25 Oct
2009
25 Oct
'09
5:40 a.m.
Hi,
I found this info:
"USB and jack
The USB interrupt period is 1 msec. To be able to get lower latency with
jack when using it with an USB device, you have to use a setting as
48kHz and 3 period. It will makes the buffer time a multiple of 1 msec
and you will get a much lower latency as with the default 2 period.
Additionaly, loading the snd-usb-audio with the parameter "nrpacks=1"
will give you a much lower latency (for this to work take care that
CONFIG_USB_BANDWIDTH is not set and CONFIG_USB_DYNAMIC_MINORS is not set
in your running kernel)."
http://proaudio.tuxfamily.org/wiki/index.php?title=Howto_RT_Kernel#USB_and_…
1) is this info still up-to-date?
2) how do I exactly take care of this:
"Additionaly, loading the snd-usb-audio with the parameter "nrpacks=1"
will give you a much lower latency (for this to work take care that
CONFIG_USB_BANDWIDTH is not set and CONFIG_USB_DYNAMIC_MINORS is not set
in your running kernel)"
(Debian (based) systems)
\r
25 Oct
25 Oct
6:18 a.m.
On Sun, 25 Oct 2009 11:40:16 +0100
rosea grammostola <rosea.grammostola(a)gmail.com> wrote:
Hi,
I found this info:
"USB and jack
The USB interrupt period is 1 msec. To be able to get lower latency
with jack when using it with an USB device, you have to use a setting
as 48kHz and 3 period. It will makes the buffer time a multiple of 1
msec and you will get a much lower latency as with the default 2
period. Additionaly, loading the snd-usb-audio with the parameter
"nrpacks=1" will give you a much lower latency (for this to work take
care that CONFIG_USB_BANDWIDTH is not set and
CONFIG_USB_DYNAMIC_MINORS is not set in your running kernel)."
http://proaudio.tuxfamily.org/wiki/index.php?title=Howto_RT_Kernel#USB_and_…
1) is this info still up-to-date?
2) how do I exactly take care of this:
"Additionaly, loading the snd-usb-audio with the parameter
"nrpacks=1" will give you a much lower latency (for this to work take
care that CONFIG_USB_BANDWIDTH is not set and
CONFIG_USB_DYNAMIC_MINORS is not set in your running kernel)"
(Debian (based) systems)
\r
In my experience 48kHz/3 periods works a bit more stable, the possible
latency settings in jack don't really change, 64 frames is still the
lower boundary and unstable.
But I haven't heard about 2) and am very curious about this myself.
Philipp
7:03 a.m.
2009/10/25 <hollunder(a)gmx.at>
On Sun, 25 Oct 2009 11:40:16 +0100
rosea grammostola <rosea.grammostola(a)gmail.com> wrote:
2) Edit /etc/modprobe.conf or /etc/modprobe.d/modprobe.conf with:
options snd-usb-audio nrpacks=1
And to "make sure". you have to have the kernel options changed. make
menuconfig, and press "/" to search for the two options.
Philipp: we already dealt with that one but _without_ substantial
cause-and-effect http://bugs.archaudio.org/task/5
Hi,
I found this info:
"USB and jack
The USB interrupt period is 1 msec. To be able to get lower latency
with jack when using it with an USB device, you have to use a setting
as 48kHz and 3 period. It will makes the buffer time a multiple of 1
msec and you will get a much lower latency as with the default 2
period. Additionaly, loading the snd-usb-audio with the parameter
"nrpacks=1" will give you a much lower latency (for this to work take
care that CONFIG_USB_BANDWIDTH is not set and
CONFIG_USB_DYNAMIC_MINORS is not set in your running kernel)."
http://proaudio.tuxfamily.org/wiki/index.php?title=Howto_RT_Kernel#USB_and_…
1) is this info still up-to-date?
2) how do I exactly take care of this:
"Additionaly, loading the snd-usb-audio with the parameter
"nrpacks=1" will give you a much lower latency (for this to work take
care that CONFIG_USB_BANDWIDTH is not set and
CONFIG_USB_DYNAMIC_MINORS is not set in your running kernel)"
(Debian (based) systems)
\r
In my experience 48kHz/3 periods works a bit more stable, the possible
latency settings in jack don't really change, 64 frames is still the
lower boundary and unstable.
But I haven't heard about 2) and am very curious about this myself.
Philipp
5:14 p.m.
On Sun, 25 Oct 2009 18:03:09 +0800
Ray Rashif <schivmeister(a)gmail.com> wrote:
2009/10/25 <hollunder(a)gmx.at>
Thanks, you're right, CONFIG_USB_DYNAMIC_MINORS is not set and CONFIG_USB_BANDWIDTH
doesn't
even show up.
I'll try to load with that option tomorrow and see how it goes.
Philipp
On Sun, 25 Oct 2009 11:40:16 +0100
rosea grammostola <rosea.grammostola(a)gmail.com> wrote:
2) Edit /etc/modprobe.conf or /etc/modprobe.d/modprobe.conf with:
options snd-usb-audio nrpacks=1
And to "make sure". you have to have the kernel options changed. make
menuconfig, and press "/" to search for the two options.
Philipp: we already dealt with that one but _without_ substantial
cause-and-effect http://bugs.archaudio.org/task/5 Hi,
I found this info:
"USB and jack
The USB interrupt period is 1 msec. To be able to get lower
latency with jack when using it with an USB device, you have to
use a setting as 48kHz and 3 period. It will makes the buffer
time a multiple of 1 msec and you will get a much lower latency
as with the default 2 period. Additionaly, loading the
snd-usb-audio with the parameter "nrpacks=1" will give you a much
lower latency (for this to work take care that
CONFIG_USB_BANDWIDTH is not set and CONFIG_USB_DYNAMIC_MINORS is
not set in your running kernel)."
http://proaudio.tuxfamily.org/wiki/index.php?title=Howto_RT_Kernel#USB_and_…
1) is this info still up-to-date?
