[linux-audio-user] MOre realtime!

James Stone jamesmstone at gmail.com
Wed Dec 20 06:36:37 EST 2006

You don't need the realtime-lsm module any more. That has been superceded by

5ms sounds pretty good to me.. depends what card you are using. I get 20ms
(512) for full duplex with SBLive! with no xruns, which is fine for my

If you really want to push the envelope with realtime, you need to install
the realtime kernel patches,

see: http://www.osadl.org/projects-realtime-kernel.0.html

and http://people.redhat.com/mingo/realtime-preempt/

but it is possible that your sound card might not be able to do this, unless
it is a proper audiophile quality one..


On 12/20/06, J M Needham <J.M.Needham at bath.ac.uk> wrote:
> Hi all,
> So I've just installed Ubuntu 6.09, and followed the instructions on
> http://fort2.xdas.com/~kor/oss2jack/install.html to install the
> realtime-lsm module and I've added
> @audio - rtprio 80
> @audio - memlock 500000
> to /etc/security/limits.conf and set the realtime mode on Jack. Seems ok,
> the only thing is that I can't get below 5.8 ms latency. Jack's behaving
> nicely with very few xruns, but won't do any better. The output of the
> messages with 32 frames for capture, for example, is:
> 10:41:35.039 Startup script...
> 10:41:35.039 artsshell -q terminate
> sound server terminated
> 10:41:35.375 Startup script terminated successfully.
> 10:41:35.381 JACK is starting...
> 10:41:35.382 /usr/bin/jackd -R -u -dalsa -dhw:0 -r44100 -p32 -n2 -S
> 10:41:35.391 JACK was started with PID=5503 (0x157f).
> jackd 0.100.0
> Copyright 2001-2005 Paul Davis and others.
> jackd comes with ABSOLUTELY NO WARRANTY
> This is free software, and you are welcome to redistribute it
> under certain conditions; see the file COPYING for details
> JACK compiled with System V SHM support.
> loading driver ..
> apparent rate = 44100
> creating alsa driver ... hw:0|hw:0|32|2|44100|0|0|nomon|swmeter|-|16bit
> control device hw:0
> configuring for 44100Hz, period = 32 frames, buffer = 2 periods
> ALSA: cannot set period size to 32 frames for capture
> ALSA: cannot configure capture channel
> cannot load driver module alsa
> 10:41:35.502 JACK was stopped successfully.
> 10:41:37.430 Could not connect to JACK server as client. Please check the
> messages window for more info
> And I can't see anything of any use in here. Any ideas?
> Jonty
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