I run music from an RPi with Hifiberry Digi into a Rotel A12 Amplifier with integrated DAC via SP-DIF.
The optical connection does not allow volume control, so I was wondering, if I could use the RS232 control-interface of the amp to control the volume.
A short test with a USB-to-Serial adapter works from the shell, letting me remote control functions of the amp.
I was wondering, what the best way of integration would be: I would like the volume slider on the GUI to control the volume of the amp. However, a quick look into the code showed me, that the volume controls (mixer with hardware, software, none) are pretty tied to the DACs configurations and I would probably need to start messing with those.
Is there an easier way to allow e.g. a plugin to read the slider and then send RS232 commands without having to add new functions to the mixer setup? Currently the slider is fixed at 100% with the default setting for the Digi.
My current idea would be a new mixer type “Websock” that would just broadcast any movement of the slider as a websocket message and each plugin wanting to act upon that info would just subscribe to the messages. Other suggestions how it could be implemented? I basically need to untie the slider from the hardware and sound processing and just be able to use it as a pure input device.