[linux-audio-user] New member wants to build a reliable DAW

[Fernando Lopez-Lezcano]

On Tue, 2006-12-19 at 23:34 -0800, Jon H wrote:

> On 12/19/06, Kjetil S. Matheussen <k.s.matheussen at notam02.no> wrote:

>         > I mentioned video cards...  I really prefer nvidia under
>         linux, due to
>         > the quality of the proprietary drivers and ease of
>         installation, and
>         
>         This is a bad advice. The proprietary drivers from nvidia
>         cause xruns, and 
>         should be avoided. But older (ie. at least 2-3 year old)
>         nvidia cards can
>         be used with the open nv driver instead, which I will
>         recommend, because I
>         have had experience with numerous nvidia gfx cards, and have
>         had very 
>         little problem.
> 
> Actually anything you do visually will require a video card.  The more
> capable the card and the drivers the less resources it will take away
> from the  remaining system that is busy processing your audio.  With a
> good video card that handles the majority of graphical rendering I
> experience almost NO xruns, that's at 5.8ms latency using an onboard
> (nforce4) chipset, and lower than that with a dedicated soundcard like
> the M-Audio stuff.  Relying on the CPU and system ram to render FFT
> graphics and such will cause xruns, a good video card will not. 

If you have a system that has a good realtime preemption patched kernel,
irq's properly optimized, a decent sound card, and a video card that has
drivers that are decent but has _no hardware acceleration_:

"Relying on the CPU and system ram to render FFT graphics and such" will
_not_ cause xruns. 

In a properly tuned system with properly designed software the screen
update will definitly slow to a crawl - and perhaps it will be unusable
- but you should not get xruns (provided that the sound apps don't max
out the audio threads with realtime processing - in that case all bets
are off and no amount of graphics acceleration will help). 

-- Fernando