PulseAudio: use multiple speakers

use_dual_monitor_speakers.sh

#!/bin/bash
set -x

# TODO: Update this strings with the actual values for your speakers
# TODO: Remember to also adjust the volumes to balance them (depending on their power and their distance from your location)
SPEAKER_1_NAME=$(pactl list sinks | grep Name | grep -Eo 'alsa_output\.pci-.+hdmi-stereo')
SPEAKER_1_VOLUME=85%
SPEAKER_2_NAME=$(pactl list sinks | grep Name | grep -Eo 'alsa_output\.pci-.+analog-stereo')
SPEAKER_2_VOLUME=100%
COMPOSITE_SPEAKER_NAME=Dual_Monitor
COMPOSITE_SPEAKER_DESCRIPTION="Dual Monitor"
COMPOSITE_SPEAKER_VOLUME=50%
PACTL_LOOPBACK_MODULE_ARGS="channels=2 latency_msec=100 adjust_time=0 rate=48000"

# Initially, remove previous state
pactl unload-module module-null-sink 2>/dev/null
pactl unload-module module-loopback 2>/dev/null

if [ "$1" = "-d" -o "$1" = "--disable" ]; then
    # Do not proceed any further, but make the single speaker at a decent volume
    pactl set-sink-volume $SPEAKER_2_NAME $COMPOSITE_SPEAKER_VOLUME

    # Mute everything
    pactl set-sink-mute "$SPEAKER_1_NAME" true
    pactl set-sink-mute "$SPEAKER_2_NAME" true
    exit 0
fi

set -e

# 1. Create a fake sink null
pactl load-module module-null-sink sink_name=$COMPOSITE_SPEAKER_NAME sink_properties="'device.description=\"$COMPOSITE_SPEAKER_DESCRIPTION\"'"

# 2. Connect fake sink to SPEAKER_1
pactl load-module module-loopback source=$COMPOSITE_SPEAKER_NAME.monitor "sink=$SPEAKER_1_NAME" $PACTL_LOOPBACK_MODULE_ARGS

# 3. Connect fake sink to SPEAKER_2
pactl load-module module-loopback source=$COMPOSITE_SPEAKER_NAME.monitor "sink=$SPEAKER_2_NAME" $PACTL_LOOPBACK_MODULE_ARGS

# 4. Set volume of the composite speaker to 50%
pactl set-sink-mute $COMPOSITE_SPEAKER_NAME false
pactl set-sink-volume $COMPOSITE_SPEAKER_NAME "$COMPOSITE_SPEAKER_VOLUME"

# 5. Set volume of SPEAKER_1
pactl set-sink-mute $SPEAKER_1_NAME false
pactl set-sink-volume $SPEAKER_1_NAME $SPEAKER_1_VOLUME

# 6. Set volume of SPEAKER_2
pactl set-sink-mute $SPEAKER_2_NAME false
pactl set-sink-volume $SPEAKER_2_NAME $SPEAKER_2_VOLUME

# 7. Set the fake sink as the default audio sink
pactl set-default-sink $COMPOSITE_SPEAKER_NAME

echo "Setup completed."