Polybar Spotify Module

This is a pure C implementation of an external polybar module that signals polybar when a track is playing/paused and when the track changes. There is also a program that retreives the title and artist of the currently playing song on spotify.

Requirements

DBus is used for listening to spotify track changes. Obviously you need spotify and polybar as well: dbus polybar spotify

To compile the program, you will need make.

You most likely already have the above packages installed. Systemd depends on DBus, and you wouldn't be looking at this, if you didn't have polybar and spotify installed.

How to Setup

Installing the Program

Run the following code to clone the repo and install the programs.

git clone https://github.com/mihirlad55/polybar-spotify-module
cd polybar-spotify-module/src/
sudo make install

Arch Linux Users

polybar-spotify-module exists as a package on the AUR! Use your favourite AUR helper to install the package.

yay -S polybar-spotify-module

The package can be found here https://aur.archlinux.org/packages/polybar-spotify-module/.

Running spotify-listener in the Background

spotify-listener must run in the background for it to be able to listen for track changes and communicate with polybar. There are two ways to keep it running in the background. If you are using systemd, you can have it start at system startup by running:

systemctl --user enable spotify-listener

Then, you can start the service now by running:

systemctl --user start spotify-listener

If you are not using systemd, make sure the spotify-listener program is executed at startup. Something like

spotify-listener &
disown

in a startup script should accomplish that.

Configuring Polybar

Your polybar configuration file should be located at .config/polybar/config

First make sure IPC is enabled. The following should be in your configuration file under the [bar/<your bar name>] section:

[bar/main]
enable-ipc = true

If you plan to use icons for next/play/previous/pause buttons, make sure you add (and have installed) an icon font accordingly such as NerdFonts or FontAwesome under the [bar/<your bar name>] section:

[bar/main]
font-1 = Font Awesome 5 Free:size=10;1

Note that the font is specified in modules as a 1-based index, so font-1 is specified by format-font = 2.

Next, add the following spotify modules:

[module/previous]
type = custom/ipc
format-font = 2
; Default
hook-0 = echo ""
; When spotify active
hook-1 = echo "Previous"
click-left = "spotifyctl -q previous"

[module/next]
type = custom/ipc
format-font = 2
; Default
hook-0 = echo ""
; When spotify active
hook-1 = echo "Next"
click-left = "spotifyctl -q next"

[module/playpause]
type = custom/ipc
format-font = 2
; Default
hook-0 = echo ""
; Playing
hook-1 = echo "Pause"
; Paused
hook-2 = echo "Play"
click-left = "spotifyctl -q playpause"

[module/spotify]
type = custom/ipc
; Default
hook-0 = echo ""
; Playing/paused show song name and artist
hook-1 = spotifyctl -q status --format '%artist%: %title%'

You can replace the text for Pause/Play/Next/Previous with icons for each of the hooks.

Lastly, make sure the new spotify modules are part of your bar. Make sure one of the following lines is part of your modules.

modules-center = spotify previous playpause next
modules-left = spotify previous playpause next
modules-right = spotify previous playpause next

Status Formatting

The spotifyctl status command has multiple formatting options. You can specify the:

• Maximum output length
• Maximum artist length
• Maxiumum track title length
• Output Format
• Truncation string

By default, the above lengths are INT_MAX (no limit). Additionally, if max length is specified, the artist and track title will not be truncated if the untruncated output satisfies the output max length constraint.

The tokens %artist% and %title% can be used to specify the output format.

For example for the artist Eminem and track title Sing For The Moment

spotifyctl status --format '%artist%: %title%' --max-length 20 \
    --max-title-length 10 --max-artist-length 10 --trunc '...'

would result in the following output

Eminem: Sing Fo...

For more information and examples, you can run the command spotifyctl help.

How it Works

The spotify-listener program connects to the DBus Session Bus and listens for two particular signals:

• org.freedesktop.DBus.ProprtyChanged for track changes
• org.freedesktop.DBus.NameOwnerChanged for spotify disconnections

Using this information, it sends messages to spotify polybar custom/IPC modules to show/hide spotify controls and display the play/pause icon based on whether a song is playing/paused.

The spotifyctl program calls org.mpris.MediaPlayer2.Properties.Get method to retreive status information and calls methods in the org.mpris.MediaPlayer2.Player interface to pause/play and go to the previous/next track.

Why Did I Make this in C

• Practice/learn low-level C
• Reduce number of dependencies
• Make something as lightweight as possible by directly interfacing with DBus
• For fun 😜

Resources

The following are very useful resources for DBus API and specs:

• https://dbus.freedesktop.org/doc/api/html/group__DBusConnection.html
• https://dbus.freedesktop.org/doc/api/html/group__DBusBus.html
• https://dbus.freedesktop.org/doc/api/html/group__DBusMessage.html
• https://dbus.freedesktop.org/doc/dbus-specification.html
• https://dbus.freedesktop.org/doc/dbus-tutorial.html

Credits

Inspired by the python implementation by dietervanhoof: https://github.com/dietervanhoof/polybar-spotify-controls