mpd/doc/user.xml

<?xml version='1.0' encoding="utf-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
               "docbook/dtd/xml/4.2/docbookx.dtd">
<book>
  <title>The Music Player Daemon - User's Manual</title>

  <chapter id="intro">
    <title>Introduction</title>

    <para>
      This document is work in progress.  Most of it may be incomplete
      yet.  Please help!
    </para>

    <para>
      <application>MPD</application> (Music Player Daemon) is, as the
      name suggests, a server software allowing you to remotely play
      your music, handle playlists, deliver music (HTTP streams with
      various sub-protocols) and organize playlists.
    </para>

    <para>
      It has been written with minimal resource usage and stability in
      mind!  Infact, it runs fine on a Pentium 75, allowing you to use
      your cheap old PC to create a stereo system!
    </para>

    <para>
      <application>MPD</application> supports also gapless playback,
      buffered audio output, and crossfading!
    </para>

    <para>
      The separate client and server design allows users to choose a
      user interface that best suites their tastes independently of
      the underlying daemon, which actually plays music!
    </para>
  </chapter>

  <chapter id="install">
    <title>Installation</title>

    <para>
      We recommend that you use the software installation routines of
      your distribution to install <application>MPD</application>.
      Most operating systems have a <application>MPD</application>
      package, which is very easy to install.
    </para>

    <section id="install_debian">
      <title>Installing on Debian/Ubuntu</title>

      <para>
        Install the package <application>MPD</application> via APT:
      </para>

      <programlisting>apt-get install mpd</programlisting>

      <para>
        When installed this way, <application>MPD</application> by
        default looks for music in
        <filename>/var/lib/mpd/music/</filename>; this may not be
        correct. Look at your <filename>/etc/mpd.conf</filename>
        file...
      </para>
    </section>

    <section id="install_source">
      <title>Compiling from source</title>

      <para>
        Download the source tarball from <ulink
        url="http://www.musicpd.org/download.html">the
        <application>MPD</application> home page</ulink> and unpack
        it:
      </para>

      <programlisting>tar xf mpd-version.tar.xz
cd mpd-version</programlisting>

      <para>
        Make sure that all the required libraries and build tools are
        installed.  The <filename>INSTALL</filename> file has a list.
      </para>

      <para>
        For example, the following installs a fairly complete list of
        build dependencies on Debian Wheezy:
      </para>

      <programlisting>
apt-get install g++ \
  libmad0-dev libmpg123-dev libid3tag0-dev \
  libflac-dev libvorbis-dev libopus-dev \
  libadplug-dev libaudiofile-dev libsndfile1-dev libfaad-dev \
  libfluidsynth-dev libgme-dev libmikmod2-dev libmodplug-dev \
  libmpcdec-dev libwavpack-dev libwildmidi-dev \
  libsidplay2-dev libsidutils-dev libresid-builder-dev \
  libavcodec-dev libavformat-dev \
  libmp3lame-dev \
  libsamplerate0-dev libsoxr-dev \
  libbz2-dev libcdio-paranoia-dev libiso9660-dev libmms-dev \
  libzzip-dev \
  libcurl4-gnutls-dev libyajl-dev libexpat-dev \
  libasound2-dev libao-dev libjack-jackd2-dev libopenal-dev \
  libpulse-dev libroar-dev libshout3-dev \
  libmpdclient-dev \
  libnfs-dev libsmbclient-dev \
  libupnp-dev \
  libavahi-client-dev \
  libsqlite3-dev \
  libsystemd-daemon-dev libwrap0-dev \
  libcppunit-dev xmlto \
  libboost-dev \
  libicu-dev
      </programlisting>

      <para>
        Now configure the source tree:
      </para>

      <programlisting>./configure</programlisting>

      <para>
        The <parameter>--help</parameter> argument shows a list of
        compile-time options.  When everything is ready and
        configured, compile:
      </para>

      <programlisting>make</programlisting>

      <para>
        And install:
      </para>

      <programlisting>make install</programlisting>
    </section>

    <section id="systemd_socket">
      <title><filename>systemd</filename> socket activation</title>

      <para>
        Using <filename>systemd</filename>, you can launch
        <application>MPD</application> on demand when the first client
        attempts to connect.
      </para>

      <para>
        <application>MPD</application> comes with two
        <application>systemd</application> unit files: a "service"
        unit and a "socket" unit.  These will only be installed when
        <application>MPD</application> was configured with
        <parameter>--with-systemdsystemunitdir=/lib/systemd</parameter>.
      </para>

      <para>
        To enable socket activation, type:
      </para>

      <programlisting>systemctl enable mpd.socket
systemctl start mpd.socket</programlisting>

      <para>
        In this configuration, <application>MPD</application> will
        ignore the <varname>bind_to_address</varname> and
        <varname>port</varname> settings.
      </para>
    </section>
  </chapter>

  <chapter id="config">
    <title>Configuration</title>

    <section id="config_music_directory">
      <title>Configuring the music directory</title>

      <para>
        When you play local files, you should organize them within a
        directory called the "music directory".  This is configured in
        <application>MPD</application> with the
        <varname>music_directory</varname> setting.
      </para>

      <para>
        By default, <application>MPD</application> follows symbolic
        links in the music directory.  This behavior can be switched
        off: <varname>follow_outside_symlinks</varname> controls
        whether <application>MPD</application> follows links pointing
        to files outside of the music directory, and
        <varname>follow_inside_symlinks</varname> lets you disable
        symlinks to files inside the music directory.
      </para>

      <para>
        Instead of using local files, you can use <link
        linkend="storage_plugins">storage plugins</link> to access
        files on a remote file server.  For example, to use music from
        the SMB/CIFS server "myfileserver" on the share called
        "Music", configure the music directory
        "<parameter>smb://myfileserver/Music</parameter>".  For a
        recipe, read the <link linkend="satellite">Satellite
        MPD</link> section.
      </para>
    </section>

    <section id="config_database_plugins">
      <title>Configuring database plugins</title>

      <para>
        If a music directory is configured, one database plugin is
        used.  To configure this plugin, add a
        <varname>database</varname> block to
        <filename>mpd.conf</filename>:
      </para>

      <programlisting>database {
    plugin "simple"
    path "/var/lib/mpd/db"
}
      </programlisting>

      <para>
        The following table lists the <varname>database</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <para>
        More information can be found in the <link
        linkend="database_plugins">database plugin reference</link>.
      </para>
    </section>

    <section id="config_neighbor_plugins">
      <title>Configuring neighbor plugins</title>

      <para>
        All neighbor plugins are disabled by default to avoid unwanted
        overhead.  To enable (and configure) a plugin, add a
        <varname>neighbor</varname> block to
        <filename>mpd.conf</filename>:
      </para>

      <programlisting>neighbors {
    plugin "smbclient"
}
      </programlisting>

      <para>
        The following table lists the <varname>neighbor</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <para>
        More information can be found in the <link
        linkend="neighbor_plugins">neighbor plugin reference</link>.
      </para>
    </section>

    <section id="config_input_plugins">
      <title>Configuring input plugins</title>

      <para>
        To configure an input plugin, add a <varname>input</varname>
        block to <filename>mpd.conf</filename>:
      </para>

      <programlisting>input {
    plugin "curl"
    proxy "proxy.local"
}
      </programlisting>

      <para>
        The following table lists the <varname>input</varname> options
        valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>enabled</varname>
                <parameter>yes|no</parameter>
              </entry>
              <entry>
                Allows you to disable a input plugin without
                recompiling.  By default, all plugins are enabled.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <para>
        More information can be found in the <link
        linkend="input_plugins">input plugin reference</link>.
      </para>
    </section>

