[Consortium] Benefit of Compiz to audio work?

[Steve Harris]

On 14 Nov 2007, at 10:38, Daniel James wrote:

> Hi Cory,
>
>> Some have said that moving the drawing of windows off the the GFX  
>> card
>> would help the load on the CPU and thus keep xruns to a minimum.
>
> I'm sceptical about that, because drawing windows shouldn't be causing
> xruns if the system is set up properly. I believe JACK Meterbridge  
> uses
> libsdl for drawing the meter needles efficiently, but I believe most
> free software audio apps don't do much in the way of graphics
> acceleration (yet).

Actually, SDL is very inefficient, there was an alpha OpenGL version  
of meterbridge (which I've since lost) that was much, much more  
efficient.

If you perform the same action on a 3D card and using the CPU the non  
average the 3D card will use less power to do the same work (it's  
optimised for that, whereas CPU are huge complex beasts). But,  
ofcourse Vista and Leopard aren't doing the same action as they would  
on the CPU.

One problem with 3D cards is that they can (or could) cause XRUNs, as  
they sometimes hold the kernel busy waiting for some action on the  
card to return. I don't know if this happens with modern drivers and  
cards though.

- Steve