Difference between revisions of "Music Player Daemon"
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As recommanded above, it is best to use MPD as a service per user. In this case, we will use {{ic|~/.mpd/mpd.conf}} and not start mpd.service as a daemon for the whole system and all users. | As recommanded above, it is best to use MPD as a service per user. In this case, we will use {{ic|~/.mpd/mpd.conf}} and not start mpd.service as a daemon for the whole system and all users. | ||
− | We will NOT use the {{ic|/usr/lib/systemd/ | + | We will NOT use the {{ic|/usr/lib/systemd/system/mpd.service}} which is intended to start the mpd.service as root and for all users. |
If you already enabled it, just disable it first: | If you already enabled it, just disable it first: | ||
{{bc| # systemctl disable mpd.service}} | {{bc| # systemctl disable mpd.service}} |
Revision as of 12:21, 4 December 2012
zh-CN:Music Player Daemon Template:Article summary start Template:Article summary text Template:Article summary heading Template:Article summary link Template:Article summary heading Template:Article summary wiki Template:Article summary wiki Template:Article summary heading Template:Article summary text Template:Article summary end
MPD (music player daemon) is an audio player that has a server-client architecture. It plays audio files, organizes playlists and maintains a music database all while using very few resources. In order to interface with it, a separate client is needed.
Contents
Installation
Stable version
The latest stable version of mpd is available in the official repositories.
You may also want to install mpd-systemd.
Git version
Should users wish to run an experimental version, the AUR offers several from which to choose. For example, mpd-gitAUR.
Setup
MPD is able to run globally (settings apply to all users), locally (per user settings), and in multiple instances. The way of setting up mpd depends on the way it is intended to be used. A local configuration may prove more useful on a desktop system than on a system that is used by several people simultaneously.
For a comfortable use, it is sensible to provide MPD access to the following files and directories:
- mpd.db - The music database
- mpd.pid - The file where mpd stores its process ID
- mpd.log - mpd logs here
- mpdstate - mpd's current state is noted here
- playlists - the folder where playlists are saved into
In order for MPD to be able to play back audio, ALSA, PulseAudio or OSS needs to be setup and working.
Global Configuration
MPD comes with an example configuration file, available at /usr/share/doc/mpd/mpdconf.example
. This file holds an abundance of information on MPD configuration, and holds default mixer values.
Normally,/etc/mpd.conf
is created when installing mpd. If not, copy the included example file to /etc/mpd.conf
.
# cp /usr/share/doc/mpd/mpdconf.example /etc/mpd.conf
Editing mpd.conf
The default Arch install keeps the setup in /var/lib/mpd
and uses "mpd" as default user.
Edit /etc/mpd.conf
to reflect as such:
/etc/mpd.conf
music_directory "/home/user/music" playlist_directory "/var/lib/mpd/playlists" db_file "/var/lib/mpd/mpd.db" log_file "/var/log/mpd/mpd.log" pid_file "/run/mpd/mpd.pid" state_file "/var/lib/mpd/mpdstate" user "mpd" # bind_to_address "127.0.0.1" # port "6600"
Now change permissions for mpd to write to /var/log/mpd/mpd.log
, otherwise mpd will return an error when it is started. The best way is to make the /var/log/mpd/mpd.log
belong to the mpd user.
# chown -R mpd /var/log/mpd
Run this to create the /run/mpd dir:
# systemd-tmpfiles --create mpd.conf
To change the volume for mpd independent from other programs, uncomment or add this switch in mpd.conf:
/etc/mpd.conf
mixer_type "software"
Users of PulseAudio will need to make the following modification:
/etc/mpd.conf
audio_output { type "pulse" name "pulse audio" }
Users of ALSA will want to have the following device definition, which allows software volume control in the MPD client to control the volume separately from other applications.
/etc/mpd.conf
audio_output { type "alsa" name "My Sound Card" mixer_type "software" # optional }
Changing the group that MPD runs as may result in errors like "output: Failed to open "My ALSA Device"" "[alsa]: Failed to open ALSA device "default": No such file or directory" "player_thread: problems opening audio device while playing "Song Name.mp3""
This is because by default MPD runs as member of audio group and the sound devices under /dev/snd/
are owned by this group, so add user mpd
to group audio
.
# gpasswd -a mpd audio
Music directory
MPD needs to have +x
permissions on all parent directories to the music collection (ie. if it's located outside of "mpd" home directory /var/lib/mpd
). By default useradd sets permissions on home directories to 1700 drwx------
. Thus users will most likely need to remount the music directory under a directory that mpd has access to -- this only applies if running as the 'mpd' user.
# mkdir /var/lib/mpd/music # echo "/home/$USER/music /var/lib/mpd/music none bind" >> /etc/fstab # mount -a # systemctl restart mpd.service
Also see this forum thread.
An additional solution would be to just create a symbolic link into /var/lib/mpd/music
.
# mkdir /var/lib/mpd/music # ln -s MUSIC_FOLDER /var/lib/mpd/music/ # systemctl restart mpd.service
If the music collection is contained under multiple directories, create symbolic links under the main music directory in /var/lib/mpd
. Remember to set permissions accordingly on the directories being linked.
Creating the required files
Now, having finished configuring MPD, the files and directories for MPD to write in need to be created:
Create the directories and files specified in /etc/mpd.conf
:
# mkdir -p /var/lib/mpd/playlists # touch /var/lib/mpd/{mpd.db,mpdstate}
Usually the init-script should properly create /run/mpd/
when starting. The daemon will use this directory to create mpd.pid
in it. However, when running mpd as a different user, requires an update to the tmpfiles.d: copy /usr/lib/tmpfiles.d/mpd.conf
to /etc/tmpfiles.d/mpd.conf
:
Change:
d /run/mpd 0755 mpd mpd
to:
d /run/mpd 0755 username groupname
Change the file's permissions so that the daemon can modify them.
