Hi everyone,
I'm having problems making the audio output work because of a "RuntimeError:
check topology failed on audio_alsa_sink(7) using ninputs=1, noutputs=0". I
did spend a few hours searching the archives and the web, but no luck.
Hardware: RPi model 3, the signal comes from an RTL-SDR dongle (the error
was reproducible with the gnu-radio and gr-osmosdr from the jessie
distribution. I installed the latest just in case it made a difference).
Software: gnuradio 3.7.9 installed from jessie-backports, gr-osmosdr
v0.1.4-72-g164a09fc (0.1.5git) built from sources, rtl-sdr built from
sources.
The flow is very simple, I want to get the audio going before doing the
real work (for testing purposes, I tuned to an NBFM weather station). I'm
still a beginner so maybe something is not correct, though. See further
down for a note on the Audio Sink.
I would appreciate some guidance as I don't understand the nature of the
problem. Some were saying that something might be wrong with the audio
sample rate, but it's not clear to me if that's the case. I also checked in
the Audio Properties (right-clicking on the speaker icon top-right) that
it's the Analog not HDMI output that's selected. Also, there is no other
program using the sound card.
Many thanks in advance,
JL
[image: Inline image 2]
Here's the output when I execute the program:
Generating: '/home/pi/top_block.py'
Executing: '/usr/bin/python -u /home/pi/top_block.py'
Using Volk machine: neon_hardfp_orc
gr-osmosdr v0.1.4-72-g164a09fc (0.1.5git) gnuradio 3.7.9
built-in source types: file fcd rtl rtl_tcp rfspace airspy redpitaya
Using device #0 Realtek RTL2838UHIDIR SN: 00000001
Found Rafael Micro R820T tuner
gr::log :INFO: audio source - Audio sink arch: alsa
len(audio_taps) = 2313
*gr::log :ERROR: audio_alsa_sink0 - [plughw:0,0]: set_channels failed:
Invalid argument*
Traceback (most recent call last):
File "/home/pi/top_block.py", line 185, in <module>
main()
File "/home/pi/top_block.py", line 174, in main
tb.start()
File "/usr/lib/python2.7/dist-packages/gnuradio/gr/top_block.py", line
109, in start
top_block_start_unlocked(self._impl, max_noutput_items)
File "/usr/lib/python2.7/dist-packages/gnuradio/gr/runtime_swig.py", line
4876, in top_block_start_unlocked
return _runtime_swig.top_block_start_unlocked(*args, **kwargs)
*RuntimeError: check topology failed on audio_alsa_sink(7) using ninputs=1,
noutputs=0*
>>> Done (return code 1)
Based on some of the results when searching for the error, I tried both
leaving the *audio device *empty or putting plughw0,0 (as suggsted by the
block's documentation). I also tried hw:0,0 without any success either.
Below are the audio devices:
pi@x:~/gr-osmosdr/build $ cat /proc/asound/cards
0 [ALSA ]: bcm2835 - bcm2835 ALSA
bcm2835 ALSA
pi@x:~/gr-osmosdr/build $ aplay -L
null
Discard all samples (playback) or generate zero samples (capture)
sysdefault:CARD=ALSA
bcm2835 ALSA, bcm2835 ALSA
Default Audio Device
dmix:CARD=ALSA,DEV=0
bcm2835 ALSA, bcm2835 ALSA
Direct sample mixing device
dmix:CARD=ALSA,DEV=1
bcm2835 ALSA, bcm2835 IEC958/HDMI
Direct sample mixing device
dsnoop:CARD=ALSA,DEV=0
bcm2835 ALSA, bcm2835 ALSA
Direct sample snooping device
dsnoop:CARD=ALSA,DEV=1
bcm2835 ALSA, bcm2835 IEC958/HDMI
Direct sample snooping device
hw:CARD=ALSA,DEV=0
bcm2835 ALSA, bcm2835 ALSA
Direct hardware device without any conversions
hw:CARD=ALSA,DEV=1
bcm2835 ALSA, bcm2835 IEC958/HDMI
Direct hardware device without any conversions
*plughw:CARD=ALSA,DEV=0*
* bcm2835 ALSA, bcm2835 ALSA*
* Hardware device with all software conversions*
plughw:CARD=ALSA,DEV=1
bcm2835 ALSA, bcm2835 IEC958/HDMI
Hardware device with all software conversions
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