Re: [xine-devel] Xine + XvMC

[Matthias H. <Mat...@in...>]

Sorry for entering the discussion late, but I just noticed the contents
of the current thread :^)

> Sorry for being harsh here, but this problem needs a solution. 

Definitely.
Actually, I have the same problem in an environment (TV mode with
interlaced signals) in which it gets even harder. Without synchronized
switches I will never be able to correctly render interlaced material.

> Do you think it will ever be possible to get Xv video output without
> tearing and judder in Xfree86 with the current architecture?

FYI: I just looked at the DGA extension, and the following paragraph
jumped into my line of sight:

------------------------------> SNIP <---------------------------------
void XDGASetViewport( Display *dpy, int screen, int x, int y, int flags);

    Set the upper left-hand corner of the rectangle of framebuffer
that is to be displayed on the screen.  Not all locations may be
supported by the hardware and requested locations will be adjusted
according to the xViewPortStep and yViewPortStep fields in the XDGAMode.

    "flags" can be XDGAFlipRetrace or XDGAFlipImmediate to adjust
the viewport location at the next vertical retrace or immediately.
Values other than the supported values advertised in the mode's
viewportFlags field will result in hardware-specific default behavior.
XDGAFlipImmediate will block until the flip is completed. 
XDGAFlipRetrace will generally NOT block so it is necessary to 
monitor the viewport status with XDGAGetViewportStatus().
------------------------------> SNIP <---------------------------------


As far as I read correctly, I can wait for the retrace by using
XDGASetViewport() with XDGAFlipRetrace and then waiting with
XDGAGetViewportStatus(). I cannot see how to do this without a busy
loop, but it will be a starter. Maybe with some intelligent timer
usage it will be possible without polling, at least for TV modes.
Additionally, I don't know yet how this could interfere with regular
X rendering...

Any comments?

CU

Matthias

-- 
Matthias Hopf - Visualization and Interactive Systems Group    \  |  |  /--
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