# chown -R mpd /var/lib/mpd
Create database
Creating the database is now accomplished via the update feature of the client, for example mpc update
. You'll need to install the mpc package for this. It is in the official repositories
Timeline of MPD startup
To depict when MPD drops its superuser privileges and assumes those of the user set in the configuration, the timeline of a normal MPD startup is listed here:
- Since MPD is started as root by systemd, it first reads the
/etc/mpd.conf
file. - MPD reads the user variable in the
/etc/mpd.conf
file, and changes from root to this user. - MPD then reads the contents of the
/etc/mpd.conf
file and configures itself accordingly.
Notice that MPD changes the running user from root to the one named in the /etc/mpd.conf
file.
This way, uses of ~
in the configuration file point correctly to the home user's directory, and not root's directory.
It may be worthwhile to change all uses of ~
to /home/username
to avoid any confusion over this aspect of MPD's behavior.
Local Configuration (per user)
MPD does not need to be run globally as a daemon and can rather work per user. The usual method to configure MPD globally is because the listed files and folders in the default configuration file point to directories owned by root (the /var
directory).
A less used (but perhaps more sensible) method is to make MPD work with files and directories owned by a normal user. Running MPD as a normal user has the benefits of:
- A single directory
~/.mpd
(or any other directory under/home/username
) that will contain all the MPD configuration files. - Easier to avoid unforeseen read/write permission errors.
Begin the setup by creating a directory for the required files and the playlists:
mkdir -p ~/.mpd/playlists
Copy the contents of the default MPD configuration file in /usr/share/mpd/mpd.conf.example
to the target user's home directory:
cp /usr/share/doc/mpd/mpdconf.example ~/.mpdconf
Create all of the requisite files:
touch ~/.mpd/{mpd.db,mpd.log,mpd.pid,mpdstate}
Edit ~/.mpdconf
to specify these files:
~/.mpdconf
music_directory "/home/USER/music" # Keep commented if your XDG directory already points to it playlist_directory "/home/USER/.mpd/playlists" db_file "/home/USER/.mpd/mpd.db" log_file "/home/USER/.mpd/mpd.log" pid_file "/home/USER/.mpd/mpd.pid" state_file "/home/USER/.mpd/mpdstate"
or you can use
sed "s/var\/lib\/mpd\/music/home\/$USER\/music/; s/var\/lib\/mpd/home\/$USER\/.mpd/; s/var\/run\/mpd/home\/$USER\/.mpd/; s/var\/log\/mpd/home\/$USER\/.mpd/" /etc/mpd.conf > ~/.mpd/mpd.conf
MPD can now be started by typing mpd
on the command line.
To have MPD start with the X server add it to xprofile.
Start MPD per user with systemd
As recommanded above, it is best to use MPD as a service per user. In this case, we will use ~/.mpd/mpd.conf
and not start mpd.service as a daemon for the whole system and all users.
We will NOT use the /usr/lib/systemd/system/mpd.service
which is intended to start the mpd.service as root and for all users.
If you already enabled it, just disable it first:
# systemctl disable mpd.service
If you used to start mpd inside your ~/.xinitrc
, comment or delete the line
mpd ~/.mpdconf
Then, edit a new file /etc/systemd/user/mpd.service
/etc/systemd/user/mpd.service
[Unit] Description = Music Player Daemon [Service] ExecStart = /usr/bin/mpd --no-daemon Restart = always [Install] WantedBy = default.target
Then, add this line to .xinitrc
~/.xinitrc
#run systemd as user intsance systemd --user &
Log out, log in your xsession. Let's first check mpd is not running. If yes, just kill it
$ ps -ef | grep mpd
Now, enable and start mpd.service as per user
$ systemctl --user enable mpd $ systemctl --user start mpd
Check the mpd status and see if mpd.service is correctly enabled and started
$ systemctl --user status mpd
Scripted Configuration
Rasi has written a script that will create the proper directory structure, configuration files and prompt for the location of the user's Music directory; it can be downloaded here.
Multi-mpd setup
Useful if running an icecast server.
For a second MPD (e.g., with icecast output to share music over the network) using the same music and playlist as the one above, simply copy the above configuration file and make a new file (e.g., /home/username/.mpd/config-icecast
), and only change the log_file, error_file, pid_file, and state_file parameters (e.g., mpd-icecast.log
, mpd-icecast.error
, and so on); using the same directory paths for the music and playlist directories would ensure that this second mpd would use the same music collection as the first one e.g., creating and editing a playlist under the first daemon would affect the second daemon as well. Users do not have to create the same playlists all over again for the second daemon. Call this second daemon the same way from ~/.xinitrc
above. (Just be sure to have a different port number, so as to not conflict with the first mpd daemon).
Clients
A separate client is needed to control mpd. Popular options are:
Console
- mpc — Simple KISS client. All basic functionality available
- ncmpc — A NCurses client for mpd
- ncmpcpp — An almost exact clone of ncmpc with some new features written in C++ (tag editor, search engine)
- pms — Highly configurable and accessible ncurses client
Graphical
- Ario — A very feature-rich GTK2 GUI client for mpd, inspired by Rhythmbox
- QmpdClient — A GUI client written with Qt 4.x
- Sonata — An elegant Python GTK+ client
- gmpc — GNOME Client
- Dmpc — Dmenu-based MPC client with a playlist manager and state-saving on playlist changes
Web
- Patchfork — web client for MPD written in PHP and Ajax
See a long list of clients at the mpd wiki.