Sound volume change notifications using pynotify

As I started to use the i3 window manager I wanted to have a visual feedback on sound volume change events. Usually it's done by a daemon that binds to specific keyboard combinations to adjust volume and to send notifications to a notify daemon. In xfce this is done by the xfce4-volumed. I should also point here to other lightweight volume daemons like volnoti or pa-applet. Without a dedicated daemon it is also pretty much simple to handle sound volume keys by a simple bash script which is bind to specific keyboard combinations.

I've seen several examples of such a script the only problem with them was that notify-send command used to send notifications still does not return an id of a notification shown which results in several notification popups floating at the same time. As it's described here one could patch notify-send command so that it will return an id if asked but I came up with an easier solution using python-notify lib. Until patched notify-send is available in an official repository one could use this pynotify workaround. Here is an example of pynotify usage in a script to adjust sound volume:

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$ cat bin/volume_notify.sh #!/bin/bash   # $0 - icon_name, $2 - volume, $3 - id print_cmd() { cat <<HEREDOC import pynotify pynotify.init("volume_notif.py") notif=pynotify.Notification("Volume", "", "$1") notif.set_hint_int32("value",$2) notif.set_property("id", $3) notif.show() print notif.get_property("id") HEREDOC }   step=5 id_file="/tmp/notify_volume.id"   icon_high="/usr/share/icons/elementary-xfce/notifications/48/audio-volume-high.png" icon_low="/usr/share/icons/elementary-xfce/notifications/48/audio-volume-low.png" icon_medium="/usr/share/icons/elementary-xfce/notifications/48/audio-volume-medium.png" icon_muted="/usr/share/icons/elementary-xfce/notifications/48/audio-volume-muted.png" icon_off="/usr/share/icons/elementary-xfce/notifications/48/audio-volume-off.png"   case $1 in   up)       amixer -q set Master $step+ ;;   down)       amixer -q set Master $step- ;;   toggle)       #pactl list sinks|grep -q Mute:.yes;pactl set-sink-mute 0 ${PIPESTATUS[1]} ;;       # amixer needs -D pulse switch as a workaround for the pulseaudio       # check http://goo.gl/4z4U6R       amixer -q -D pulse set Master toggle ;;   *)       echo "Usage: $0 up/down/toggle"       exit 1 ;; esac   muted=$(amixer get Master | tail -n1 | sed -nr 's/.*\[([a-z]+)\].*/\1/p') volume=$(amixer get Master | tail -n1 | sed -nr 's/[^\[]*.([^%]*).*/\1/p') if ((volume==0)); then   icon=$icon_off elif ((volume<34)); then   icon=$icon_low elif ((volume<67)); then   icon=$icon_medium else   icon=$icon_high fi if [[ $muted == "off" ]]; then   icon=$icon_muted fi   id=$(cat $id_file 2>/dev/null);id=${id:-0} idn=$(python -c "$(print_cmd $icon $volume $id)") (($idn != $id)) && echo "$idn" > "$id_file" exit 0

Here pynotify module is used to send a notification and return its id. This id is stored in a temp file defined by id_file variable so that it can be accessed by another script process.

ps: lines 42-43 could be optimized to this:

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val=$(amixer get Master | tail -n1 | sed -nr 'h;s/[^\[]*.([^%]*).*/\1/p;g;s/.*\[([a-z]+)\].*/\1/p') muted=${val#*$'\n'} volume=${val%$'\n'*}

This reduces number of created subprocesses two times

Edit 2020.11:

The script above uses older python lib which isn't available any longer. Additionally it controls amixer but pulseaudio should be used instead. Here is an updated version:

 

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$ cat bin/volume_notify_pa.sh #!/bin/bash   # this script requires python3-notify2 lib to be installed first   STEP='5%'   # some sound cards could have different MIN/MAX values # this isn't implemented yet as I can't test it MIN_VOLUME=0 MAX_VOLUME=65536   # file where notification ids are stored ID_FILE="/tmp/notify_volume.id"   # $1 - icon_name, $2 - volume, $3 - id print_cmd() { cat <<HEREDOC import notify2 notify2.init("volume_notify.py") notif=notify2.Notification("Volume", "", "$1") notif.set_hint_int32("value",$2) notif.id = $3 notif.show() print(notif.id) HEREDOC }   # input parameters are: $1 - volume, $3 - muted status send_notification() {   local icon id idn   local volume_raw=$1   local muted=$2     local volume=$(( (100*(volume_raw-MIN_VOLUME))/(MAX_VOLUME-MIN_VOLUME) ))     if ((volume==0)); then     icon=$icon_off   elif ((volume<34)); then     icon=$icon_low   elif ((volume<67)); then     icon=$icon_medium   else     icon=$icon_high   fi   if [[ "$muted" == "yes" ]]; then     icon=$icon_muted   fi   id=$(cat $ID_FILE 2>/dev/null);id=${id:-0}   idn=$(python3 -c "$(print_cmd "$icon" "$volume" "$id")")   (("$idn" != "$id")) && echo "$idn" > "$ID_FILE" }   get_volume() {   local VOLHEX=$(pacmd dump | awk '/^set-sink-volume/{printf("%s", $3)}')   [ -n "$VOLHEX" ] || {     echo "$MIN_VOLUME"     return   }   printf '%d' $VOLHEX }   # returns 'yes' or 'no' get_muted() {     MUTED=$(pacmd dump | awk '/set-sink-mute/{print $3}')     printf "%s" "$MUTED" }     icon_high="audio-volume-high" icon_low="audio-volume-low" icon_medium="audio-volume-medium" icon_muted="audio-volume-muted" icon_off="audio-volume-off"   SINK=$(pactl info | awk '/Default Sink/{print $3}') [ -n "$SINK" ] || exit 1   case $1 in   up)       pactl set-sink-volume  "$SINK" "+$STEP"       [ "$(get_volume)" -gt $MAX_VOLUME ] && pactl set-sink-volume  "$SINK" "$MAX_VOLUME"              ;;   down)       pactl set-sink-volume  "$SINK" "-$STEP"       [ "$(get_volume)" -le $MIN_VOLUME ] && pactl set-sink-volume  "$SINK" "$MIN_VOLUME"              ;;   toggle)       MUTED=$(pacmd dump | awk '/set-sink-mute/{print $3}')       if [ "yes" = "$MUTED" ]; then         pactl set-sink-mute "$SINK" 0       else         pactl set-sink-mute "$SINK" 1       fi       ;;   *)       echo "Usage: $0 up/down/toggle"       exit 1 ;; esac   send_notification "$(get_volume)" "$(get_muted)"   exit 0