A script to fade volume when toggling MPD via mpc based on lcpz's script.

mpc-fade

#!/bin/sh

# A script to fade volume when toggling MPD via mpc

mpc=`which mpc`

SINKAPP="mpd"
SECS=2.0

sinks=$(pactl list sink-inputs)
sinkbinaryindex=$(awk -v sinks="$sinks" -v app="$SINKAPP" 'BEGIN {print index(sinks,app)}'  )
sink=$(echo "${sinks:0:$sinkbinaryindex}" | tr "\n" "[racecar]" | rev | tr "[racecar]" "\n" | grep -m 1 "tupnI" | tr -d "#" | awk '{print $1}' | rev )

VOLUME=$(pactl list sink-inputs | sed -n "/Sink Input #$sink/,\$p" | tail -n +2 | sed '/Sink Input/q' | awk '/Volume: /{print substr($5, 1, length($5)-1)}')

# volume commands, customize here
decrease="pactl set-sink-input-volume $sink -1%"
increase="pactl set-sink-input-volume $sink +1%"
resetvolume="pactl set-sink-input-volume $sink $VOLUME%"
mutevolume="pactl set-sink-input-volume $sink 0%"

for arg in "$@"
do
  if [ "$arg" == "--help" ] || [ "$arg" == "-h" ]
  then
    echo "usage: mpc-fade <volume fade percentage> <fade length in secs>"
    exit 1
  fi
done

while getopts h:p:s: option ; do
  case "${option}"
    in
    p) VOLUME=${OPTARG};;
    s) SECS=${OPTARG};;
  esac
done

fade() {
  SLEEP=$(echo "scale=4; $SECS/$VOLUME" | bc)
  while [ $VOLUME -ge 1 ] ; do
    $1
    VOLUME=$(($VOLUME-1))
    sleep $SLEEP
  done
}

playing=$(mpc status | grep playing)

if [ ${#playing} -gt 0 ] ; then
  fade "$decrease"
  mpc toggle -q
  eval "$resetvolume"
else
  eval "$mutevolume"
  mpc toggle -q
  fade "$increase"
fi

exit 0

# eof