Subject: RE: [linux-audio-user] clicks and pops
From: Mark Knecht (markknecht_AT_attbi.com)
Date: Thu Nov 21 2002 - 05:45:38 EET
This is some of what I suggested earlier. Let's go through this logically
and see what we find out...
If you don't have this already, try out gkrellm. You can use this to
monitor what your machine is doing. (BTW - I'm not that deep in Linux tools,
so if someone knows of better tools I'm certainly interested.)
If you start jack by itself, do you see any xruns? I think the answer is
no, but let us know. Start qjackconnect. Do you see anything yet? I'm
running on a 500MHz P3 with 768MB, with a Hammerfall Light and a good EIDE
controller and audio drive. Start ardour and create a new session, but don't
start recording. I'm at 2% of CPU at this point, with no disk activity.
Start alsaplayer using 'alsaplayer -R -o jack &'. How much CPU are you
using? Any xruns yet? I'm using about 6% of my CPU with no CD playing. No
Start playing a CD. Any xruns? I'm at about 12% CPU, bouncing around.
So, currently I'm running:
alsaplayer playing a CD
Stop alsaplayer, go into your ardour session and create a two diskstreams
with mixer strips and do some recording. Just let it record for a few
minutes. Put the ardour session on a different desktop, then go back and
watch the xterm that reports xruns and watch gkrellm at the same time. What
is it telling you about disk usage when you see an xrun? How much CPU? I'm
at about 22%, bouncing around. Disk usage is just little blips.
Stop the recording. Create more diskstreams. I created 10 total. Before
starting recording I'm at about 28% CPU, no xruns. Start recording on ALL
the tracks at the same time. I'm at about 50% CPU and disk stuff is still
What does you system do?
I suspect that you are going to determine that you are not CPU limited,
at least with sessions this size, and that your xruns have some correlation
with what you see going on in gkrellm.
In my case, I've discovered under Windows and Linux that you should not
record to the system drive. I have a Promise ATA-100 controller with
nothing but an IBM audio drive attached. My session directory is on that
drive. I use reiserfs for the audio drive and I get great performance.
I also have seen fewer xruns with the Hammerfall than with my AP2496, but
even that card isn't too bad.
If you want to solve these problems, and I believe they are solvable,
you'll have to dig in an get your hands dirty. Post back what you find out.
I'm interested and willing to help, but at a distance we need good info.
[mailto:linux-audio-user-admin_AT_music.columbia.edu]On Behalf Of Brian
Sent: Wednesday, November 20, 2002 12:11 PM
Subject: Re: [linux-audio-user] clicks and pops
I wonder if having a somewhat cruddy old 20 gig HD is a problem, HD's are
cheap these days. I just downloaded Dmudi via apt-get last night, so I'm
trying for an install on my desktop and I'll tell everyone how that
goes. Apparently its still not the 0.9 version of Demudi, that won't come
out until the end of this month, but by then I can just use apt-get update
to grab the 0.9 version, it'll be interesting to compare the performance
of DeMudi versus Redhat 8.0 with the low latency activated.
On Wed, 20 Nov 2002, Paul Winkler wrote:
> On Wed, Nov 20, 2002 at 11:24:13AM -0800, Brian Redfern wrote:
> > I think in my case my audio card is on irq 11, maybe that's just too
> > up and I won't see things working without xruns until I can jimmy it to
> > get it at irq 5 instead.
> 11 is actually good.
> IRQ priority is one of those ugly things that evolved
> into something completely non-sensible.
> Paul Winkler
> "Welcome to Muppet Labs, where the future is made - today!"
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