[op25-dev] Audio to Darkce/IceCast Server - No audio???? No tags, Local audio good.

op25 at zellners.com op25 at zellners.com
Wed Jan 2 17:41:08 UTC 2019

OK... I've put my RPi3B+ to work...

Raspbian Image, updated, fully loaded.. (NOT NOOBS, this is just  
Raspbian Full )

Run through the install setup for OP25 from:


Did this for my reclaimed laptop and this Pi...

OP25 working on both... Local audio good on both. Tracks the PII  
system I need to put under review...

So that works good..

The problem is feeding audio to my IceCast server..  :( :( :(

I installed a MP3 capable Darkice with its deps... its starts up  
fine.. The feed appears on my server

I am using the info at  

I created /etc/asound.conf and /etc/modprobe.d/bcm2835.conf

I rebooted the Pi rather than any reloading of things, to ensure that  
loopback created and loaded etc...

For the ALSA Loopback etc. info and setup.....

so is the ALSA loopback setup????

/darkice $ cat /proc/modules | grep snd
snd_aloop 24576 0 - Live 0x7f3a6000
snd_bcm2835 32768 1 - Live 0x7f399000 (C)

Check! Pi audio and ALSA loopback... CHECK CHECK!

snd_pcm 98304 2 snd_aloop,snd_bcm2835, Live 0x7f138000
snd_timer 32768 1 snd_pcm, Live 0x7f11d000
snd 69632 6 snd_aloop,snd_bcm2835,snd_pcm,snd_timer, Live 0x7f102000

ALSA seems to be a dark arts thing.. I use some plugins on another  
setup to create L/R into separate feeds into darkice and that works  
great.... so I took it this loopback thing would do the same...

Seems the loopback exists....from:

~/darkice $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
   Subdevices: 7/7
   Subdevice #0: subdevice #0
   Subdevice #1: subdevice #1
   Subdevice #2: subdevice #2
   Subdevice #3: subdevice #3
   Subdevice #4: subdevice #4
   Subdevice #5: subdevice #5
   Subdevice #6: subdevice #6
card 0: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]
   Subdevices: 1/1
   Subdevice #0: subdevice #0

card 1: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
   Subdevices: 2/2
   Subdevice #0: subdevice #0
   Subdevice #1: subdevice #1
card 1: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
   Subdevices: 2/2
   Subdevice #0: subdevice #0
   Subdevice #1: subdevice #1

Loopbacks!!!! WOOT!

With this I will take it that the loopback and needed config files are  
correct, and have not posted them...

Darkice cfg IS SET to loop0

~/darkice $ cat lakelandp25.cfg
# sample DarkIce configuration file, edit for your needs before using
# see the darkice.cfg man page for details

# this section describes general aspects of the live streaming session
duration        = 0        # duration of encoding, in seconds. 0 means forever
bufferSecs      = 1         # size of internal slip buffer, in seconds
reconnect       = yes       # reconnect to the server(s) if disconnected

# this section describes the audio input that will be streamed
device          = loop0  # OSS DSP soundcard device for the audio input
sampleRate      = 22050  # sample rate in Hz. 22050 i
bitsPerSample   = 16     # bits per sample. 16 for mono feeds, 32 for  
stereo feeds
channel         = 1      # channels. 1 = mono, 2 = stereo

# this section describes a streaming connection to an IceCast server
# there may be up to 8 of these sections, named [icecast-0] ... [icecast-7]
# these can be mixed with [icecast2-x] and [shoutcast-x] sections

# If you want to send to your own icecast server, you basically copy
# this whole section and put in the values to point the feed to your own
# server i

# Don't forget, the name [icecast2-0] needs to change to [icecast2-1]
# and 2 and 3 as you add more feed destinations.

# The audio format to encode to, we're using mp3 here
format          = mp3

# The bit rate mode to use, the commented out lines are for a fixed bit
# rate "constant bit rate" at 16 bits.  I prefer the variable bit rate
# for the sound quality it has and the throughput is very similar on avg

#bitrateMode    = cbr
#bitrate        = 16

sampleRate      = 22050     # sample rate in Hz. 22050 is the
bitrateMode     = cbr
bitrate         = 16

# Quality at .1, max is 1.0, but as you increase, so does the bandwidth
# used.  For mono scanner audio .1 is totally fine.
quality         = 0.1

# Takes the input and mixes it down to a mono output for the feed.
channel         = 1

# Cuts frequency response over 5kHz.  For scanner feed this mostly
# eliminates hiss and harshness on paging tones.  Saves a bunch of
# bandwidth as well.
lowpass         = 5000

# From Feed Technical Details, the "Server"
server          = audio.myserver.net

# From Feed Technical Details, the "Port"
port            = 8000      # port of the IceCast server, usually 8000

# From Feed Technical Details, the Password exactly as shown
password        = hackmeNOT!

# From Feed Technical Details, the mount...remove the leading "/", it's
# not needed in this file.  So if it is /999999 make it just 999999
mountPoint      = Redacatedfeed

# name of the stream
# On My Live Audio Feeds, it's the first part ending in a colon ":"
name            = Redactedfeed

# On My Live Audio Feeds, it's the part in parentheses in the Feed name
description     = redactedfeed

start up OP25

./rx.py --args 'rtl' -N 'LNA:19' -l http: -S 2400000  
-f 8xx.7xxxxe6 -o 25000 -q 26 -T trunk.tsv -V -2 -O loop0 2>  

OP25 starts up... SILENCE on the feed

./rx.py --args 'rtl' -N 'LNA:19' -l http: -S 2400000  
-f 8xx.7xxxe6 -o 25000 -q 26 -T trunk.tsv -V -2 -M myststem.json -O  
loop0 2> stderrstream.2

SILENCE  BUT I GET TAGS! ! ! ! So the audio is not piped through some  

I figured if it was a issue with audio, tags would come through with  
out the audio...

./rx.py --args 'rtl' -N 'LNA:19' -l http: -S 2400000  
-f 8xx.xxxxe6 -o 25000 -q 26 -T trunk.tsv -V -2 -U -W 2>  

Watching the http output I see data come in, TSBK count goes up, TG's  
appear etc... NO AUDIO :( on the feed, WITH tags.... :)

Local audio comes out the speakers.... So audio is recovered and in  
good quality even for a Pi..

Any hints, clues? ?? ?  I've tried a couple of different setups for  
the loopback with an .asound.rc in the /home/user, used loop1, hw:1,0,  
hw:1,1 etc. tried as 2 channel audio v. single channel audio in  
darkice... still silence is not golden.... :(

Any hints on getting the loopback audio working?? ? ? ? ?  I might try  
it on the laptop setup too to see if its a Pi thing...  My hunch is  
the magic dark arts of the right ALSA name for where the audio is at  
is wrong in the darkice config....but I've tried everything I can  
think of


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