RaspDAB/Get ODR-AudioEnc to operate
If you have checked the installation of the OpenDigitalRadio software with the -h option for odr-audioenc you will have seen it is possible to issue a large number of options. On this page we just focus on the most commonly used ones, necessary at first to encode audio that comes from an Internet stream into a signal that can be used in a DAB multiplex. It is assumed this is a situation that is very common: the radio station already has an internet stream running, so for the first test we can use that to insert the audio in the DAB stream. For now we assume you will run all necessary OpenDigitalRadio modules in the same Raspberry Pi. In another page we will discuss other situations.
A typical invokation of odr-audioenc looks like:
$ odr-audioenc -v http://server-66.stream-server.nl:8852 -C 200 -b 64 -o tcp://localhost:59000 -D -L --audio-resampler=samplerate -L --src-converter-type=1 -l -V
(all typed on one line, don't press ENTER in between !) Let's look in more detail to each of the options:
-v http://server-66.stream-server.nl:8852 is the source of the audio. In this case it is a stream from the Internet that will be handled by the VLC input. Audio-enc can include a library from the well-known VLC player, such that all its features are available ! -C 200 this specifes the VLC cache lenght -b 64 tells the encoder to encode at a bitrate of 64 kilobits per seconds -o tcp://localhost:59000 where the output signal should go. In this case it is made available on port 59000 of the 'localhost', which means this computer (Raspberry Pi) ODR_DabMux will reference this port and pick up the signal. D Drift compensation. There is always some difference between the clock signal of the audio encoder of e.g. the incoming stream and the output clock signal (crystals always have a small deviation, and with many stations sharing a single DAB multiplex some drift compensation is necessary). See also the explanation in the help information for odr-audioenc. -L --audio-resampler=samplerate -L --src-converter-type=1 these are options for the VLC library, informing it should use the 'samplerate' resampler and use the best quality available -l this will show a display of the input signal like a VU meter -V this will provide some detail about what the program is doing
If you run the program with the command line as shown above you will see it provides some information on what it is doing and a display showing the volume of the audio signal.
Leave this program running while we start for a look at the ODR-DabMux program.