    <section id="config_decoder_plugins">
      <title>Configuring decoder plugins</title>

      <para>
        Most decoder plugins do not need any special configuration.
        To configure a decoder, add a <varname>decoder</varname> block
        to <filename>mpd.conf</filename>:
      </para>

      <programlisting>decoder {
    plugin "wildmidi"
    config_file "/etc/timidity/timidity.cfg"
}
      </programlisting>

      <para>
        The following table lists the <varname>decoder</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>enabled</varname>
                <parameter>yes|no</parameter>
              </entry>
              <entry>
                Allows you to disable a decoder plugin without
                recompiling.  By default, all plugins are enabled.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <para>
        More information can be found in the <link
        linkend="decoder_plugins">decoder plugin reference</link>.
      </para>
    </section>

    <section id="config_encoder_plugins">
      <title>Configuring encoder plugins</title>

      <para>
        Encoders are used by some of the output plugins (such as <link
        linkend="shout_output"><varname>shout</varname></link>).  The
        encoder settings are included in the
        <varname>audio_output</varname> section.  More information can
        be found in the <link linkend="encoder_plugins">encoder plugin
        reference</link>.
      </para>
    </section>

    <section id="config_audio_outputs">
      <title>Configuring audio outputs</title>

      <para>
        Audio outputs are devices which actually play the audio chunks
        produced by <application>MPD</application>.  You can configure
        any number of audio output devices, but there must be at least
        one.  If none is configured, <application>MPD</application>
        attempts to auto-detect.  Usually, this works quite well with
        ALSA, OSS and on Mac OS X.
      </para>

      <para>
        To configure an audio output manually, add an
        <varname>audio_output</varname> block to
        <filename>mpd.conf</filename>:
      </para>

      <programlisting>audio_output {
    type "alsa"
    name "my ALSA device"
    device "hw:0"
}
      </programlisting>

      <para>
        The following table lists the <varname>audio_output</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>type</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>name</varname>
              </entry>
              <entry>
                The name of the audio output.  It is visible to the
                client.  Some plugins also use it internally, e.g. as
                a name registered in the PULSE server.
              </entry>
            </row>
            <row id="ao_format">
              <entry>
                <varname>format</varname>
              </entry>
              <entry>
                <para>
                  Always open the audio output with the specified audio
                  format (samplerate:bits:channels), regardless of the
                  format of the input file.  This is optional for most
                  plugins.
                </para>
                <para>
                  Any of the three attributes may be an asterisk to
                  specify that this attribute should not be enforced,
                  example: <parameter>48000:16:*</parameter>.
                  <parameter>*:*:*</parameter> is equal to not having
                  a <varname>format</varname> specification.
                </para>
                <para>
                  The following values are valid for
                  <varname>bits</varname>: <varname>8</varname>
                  (signed 8 bit integer samples),
                  <varname>16</varname>, <varname>24</varname> (signed
                  24 bit integer samples padded to 32 bit),
                  <varname>32</varname> (signed 32 bit integer
                  samples), <varname>f</varname> (32 bit floating
                  point, -1.0 to 1.0).
                </para>
              </entry>
            </row>
            <row>
              <entry>
                <varname>enabled</varname>
                  <parameter>yes|no</parameter>
              </entry>
              <entry>
                Specifies whether this audio output is enabled when
                <application>MPD</application> is started.  By
                default, all audio outputs are enabled.
              </entry>
            </row>
            <row>
              <entry>
                <varname>tags</varname>
                <parameter>yes|no</parameter>
              </entry>
              <entry>
                If set to <parameter>no</parameter>, then
                <application>MPD</application> will not send tags to
                this output.  This is only useful for output plugins
                that can receive tags, for example the <link
                linkend="httpd_output"><varname>httpd</varname></link>
                output plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>always_on</varname>
                  <parameter>yes|no</parameter>
              </entry>
              <entry>
                If set to <parameter>yes</parameter>, then
                <application>MPD</application> attempts to keep this
                audio output always open.  This may be useful for
                streaming servers, when you don't want to disconnect
                all listeners even when playback is accidentally
                stopped.
              </entry>
            </row>
            <row>
              <entry>
                <varname>mixer_type</varname>
                <parameter>hardware|software|null|none</parameter>
              </entry>
              <entry>
                Specifies which mixer should be used for this audio
                output: the hardware mixer (available for <link
                linkend="alsa_output">ALSA</link>, <link
                linkend="oss_output">OSS</link> and <link
                linkend="pulse_output">PulseAudio</link>), the
                software mixer, the "null" mixer
                (<parameter>null</parameter>; allows setting the
                volume, but with no effect) or no mixer
                (<parameter>none</parameter>).  By default, the
                hardware mixer is used for devices which support it,
                and none for the others.
              </entry>
            </row>
            <row>
              <entry>
                <varname>replay_gain_handler</varname>
                <parameter>software|mixer|none</parameter>
              </entry>
              <entry>
                Specifies how replay gain is applied.  The default is
                <parameter>software</parameter>, which uses an
                internal software volume control.
                <parameter>mixer</parameter> uses the configured
                (hardware) mixer control.  <parameter>none</parameter>
                disables replay gain on this audio output.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>
    </section>

    <section id="config_filters">
      <title>Configuring filters</title>

      <para>
        Filters are plugins which modify an audio stream.
      </para>

      <para>
        To configure a filter, add a <varname>filter</varname> block
        to <filename>mpd.conf</filename>:
      </para>

      <programlisting>filter {
    plugin "volume"
    name "software volume"
}
      </programlisting>

      <para>
        The following table lists the <varname>filter</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>name</varname>
              </entry>
              <entry>
                The name of the filter.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>
    </section>

    <section id="config_playlist_plugins">
      <title>Configuring playlist plugins</title>

      <para>
        Playlist plugins are used to load remote playlists.  This is
        not related to <application>MPD</application>'s playlist
        directory.
      </para>

      <para>
        To configure a playlist plugin, add a
        <varname>playlist_plugin</varname> block to
        <filename>mpd.conf</filename>:
      </para>

      <programlisting>playlist_plugin {
    name "m3u"
    enabled "true"
}
      </programlisting>

      <para>
        The following table lists the
        <varname>playlist_plugin</varname> options valid for all
        plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>name</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>enabled</varname>
                <parameter>yes|no</parameter>
              </entry>
              <entry>
                Allows you to disable a input plugin without
                recompiling.  By default, all plugins are enabled.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <para>
        More information can be found in the <link
        linkend="playlist_plugins">playlist plugin reference</link>.
      </para>
    </section>

    <section id="config_audio_format">
      <title>Audio Format Settings</title>

      <section id="config_global_audio_format">
        <title>Global Audio Format</title>

        <para>
          The setting <varname>audio_output_format</varname> forces
          <application>MPD</application> to use one audio format for
          all outputs.  Doing that is usually not a good idea.  The
          values are the same as in <link
          linkend="ao_format"><varname>format</varname> in the <link
          linkend="config_audio_outputs"><varname>audio_output</varname></link>
          section</link>.
        </para>
      </section>

      <section>
        <title>Resampler</title>

        <para>
          Sometimes, music needs to be resampled before it can be
          played; for example, CDs use a sample rate of 44,100 Hz
          while many cheap audio chips can only handle 48,000 Hz.
          Resampling reduces the quality and consumes a lot of CPU.
          There are different options, some of them optimized for high
          quality and others for low CPU usage, but you can't have
          both at the same time.  Often, the resampler is the
          component that is responsible for most of
          <application>MPD</application>'s CPU usage.  Since
          <application>MPD</application> comes with high quality
          defaults, it may appear that <application>MPD</application>
          consumes more CPU than other software.
        </para>

