Soundcard 'monitor' stream doesn't arrive with Spectrum plugin

[Stefan Sauer]

On 06/18/2012 09:19 PM, Cefn Hoile wrote:
> On 18 June 2012 17:11, Cefn Hoile <lists.freedesktop.org at cefn.com> wrote:
>> On 18 June 2012 16:27, Stefan Sauer <ensonic at hora-obscura.de> wrote:
>>> On 06/12/2012 04:25 PM, Cefn Hoile wrote:
>>>> On 12 June 2012 14:40, Stefan Sauer <ensonic at hora-obscura.de> wrote:
>>>>> On 06/12/2012 04:13 AM, Cefn Hoile wrote:
>>>>>> I'm hoping to base a tutorial demo on the first python example linked
>>>>>> below, and I attempted to test its logic by playing music from
>>>>>> Rhythmbox through my (Ubuntu Oneiric) soundcard while visualising the
>>>>>> result of the 'spectrum' FFT as changing numbers streaming on the
>>>>>> console. Sadly this first debugging step was a failure.
>>>>>>
>>>>>> http://pzwart3.wdka.hro.nl/wiki/Spectrum.py
>>>>>>
>>>>>> The spectrum plugin loaded by this python script only ever reports -60
>>>>>> decibels for every frequency band in the spectrum, regardless how loud
>>>>>> I turn up the music!
>>>>> You can change that:
>>>>> spectrum threshold=-96
>>>>>
>>>>> Stefan
>>>>>> I have tried both alsasrc and pulsesrc with various device names
>>>>>> (default, pulse, the introspected alsa monitor device name from pactl)
>>>>>> at the beginning of the listener_desc pipeline (declared in the linked
>>>>>> code). In most of the cases I've tried (barring typos) the pipeline
>>>>>> seems to be established and run perfectly fine (as far as I can tell)
>>>>>> but somehow no sound frequencies show up in the frequency analysis
>>>>>> from the spectrum plugin.
>>>>>>
>>>>>> Does this python code work for anyone else? How would I verify that
>>>>>> the pipeline is correct, or narrow down the problem? Any suggestions
>>>>>> what the initial source plugin or entire pipeline should in fact be on
>>>>>> an Ubuntu system to get loudnesses per frequency range streaming out
>>>>>> of the spectrum plugin to the console using this code as a reference?
>>>>>>
>>>>>> Thanks for any help.
>>>>>>
>>>>>> Cefn
>>>>>> http://cefn.com
>>>>>> _______________________________________________
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>>>>>> gstreamer-devel at lists.freedesktop.org
>>>>>> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>>>>> _______________________________________________
>>>>> gstreamer-devel mailing list
>>>>> gstreamer-devel at lists.freedesktop.org
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>>>> Thanks for the suggestion, Stefan. You're right you can change it :)
>>>> Now I get regular lines which report -96 instead of -60 ...
>>>>
>>>> data: -96.0 -96.0 -96.0 -96.0 -96.0 -96.0 -96.0 -96.0
>>>>
>>>> My current pipeline looks like this...
>>>>
>>>> pulsesrc device="alsa_output.pci-0000_00_1b.0.analog-stereo.monitor" !
>>>> spectrum threshold=-96 interval=1000000000 bands=8 ! fakesink
>>>>
>>>> ...and still the DB levels never vary depending on output from the soundcard.
>>> Then I'd say there is a different problem. Are you sure you are
>>> monitoring the right monitor-port?
>>> Try gst-launch -e pulsesrc
>>> device="alsa_output.pci-0000_00_1b.0.analog-stereo.monitor" ! wavenc !
>>> filesink location=monitor.wav
>>> and check the resulting wav file.
>>>
>>> Stefan
>>>> Cefn
>>>> http://cefn.com
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>>>> gstreamer-devel at lists.freedesktop.org
>>>> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
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>> Based on the results of the test you suggest, it is indeed silent. It
>> makes me think I must have the wrong audio device but then I don't
>> know what other choices I have. Does monitor need to be activated
>> somehow?
>>
>> If I run the following to see all the possible names pulseaudio can
>> make sense of, I've tried all the values which appear and they all
>> produce silent .wav files. As you can see from the 'RUNNING' output
>> below, Gstreamer is able to activate the streams though.
>>
>> pactl list short sources
>> 0       alsa_output.pci-0000_01_00.1.hdmi-stereo.monitor        module-alsa-card.c      s16le
>> 2ch 44100Hz     RUNNING
>> 1       alsa_output.pci-0000_00_1b.0.analog-stereo.monitor      module-alsa-card.c      s16le
>> 2ch 44100Hz     IDLE
>> 2       alsa_input.pci-0000_00_1b.0.analog-stereo       module-alsa-card.c      s16le
>> 2ch 44100Hz     SUSPENDED
>>
>> Any ideas for something to try? I believe I have a stock build (had no
>> asound.conf or ~/asoundrc until just now when I was experimenting and
>> trying an alsa force-reload according to
>> https://wiki.archlinux.org/index.php/PulseAudio/Examples#ALSA_Monitor_source).
> I have success!
>
> Seeing all the reported problems with NVidia cards at
> https://wiki.archlinux.org/index.php/PulseAudio/Examples#ALSA_Monitor_source
> I checked to see if I had NVidia. I have dual audio combining Intel
> and NVidia, which is probably subject to the bug at
> ftp://download.nvidia.com/XFree86/gpu-hdmi-audio-document/gpu-hdmi-audio.html#_issues_in_pulseaudio
>
> I speculatively installed Pavucontrol and turned off the HDMI output
> (which wasn't being used by my audio programs anyway according to
> pavucontrol). Restarted alsa and pulseaudio with 'alsa force-reload'
> and suddenly GStreamer is responding to the monitor output from my
> soundcard.
>
> Thanks for the steer, it helped me along the way to a fix.

Awesome, glad to head that it now works.

Stefan
>
> Cefn
> http://cefn.com
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