RFC: Xv field order

[Krzysztof Halasa]

Thomas Hilber <xorg at toh.cx> writes:

> with a slight modification the patches can output BFF or TFF.
> But I'm living in PAL land so I use TFF only ATM.

I'm here as well but I routinely use PAL MPEG2 (DVD) with BFF encoding
(originating as DV which is always BFF, I could of course shift the
audio and reverse fields but it creates some minor additional problems).

>> going to implement is the BFF/TFF(/progressive) interface at XVideo and
>
> what do you mean with progressive here? Do you mean 2 interlaced
> fields in weaved format?

Progressive video playback on interlaced display. This means the driver
is free to sync to either field (for example, to the previously selected
one).

> The vga-sync-fields patches effectively use these 2 weaved fields of 
> softdecoder output and forward these directly to VGA/DVI output. To keep
> synchronicity between stream and video timing the output line frequency
> is continuously trimmed in very small steps. This works very well even
> for live-TV where you must adopt exactly the stream clock delivered by
> the TV station.

Right. This is well beyond my needs.

>> DRM level. Unless I'm mistaken the patches don't touch the field order
>> and sync, at least on the intel and/or i915 driver.
>
> moving the sync point by 20ms yields in reversed field order output

Ah... But there is a simple interrupt-based way. And it doesn't depend
on the timings, the card signals end of each field. You may want to see
intelfb for details, I was using fb because the X playback was unusable.
-- 
Krzysztof Halasa