2) how do I exactly take care of this:
"Additionaly, loading the snd-usb-audio with the parameter
"nrpacks=1" will give you a much lower latency (for this to work
take care that CONFIG_USB_BANDWIDTH is not set and
CONFIG_USB_DYNAMIC_MINORS is not set in your running kernel)"
(Debian (based) systems)
\r
In my experience 48kHz/3 periods works a bit more stable, the
possible latency settings in jack don't really change, 64 frames is
still the lower boundary and unstable.
But I haven't heard about 2) and am very curious about this
myself.
Philipp 
24 Jan
24 Jan
7:52 a.m.
hollunder(a)gmx.at schrieb:
On Sun, 25 Oct 2009 18:03:09 +0800
Ray Rashif <schivmeister(a)gmail.com> wrote:
Hi,
don't know where I found this on the net that setting the buffer size
for usb audio a multiple of 1 ms duration, e.g. for 48000 kHz p=48 will
allow very low latencies. I tried this today with the latest rt kernel
and the cheap burr brown usb codec pcm2902 used in my behringer uca202:
options snd_usb_audio nrpacks=1
/usr/bin/jackd -R -P79 -dalsa -dhw:1,0 -r48000 -p48 -n2 -Xseq
It runs smoothly on a centrino laptop (pentium M, cpu freq stepping
between 0.6 and 1.6 GHz).
I built a plain vanilla 2.6.31.12 with the latest rt20 patch applied,
debs available my repo - read more:
http://www.sidux.com/index.php?name=PNphpBB2&file=viewtopic&t=9396&…
Imho the latest rt20 is much more robust than rt19 - I like it!
Maybe some of the jack and usb gurus (Paul?, Clemens?) can confirm the
-p48 -n2 setting.
Ciao Martin
2009/10/25 <hollunder(a)gmx.at>
Thanks, you're right, CONFIG_USB_DYNAMIC_MINORS is not set and CONFIG_USB_BANDWIDTH
doesn't
even show up.
I'll try to load with that option tomorrow and see how it goes.
Philipp
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On Sun, 25 Oct 2009 11:40:16 +0100
rosea grammostola <rosea.grammostola(a)gmail.com> wrote:
2) Edit /etc/modprobe.conf or /etc/modprobe.d/modprobe.conf with:
options snd-usb-audio nrpacks=1
And to "make sure". you have to have the kernel options changed. make
menuconfig, and press "/" to search for the two options.
Philipp: we already dealt with that one but _without_ substantial
cause-and-effect http://bugs.archaudio.org/task/5
Hi,
I found this info:
"USB and jack
The USB interrupt period is 1 msec. To be able to get lower
latency with jack when using it with an USB device, you have to
use a setting as 48kHz and 3 period. It will makes the buffer
time a multiple of 1 msec and you will get a much lower latency
as with the default 2 period. Additionaly, loading the
snd-usb-audio with the parameter "nrpacks=1" will give you a much
lower latency (for this to work take care that
CONFIG_USB_BANDWIDTH is not set and CONFIG_USB_DYNAMIC_MINORS is
not set in your running kernel)."
http://proaudio.tuxfamily.org/wiki/index.php?title=Howto_RT_Kernel#USB_and_…
1) is this info still up-to-date?
2) how do I exactly take care of this:
"Additionaly, loading the snd-usb-audio with the parameter
"nrpacks=1" will give you a much lower latency (for this to work
take care that CONFIG_USB_BANDWIDTH is not set and
CONFIG_USB_DYNAMIC_MINORS is not set in your running kernel)"
(Debian (based) systems)
\r
In my experience 48kHz/3 periods works a bit more stable, the
possible latency settings in jack don't really change, 64 frames is
still the lower boundary and unstable.
But I haven't heard about 2) and am very curious about this
myself.
Philipp
25 Jan
25 Jan
12:16 p.m.
Martin Homuth-Rosemann wrote:
don't know where I found this on the net that
setting the buffer size
for usb audio a multiple of 1 ms duration, e.g. for 48000 kHz p=48 will
allow very low latencies. I tried this today with the latest rt kernel
and the cheap burr brown usb codec pcm2902 used in my behringer uca202:
options snd_usb_audio nrpacks=1
You don't need this option; the driver was fixed to use sensible
values years ago.
/usr/bin/jackd -R -P79 -dalsa -dhw:1,0 -r48000 -p48
-n2 -Xseq
It runs smoothly on a centrino laptop (pentium M, cpu freq stepping
between 0.6 and 1.6 GHz).
Maybe some of the jack and usb gurus (Paul?, Clemens?) can confirm the
-p48 -n2 setting.
For most USB audio devices, using period sizes that are an integer
multiple to the USB packet size (1 ms) will definitely help. Some
devices like the SB Audigy 2 NX or UA-101 do not synchronize their
sample clock to the USB clock (and this has nothing to do with USB
2.0), and in those cases, the period size does not matter.
(I did not know that Jack now supports lengths that are not powers
of two.)
Best regards,
Clemens
5444
days inactive
5536
days old
linux-audio-user@lists.linuxaudio.org
6 comments
6 participants
participants (6)
-
Clemens Ladisch -
hollunder＠gmx.at -
Martin Homuth-Rosemann -
Paul Davis -
Ray Rashif -
rosea grammostola