subs-volume

#!/usr/bin/env bash
#
# Script to subscribe and notify for volume changes
#

current_vol() {
    pactl get-sink-volume ${@:-\@DEFAULT_SINK\@} | grep -Po '\d+(?=%)' | head -n 1
}

notify_vol() {
    local volume=muted

    if [[ $2 -gt 63 ]]; then
        level=high
    elif [[ $2 -le 63 && $2 -gt 33 ]]; then
        level=medium
    elif [[ $2 -gt 0 ]]; then
        level=low
    fi

    notify-send -p -r $1 -i "audio-volume-$level" -h "int:value:$2" "Volume"
}

main() {
    local sink=$1
    local vol=$(current_vol $sink)
    local last_volume=$vol
    local notify_id=0

    pactl subscribe | grep --line-buffered -E "chan.*sink " | while read -r buf; do
        vol=$(current_vol $sink)
        if [[ "$last_volume" != "$vol" ]]; then
            last_volume=$vol
            notify_id=$(notify_vol $notify_id $vol)
        fi
    done
}

main "$@"