        <para>
          Check the <link linkend="resampler_plugins">resampler plugin
          reference</link> for a list of resamplers and how to
          configure them.
        </para>
      </section>
    </section>

    <section id="config_other">
      <title>Other Settings</title>

      <section>
        <title>The State File</title>

        <para>
          The <emphasis>state file</emphasis> is a file where
          <application>MPD</application> saves and restores its state
          (play queue, playback position etc.) to keep it persistent
          across restarts and reboots.  It is an optional setting.
        </para>

        <para>
          <application>MPD</application> will attempt to load the
          state file during startup, and will save it when shutting
          down the daemon.  Additionally, the state file is refreshed
          every two minutes (after each state change).
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>state_file</varname>
                  <parameter>PATH</parameter>
                </entry>
                <entry>
                  Specify the state file location.  The parent
                  directory must be writable by the
                  <application>MPD</application> user
                  (<parameter>+wx</parameter>).
                </entry>
              </row>

              <row>
                <entry>
                  <varname>state_file_interval</varname>
                  <parameter>SECONDS</parameter>
                </entry>
                <entry>
                  Auto-save the state file this number of seconds
                  after each state change.  Defaults to
                  <parameter>120</parameter> (2 minutes).
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title>Resource Limitations</title>

        <para>
          These settings are various limitations to prevent
          <application>MPD</application> from using too many
          resources (denial of service).
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>

              <row>
                <entry>
                  <varname>connection_timeout</varname>
                  <parameter>SECONDS</parameter>
                </entry>
                <entry>
                  If a client does not send any new data in this time
                  period, the connection is closed.  Clients waiting
                  in "idle" mode are excluded from this.  Default is
                  <parameter>60</parameter>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>max_connections</varname>
                  <parameter>NUMBER</parameter>
                </entry>
                <entry>
                  This specifies the maximum number of clients that
                  can be connected to <application>MPD</application>
                  at the same time.  Default is
                  <parameter>5</parameter>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>max_playlist_length</varname>
                  <parameter>NUMBER</parameter>
                </entry>
                <entry>
                  The maximum number of songs that can be in the
                  playlist.  Default is <parameter>16384</parameter>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>max_command_list_size</varname>
                  <parameter>KBYTES</parameter>
                </entry>
                <entry>
                  The maximum size a command list.  Default is
                  <parameter>2048</parameter> (2 MiB).
                </entry>
              </row>

              <row>
                <entry>
                  <varname>max_output_buffer_size</varname>
                  <parameter>KBYTES</parameter>
                </entry>
                <entry>
                  The maximum size of the output buffer to a client
                  (maximum response size).  Default is
                  <parameter>8192</parameter> (8 MiB).
                </entry>
              </row>

            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title>Buffer Settings</title>

        <para>
          Do not change these unless you know what you are doing.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>

              <row>
                <entry>
                  <varname>audio_buffer_size</varname>
                  <parameter>KBYTES</parameter>
                </entry>
                <entry>
                  Adjust the size of the internal audio buffer.
                  Default is <parameter>4096</parameter> (4 MiB).
                </entry>
              </row>

              <row>
                <entry>
                  <varname>buffer_before_play</varname>
                  <parameter>PERCENT</parameter>
                </entry>
                <entry>
                  Control the percentage of the buffer which is filled
                  before beginning to play.  Increasing this reduces
                  the chance of audio file skipping, at the cost of
                  increased time prior to audio playback.  Default is
                  <parameter>10%</parameter>.
                </entry>
              </row>

            </tbody>
          </tgroup>
        </informaltable>
      </section>
    </section>
  </chapter>

  <chapter id="advanced_config">
    <title>Advanced configuration</title>

    <section id="satellite">
      <title>Satellite setup</title>

      <para>
        <application>MPD</application> runs well on weak machines such
        as the <ulink url="http://www.raspberrypi.org/">Raspberry
        Pi</ulink>.  However, such hardware tends to not have storage
        big enough to hold a music collection.  Mounting music from a
        file server can be very slow, especially when updating the
        database.
      </para>

      <para>
        One approach for optimization is running
        <application>MPD</application> on the file server, which not
        only exports raw files, but also provides access to a readily
        scanned database.  Example configuration:
      </para>

      <programlisting>music_directory "nfs://fileserver.local/srv/mp3"
#music_directory "smb://fileserver.local/mp3"

database {
    plugin "proxy"
    host "fileserver.local"
}
      </programlisting>

      <para>
        The <link
        linkend="config_music_directory"><varname>music_directory</varname></link>
        setting tells <application>MPD</application> to read files
        from the given NFS server.  It does this by connecting to the
        server from userspace.  This does not actually mount the file
        server into the kernel's virtual file system, and thus
        requires no kernel cooperation and no special privileges.  It
        does not even require a kernel with NFS support, only the
        <link linkend="nfs_storage"><filename>nfs</filename></link>
        storage plugin (using the <filename>libnfs</filename>
        userspace library).  The same can be done with SMB/CIFS using
        the <link
        linkend="smbclient_storage"><filename>smbclient</filename></link>
        storage plugin (using <filename>libsmbclient</filename>).
      </para>

      <para>
        The <link
        linkend="config_database_plugins"><varname>database</varname></link>
        setting tells <application>MPD</application> to pass all
        database queries on to the <application>MPD</application>
        instance running on the file server (using the <link
        linkend="proxy_database"><filename>proxy</filename></link>
        plugin).
      </para>
    </section>

    <section id="realtime">
      <title>Real-Time Scheduling</title>

      <para>
        On Linux, <application>MPD</application> attempts to configure
        <ulink
        url="https://en.wikipedia.org/wiki/Real-time_computing">real-time
        scheduling</ulink> for some threads that benefit from it.
      </para>

      <para>
        This is only possible you allow <application>MPD</application>
        to do it.  This privilege is controlled by
        <varname>RLIMIT_RTPRIO</varname>
        <varname>RLIMIT_RTTIME</varname>.  You can configure this
        privilege with <command>ulimit</command> before launching
        <application>MPD</application>:
      </para>

      <programlisting>ulimit -HS -r 50; mpd</programlisting>

      <para>
        Or you can use the <command>prlimit</command> program from the
        <application>util-linux</application> package:
      </para>

      <programlisting>prlimit --rtprio=50 --rttime=unlimited mpd</programlisting>

      <para>
        The <application>systemd</application> service file shipped
        with <application>MPD</application> comes with this setting.
      </para>

      <para>
        This works only if the Linux kernel was compiled with
        <varname>CONFIG_RT_GROUP_SCHED</varname> disabled.  Use the
        following command to check this option for your current
        kernel:
      </para>

      <programlisting>zgrep ^CONFIG_RT_GROUP_SCHED /proc/config.gz</programlisting>

      <note>
        <para>
          There is a rumor that real-time scheduling improves audio
          quality.  That is not true.  All it does is reduce the
          probability of skipping (audio buffer xruns) when the
          computer is under heavy load.
        </para>
      </note>
    </section>
  </chapter>

  <chapter id="use">
    <title>Using <application>MPD</application></title>

    <section id="client">
      <title>The client</title>

      <para>
        After you have installed, configured and started
        <application>MPD</application>, you choose a client to control
        the playback.
      </para>

