20 Dec
2006
20 Dec
'06
6:54 a.m.
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
20 Dec
20 Dec
7:36 a.m.
You don't need the realtime-lsm module any more. That has been superceded by
rtlimits.
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
purposes.
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..
James
On 12/20/06, J M Needham <J.M.Needham(a)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
26 Dec
26 Dec
6:13 a.m.
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On Wed, Dec 20, 2006 at 11:36:37AM +0000, James Stone wrote:
You don't need the realtime-lsm module any more.
That has been superceded by
rtlimits.
I'm sorry, but this makes me crazy.
"Superceded" as of which kernel revision, exactly?
- -ken
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.1 (GNU/Linux)
iD8DBQFFkPMHe8HF+6xeOIcRAlVJAKD+JVQK8q5ZV9+zxMRQb5EPaxtioQCeIWle
Rsi1VJ+xVcTIVldsLu8bFes=
=TcS1
-----END PGP SIGNATURE-----
7:14 a.m.
Ken Restivo <ken(a)restivo.org> wrote:
Well not really "superceded".
I think this is how it happened(anyone correct me if I'm wrong):
The realtime-lsm was more of a hack then anything, not really condoned by the mainline
kernel folks because it was too much of a security risk. It was created to help us linux
audio people be able to get decent latency from our machines, and dates back to the 2.4
series kernels.
The rtlimits is part of a revised pam(pluggable authentication modules?). It seems to sit
better with most people because it gives very selected abilities to a targeted group. If
I can remember correctly, I think it came out somewhere around 2.6.12 or slightly after?
As an aside; the udev system came out around the same time. I find both of those systems
to be so much easier to config.
Some distros still use the realtime-lsm even with the newer kernels mostly because they
haven't gotten around to upgrading pam to support rtlimits. Some of the machines here
use realtime-lsm, and others use rtlimits. I'd prefer to use the later, but oh
well....
Tracey.
You don't
need the realtime-lsm module any more. That has been superceded by
rtlimits.
I'm sorry, but this makes me crazy.
"Superceded" as of which kernel revision, exactly? 
20 Dec
20 Dec
7:40 a.m.
On Wed, 2006-12-20 at 10:34 +0000, J M Needham wrote:
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...
...
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
It looks like your hardware simply can't handle buffer sizes that small.
--
Lars Luthman - please encrypt any email sent to me if possible
PGP key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x04C77E2E
Fingerprint: FCA7 C790 19B9 322D EB7A E1B3 4371 4650 04C7 7E2E
10:28 a.m.
Ok, thanks Lars. I guess I'll be treating myself to an audiophile for
Christmas unless anyone's got a better idea.
On Wed, 20 Dec 2006, Lars Luthman wrote:
On Wed, 2006-12-20 at 10:34 +0000, J M Needham wrote:
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...
...
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
It looks like your hardware simply can't handle buffer sizes that small.
10:56 a.m.
The M-Audio Delta 1010 has good reviews, and apparently works well under
linux, but is pretty costly.
James
On 12/20/06, J M Needham <J.M.Needham(a)bath.ac.uk> wrote:
Ok, thanks Lars. I guess I'll be treating myself to an audiophile for
Christmas unless anyone's got a better idea.
On Wed, 20 Dec 2006, Lars Luthman wrote:
On Wed, 2006-12-20 at 10:34 +0000, J M Needham
wrote:
> 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...
...
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
It looks like your hardware simply can't handle buffer sizes that small.
1:53 p.m.
On Wed, 2006-12-20 at 14:27 +0000, J M Needham wrote:
Ok, thanks Lars. I guess I'll be treating myself
to an audiophile for
Christmas unless anyone's got a better idea.
These hardware constraints are defined in max/min bytes per period
across all supported formats. So, to get lower latency, increase the
channel count or sample rate.
64 frames at 44100Hz is ~1.45ms each way or 2.9ms (plus any hardware
latency) round trip. At 48000Hz this would give 2.66ms, and at 96000Hz
1.33ms.
Lee
On Wed, 20 Dec 2006, Lars Luthman wrote:
On Wed, 2006-12-20 at 10:34 +0000, J M Needham
wrote:
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...
...
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
It looks like your hardware simply can't handle buffer sizes that small.
1:34 p.m.
J M Needham 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:
One quick tip:
I just recently installed 6.10 (wich I guess you are referring to..?),
and discovered a hackish-but-working method of getting RT in Ubuntu:
Install the 64studio multimedia-kernel package. Works great here, I now
got a rock steady 2.9ms on an el crap'o laptop soundcard, running with
Beryl and Emerald! Didn't need to edit limits.conf.
Now beat that, Windows...
More here:
http://ubuntuforums.org/showthread.php?t=313612&highlight=realtime+kern…
You won't get all modules etc from the ubuntu kernel, so if you need any
of those that might require some more hacking.
--
Ringheims Auto - Fri musikk for bilstereo!
http://ringheimsauto.org
6337
days inactive
6343
days old
linux-audio-user@lists.linuxaudio.org
8 comments
7 participants
participants (7)
-
J M Needham -
James Stone -
Johannes Mario Ringheim -
Ken Restivo -
Lars Luthman -
Lee Revell -
Tracey Hytry