[ardour-users] ardour not fast enough

Edwin Peer edwin at peer.co.za
Mon Mar 27 06:57:44 PST 2006

On Monday 27 March 2006 16:34, Paul Davis wrote:

> sounds like a plugin denormal issue. 

Please excuse my total ignorance on this, but what is exactly is this "plugin 
denormal issue"? I've seen it mentioned once or twice on this list before 
(with respect to gverb, I think), but don't really understand what it means.

> pentium processors get *dog slow* when handling very very small floating
> point numbers. 

That's just about enough information for me to start some dangerous hacking / 
guessing as to how to fix the problem. 

I would be inclined to set those very small values equal to zero and see what 
happens. Perhaps, that is exactly what's needed, but I dunno. I'm certainly 
not an expert in DSP and don't know what the effect (on the audio) of doing 
something like that would be. I would feel a lot more comfortable trying to 
do something about the problem, if I had some more details.  :)

> turn off freeverb and my guess is that it will never happen.

I'm pretty sure most of our projects make use of reverb in some form, so yes, 
that might well be the problem. I'll take a closer look at our usage and see 
if there's a pattern.

> now, whether this is ardour's responsibility to fix, or each individual
> plugins, 

I would be inclined to say (or agree), that it's the plugin's responsibility 
to finish up whatever it must do in time, given legal input. But what exactly 
is the precondition that defines the input of a plugin. Are plugins allowed 
to assume that their input is sanitised so that they don't have to deal with 
very small floating point samples, which are essentially zero? If it's a 
single line of code in one place that fixes the issue for all plugins? Even 
though a bunch of plugins may be at fault, that may just be the better 
option. Again, I don't know.

> or whether you should not use pentiums and stick with opterons ... a tough
> question :) 

Yeah, I actually wanted to get AMD processors for our studio, but the only 
favorable price / performance / service package available locally was from 
Dell... The same kind of SLA from IBM / Sun (4 hours response time, etc) with 
an Opteron configuration came out at arround 4 times the price and I really 
didn't think the AMD's would give me 4x the performace. Perhaps I was wrong.

Bah. :(


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