      <para>
        The most basic client is <filename>mpc</filename>, which
        provides a command line interface.  It is useful in shell
        scripts.  Many people bind specific <filename>mpc</filename>
        commands to hotkeys.
      </para>

      <para>
        The <ulink
        url="http://www.musicpd.org/clients/"><application>MPD</application>
        Wiki</ulink> contains an extensive list of clients to choose
        from.
      </para>
    </section>

    <section id="music_directory_and_database">
      <title>The music directory and the database</title>

      <para>
        The "music directory" is where you store your music files.
        <application>MPD</application> stores all relevant meta
        information about all songs in its "database".  Whenever you
        add, modify or remove songs in the music directory, you have
        to update the database, for example with
        <filename>mpc</filename>:
      </para>

      <programlisting>mpc update</programlisting>

      <para>
        Depending on the size of your music collection and the speed
        of the storage, this can take a while.
      </para>

      <para>
        To exclude a file from the update, create a file called
        <filename>.mpdignore</filename> in its parent directory.  Each
        line of that file may contain a list of shell wildcards.
        Matching files in the current directory and all subdirectories
        are excluded.
      </para>
    </section>

    <section id="queue">
      <title>The queue</title>

      <para>
        The queue (sometimes called "current playlist") is a list of
        songs to be played by <application>MPD</application>.  To play
        a song, add it to the queue and start playback.  Most clients
        offer an interface to edit the queue.
      </para>
    </section>
  </chapter>

  <chapter id="advanced_usage">
    <title>Advanced usage</title>

    <section id="bit_perfect">
      <title>Bit-perfect playback</title>

      <para>
        "Bit-perfect playback" is a phrase used by audiophiles to
        describe a setup that plays back digital music as-is, without
        applying any modifications such as resampling, format
        conversion or software volume.  Naturally, this implies a
        lossless codec.
      </para>

      <para>
        By default, <application>MPD</application> attempts to do
        bit-perfect playback, unless you tell it not to.  Precondition
        is a sound chip that supports the audio format of your music
        files.  If the audio format is not supported,
        <application>MPD</application> attempts to fall back to the
        nearest supported audio format, trying to lose as little
        quality as possible.
      </para>

      <para>
        To verify if <application>MPD</application> converts the audio
        format, enable verbose logging, and watch for these lines:
      </para>

      <programlisting>decoder: audio_format=44100:24:2, seekable=true
output: opened plugin=alsa name="An ALSA output" audio_format=44100:16:2
output: converting from 44100:24:2</programlisting>

      <para>
        This example shows that a 24 bit file is being played, but the
        sond chip cannot play 24 bit.  It falls back to 16 bit,
        discarding 8 bit.
      </para>

      <para>
        However, this does not yet prove bit-perfect playback;
        <application>ALSA</application> may be fooling
        <application>MPD</application> that the audio format is
        supported.  To verify the format really being sent to the
        physical sound chip, try:
      </para>

      <programlisting>cat /proc/asound/card*/pcm*p/sub*/hw_params
access: RW_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2
rate: 44100 (44100/1)
period_size: 4096
buffer_size: 16384</programlisting>

      <para>
        Obey the "format" row, which indicates that the current
        playback format is 16 bit (signed 16 bit integer, little
        endian).
      </para>

      <para>
        Check list for bit-perfect playback:
      </para>

      <itemizedlist>
        <listitem>
          <para>
            Use the <link linkend="alsa_output">ALSA</link> output
            plugin.
          </para>
        </listitem>

        <listitem>
          <para>
            Disable sound processing inside
            <application>ALSA</application> by configuring a
            "hardware" device (<parameter>hw:0,0</parameter> or
            similar).
          </para>
        </listitem>

        <listitem>
          <para>
            Don't use software volume (setting <link
            linkend="config_audio_outputs"><varname>mixer_type</varname></link>).
          </para>
        </listitem>

        <listitem>
          <para>
            Don't force <application>MPD</application> to use a
            specific audio format (settings <link
            linkend="config_audio_outputs"><varname>format</varname></link>,
            <link
            linkend="config_global_audio_format"><varname>audio_output_format</varname></link>).
          </para>
        </listitem>

        <listitem>
          <para>
            Verify that you are really doing bit-perfect playback
            using <application>MPD</application>'s verbose log and
            <filename>/proc/asound/card*/pcm*p/sub*/hw_params</filename>.
            Some DACs can also indicate the audio format.
          </para>
        </listitem>
      </itemizedlist>
    </section>

    <section id="dsd">
      <title>Direct Stream Digital (DSD)</title>

      <para>
        DSD (<ulink
        url="https://en.wikipedia.org/wiki/Direct_Stream_Digital">Direct
        Stream Digital</ulink>) is a digital format that stores audio
        as a sequence of single-bit values at a very high sampling
        rate.
      </para>

      <para>
        <application>MPD</application> understands the file formats
        <link linkend="dsdiff_decoder"><filename>dff</filename></link>
        and <link
        linkend="dsf_decoder"><filename>dsf</filename></link>.  There
        are three ways to play back DSD:
      </para>

      <itemizedlist>
        <listitem>
          <para>
            Native DSD playback.  Requires
            <application>ALSA</application> 1.0.27.1 or later, a sound
            driver/chip that supports DSD and of course a DAC that
            supports DSD.
          </para>
        </listitem>

        <listitem>
          <para>
            DoP (DSD over PCM) playback.  This wraps DSD inside fake
            24 bit PCM according to the <ulink
            url="http://dsd-guide.com/dop-open-standard">DoP
            standard</ulink>.  Requires a DAC that supports DSD.  No
            support from ALSA and the sound chip required (except for
            <link linkend="bit_perfect">bit-perfect</link> 24 bit PCM
            support).
          </para>
        </listitem>

        <listitem>
          <para>
            Convert DSD to PCM on-the-fly.
          </para>
        </listitem>
      </itemizedlist>

      <para>
        Native DSD playback is used automatically if available.  DoP
        is only used if enabled explicitly using the <link
        linkend="alsa_output"><varname>dop</varname></link> option,
        because there is no way for <application>MPD</application> to
        find out whether the DAC supports it.  DSD to PCM conversion
        is the fallback if DSD cannot be used directly.
      </para>
    </section>
  </chapter>

  <chapter id="plugin_reference">
    <title>Plugin reference</title>

    <section id="database_plugins">
      <title>Database plugins</title>

      <section>
        <title><varname>simple</varname></title>

        <para>
          The default plugin.  Stores a copy of the database in
          memory.  A file is used for permanent storage.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>path</varname>
                </entry>
                <entry>
                  The path of the database file.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>cache_directory</varname>
                </entry>
                <entry>
                  The path of the cache directory for additional
                  storages mounted at runtime.  This setting is
                  necessary for the <command>mount</command> protocol
                  command.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>compress</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Compress the database file using
                  <filename>gzip</filename>?  Enabled by default (if
                  built with <filename>zlib</filename>).
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="proxy_database">
        <title><varname>proxy</varname></title>

        <para>
          Provides access to the database of another
          <application>MPD</application> instance using
          <filename>libmpdclient</filename>.  This is useful when you
          run mount the music directory via NFS/SMB, and the file
          server already runs a <application>MPD</application>
          instance.  Only the file server needs to update the
          database.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>host</varname>
                </entry>
                <entry>
                  The host name of the "master"
                  <application>MPD</application> instance.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>port</varname>
                </entry>
                <entry>
                  The port number of the "master"
                  <application>MPD</application> instance.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>keepalive</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Send TCP keepalive packets to the "master"
                  <application>MPD</application> instance?  This option can
                  help avoid certain firewalls dropping inactive
                  connections, at the expensive of a very small amount of
                  additional network traffic.  Disabled by default.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>upnp</varname></title>

