[LAD] JACK and computer sleeping

[Emanuel Rumpf]

2009/3/9 nescivi <nescivi at gmail.com>:
>
>> Wouldn't it make sense, to provide a notify for jack (from the
>> hibernate script),
>> before the system goes to sleep, so jack could then pause processing
>> appropriately?
>> Hibernation is becoming very common and a favored feature.
>
> On Friday 06 March 2009 07:05:35 Paul Davis wrote:
>> On Fri, Mar 6, 2009 at 4:51 AM, Ray Rashif <schivmeister at gmail.com> wrote:
>> > Only for mobile machines. I really cannot do without at least frequency
>> > scaling (heat) and sleep (suspend-to-ram; quick access).
>>
>> sorry, but you just don't do realtime low latency audio on a machine that
>> has either of these things happening to it. at least not today.
>>
>> i agree that a signal to tell JACK to "sleep" when the machine is
>> suspended, hibernated or whatever would be a good idea. it probably already
>> exists via d-bus and/or other similar mechanisms on non-linux platforms.
>

> Any hints/examples on how to do this?
>

There seem to be different methods/scripts for sleeping available.
A comparision:
http://www.tuxonice.net/features

The freedesktop approach (pm-utils):
http://pm-utils.freedesktop.org/wiki/

More HAL/sleep info:
http://people.freedesktop.org/~hughsient/quirk/quirk-suspend-index.html

kpowersave seems to use powersave:
http://powersave.sourceforge.net/powersave/Events.html#Events

Here is uwsusp:
http://suspend.sourceforge.net/


I think, one needed to notify jack over dbus
from either a script (in /etc/pm or /etc/powersave)
or from a HAL callback.
Although I could not find any event-hook in the HAL specifications:
http://people.freedesktop.org/~david/hal-spec/hal-spec.html#device-properties-power-management

I think resume doesn't work with jack, because my
usb-card requires 2 seconds to power on itself (over the usb-port).
So jack would have to sleep about 2.2 seconds, before
reenabling audio processing.


--
Emanuel Rumpf