[Intel-gfx] HD (x)video troubles

[Barry Scott]

Jin, Gordon wrote:
> David Amiel wrote on Wednesday, July 22, 2009 6:20 AM:
>   
>> Hello,
>>
>> Le Mar 21 juillet 2009 22:43, Arne a écrit :
>>     
>>> Hello there,
>>>
>>> we are working on an "embedded" platform displaying images from a
>>> firewire-camera in realtime and replaying recorded videos with a
>>> resolution of 1280x1024. On our current platform (945GME) we get
>>> flaws (small video lags every 20-25 secs) when we put the camera at
>>> 30 fps, so we stay at 29 fps, which is suboptimal sadly. So, this
>>> week, we got a new mainboard with a GM45 chipset, and it got even
>>> worse - I think it's something like the horizontal tearing bug I
>>> read about in this list
>>> (http://lists.freedesktop.org/archives/intel-gfx/2008-December/000745.html).
>>>
>>> For info, we're using a minimal debian system (ratpoison as
>>> windowmanager, awesome btw ;) ), our current platform uses etch and a
>>> custom 2.6.24 kernel with debian's i810 driver. On the test platform
>>> I got the tearing bug with both stock debian kernel 2.6.26 (lenny)
>>> and custom 2.6.28.9, using lenny's 2.3.2 intel driver. Lastly, I
>>> tried with debian unstable and the 2.6.30 kernel, but X crashes on
>>> the second startup, with driver version 2.7.1 and 2.7.99.
>>> Finally, our program displaying the camera images uses XVideo, so
>>> we're stuck with that for now. 
>>>
>>> I am going to try driver verrsion 2.5.1 tomorrow (cf
>>> http://lists.freedesktop.org/archives/intel-gfx/2008-December/000818.html),
>>> but am willing to do tests on other versions. I can post
>>> xorg.conf/logs tomorrow as well.
>>>       
>> I've got a G45 and I've the same problems as you.
>>
>> The last working driver is 2.5.1, but you'll have some bad tearing
>> with it To be able to use a 2.6 driver I've to disable GEM (I've put
>> a patch in attachment for example on how to do this), it works but
>> there is soft tearing
>> For instant I didn't manage to have a successfully working 2.7 or 2.8
>> driver, xorg crashes at start
>>
>>     
>>> For now, I have just a simple question - is there any kernel/driver
>>> combination you would recommend for HD video playback using xvideo on
>>> either of those boards ?
>>>       
>> as tearing free feature seems important for you, the only combination
>> I know to reach this is to have an old intel graphic card (with
>> overlay hardware inside), with an old driver where you can force the
>> use of the overlay over the textured mode
>>     
>
> Arne and David,
>
> The textured video tearing issue is expected to be fixed in 2009Q2 release.
>   
At the expense of blocking the GPU until the video is drawn. We think 
this is
because you only have one graphics context setup. We think you need one 
graphics
context/textured video to solve the GPU blocking problems.

This may be why you see dropped frames, the GPU is blocked on your previous
XVPutImage call and you do not have enough time after it returns to 
prepare the
next frame of video before the first line should be drawn. If this is so 
then better
video player design will help, prepared frames in another thread.

Barry