        <para>
          Provides access to UPnP media servers.
        </para>
      </section>
    </section>

    <section id="storage_plugins">
      <title>Storage plugins</title>

      <section>
        <title><varname>local</varname></title>

        <para>
          The default plugin which gives
          <application>MPD</application> access to local files.  It is
          used when <varname>music_directory</varname> refers to a
          local directory.
        </para>
      </section>

      <section id="smbclient_storage">
        <title><varname>smbclient</varname></title>

        <para>
          Load music files from a SMB/CIFS server.  It used used when
          <varname>music_directory</varname> contains a
          <parameter>smb://</parameter> URI, for example
          "<parameter>smb://myfileserver/Music</parameter>".
        </para>
      </section>

      <section id="nfs_storage">
        <title><varname>nfs</varname></title>

        <para>
          Load music files from a NFS server.  It used used when
          <varname>music_directory</varname> contains a
          <parameter>nfs://</parameter> URI according to <ulink
          url="http://tools.ietf.org/html/rfc2224">RFC2224</ulink>,
          for example "<parameter>nfs://servername/path</parameter>".
        </para>

        <para>
          This plugin uses <ulink
          url="https://github.com/sahlberg/libnfs"><filename>libnfs</filename></ulink>,
          which supports only NFS version 3.  Since
          <application>MPD</application> is not allowed to bind to
          "privileged ports", the NFS server needs to enable the
          "insecure" setting; example
          <filename>/etc/exports</filename>:
        </para>

        <programlisting>/srv/mp3 192.168.1.55(ro,insecure)</programlisting>

        <para>
          Don't fear: "insecure" does not mean that your NFS server is
          insecure.  A few decades ago, people thought the concept of
          "privileged ports" would make network services "secure",
          which was a fallacy.  The absence of this obsolete
          "security" measure means little.
        </para>
      </section>
    </section>

    <section id="neighbor_plugins">
      <title>Neighbor plugins</title>

      <section id="smbclient_neighbor">
        <title><varname>smbclient</varname></title>

        <para>
          Provides a list of SMB/CIFS servers on the local network.
        </para>
      </section>

      <section id="upnp_neighbor">
        <title><varname>upnp</varname></title>

        <para>
          Provides a list of UPnP servers on the local network.
        </para>
      </section>
    </section>

    <section id="input_plugins">
      <title>Input plugins</title>

      <section>
        <title><varname>alsa</varname></title>

        <para>
          Allows <application>MPD</application> on Linux to play audio
          directly from a soundcard using the scheme
          <filename>alsa://</filename>. Audio is formatted as 44.1 kHz
          16-bit stereo (CD format). Examples:
        </para>

        <para>
          <filename>mpc add alsa://</filename> plays audio from device hw:0,0
        </para>
        <para>
          <filename>mpc add alsa://hw:1,0</filename> plays audio from device
          hw:1,0
        </para>
      </section>

      <section>
        <title><varname>cdio_paranoia</varname></title>

        <para>
          Plays audio CDs.  The URI has the form:
          "<filename>cdda://[DEVICE][/TRACK]</filename>".  The
          simplest form <filename>cdda://</filename> plays the whole
          disc in the default drive.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>default_byte_order</varname>
                <parameter>little_endian|big_endian</parameter>
                </entry>
                <entry>
                  If the CD drive does not specify a byte order,
                  <application>MPD</application> assumes it is the
                  CPU's native byte order.  This setting allows
                  overriding this.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>curl</varname></title>

        <para>
          Opens remote files or streams over HTTP.
        </para>

        <para>
          Note that unless overridden by the below settings (e.g. by
          setting them to a blank value), general curl configuration
          from environment variables such as
          <varname>http_proxy</varname> or specified in
          <filename>~/.curlrc</filename> will be in effect.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>proxy</varname>
                </entry>
                <entry>
                  Sets the address of the HTTP proxy server.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>proxy_user</varname>,
                  <varname>proxy_password</varname>
                </entry>
                <entry>
                  Configures proxy authentication.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>verify_peer</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Verify the peer's SSL certificate?  <ulink
                  url="http://curl.haxx.se/libcurl/c/CURLOPT_SSL_VERIFYPEER.html">More
                  information</ulink>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>verify_host</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Verify the certificate's name against host?  <ulink
                  url="http://curl.haxx.se/libcurl/c/CURLOPT_SSL_VERIFYHOST.html">More
                  information</ulink>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>file</varname></title>

        <para>
          Opens local files.
        </para>
      </section>

      <section>
        <title><varname>mms</varname></title>

        <para>
          Plays streams with the MMS protocol.
        </para>
      </section>

      <section>
        <title><varname>nfs</varname></title>

        <para>
          Allows <application>MPD</application> to access files on
          NFSv3 servers without actually mounting them (i.e. in
          userspace, without help from the kernel's VFS layer).  All
          URIs with the <filename>nfs://</filename> scheme are used
          according to <ulink
          url="http://tools.ietf.org/html/rfc2224">RFC2224</ulink>.
          Example:
        </para>

        <para>
          <filename>mpc add nfs://servername/path/filename.ogg</filename>
        </para>

        <para>
          Note that this usually requires enabling the "insecure" flag
          in the server's <filename>/etc/exports</filename> file,
          because <application>MPD</application> cannot bind to
          so-called "privileged" ports.  Don't fear: this will not
          make your file server insecure; the flag was named in a time
          long ago when privileged ports were thought to be meaningful
          for security.  By today's standards, NFSv3 is not secure at
          all, and if you believe it is, you're already doomed.
        </para>
      </section>

      <section>
        <title><varname>smbclient</varname></title>

        <para>
          Allows <application>MPD</application> to access files on
          SMB/CIFS servers (e.g. Samba or Microsoft Windows).  All
          URIs with the <filename>smb://</filename> scheme are used.
          Example:
        </para>

        <para>
          <filename>mpc add smb://servername/sharename/filename.ogg</filename>
        </para>
      </section>
    </section>

    <section id="decoder_plugins">
      <title>Decoder plugins</title>

      <section id="dsdiff_decoder">
        <title><varname>dsdiff</varname></title>

        <para>
          Decodes DFF files containing DSDIFF data (e.g. SACD rips).
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>lsbitfirst</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Decode the least significant bit first.  Default is
                  <parameter>no</parameter>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="dsf_decoder">
        <title><varname>dsf</varname></title>

        <para>
          Decodes DSF files containing DSDIFF data (e.g. SACD rips).
        </para>

      </section>

      <section>
        <title><varname>fluidsynth</varname></title>

        <para>
          MIDI decoder based on <ulink
          url="http://www.fluidsynth.org/"><application>FluidSynth</application></ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>sample_rate</varname>
                </entry>
                <entry>
                  The sample rate that shall be synthesized by the
                  plugin.  Defaults to 48000.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>soundfont</varname>
                </entry>
                <entry>
                  The absolute path of the soundfont file.  Defaults
                  to
                  <filename>/usr/share/sounds/sf2/FluidR3_GM.sf2</filename>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>gme</varname></title>

        <para>
          Video game music file emulator based on <ulink
          url="https://bitbucket.org/mpyne/game-music-emu/wiki/Home"><application>game-music-emu</application></ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>accuracy</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Enable more accurate sound emulation.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>mikmod</varname></title>

