Problem with persistent scaling/shifting in RADEONDisplayVideo()

Thomas Hilber xorg-driver-ati at
Mon Jul 28 08:24:55 PDT 2008

On Mon, Jul 28, 2008 at 10:11:31AM -0400, Alex Deucher wrote:
> Unfortunately, I haven't really looked at the overlay code in ages.
> As far as I know, no documentation on the overlay has been released
> without nda.  I'm guessing it's some slight mis-configuration of the

ok, I got this. Without documentation it's very hard to understand 
what's going on in that aged little piece of code. 

> something in the display video code, but I'm not sure what off hand.
> Perhaps an issue with interlaced material as Roland suggested.

it's funny: if I use a deinterlaced source instead (by feeding it through 
tvtime deinterlacers first) I don't notice any problem. Though everything 
else in the system is kept completely unchanged. This is because a 
deinterlaced frame does not contain even/odd fields that could be 
intermixed in the framebuffer. So the tiny scaling misalignment does not 

> If you can find what's different in the directfb code, that would be
> great.  Also, if you have any questions about any of the overlay
> registers, I can definitely look up the information for you.
> Unfortunately, I don't really have the time to dig into this myself at
> the moment.

Thank you very much for this nice proposal! These things are very time
consuming and I think you've got more important and interesting
things to do:)

It's no problem for me. I currently can live with my directFB
'solution'. For sure I will let you know if I could fix the
issue in the Radeon DDX.

> I think the real solution is composite and pageflipping.  Although the
> single triangle trick would definitely help.

It would be great if this would fix the textured-XV-tearing problem I 
described above.

It then would solve all my current probs with Radeon-XV anyway. And by the
way would help other people in this thread too.

- Thomas

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