switch audio output (PulseAudio)

audio-device-switch.sh

#!/bin/bash

# For PulseAudio.

# FOR THIS TO WORK, I needed to edit /etc/pulse/default.pa so that this line:
#   load-module module-stream-restore
# is instead like this:
#   load-module module-stream-restore restore_device=false
#
# I believe this will also undermine the ability to set some app to use a
# non-default sink, and have it stay that way across app restarts, but my
# amount of care about that usecase is zero.

# The grepping/sed-ing patterns for various bits of command output may need
# to be tweaked to work with other systems or audio devices.

# We're going to be dealing with an list of sink indexes stored in a bash
# array. To avoid confusion (maybe) the sink indexes will be called "IDs" in
# the code/comments below, and the array index where an ID is stored will be
# called its index.


# Create an array of sink IDs.
sink_ids=()
mapfile -t sink_ids < <(pacmd list-sinks | grep -oP '^([[:space:]]|\*)*index:[[:space:]]\K[[:digit:]]+')
# Get the ID of the default sink (marked with asterisk).
default_sink_id=$(pacmd list-sinks | grep -oP '^[[:space:]]*\*[[:space:]]*index:[[:space:]]\K[[:digit:]]+')
# Get the index of the default sink.
for index in "${!sink_ids[@]}"; do
  if [[ "${sink_ids[$index]}" == "$default_sink_id" ]]; then
    default_sink_index=$index
  fi
done
# Get the last index in the array.
final_sink_index=$((${#sink_ids[@]} - 1))
# Create a list of the sink descriptions.
sink_descriptions=()
mapfile -t sink_descriptions < <(pacmd list-sinks | sed -n -e 's/.*\(alsa.name\|bluez.alias\)[[:space:]]=[[:space:]]"\(.*\)"/\2/p')

# OK we want to cycle to a new sink ID that should become the default sink. We
# don't want to just "pick the next one" because some sinks are not hooked up
# to anything in reality.

# Ideally I'd support a list of sinks-to-skip here, but in practice right now
# there's only one that I need to skip.
blacklisted_sink_desc="HDMI 0"

# Start our search for next-sink-to-use at the current default sink.
next_sink_index=$default_sink_index

# Begin the search.
looping=true
while [[ $looping == true ]] ; do

# Choose the next sink in the array. Wrap around to the beginning if needed.
if [[ $next_sink_index -ne $final_sink_index ]] ; then
  next_sink_index=$((next_sink_index + 1))
else
  next_sink_index=0
fi
next_sink_id=${sink_ids[$next_sink_index]}

# Terminate the search if we've come back to our original starting point.
if [[ "$next_sink_index" == "$default_sink_index" ]] ; then
  looping=false
fi

# Terminate the search if we found a non-blacklisted sink.
if [[ "${sink_descriptions[$next_sink_index]}" != "$blacklisted_sink_desc" ]] ; then
  looping=false
fi

done

# Change the default sink.
pacmd set-default-sink $next_sink_id

# Move all current inputs to the new default sink.
for input_id in $(pacmd list-sink-inputs | grep -oP '^[[:space:]]*index:[[:space:]]\K[[:digit:]]+');
do
  pacmd move-sink-input $input_id $next_sink_id
done

# And notify!
notify-send -i audio-volume-high "Sound output switched to ${sink_descriptions[$next_sink_index]}"