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
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