Re: [Discuss-gnuradio] use of pulseaudio -- some parameters to call?

[Alexandru Csete]

Hi Michael,

Unfortunately I do not have any good answers to your questions, but I
have added some comments below that might help.

On Wed, Sep 1, 2010 at 12:09 PM, Michael Hartje
<address@hidden> wrote:
> Opensuse 11.3 uses pulseaudio as a standard audio-io. Gnuradio 3.3.x
> offers alsa audiosink and audiosource.

I believe all linux distributions have been using pulseaudio for many
years now, but pulseaudio is built on top of alsa drivers so we have
both systems.

> When I put "pulse" as parameter for the "device_name" in GRC, with
> "verbose" in the "~/.gnuradio/config.conf" I got information about
> samplerate and other parameters (see below) -- in my case: the format
> S32LE is selected. -- How can I change to use S16LE?

Can you actually get usable audio in and out when you use "pulse" for
device? I use Ubuntu 9.10 and 10.04 and none of my computers are able
to work with that setting. Using the default alsa devices, i.e.
leaving it empty, works quite all right. According to the pulseaudio
docs, alsa applications will automatically be routed through
pulseaudio via the alsa-plugin.

> How can I change these audio parameters in GRC? What other parameters
> can be changed in ~/.gnuradio/config.conf or by call?
> I like to reduce the audio samplerate down to 1000 Hz or up to 192 kHz
> -- is there any limit to do this when the hardware supports it?

The sample rate in GNU Radio is a parameter for the audio source and
sink - I think you can enter any value there.
Are you sure your hardware actually supports all those sample rates? I
suspect the reported sample rates are software rates from the mixer
and not native rates of the hardware. I have hardware that only
supports 44.1 and 48 kHz yet I get the same list as you get.


Alex