Re: [Fwd: Re: How To Reduce/Eliminate Horizontal Tearing]

[elupus]

On Thu, 11 Dec 2008 00:34:47 -0500 (EST), Nick Nobody wrote:
 
 That would be really cool, I obviously have no idea how to implement it
 though... At the moment I'm using XBMC to play back videos and it does
 have a Vertical Blank Sync option but I'm not sure of how it's
 implemented (it clearly doesn't work as advertised). I doubt they're using
 Xv anyway so that's irrelevant.


Hmm.. There shouldn't be a problem with tearing in xbmc for intel cards.
Atleast I don't have it anymore. I have noted that if driconf is set to
always wait on blank, on some systems we end up waiting twice (just set it
to driver select in settings), but otherwise there shouldn't be a problem.

Then again, I've not tested master of current xorg/xserver/dri. But
hardy/gutsy versions work just fine.

The only issue was that we have to force a glFinish() before swapping in
case of driconf set to always wait, since driver seem to wait for vblank
then flush/finish opengl commands which makes it often miss the vblank.

And no we don't use xv.

Regards
elu...@xbmc.org

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[Fwd: Re: How To Reduce/Eliminate Horizontal Tearing]

[Nick Nobody]

Forgot to reply to all :S

 Original Message 
Subject: Re: How To Reduce/Eliminate Horizontal Tearing
From:Nick Nobody [EMAIL PROTECTED]
Date:Thu, December 11, 2008 00:30
To:  Keith Packard [EMAIL PROTECTED]
--

On Thu, December 11, 2008 00:11, Keith Packard wrote:
 On Wed, 2008-12-10 at 23:14 -0500, Nick Nobody wrote:
 Hello,

 I'm using Ubuntu 8.10 with a GM945 (at 1920x1080) for my media center
 PC.
 The problem I'm running into is a bunch of horizontal tearing on higher
 resolution videos (720p or greater). From what I can tell it's not a CPU
 limitation but rather something related to the graphics card...

 Are there any options that I can enable in my xorg.conf to help
 reduce/eliminate this tearing? Or is this simply a hardware limitation?
 Can XvMC somehow help me here?

 There aren't any options at this point, but I'm wondering -- is this
 full-screen? If we made full-screen Xv operations block until vblank
 (which would lock up the X server), would that be an acceptable option?

 It's actually very easy to do, just stick a 'wait for vblank' command
 into the ring right before the 'copy the new picture' command in the Xv
 extension code. It's just annoying when you're watching a tiny movie and
 your whole session stops responding.

 --
 [EMAIL PROTECTED]


Hi Keith!

That would be really cool, I obviously have no idea how to implement it
though... At the moment I'm using XBMC to play back videos and it does
have a Vertical Blank Sync option but I'm not sure of how it's
implemented (it clearly doesn't work as advertised). I doubt they're using
Xv anyway so that's irrelevant.

Seeing as this is a media center PC, I really don't care if the system has
to wait for the next vblank, it's only being used to watch videos. And at
at a 60Hz vsync I doubt it would even be noticeable

I just wanted to make sure that my hardware is capable of playing back
this content. I got quite worried when I noticed the tearing on this new
box that I bought :)

Thanks,

nick


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