[pulseaudio-discuss] PulseAudio / Jack main purposes in life?

Len Ovens len at ovenwerks.net
Tue Mar 19 15:18:54 PDT 2013

On Tue, March 19, 2013 2:37 pm, Bill Turner, WB4ALM wrote:
> I have read a lot of material available to me on the Internet, and I am
> still not sure about what PulseAudio's main purpose is...
> Is PulseAudio's main purpose to primarily function as a "mixer" and
> allow many different sound sources to be combined into a "single" set of
> outputs such as a multi-channel room stereo, or is PulseAudio capable of
> functioning as a Master Studio console that might be used to support
> several (many) different rooms all with different content?

Pulseaudio has a lot of different capabilities. It is certainly possible
to route different sound sources to various sinks on a per use basis. The
available GUIs for doing so are not the easiest to use that way...
probably because not very many people have a use for that. Those who do
generally use jack. I would note, that those who use jack have apps that
are built to use it.
> I have a need for a simple (normal) stereo set-up to handle normal
> system sounds, along with an occasional audio feed from the Internet,
> while allowing several communication radios to feed separate,
> independent, digital audio tones to one or more software programs used
> to decode those tones. In the future, I might want to have the same
> computer system also handle the audio for an entertainment room audio
> system.

The big question is what are the apps you use to decode tones looking for?
What ports are they designed for? If they are designed for jack then use
jack, if they are designed for pulse (or even alsa) pulse is the thing to

If you are going to use jack, you need to be aware that jack is a one card
solution. It can use more than one card if they are syncable (with a
hack), or through external programs. The best thing though would be to use
one multi channel card and use the ports separately for each application.
There is nothing stopping you from using track 1 input and track 7 output
for one application and track 2 input and track 5 output for another.
Cannect then as you wish, think of jack as a soft patch panel.

Pulse on the other hand tends to route all inputs (or outputs) on a card
to the same application.

> I currently have multiple sound cards, each connected to a specific
> communications receiver, for the purpose of creating "digital audio"
> that can be passed to appropriate software programs.

Sounds like pulse works better with that scenario. Though jack would allow
you to use fewer cards to do the same thing. The problem with lots of
soundcards is running out of free and clear irqs...

> One of the catchers here, is that from time to time I will need to
> dynamically reconnect the digitalised audio from a particular receiver
> and "patch" it to a different software program.
>  From what little I know, it sounds like PulseAudio & Jack would provide
> the capabilities that I need. But I kept reading that these products do
> not behave well together, and I have also read the PulseAudio and Ubuntu
> don't always do what the designers intended. (???)

The last few revisions do quite well... Though I have yet to try that many
cards :)  the one thing I have found though, is that irq problems on one
audio card can effect other audio cards.

First look at what the apps you are using require.

Len Ovens

More information about the pulseaudio-discuss mailing list