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Microphone Auto Switch

  When headhones are plugged in the output switches atomatically to them
  But the microphone does not, and needs to be manually switched!

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PusleAudio Configuration Change
https://bugs.freedesktop.org/show_bug.cgi?id=101798#c5

Add the following to
/usr/share/pulseaudio/alsa-mixer/paths/analog-input-internal-mic.conf

=======8<--------
[Jack Headphone Mic]
state.plugged = no
state.unplugged = unknown

[Jack Headset Mic]
state.plugged = no
state.unplugged = unknown
=======8<--------

This basically makes the internal mic 'unknown' while a headset
is plugged in so it switches to the next available mic, on the headset

This WORKS, but may get overwritten on pulse audio updates

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Using a acpid daemon
https://askubuntu.com/questions/1098683/

    acpi_listen    #  watch devices being pluged in and out

  Pulseaudio is what can swicth the values

    # Set headphone microphone
    pacmd set-source-port alsa_input.pci-0000_00_1f.3.analog-stereo \
          analog-input-headset-mic
    # Set back to internal microphone
    pacmd set-source-port alsa_input.pci-0000_00_1f.3.analog-stereo \
          analog-input-internal-mic


  Create a script to auto swicth between them on plugin
  This has to be adjusted to suit.

    echo '                # append ports to a firewall config file
    | #!/bin/sh
    | #
    | # switch between microphones
    | #
    | export PULSE_RUNTIME_PATH="/run/user/1000/pulse/"
    | sudo -u you -E pacmd set-source-port \
    |   alsa_input.pci-0000_00_1f.3.analog-stereo \
    |     analog-input-"${1@Q}"-mic
    |
    ' perl -ne 's/\s*#.*$//; s/^\s*\| // && print' \
       > /etc/acpi/actions/headset-microphone.sh

  Create a listener files to do the switch according to the
  acpi_listen

    echo '
    | event=jack/headphone HEADPHONE plug
    | action=/etc/acpi/actions/headset-microphone.sh headset
    ' perl -ne 's/\s*#.*$//; s/^\s*\| // && print' \
       > /etc/acpi/events/headset-microphone-plug

    echo '
    | event=jack/headphone HEADPHONE unplug
    | action=/etc/acpi/actions/headset-microphone.sh internal
    ' perl -ne 's/\s*#.*$//; s/^\s*\| // && print' \
       > /etc/acpi/events/headset-microphone-unplug

  Enable Additions

    systemctl restart acpid.service


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Using a acpid daemon
Alternative - one event file
https://bbs.archlinux.org/viewtopic.php?id=215248

This script not only adjusts the headset,
but determined the user involved.

  echo '                # append ports to a firewall config file
  | #!/bin/sh
  | #
  | # swicth between microphones
  | #
  | [ "$1" = jack/headphone ] && [ "$2" = HEADPHONE ] || exit 0
  |
  | SRC="alsa_input.pci-0000_00_1f.3.analog-stereo"
  | SINK="alsa_output.pci-0000_00_1f.3.analog-stereo"
  |
  | case "$3" in
  | unplug) SRCE_DEV="analog-input-internal-mic"
  |         SINK_DEV="analog-output-speaker"
  |         ;;
  | plug)   SRCE_DEV="analog-input-headset-mic"
  |         SINK_DEV="analog-output-headphones"
  |         ;;
  | esac
  | 
  | USERS="$(ps axc -o command,user | sed -n 's/^pulseaudio  *//p' | sort -u)"
  |
  | for user in $USERS; do
  |   export PULSE_RUNTIME_PATH="/run/user/$id -u $user)/pulse/" 
  |   su $user -c "pacmd set-sink-port $SINK $SINK_DEV"
  |   su $user -c "pacmd set-source-port $SRCE $SRCE_DEV"
  | done
  |
  ' perl -ne 's/\s*#.*$//; s/^\s*\| // && print' \
     > /etc/acpi/actions/headset-jack.sh

  echo '
  | event=jack/headphone
  | action=/etc/acpi/actions/headset-jack.sh %e
  ' perl -ne 's/\s*#.*$//; s/^\s*\| // && print' \
     > /etc/acpi/events/headset-microphone

  systemctl restart acpid.service

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