[pulseaudio-discuss] Questions about multiple channel volume control

[Lennart Poettering]

On Thu, 12.11.09 15:04, Gerald Hofer (hofer at sgi.com) wrote:

> Hi,
> 
> I have a particular problem with Pulseaudio (0.9.19 on Opensuse
> 11.2)  that I don't seem to be able to solve with the current user
> interface.
> 
> I am using a Firefox plugin to check on Nagios servers. In case of
> faults this plugin produces a short warning sound every time it
> finds a fault during the periodic check (every 5 minutes). Pulse
> audio now finally allows me (in theory) to set a volume level
> independent from other audio sources. The problem is that the stream
> (and it is a seperate stream, not a system sound) only shows up for
> the very brief period it plays (maybe a second or so) in
> pavucontrol. So in reality it is almost impossible to change the
> audio level on this stream.

For me that sounds as if this was an event sound, and hence should be
tagged with the 'role' of 'event' in which case you could use the
existing system sound slider in g-v-c and pavucontrol.

> I found  ticket #159 http://pulseaudio.org/ticket/159 that explains
> exactly my problem, but clearly that "solution" to the problem is
> not adequate here. I would be also not happy to mix that application
> up with "system sounds". For me that is a different category again.

Is it? It's an event sound. And event sounds are controllable via the
system sound slider.

> So for me this would be perfect counter example. I want to change
> the volume for that application _before_ it will play the next time.

Sure, you can do this if you tag it properly as an event sound. And if
you tag it improperly you could still do this by manipulating the
module-stream-restore database, which is accessible to clients, but
for which there currently is not client tool except for pavucontrol
which however controls only a single item of it (the one for event
sounds)

> [For example because I know that my wife hates this tone and I have
> to tune it down in advance :-), or I am in a noisy environment and I
> don't want to miss the next warning]. Maybe this can be solved with
> changes to the application (but I doubt that a plugin in Firefox has
> any access to that) - but I really think that pulseaudio would be
> the right place. [I am still dreaming from the big mixer, where I
> can randomly plug things together in hierarchies]

I mean, what you are suggesting would mean that we would have seperate
sliders not only for event sounds but for each type of event sound. I
am pretty sure we don't want that for the general case.

But then again, the APIs are there. It's just a matter of getting your
hands dirty, and writing a client for this.
> 
> The user interface that was suggested in ticket #159 is what would
> work for me. A way to switch on all the applications that have
> played in the past, probably sorted by time and a way to change the
> parameters.

I am not convinced we want to show the user gazillions of old clients
he used years ago.

Aynway, I guess this boils down to this: the server already supports
this. The available UIs doesn't and shouldn't in my opinion. However
you are welcome to write your own UI that does control all saved
stream info data and not just one.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4