Re: Audio underruns

On 08/20/2020 11:29 AM, Barry Duggan wrote:
> Ubuntu 20.04.1
> GRC 3.9.0.0-git
> The
> https://github.com/gnuradio/gnuradio/blob/master/gr-analog/examples/USRP_FM_stereo.grc
> flowgraph works properly with the device name blank.
>
> With a copy of that file, I replaced the "WBFM Receive PLL" block with
> a "WBFM Receive" block (the monophonic version).
>
> The mono FM audio is terribly distorted and has lots of audio
> underruns when the device name is blank, but works well with a device
> name of "hw:CARD=Generic,DEV=0".
>
> This does not make any sense to me. How can changing the ALSA device
> name affect the audio underruns? Or, how does changing the demodulator
> require changing the ALSA device name?
>
> ---
> Barry Duggan KV4FV
> https://github.com/duggabe
Gnu Radio doesn't have much control over what your audio subsystem
actually *does* for the "default" device, which is what happens when you
leave that field blank.

What's actually happening depends on your audio system configuration, so
I'm guessing that the default may go through pulse-audio, which is
trying to re-sample, and failing. Just a guess. Linux audio is, to
a first order, less-than-wonderful.