A simple mqtt controlled track volume audio player.
It uses pygame and the paho mqtt library.
At launch it start playing the 8 tracks simultaneously in sync, in an infinite loop. The mqtt messages then control the volume.
The default topic is sound/{channel 0-7} and expects a value between 0 and 1 for the volume.
example: setting volume of channel 3 at 75%
mosquitto_pub -h 127.0.0.1 -t "sound/3" -m 0.75