        <para>
          Module player based on <ulink
          url="http://mikmod.sourceforge.net/"><application>MikMod</application></ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>loop</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Allow backward loops in modules.  Default is
		  <parameter>no</parameter>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>sample_rate</varname>
                </entry>
                <entry>
                  Sets the sample rate generated by
                  <filename>libmikmod</filename>.  Default is 44100.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>modplug</varname></title>

        <para>
          Module player based on <application>MODPlug</application>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>loop_count</varname>
                </entry>
                <entry>
                  Number of times to loop the module if it uses backward loops.
                  Default is <parameter>0</parameter> which prevents looping.
                  <parameter>-1</parameter> loops forever.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="sidplay_decoder">
        <title><varname>sidplay</varname></title>

        <para>
          C64 SID decoder based on
          <application>libsidplay</application>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>songlength_database</varname>
                  <parameter>PATH</parameter>
                </entry>
                <entry>
                  Location of your songlengths file, as distributed
                  with the HVSC.  The <varname>sidplay</varname>
                  plugin checks this for matching MD5 fingerprints.
                  See <ulink
                  url="http://www.c64.org/HVSC/DOCUMENTS/Songlengths.faq">http://www.c64.org/HVSC/DOCUMENTS/Songlengths.faq</ulink>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>default_songlength</varname>
                  <parameter>SECONDS</parameter>
                </entry>
                <entry>
                  This is the default playing time in seconds for
                  songs not in the songlength database, or in case
                  you're not using a database.  A value of 0 means
                  play indefinitely.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>filter</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Turns the SID filter emulation on or off.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>wildmidi</varname></title>

        <para>
          MIDI decoder based on <ulink
          url="http://www.mindwerks.net/projects/wildmidi/"><application>libwildmidi</application></ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>config_file</varname>
                </entry>
                <entry>
                  The absolute path of the timidity config file.  Defaults
                  to
                  <filename>/etc/timidity/timidity.cfg</filename>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>
    </section>

    <section id="encoder_plugins">
      <title>Encoder plugins</title>

      <section>
        <title><varname>flac</varname></title>

        <para>
          Encodes into <ulink
          url="https://xiph.org/flac/">FLAC</ulink> (lossless).
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>compression</varname>
                </entry>
                <entry>
                  Sets the <filename>libFLAC</filename> compression
                  level.  The levels range from 0 (fastest, least
                  compression) to 8 (slowest, most compression).
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>lame</varname></title>

        <para>
          Encodes into MP3 using the <ulink
          url="http://lame.sourceforge.net/"><application>LAME</application></ulink>
          library.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>quality</varname>
                </entry>
                <entry>
                  Sets the quality for VBR.  0 is the highest quality,
                  9 is the lowest quality.  Cannot be used with
                  <varname>bitrate</varname>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>bitrate</varname>
                </entry>
                <entry>
                  Sets the bit rate in kilobit per second.  Cannot be
                  used with <varname>quality</varname>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>null</varname></title>

        <para>
          Does not encode anything, passes the input PCM data as-is.
        </para>
      </section>

      <section>
        <title><varname>shine</varname></title>

        <para>
          Encodes into MP3 using the <ulink
          url="https://github.com/savonet/shine"><application>Shine</application></ulink>
          library.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>bitrate</varname>
                </entry>
                <entry>
                  Sets the bit rate in kilobit per second.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>twolame</varname></title>

        <para>
          Encodes into MP2 using the <ulink
          url="http://www.twolame.org/"><application>TwoLAME</application></ulink>
          library.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>quality</varname>
                </entry>
                <entry>
                  Sets the quality for VBR.  0 is the highest quality,
                  9 is the lowest quality.  Cannot be used with
                  <varname>bitrate</varname>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>bitrate</varname>
                </entry>
                <entry>
                  Sets the bit rate in kilobit per second.  Cannot be
                  used with <varname>quality</varname>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="vorbis_encoder">
        <title><varname>vorbis</varname></title>

        <para>
          Encodes into <ulink url="http://www.vorbis.com/">Ogg
          Vorbis</ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>quality</varname>
                </entry>
                <entry>
                  Sets the quality for VBR.  -1 is the lowest quality,
                  10 is the highest quality.  Cannot be used with
                  <varname>bitrate</varname>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>bitrate</varname>
                </entry>
                <entry>
                  Sets the bit rate in kilobit per second.  Cannot be
                  used with <varname>quality</varname>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>wave</varname></title>

        <para>
          Encodes into WAV (lossless).
        </para>
      </section>
    </section>

    <section id="resampler_plugins">
      <title>Resampler plugins</title>

      <para>
        The resampler can be configured in a block named
        <varname>resampler</varname>, for example:
      </para>

      <programlisting>resampler {
  plugin "soxr"
  quality "very high"
}</programlisting>

      <para>
        The following table lists the <varname>resampler</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <section id="internal_resampler">
        <title><varname>internal</varname></title>

        <para>
          A resampler built into <application>MPD</application>.  Its
          quality is very poor, but its CPU usage is low.  This is the
          fallback if <application>MPD</application> was compiled
          without an external resampler.
        </para>
      </section>

      <section id="libsamplerate_resampler">
        <title><varname>libsamplerate</varname></title>

        <para>
          A resampler using <ulink
          url="http://www.mega-nerd.com/SRC/"><application>libsamplerate</application></ulink>
          a.k.a. Secret Rabbit Code (SRC).
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>
                  Name
                </entry>
                <entry>
                  Description
                </entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>type</varname>
                </entry>
                <entry>
                  The interpolator type.  See below for a list of
                  known types.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>

        <para>
          The following converter types are provided by
          <application>libsamplerate</application>:
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>
                  Type
                </entry>
                <entry>
                  Description
                </entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  "<parameter>Best Sinc Interpolator</parameter>" or
                  "<parameter>0</parameter>"
                </entry>
                <entry>
                  Band limited sinc interpolation, best quality, 97dB
                  SNR, 96% BW.
                </entry>
              </row>

              <row>
                <entry>
                  "<parameter>Medium Sinc Interpolator</parameter>" or
                  "<parameter>1</parameter>"
                </entry>
                <entry>
                  Band limited sinc interpolation, medium quality,
                  97dB SNR, 90% BW.
                </entry>
              </row>

              <row>
                <entry>
                  "<parameter>Fastest Sinc Interpolator</parameter>" or
                  "<parameter>2</parameter>"
                </entry>
                <entry>
                  Band limited sinc interpolation, fastest, 97dB SNR,
                  80% BW.
                </entry>
              </row>

              <row>
                <entry>
                  "<parameter>ZOH Sinc Interpolator</parameter>" or
                  "<parameter>3</parameter>"
                </entry>
                <entry>
                  Zero order hold interpolator, very fast, very poor
                  quality with audible distortions.
                </entry>
              </row>

              <row>
                <entry>
                  "<parameter>Linear Interpolator</parameter>" or
                  "<parameter>4</parameter>"
                </entry>
                <entry>
                  Linear interpolator, very fast, poor quality.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="soxr_resampler">
        <title><varname>soxr</varname></title>

        <para>
          A resampler using <ulink
          url="http://sourceforge.net/projects/soxr/"><application>libsoxr</application></ulink>,
          the SoX Resampler library
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>
                  Name
                </entry>
                <entry>
                  Description
                </entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>quality</varname>
                </entry>
                <entry>
                  The <application>libsoxr</application> quality
                  setting.  Valid values are:

                  <itemizedlist>
                    <listitem>
                      <para>
                        "<parameter>very high</parameter>"
                      </para>
                    </listitem>

                    <listitem>
                      <para>
                        "<parameter>high</parameter>" (the default)
                      </para>
                    </listitem>

