[linux-audio-user] denormals or ... ?

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To: LAD Mail List <linux-audio-dev@...>, LAU Mail List <linux-audio-user@...>
Date: Tuesday, March 13, 2007 - 1:58 pm


I have a problem with a piece I'm working on in Rosegarden 1.5. I've
appended the text I sent to Chris Cannam, along with his response (I
hope he doesn't mind). Btw, the machine is based on an AMD64 3200+, with
2G RAM and an 80G hard drive. Sound runs through an M-Audio Delta 66.
Distro is 64Studio 2.0.

My questions lead, Chris's replies follow :

>> 2) I've written a piece consisting of six tracks with these specs:

That sounds a bit like a plugin denormal problem. Although denormals
are usually less of a problem on AMD64.

The 0(1024) in qjackctl I think means that JACK has reported 1024 xruns
via the reporting API but they haven't been mentioned in the message
log. I don't actually know what causes that. Does CPU usage (as
reported by a plain old CPU usage reporting program) actually peak at
that point?

>> So my question is: Given my machine, should my CPU be topping out in

Probably not, or at least I wouldn't expect it to suddenly peak if usage
has previously been on the low side.

The only thing RG does that may affect CPU usage drastically during
playback is that it doesn't start running plugins until they actually
have something to work on, and it stops running them if they've fallen
silent for a certain period and have no more input coming up (this is
in contrast to e.g. Ardour which runs plugins all the time during
playback, taking a more strictly correct view).

So, if anyone has anything to add to Chris's assessment, I'd like to
know about it. If the problem is indeed related to denormals, is there a
way to fix it ? Comments and suggestions are most welcome.



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Messages in current thread:
[linux-audio-user] denormals or ... ?, Dave Phillips, (Tue Mar 13, 1:58 pm)
Re: [linux-audio-user] denormals or ... ?, Leonard Ritter, (Tue Mar 13, 2:36 pm)