RaBe DAB+ On Air Processing

RaBe DAB+ On Air Processing processes and encodes an audio stream for later broadcasting at an opendigitalradio broadcast service provider.

This uses simple internet radio processing technology to prepare our DAB+ stream letting us save the cost of buying a gold standard Omnia DAB+ processor.

It is written in liquidsoap and integrates mk_liquidsoap_process from mkpascal with the fdk-aac-dabplus-odr encoder. Parts of the processing chain are inspired by conduit.

Requirements

A working install of the RaBe Liquidsoap distribution or any other liquidsoap install. The examples below depend on the systemd configuration from the RaBe dist.

Install

RaBe DAB+ On Air Processing is packaged for CentOS7.

yum install -y epel-release
yum install -y http://li.nux.ro/download/nux/dextop/el7/x86_64/nux-dextop-release-0-5.el7.nux.noarch.rpm
curl -o /etc/yum.repos.d/liquidsoap.repo \
  http://download.opensuse.org/repositories/home:/radiorabe:/liquidsoap/CentOS_7/home:radiorabe:liquidsoap.repo
curl -o /etc/yum.repos.d/dab.repo \
  http://download.opensuse.org/repositories/home:/radiorabe:/dab/CentOS_7/home:radiorabe:dab.repo

yum install -y dabplus-on-air-processing

Usage

Enable and start the processor and odr-padenc.

systemctl enable dabplus-odr-padenc@dabplus-on-air-processing
systemctl enable liquidsoap@dabplus-on-air-processing

systemctl start dabplus-odr-padenc@dabplus-on-air-processing
systemctl start liquidsoap@dabplus-on-air-processing

systemctl status dabplus-odr-padenc@dabplus-on-air-processing
systemctl status liquidsoap@dabplus-on-air-processing

You may put slides and DL text files into /var/tmp/odr/padenc/dabplus-on-air-processing/{slides,texts}.

Testing

You can listen to the encoded zmq frames from the encoder by muxing them and piping the results to dablin.

yum install -y odr-dabmux dablin

odr-dabmux /usr/share/doc/odr-dabmux-1.0.0/example.mux | dablin -s 0x8dab

You'll need to remove the comp-fu component and its subchannel and service from the example above and you should work on a copy of the file. Remember to set nbframes to zero if you want the mux to run forever.

Development

This repository contains the main processing script as well as the tooling needed to package it on the openbuild service.