                    <listitem>
                      <para>
                        "<parameter>medium</parameter>"
                      </para>
                    </listitem>

                    <listitem>
                      <para>
                        "<parameter>low</parameter>"
                      </para>
                    </listitem>

                    <listitem>
                      <para>
                        "<parameter>quick</parameter>"
                      </para>
                    </listitem>
                  </itemizedlist>
                </entry>
              </row>

              <row>
                <entry>
                  <varname>threads</varname>
                </entry>
                <entry>
                  The number of <application>libsoxr</application>
                  threads.  "0" means "automatic".  The default is "1"
                  which disables multi-threading.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>
    </section>

    <section id="output_plugins">
      <title>Output plugins</title>

      <section id="alsa_output">
        <title><varname>alsa</varname></title>

        <para>
          The <ulink
          url="http://www.alsa-project.org/"><application>Advanced
          Linux Sound Architecture</application>
          (<application>ALSA</application>)</ulink> plugin uses
          <filename>libasound</filename>.  It is recommended if you
          are using Linux.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>device</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Sets the device which should be used.  This can be
                  any valid ALSA device name.  The default value is
                  "default", which makes
                  <filename>libasound</filename> choose a device.  It
                  is recommended to use a "hw" or "plughw" device,
                  because otherwise, <filename>libasound</filename>
                  automatically enables "dmix", which has major
                  disadvantages (fixed sample rate, poor resampler,
                  ...).
                </entry>
              </row>
              <row>
                <entry>
                  <varname>use_mmap</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>yes</parameter>, then
                  <filename>libasound</filename> will try to use
                  memory mapped I/O.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>buffer_time</varname>
                  <parameter>US</parameter>
                </entry>
                <entry>
                  Sets the device's buffer time in microseconds.
                  Don't change unless you know what you're doing.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>period_time</varname>
                  <parameter>US</parameter>
                </entry>
                <entry>
                  Sets the device's period time in microseconds.
                  Don't change unless you really know what you're
                  doing.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>auto_resample</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>no</parameter>, then
                  <filename>libasound</filename> will not attempt to
                  resample, handing the responsibility over to
                  <application>MPD</application>.  It is recommended
                  to let <application>MPD</application> resample (with
                  <application>libsamplerate</application>), because
                  ALSA is quite poor at doing so.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>auto_channels</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>no</parameter>, then
                  <filename>libasound</filename> will not attempt to
                  convert between different channel numbers.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>auto_format</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>no</parameter>, then
                  <filename>libasound</filename> will not attempt to
                  convert between different sample formats (16 bit, 24
                  bit, floating point, ...).
                </entry>
              </row>
              <row>
                <entry>
                  <varname>dop</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>yes</parameter>, then DSD over
                  PCM according to the <ulink
                  url="http://dsd-guide.com/dop-open-standard">DoP
                  standard</ulink> is enabled.  This wraps DSD
                  samples in fake 24 bit PCM, and is understood by
                  some DSD capable products, but may be harmful to
                  other hardware.  Therefore, the default is
                  <parameter>no</parameter> and you can enable the
                  option at your own risk.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>

        <para>
          The according hardware mixer plugin understands the
          following settings:
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>mixer_device</varname>
                  <parameter>DEVICE</parameter>
                </entry>
                <entry>
                  <para>
                    Sets the ALSA mixer device name, defaulting to
                    <parameter>default</parameter> which lets ALSA
                    pick a value.
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <varname>mixer_control</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  <para>
                    Choose a mixer control, defaulting to
                    <parameter>PCM</parameter>.  Type <command>amixer
                    scontrols</command> to get a list of available
                    mixer controls.
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <varname>mixer_index</varname>
                  <parameter>NUMBER</parameter>
                </entry>
                <entry>
                  Choose a mixer control index.  This is necessary if
                  there is more than one control with the same name.
                  Defaults to <parameter>0</parameter> (the first
                  one).
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>ao</varname></title>

        <para>
          The <varname>ao</varname> plugin uses the portable <ulink
          url="https://www.xiph.org/ao/"><filename>libao</filename></ulink>
          library.  Use only if there is no native plugin for your
          operating system.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>driver</varname>
                  <parameter>D</parameter>
                </entry>
                <entry>
                  The <filename>libao</filename> driver to use for
                  audio output.  Possible values depend on what libao
                  drivers are available.  See <ulink
                  url="http://www.xiph.org/ao/doc/drivers.html">http://www.xiph.org/ao/doc/drivers.html</ulink>
                  for information on some commonly used drivers.
                  Typical values for Linux include "oss" and "alsa09".
                  The default is "default", which causes libao to
                  select an appropriate plugin.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>options</varname>
                  <parameter>O</parameter>
                </entry>
                <entry>
                  Options to pass to the selected
                  <filename>libao</filename> driver.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>write_size</varname>
                  <parameter>O</parameter>
                </entry>
                <entry>
                  This specifies how many bytes to write to the audio
                  device at once.  This parameter is to work around a
                  bug in older versions of libao on sound cards with
                  very small buffers.  The default is 1024.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>fifo</varname></title>

        <para>
          The <varname>fifo</varname> plugin writes raw PCM data to a
          FIFO (First In, First Out) file.  The data can be read by
          another program.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>path</varname>
                  <parameter>P</parameter>
                </entry>
                <entry>
                  This specifies the path of the FIFO to write to.
                  Must be an absolute path.  If the path does not
                  exist, it will be created when
                  <application>MPD</application> is started, and
                  removed when <application>MPD</application> is
                  stopped.  The FIFO will be created with the same
                  user and group as <application>MPD</application> is
                  running as.  Default permissions can be modified by
                  using the builtin shell command
                  <filename>umask</filename>.  If a FIFO already
                  exists at the specified path it will be reused, and
                  will not be removed when
                  <application>MPD</application> is stopped.  You can
                  use the "mkfifo" command to create this, and then
                  you may modify the permissions to your liking.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>jack</varname></title>

        <para>
          The <varname>jack</varname> plugin connects to a <ulink
          url="http://jackaudio.org/"><application>JACK</application></ulink>
          server.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>client_name</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  The name of the <application>JACK</application>
                  client.  Defaults to "Music Player Daemon".
                </entry>
              </row>
              <row>
                <entry>
                  <varname>server_name</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Optional name of the <application>JACK</application>
                  server.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>autostart</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>yes</parameter>, then
                  <filename>libjack</filename> will automatically
                  launch the <application>JACK</application> daemon.
                  Disabled by default.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>source_ports</varname>
                  <parameter>A,B</parameter>
                </entry>
                <entry>
                  The names of the <application>JACK</application>
                  source ports to be created.  By default, the ports
                  "left" and "right" are created.  To use more ports,
                  you have to tweak this option.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>destination_ports</varname>
                  <parameter>A,B</parameter>
                </entry>
                <entry>
                  The names of the <application>JACK</application>
                  destination ports to connect to.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>ringbuffer_size</varname>
                  <parameter>NBYTES</parameter>
                </entry>
                <entry>
                  Sets the size of the ring buffer for each channel.
                  Do not configure this value unless you know what
                  you're doing.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="httpd_output">
        <title><varname>httpd</varname></title>

        <para>
          The <varname>httpd</varname> plugin creates a HTTP server,
          similar to <ulink
          url="http://www.shoutcast.com/"><application>ShoutCast</application></ulink>
          / <ulink
          url="http://icecast.org/"><application>IceCast</application></ulink>.
          HTTP streaming clients like
          <application>mplayer</application> can connect to it.
        </para>

