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

Bill Turner, WB4ALM wb4alm at arrl.net
Wed Mar 20 10:12:51 PDT 2013

Len, thank you very much for the quick review / definition...

If Jack is a "one card" solution, then it will not meet my needs - and 
in fact, none of the applications I wish to use know anything about Jack.

As a retiree, now on a fixed income budget, I doubt that I could afford 
a multi-channel audio card. If, however, you would like to mention a 
name or two, it would be appreciated.

My biggest problem is that I have lots of separate audio, and a lot of 
audio to be kept separated...

At this point in time, the majority of the applications are, in effect, 
software modems.

With one major exception, most of the applications that I use, do not 
provide any choices as to selection of the sound card. The majority 
assume that they have exclusive use of the system default sound card.

FLDIGI is a major exception to this. It allows configuration for the use 
of (1) OSS, (2) PortAudio, (3) PulseAudio, and if you are using OSS or 
PortAudio then you have control over the Linux device name, or the sound 
card name and the ports that you wish to use. If you are using 
PulseAudio, then you can specify the name of a remote server.

My initial tests indicated that PulseAudio was intended to mix whatever 
sources were not "muted" into a single "output", which then caused 
system sounds, etc to appear in the audio stream being sent to my 
primary speakers and the application being run.  This is why I asked my 
original question the way that I did -- and your response seems to 
confirm that PulseAudio is a single "studio" control and not a "Master 
Control" for a bunch of different studios.

As a result, I have told PulseAudio "hands off" for two of my audio 
cards, and I use the PortAudio feature of FLDIGI on two separate 
instances to allow each instance to control a separate sound card (which 
in turn are connected to two different radios).

My fear is that "PortAudio" might cease to exist (or be supported by the 
application or the Operating System) and then I would be out on a limb 
with no place to go.

- - -

So I believe that I need a program or group of programs that can handle 
multiple audio cards. Some of these cards will be connected via USB, so 
IRQ conflicts should not be a major issue.The majority of the audio 
being processed will generally be between 300 and 3000 Hz.

One of my internal cards is a PCI "sound blaster" card, because a few 
special purpose programs that I have make use of some of the on-board 
hardware features of that card.

Since the programs that use the SB card are also used in two-way radio 
communications, absolutely NO unauthorised or unexpected audio can be 
inserted into an outbound signal, such as system sounds, music, etc.

Having something like PulseAudio control the SB card is feasible, as it 
is unlikely that PulseAudio would try to connect to ALL of the on-board 
SB card features. (Feasible, that is, as long as PulseAudio did not try 
to mix the audio with other audio streams before presenting it to the 

I also have a special purpose external USB connected sound card 
(SignaLink USB) that is used to process audio to and from one of my 
transceivers. It must also be segregated from system sounds or other 
audio sources. (The input and output audio channels could be mixed into 
other streams for monitoring purposes, as long as the monitoring is 
volume controlled and/or mutable.)

Some programs that I use, such as QSSTV, only allow audio to and from 
the default audio card. No other options are provided by the author.
  I would assume it uses OSS or ALSA, since the author makes no mention 
about it.

Ideally, I'd love to have something like PulseAudio control all of the 
sound cards, and then provide addressable in/out ports (or channels), 
that could then be independently connected to the appropriate 
applications. It would also be VERY nice, if channel inputs and outputs 
could be dynamically configured.

It doesn't really matter that current GUI's don't make independent 
control easy or not - and assuming that PulseAudio uses a config file, 
as I could then create a script or two to reconfigure PulseAudio on an 
as-needed basis. This is assuming, of course, that there is documention 
available. I am a retired programmer, so I could learn "C" if necessary.

Even the problem with QSSTV could be eliminated, again assuming that 
some sort of "dummy default" definition could be established within 

- - - -

As an aside, I multitask when sitting at my computer, as I might be 
browsing or creating documentation and/or web pages; writing a program; 
conducting a keyboard conversation over the air; or participating in a 
controlled Radio Net.

This could be occurring while waiting for information and pictures to 
finish "downloading" from the Internet or from one of my radios.

I might even be "listening" to a commercial Television or Radio Stations 
or a Weather Service.

"Lots of separate audio, and a lot of audio to be kept separated."

Again Len, thanks for sharing...

/s/ Bill Turner, wb4alm

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