[alsa-devel] [pulseaudio-discuss] idea: a reserve alsa plugin

David Henningsson david.henningsson at canonical.com
Thu May 2 15:23:59 CEST 2013

On 05/02/2013 02:37 PM, Arun Raghavan wrote:
> On Thu, 2013-05-02 at 12:55 +0200, David Henningsson wrote:
>> Just had an idea which I'll write down here before I forget it
>> again...and I'm not saying I'll implement this anytime soon either, but
>> here goes:
>> There is a device reserve protocol between PulseAudio and JACK2 - when
>> JACK needs the sound card, it'll send a dbus message to PulseAudio and
>> grab a name in D-Bus.
>> However, there are plenty of applications who like to access ALSA
>> directly, without going through JACK2 or PulseAudio. By making a
>> "reserve" plugin, we could have this functionality for those apps too.
>> In practice, if the app usually opens "plughw:0" or "hw:0", it could
>> instead open "reserve:plughw:0" or "reserve:hw:0" to also reserve the
>> device from PulseAudio usage while the device is open. Meanwhile,
>> PulseAudio is free to use other audio devices (which is not the case
>> when using e g pasuspender).
>> How does that sound?
> Might be neat to do have desktops set up to do this whenever an ALSA
> device is opened (that is do it unconditionally when hw:X or plughw:X is
> opened).

Including when PA opens it? :P

I would prefer to do it explicitly, due to the possible overhead of 
talking to D-Bus.

One could possibly imagine it being done automatically with plughw, but 
definitely not with hw only because that's meant to be as low as you can 
possibly get.

David Henningsson, Canonical Ltd.

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