[MPlayer-users] Big fun with sandy bridge on linux (was: No Fun)

[Reimar Döffinger]

On 29 Feb 2012, at 09:39, Oliver Seitz <info at vtnd.de> wrote:
>> 
>> The patchset seems still maintained here:
>> http://gitorious.org/vaapi/mplayer
> 
> Thanks again for finding this link, Laurent!
> 
> (Merci encore une fois :-) )
> 
> It compiles on debian wheezy, using stock libva.
> 
> HD video is played back smooth and without any tearing.
> 
> CPU load is around 6% on an i3 at 3100MHz for 1920x1080 at 50fps.
> 
> (Just curious: VLC, for 1920x1080 at 24fps, with libva acceleration, on the same machine uses about 150% CPU. It is a bit of an unfair comparison as VLC can apply any video filter on top of the decoded video, but I do not need that...)

But it is exactly the reason.
Those embedded GPU systems generally have _far_ too low memory bandwidth anyway and I think no DMA system to help out either, so copying the decoded frame to ordinary CPU memory and then back yet again to the GPU for display just kills performance.
(in theory it is possible to do this much cleverer without so much copying but I don't think it is supported - it would mean exposing some implementation details of the decoder and GPU vendors are very allergic to anything that makes it harder for them to change internals).


> 
> Greets,
> Kiste
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