CentOS 7 RPM Specfile for Opendigitalradio's ODR-AudioEnc which is part of RaBe's DAB / DAB+ broadcasting package collection.

There are pre-built binary packages for CentOS 7 available on Radio RaBe's OBS DAB / DAB+ broadcasting package repository, which can be installed as follows:

curl -o /etc/yum.repos.d/home:radiorabe:dab.repo \
     http://download.opensuse.org/repositories/home:/radiorabe:/dab/CentOS_7/home:radiorabe:dab.repo
     
yum install odr-audioenc

odr-audioenc can be started via the installed systemd service unit template (and therefore supports multiple instances):

systemctl start odr-audioenc@<INSTANCE>.service

# To start an instance named "example":
systemctl start [email protected]

To start an odr-audioenc service on boot:

systemctl enable odr-audioenc@<INSTANCE>.service

# To start an instance named "example":
systemctl enable [email protected]

Status and logs of an odr-audioenc service instance:

systemctl status odr-audioenc@<INSTANCE>.service
journalctl -u odr-audioenc@<INSTANCE>.service

# Status and journal entries of an instance named "example"
systemctl status [email protected]
journalctl -u [email protected]

The service uses an ALSA input and encodes to a ZeroMQ via TCP (tcp://localhost:9000) output by default.

All the default odr-audioenc command options and arguments can be overriden by modifying the respective environment variables via the systemd service Environment= options (Environment="AUDIOENC_*"). The following options can be overriden (including their default values):

• Environment="AUDIOENC_INPUT_OPTS=--device=default"
  Options controlling odr-audioenc's input (default ALSA device)
• Environment="AUDIOENC_ENCODER_BITRATE=64"
  Encoder output bitrate in kbits/s
• Environment="AUDIOENC_ENCODER_CHANNELS=2"
  Number of input channels
• Environment="AUDIOENC_ENCODER_SAMPLERATE=48000"
  Input sample rate in Hz
• Environment="AUDIOENC_OUTPUT_OPTS=--output=tcp://localhost:9000"
  Options controlling odr-audioenc's output
• Environment="AUDIOENC_MISC_OPTS="
  Miscellaneous options and arguments to pass to odr-audioenc

To override the options, you can either interactively edit a service instance or directly install an override file:

# Interactively edit and instance
systemctl edit odr-audioenc@<INSTANCE>.service

# Interactively edit the instance named "example":
systemctl enable [email protected]


# Install an override file
mkdir /etc/systemd/system/odr-audioenc@<INSTANCE>.service.d/

cat << EOF >> /etc/systemd/system/odr-audioenc@<INSTANCE>.service.d/override.conf
[Service]

# Change bitrate to 96 kbit/s
Environment="AUDIOENC_ENCODER_BITRATE=96"

# Include PAD data from odr-padenc
Environment="AUDIOENC_MISC_OPTS=--pad=6 --pad-fifo=/var/tmp/odr/padenc/%i/pad.fifo"
EOF

systemctl cat [email protected] shows further (commented) override examples.

From the previous override example, it can be seen, that an odr-audioenc service unit instance plays nicely together with an odr-padenc service unit instance. Simply create an odr-audioenc and odr-padenc instance with the same instance name and they will use the same PAD data FIFO:

# Start the odr-padenc example instance
systemctl start [email protected]
systemctl enable [email protected]


# Enable PAD data via FIFO on the odr-audioenc example instance
mkdir /etc/systemd/system/[email protected]

cat << "EOF" >> /etc/systemd/system/[email protected]/override.conf
[Service]
Environment="AUDIOENC_MISC_OPTS=--pad=58 --pad-fifo=/var/tmp/odr/padenc/%i/pad.fifo"
EOF

# Start the odr-audioenc example instance
systemctl start [email protected]
systemctl enable [email protected]

An odr-audioenc service unit instance will be started after a potential odr-padenc instance with the same instance name (After=... odr-padenc@%i.service) during boot-up. This ensures that odr-padenc can create the FIFO socket beforehand.