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Jos
Asked: 2017-05-10 22:54:59 +0800 CST

Changing the ALSA volume remotely

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I have a Raspberry Pi (called Igor) in my room that plays music, and occasionally speaks a warning message. If I want to change its volume, or mute it, I need to ssh into it from my laptop and start alsamixer. This is a bit of a hassle and I'd like to use some keyboard shortcuts, or an onscreen control, just for changing Igor's volume.

I suppose I could cobble up a small server on the RPi that listens for network messages and adjusts the volume accordingly. From my laptop I could set up keyboard shortcuts that do something like 

echo "+10%" | nc igor $portnumber

for 10% louder, and "-10%" for softer. Create my own API, so to say. But isn't there already something out there that does that? Does ALSA have an API for network access? Or does PulseAudio?

Just to make it clear, I don't want to stream the music itself to the RPi. Igor has its own sources of music.

pulseaudio

1 Answers

  1. @CL. gave me the idea of running a single command through ssh, triggered by a keyboard shortcut.

    On the RPi, I have a script softer.sh like this:

    #!/bin/bash
# Turn the volume down 10%
amixer -c0 set PCM -- $[$(amixer -c0 get PCM|grep -o [0-9]*%|sed 's/%//')-10]% > /dev/null 2>&1

    This gets the current volume from amixer (which is a percentage), subtracts 10, sticks the "%" symbol to the end, and sets the volume to the result. Same for louder.sh which adds 10%.

    On my laptop I set CTRL + F7 to execute:

    ssh pi@igor softer.sh

    and of course CTRL + F8 to

    ssh pi@igor louder.sh
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