlayer-dev-eng] Some stuff I can't figure out from the docs..

[D Richard Felker III]

On Wed, Oct 09, 2002 at 05:05:26PM +0200, Per Wigren wrote:
> Tuesday 08 October 2002 01.10 skrev Arpi:
> > > TV/v4l and I always get YV12.. That's fine though, but I want to be sure
> > > I don't have to implement a whole bunch of different "plotters" or
> > > whatever I should call it ;)
> >
> > you can tell libmpcodecs core that you only support YV12 (in
> > query_format()) so it will convert input to yv12 for you.
> 
> I've tried but couldn't figure out how to do this.. :(  Can you give a short 
> example of a query_format() function that ensures me I always get YV12 data 
> (or even better, RGB24!!!)?

You probably don't want to force RGB24; if you do, then playing movies
on BES (xv, mga, vidix, etc.) will require colorspace conversion
filters both before and after your filter, which will be very slow.

> 
> > > 3)  Is it at all possible to apply the filter after everything is
> > > (hardware) scaled?
> >
> > no
> > except if the hardware support subpictures (liek m g400 on 2nd head) but it
> > requires supoprt by linbo and probably by kernel driver too...
> 
> Do the scale-filter use hardware scaling if it is available?

No. Most hardware scalers are backend scalers, which don't actually
write the scaled image in RGB space to any framebuffer, they just scan
it out to the monitor on top of the main image in the fb. Even if your
hardware scaler does output the scaled image to video memory though,
copying that image over the bus from vid mem to system mem would be
well over 10x slower than software scaling.

Rich