silentdisco

Launch azuracast

In silentdisco root folder execute:

 ./docker.sh install

Log in to localhost:8080 and complete the configuration

Launch server

The azuracast stream is propagated to the network by a nodejs server; it reads the stream and broadcasts it to all connected websockets.

In silentdisco/server folder execute the command to build and run the application, specifying the environment variables

• SERVER_IP: the ip address of the machine on the lan
• STREAM_URL: the URL of the azuracast stream

An example of the launch script would be as follows:

 export SERVER_IP=192.168.1.46
 export STREAM_URL=http://192.168.1.46:8000/radio.mp3
 docker-compose up -d --build

In order to see the execution logs you may run the following command (where server_silentdisco_1 is the name of the container generated by the build):

 docker logs server_silentdisco_1

When everything is setup, the clients may connect to the server using a web browser

Performance note

The server relies on io.emit() in order to broadcast the stream as fast as possible with fixed packet size. In order to reduce the amount of exchanged data, a mono mixdown is performed. On client side the major bottleneck is represented by the time needed by AudioContext.decodeAudioData(), expecially on less modern devices. The delay needed to synchronize the streams is applied with amortization, otherwise would result in choppy playback: it takes around a minute to synchronize two devices having 500 ms of difference in latency

Credits

silentdisco is using the following third party software:

• azuracast https://www.azuracast.com/
• socket.io https://socket.io/
• timesync https://github.com/enmasseio/timesync