My partner has been overseas for a few months and was desperately missing a local radio station. It doesn’t have an online stream that she can listen to and so she asked me whether I could record the station for ten hours – this just sounded like a hassle, so I set up an internet streaming station to permanently re-stream the local broadcast over the internet using my Raspberry Pi, a cheap USB sound card, a cheap DAB digial radio, and darkice/icecast to run the streaming server.

The output of lsusb showed the cheap USB sound card to be a “C-Media Electronics, Inc. CM108 Audio Controller”. I found that I could access the device using ALSA and the arecord utility (as long as I didn’t specify 2 channels):

arecord -D hw:1,1 -f s16_le > test.wav

Next, I tried to set up icecast2 with darkice. I’m using Raspbian and the standard raspbian-distributed package for darkice is not compiled with ALSA support, and I nearly fell down a rabbit-hole trying to get OSS-compatible emulation working.

In the end, I was able to compile and install darkice with ALSA and mp3 support by following the excellent instructions here:

http://mattkaar.com/blog/2013/05/26/web-streaming-with-the-raspberry-pi-baby-monitor/

My darkice.cfg file looks like this:

[general]
duration      = 0                # duration of encoding, in seconds. 0 means forever
bufferSecs    = 5                # 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
[input]
device        = hw:1,0           # Alsa soundcard device for the audio input
sampleRate    = 44100            # sample rate in Hz. try 11025, 22050 or 44100
bitsPerSample = 16               # bits per sample. try 16
channel       = 1                # channels. 1 = mono, 2 = stereo
# this section describes a streaming connection to an IceCast2 server
# there may be up to 8 of these sections, named [icecast2-0] ... [icecast2-7]
# these can be mixed with [icecast-x] and [shoutcast-x] sections
[icecast2-0]
bitrateMode   = vbr              # variable bit rate
format        = mp3              # format of the stream: mp3
quality       = 0.6              # quality of the stream sent to the server
server        = localhost        # host name of the server
port          = 8000             # port of the IceCast2 server, usually 8000
password      = ******  	   # source password to the IceCast2 server
mountPoint    = 1080         	   # mount point of this stream on the IceCast2 server
name          = 6ix - Forever Classic            # name of the stream
description   = DarkIce on RasPi # description of the stream
#url           = http://192.168.88.17 # URL related to the stream
genre         = Forever Classic         # genre of the stream
public        = no               # advertise this stream?
localDumpFile = recording.mp3    # Record also to a file

The setup works beautifully and CPU (original rPi) hits around 25% per streaming client. Since I only expect to stream to one client, this is fine.

As AM has quite a limited bandwidth I expect I could drastically lower the bitrate that darkice is encoding at, and also add a highpass parameter to filter out any noise.

To round off the project I also made the rPi serve a little webpage, with a link to .m3u file plus an embedded HTML5 player:

Hear it here: radio.jeremyhall.com.au

Finally, I made darkice run as a service using daemontools using the instructions on this stackexchange post: http://unix.stackexchange.com/questions/92545/starting-darkice-automatically-via-daemontools

Update: It’s still running strong a few months later. Having now joined my partner overseas, we listen to it every day!

Second update (June 2017): The radio station that was being re-streamed has now started their own official stream, so my stream is no longer running.