Airspy mini on Linux: audio buffer underflows and no audio fft data

[Robert Eckelmann]

Hi Alex &Group,

Has any one seen these error messages before?


No audio FFT data.
portaudio_sink::work(): Error writing to audio device: Output underflowed
No audio FFT data.
No audio FFT data.
No audio FFT data.
(Complete log is attached at the end of this message)

Was using gqrx and FCD before and had no issues, but now as I upgraded to airspy mini I get these messages.

I am running the latest gqrx version from git currently compiled w/ PortAudio (debug build with cmake) as Pulseaudio would only create a core dump when the demodultion is started.

CPU is a Intel core2quad Q6600 @2.4GHz w/ 4 gig of RAM running on Arch/Linux.

I am not sure if this is an issue of gqrx, GNURadio, the audio-backend of this machine or what ever.

Any hints for gettings more details on what is happing or how to get a better understanding are appreciated.

Greetings,
Rob JI1MNC/DC6XS


[robby@robquad ~]$ uname -a
Linux robquad 4.9.1-1-ARCH #1 SMP PREEMPT Fri Jan 6 20:42:57 CET 2017 x86_64 GNU/Linux


[robby@robquad builds]$ gqrx
linux; GNU C++ version 6.2.1 20160830; Boost_106300; UHD_003.009.005-0-unknown

Controlport disabled
ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM dsnoop:0
ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM dmix:0
ALSA lib pulse.c:243:(pulse_connect) PulseAudio: Unable to connect: Connection refused

ALSA lib pulse.c:243:(pulse_connect) PulseAudio: Unable to connect: Connection refused

ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM dsnoop:0
ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM dmix:0
connect(2) call to /dev/shm/jack-1000/default/jack_0 failed (err=No such file or directory)
attempt to connect to server failed
No user supplied config file. Using "default.conf"
gr-osmosdr v0.1.4-75-gae686c46 (0.1.5git) gnuradio 3.7.10.1
built-in source types: file osmosdr fcd rtl rtl_tcp uhd hackrf bladerf rfspace airspy soapy redpitaya
FM demod gain: 3.05577
Resampling audio 96000 -> 48000
IQ DCR alpha: 1.04166e-05
PortAudio V19.6.0-devel, revision 396fe4b6699ae929d3a685b3ef8a7e97396139a4 (version 1246720)
Number of audio devices: 1
  0:  USB PnP Audio Device: Audio (hw:0,0)  I:1  O:2
Using default audio device
Using audio backend: auto
BookmarksFile is /home/robby/.config/gqrx/bookmarks.csv
getDeviceList : Available input devices:
    0 : "RFSPACE SDR-IQ Receiver"
    1 : "RFSPACE SDR-IP Receiver"
    2 : "RFSPACE NetSDR Receiver"
    3 : "RFSPACE Cloud-IQ Receiver"
    4 : "AirSpy AIRSPY"
    5 : "RTL-SDR Spectrum Server"
    6 : "Red Pitaya Transceiver Server"
    7 : "Complex Sampled (IQ) File"
Loading configuration from: "default.conf"
Configuration file: "/home/robby/.config/gqrx/default.conf"
gr-osmosdr v0.1.4-75-gae686c46 (0.1.5git) gnuradio 3.7.10.1
built-in source types: file osmosdr fcd rtl rtl_tcp uhd hackrf bladerf rfspace airspy soapy redpitaya
Using AirSpy MINI v1.0.0-rc10-0-g946184a 2016-09-19, samplerates: 3M 6M
IQ DCR samp_rate: 3e+06
IQ DCR alpha: 3.33333e-07
Changing NB_RX quad rate: 96000 -> 3e+06
New antenna selected: "RX"
********************
Gain name: "LNA"
      min: 0
      max: 15
     step: 1
Gain name: "MIX"
      min: 0
      max: 15
     step: 1
Gain name: "IF"
      min: 0
      max: 15
     step: 1
********************
New audio output device:
   old:
   new: USB PnP Audio Device: Audio (hw:0,0)
PortAudio V19.6.0-devel, revision 396fe4b6699ae929d3a685b3ef8a7e97396139a4 (version 1246720)
Number of audio devices: 1
  0:  USB PnP Audio Device: Audio (hw:0,0)  I:1  O:2
Audio device 'USB PnP Audio Device: Audio (hw:0,0)' has index 0
IQ DCR samp_rate: 6e+06
IQ DCR alpha: 1.66667e-07
Changing NB_RX quad rate: 3e+06 -> 6e+06
Requested sample rate: 6000000
Actual sample rate   : "6000000.000000"
New FFT rate: 25 Hz
Requested bandwidth: 6000000 Hz
Actual bandwidth   : 1e+07 Hz
setFreqCorr : 0 ppm
New LNB LO: 0 Hz
New mode index: 3
Filter preset for mode 3 LO: -5000 HI: 5000
Genrating taps for new filter   LO:-5000   HI:5000 TW:2000   Taps: 115
setFftRate to "30 fps"
New FFT rate: 30 Hz
New FFT rate: 30 Hz
New FFT rate: 30 Hz
New FFT rate: 30 Hz
setFftSize to "131072"
Changing baseband FFT size to 131072
New FFT rate: 30 Hz
New FFT rate: 30 Hz
Genrating taps for new filter   LO:-5000   HI:5000 TW:2000   Taps: 115
New FFT rate: 30 Hz
New FFT rate: 30 Hz
No audio FFT data.
portaudio_sink::work(): Error writing to audio device: Output underflowed
No audio FFT data.
No audio FFT data.
No audio FFT data.

