Mute sound on Headphone unplug?

Howto detect an unplug

Basically what worked for me was:

# When plugged in:
cat /proc/asound/card0/codec#0 > pluggedin.txt

# When not plugged in:
cat /proc/asound/card0/codec#0 > notplugged.txt

# Then compare the differences
diff pluggedin.txt notplugged.txt

For me the difference was in 'Node 0x16' under 'Amp-Out vals':

Node 0x16 [Pin Complex] wcaps 0x40058d: Stereo Amp-Out             Node 0x16 [PinComplex] wcaps 0x40058d: Stereo Amp-Out
  Amp-Out caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1         Amp-Out caps:ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-Out vals:  [0x80 0x80]                                    |    Amp-Out vals:  [0x00 0x00]

So I based the detection on the difference found.

Howto mute

With this knowledge you can have a script running in the background. If unplugged the scripts mutes your speakers like using amixer sset Master playback 0% (or any other command).

#!/bin/bash
# This scripts detecs unplugging headphones.

oldstatus="unrelated string"
while [ 1 ]; do
    # The following line has to be changed depending on the difference (use diff) in '/proc/asound/card0/code#0'
    status=$(grep -A 4 'Node 0x16' '/proc/asound/card0/codec#0' |  grep 'Amp-Out vals:  \[0x80 0x80\]')
    if [ "$status" != "$oldstatus" ]; then
        if [ -n "$status" ]; then
            echo "Plugged in"
             amixer sset Master playback 80% # Set volume to 80%
            oldstatus="$status"
        else
            echo "Unplugged"
            amixer sset Master playback 0%  # Mute
            oldstatus="$status"
        fi
    fi
done

You can make it executable with chmod +x scriptname.sh and put it in the startup applications. You will have to adjust the unplug detection though by finding your own difference in /proc/asound/card0/codec#0 (maybe even change the numbers here for multiple soundcards.

Mute sound on Headphone unplug?

Howto detect an unplug

Howto mute

Tags:

Headphones

Sound

Speakers

Audio Jack

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