RFC: Xv field order

[Thomas Hilber]

On Tue, Jun 23, 2009 at 08:08:38PM +0200, Krzysztof Halasa wrote:
> Come on, playback of interlaced video only makes sense with vertically
> unscaled display. Otherwise you have to deinterlace first and this is
> hardly usable (except for maybe 1:2 scaling when you can just strip every

the newer type intel chips do that transparently in hardware. I have not
found documentation about how they exactly handle this (by scaling each field
independently or by deinterlacing?). But for watching 16:9
material on an 4:3 TV it's a very useful feature. Picture quality is
still very good.

> It doesn't depend on the chip.

yes it does. i815 chips and radeon pre-avivo chips can't scale
interlaced material vertically. But i9xx chips can do.

> I wonder... Can your current code support textured video? Multiple video
> windows? Don't you have reliability problems, caused by the 20 ms sleep
> taking longer than requested (due to lack of RT scheduling)?

no, my patch collection is for conventional TV - one screen only. 
My major concern was not to encounter any field loss. That's why I
synchronize field timing dynamically to the stream clock.

The stream clock is calculated within xine-lib (in my case). I built
extensive debug tools showing any reliability problems. If you aren't
running number crunching processes on the machine whilst watchin TV
there are no problems at all. On 2.6.26 or newer kernels I need not
alter scheduling policies.

- Thomas