[Alexandru Csete]

Hi Rob,

Have you found some hints regarding this issue? I really feel we have
discussed similar topics many times, but if you can't find anything I
will give you some hints.

Alex

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[Robert Eckelmann]

Hi Alex,

This eveing I followed an idea and tried a different USB Hub but this did not change anything.

Also when Iuse the audio recorder function in GQRX it writes proper files without any problems.

My assumption is it is somewhere in the pipe between gnuradio and alsa/portaudio.pulseradio.

I will try testing and will alos try mother soundcard, to see if theis improves the situation...

Also I will try resetting the Pulseausio settings, maybe there is something that makes problems..

If you have further hints where to look for, please let me know.

Is there some switch for getting debug details from gnuradio-runtime?

Thanks,

Rob

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[Alexandru Csete]

Ok, my thoughts were CPU load issue, but that would also affect audio
recording. But you should still check if the issue also exists with a
release build if you haven't already done so. Debug builds have
optimisations turned off and so require much more CPU and may also
affect timing even if CPU load is not high. Also be sure to run
volk_profile to at least have that out of the way.

I'm a bit confused which audio backend you are using... The preferred
backends from gqrx point of view are Pulseaudio, Portaudio and finally
gr-audio.

It is possible to enable some debug in GNU Radio through the
configuration files but I don't remember the details. Look at some
gnuradio config files in /etc .

Alex

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[Robert Eckelmann]

Thanks for the input.

I was running a debug build with portaudio.

While I am writing this a release build w/ pulseaudio is running.

I will check for the gnuradio config files.

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[Robert Eckelmann]

Hi Alex,

here is a follow up:

for the meoment i have  astable running system with no audio issues any more.
Running the lastest git version built as release with Pulseaduio

I reset the pulseaudio config and I think that is what fixed most of it..


What I noticed, is that the Audio-FFT rate seems sometimes slow.
Are the FFT rate for audio and baseband display linked?

Thanks again for the support!

[Alexandru Csete]

On Sat, Jan 14, 2017 at 3:27 PM, Robert Eckelmann <longn...@gmail.com> wrote:
> Hi Alex,
>
> here is a follow up:
>
> for the meoment i have astable running system with no audio issues any
> more.
> Running the lastest git version built as release with Pulseaduio
>
> I reset the pulseaudio config and I think that is what fixed most of it..

Sounds good! Thanks for the followup.

> What I noticed, is that the Audio-FFT rate seems sometimes slow.
> Are the FFT rate for audio and baseband display linked?

Yes, that happens sometimes and I don't know what to do about it. It's
out of my control because it is the GNU Radio scheduler that
determines how to call and activate the DSP blocks. I don't know if it
is some USB or other linux event that causes it to change scheduling
mode but it is very annoying. Usually it resets if you do something
like changing modes (even if it is to the same mode).

Alex