[LAU] usb and jack

[hollunder at gmx.at]

On Sun, 25 Oct 2009 11:40:16 +0100
rosea grammostola <rosea.grammostola at 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_jack
> 
> 
> 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