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Re: [Discuss-gnuradio] First time user - fm radio tutorial has choppy au

From: Remington Furman
Subject: Re: [Discuss-gnuradio] First time user - fm radio tutorial has choppy audio
Date: Thu, 15 Jan 2015 20:42:00 -0800

Ok, here are the contents of my ~/.gnuradio/config.conf:

default_input_device = default
default_output_device = default
#period_time = 0.010                      # in seconds (default)
period_time = 0.100                      # in seconds
nperiods = 4                 # total buffering = period_time * nperiods
#verbose = false
verbose = true

The actual change I made was to increase audio_alsa/period_time from 0.010 to 0.100.  Play around with it until it works on your system.  My only guess is that perhaps the default ALSA buffer sizes are small enough that they are often consumed by ALSA before GnuRadio will fill them.


PS. Thanks to everyone for your fantastic work on building this whole system and answering all the questions on the list.  I've been learning a ton reading this over the last year, and I appreciate it.  I'll try not to be so shy next time I know something that might be useful to others.

On Thu, Jan 15, 2015 at 1:38 PM, Remington Furman <address@hidden> wrote:

I had this same aU problem a few months ago on Linux Mint, but was able to resolve it by editing the default ALSA settings in ~/.gnuradio/config.conf .

I will send detailed notes on the exact fix I made when I get home, but I just found this page also describing the fix:
(Increase 'nperiods' under [audio_alsa])

After the config change ALSA audio worked with my own WBFM flowgraph and all the sample flowgraphs that were previously broken for me.

Apologies for not sending something to the list when I found the problem.  I knew it would have saved folks from some hair pulling.

Hope this helps,

On Thu, Jan 15, 2015 at 4:47 AM, Ralph A. Schmid, dk5ras <address@hidden> wrote:
No chance, I do not get any stable audio performance, I assume the Kubuntu
sound system is defective somehow. It is not about sampling rates, the pitch
is correct, just choppy. When calling the dial tone script repeatedly,
sometimes it works, sometimes it causes garbled sounds, then again it works,
with one attempt after another without doing anything else.

Update: Right now I was so brave to uninstall some pulse library stuff, and
what should I say, the stuttering is gone, DMR is not decoding 100% fine,
but I assume now it is a matter of fine tuning the receiver chain and
decoder, audio itself looks OK. Thank you very much for putting me into the
right direction! How can find such a load of BS its way into an official and
widely used Linux distribution?!


> -----Original Message-----
> From: discuss-gnuradio-bounces+ralph=address@hidden
> [mailto:discuss-gnuradio-bounces+ralph=address@hidden] On Behalf Of
> Ralph A. Schmid, dk5ras
> Sent: Thursday, January 15, 2015 8:14 AM
> To: 'Marcus D. Leech'; 'Tom Rondeau'
> Cc: 'GNURadio Discussion List'
> Subject: Re: [Discuss-gnuradio] First time user - fm radio tutorial has
> audio
> Hi Marcus,
> > If you use "plughw:0,0" as the hardware designator, it's often willing
> > to do resampling to the actual hardware rate.
> Yep, I will try this later. Made my tests this morning on my way to work
> train, now it has to wait until lunch break :)
> Ralph.
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

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