        <para>
          It is highly recommended to configure a fixed
          <varname>format</varname>, because a stream cannot switch
          its audio format on-the-fly when the song changes.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>port</varname>
                  <parameter>P</parameter>
                </entry>
                <entry>
                  Binds the HTTP server to the specified port.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>bind_to_address</varname>
                  <parameter>ADDR</parameter>
                </entry>
                <entry>
                  Binds the HTTP server to the specified address (IPv4 or
                  IPv6). Multiple addresses in parallel are not supported.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>encoder</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Chooses an encoder plugin.  A list of encoder
                  plugins can be found in the <link
                  linkend="encoder_plugins">encoder plugin
                  reference</link>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>max_clients</varname>
                  <parameter>MC</parameter>
                </entry>
                <entry>
                  Sets a limit, number of concurrent clients. When set
                  to 0 no limit will apply.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>null</varname></title>

        <para>
          The <varname>null</varname> plugin does nothing.  It
          discards everything sent to it.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>sync</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>no</parameter>, then the timer
                  is disabled - the device will accept PCM chunks at
                  arbitrary rate (useful for benchmarking).  The
                  default behaviour is to play in real time.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="oss_output">
        <title><varname>oss</varname></title>

        <para>
          The "Open Sound System" plugin is supported on most Unix
          platforms.
        </para>

        <para>
          On Linux, <application>OSS</application> has been superseded
          by <application>ALSA</application>.  Use the <link
          linkend="alsa_output"><application>ALSA</application> output
          plugin</link> instead of this one on Linux.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>device</varname>
                  <parameter>PATH</parameter>
                </entry>
                <entry>
                  Sets the path of the PCM device.  If not specified,
                  then <application>MPD</application> will attempt to
                  open <filename>/dev/sound/dsp</filename> and
                  <filename>/dev/dsp</filename>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>

        <para>
          The according hardware mixer plugin understands the
          following settings:
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>mixer_device</varname>
                  <parameter>DEVICE</parameter>
                </entry>
                <entry>
                  <para>
                    Sets the OSS mixer device path, defaulting to
                    <filename>/dev/mixer</filename>.
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <varname>mixer_control</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  <para>
                    Choose a mixer control, defaulting to
                    <parameter>PCM</parameter>.
                  </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>openal</varname></title>

        <para>
          The "OpenAL" plugin uses <ulink
          url="http://kcat.strangesoft.net/openal.html"><filename>libopenal</filename></ulink>.
          It is supported on many platforms.  Use only if there is no
          native plugin for your operating system.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>device</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Sets the device which should be used.  This can be
                  any valid OpenAL device name. If not specified, then
                  <filename>libopenal</filename> will choose a default device.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>osx</varname></title>

        <para>
          The "Mac OS X" plugin uses Apple's CoreAudio API.
        </para>
      </section>

      <section>
        <title><varname>pipe</varname></title>

        <para>
          The <varname>pipe</varname> plugin starts a program and
          writes raw PCM data into its standard input.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>command</varname>
                  <parameter>CMD</parameter>
                </entry>
                <entry>
                  This command is invoked with the shell.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="pulse_output">
        <title><varname>pulse</varname></title>

        <para>
          The <varname>pulse</varname> plugin connects to a <ulink
          url="http://www.freedesktop.org/wiki/Software/PulseAudio/"><application>PulseAudio</application></ulink>
          server.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>server</varname>
                  <parameter>HOSTNAME</parameter>
                </entry>
                <entry>
                  Sets the host name of the
                  <application>PulseAudio</application> server.  By
                  default, <application>MPD</application> connects to
                  the local <application>PulseAudio</application>
                  server.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>sink</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Specifies the name of the
                  <application>PulseAudio</application> sink
                  <application>MPD</application> should play on.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>roar</varname></title>

        <para>
          The <varname>roar</varname> plugin connects to a <ulink
          url="http://roaraudio.keep-cool.org/">RoarAudio</ulink>
          server.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>server</varname>
                  <parameter>HOSTNAME</parameter>
                </entry>
                <entry>
                  The host name of the RoarAudio server.  If not
                  specified, then <application>MPD</application> will
                  connect to the default locations.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>role</varname>
                  <parameter>ROLE</parameter>
                </entry>
                <entry>
                  The "role" that <application>MPD</application>
                  registers itself as in the RoarAudio server.  The
                  default is "music".
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>recorder</varname></title>

        <para>
          The <varname>recorder</varname> plugin writes the audio
          played by <application>MPD</application> to a file.  This
          may be useful for recording radio streams.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>path</varname>
                  <parameter>P</parameter>
                </entry>
                <entry>
                  Write to this file.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>format_path</varname>
                  <parameter>P</parameter>
                </entry>
                <entry>
                  <para>
                    An alternative to <varname>path</varname> which
                    provides a format string referring to tag values.

                    The special tag <varname>iso8601</varname> emits
                    the current date and time in <ulink
                    url="https://en.wikipedia.org/wiki/ISO_8601">ISO8601</ulink>
                    format (UTC).
                    Every time a new song starts or a new tag gets
                    received from a radio station, a new file is
                    opened.  If the format does not render a file
                    name, nothing is recorded.
                  </para>

                  <para>
                    A tag name enclosed in percent signs ('%') is
                    replaced with the tag value.  Example:
                    <parameter>~/.mpd/recorder/%artist% -
                    %title%.ogg</parameter>
                  </para>

                  <para>
                    Square brackets can be used to group a substring.
                    If none of the tags referred in the group can be
                    found, the whole group is omitted.  Example:
                    <parameter>[~/.mpd/recorder/[%artist% -
                    ]%title%.ogg]</parameter> (this omits the dash
                    when no artist tag exists; if title also doesn't
                    exist, no file is written)
                  </para>

                  <para>
                    The operators "|" (logical "or") and "&amp;"
                    (logical "and") can be used to select portions of
                    the format string depending on the existing tag
                    values.  Example:
                    <parameter>~/.mpd/recorder/[%title|%name%].ogg</parameter>
                    (use the "name" tag if no title exists)
                  </para>
                </entry>
              </row>

              <row>
                <entry>
                  <varname>encoder</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Chooses an encoder plugin.  A list of encoder
                  plugins can be found in the <link
                  linkend="encoder_plugins">encoder plugin
                  reference</link>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="shout_output">
        <title><varname>shout</varname></title>

        <para>
          The <varname>shout</varname> plugin connects to a <ulink
          url="http://www.shoutcast.com/"><application>ShoutCast</application></ulink>
          or <ulink
          url="http://icecast.org/"><application>IceCast</application></ulink>
          server.  It forwards tags to this server.
        </para>

        <para>
          You must set a <varname>format</varname>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>host</varname>
                  <parameter>HOSTNAME</parameter>
                </entry>
                <entry>
                  Sets the host name of the <ulink
                  url="http://www.shoutcast.com/"><application>ShoutCast</application></ulink>
                  / <ulink
                  url="http://icecast.org/"><application>IceCast</application></ulink>
                  server.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>port</varname>
                  <parameter>PORTNUMBER</parameter>
                </entry>
                <entry>
                  Connect to this port number on the specified host.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>timeout</varname>
                  <parameter>SECONDS</parameter>
                </entry>
                <entry>
                  Set the timeout for the shout connection in seconds.
                  Defaults to 2 seconds.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>protocol</varname>
                  <parameter>icecast2|icecast1|shoutcast</parameter>
                </entry>
                <entry>
                  Specifies the protocol that wil be used to connect
                  to the server.  The default is
                  "<parameter>icecast2</parameter>".

                </entry>
              </row>
              <row>
                <entry>
                  <varname>mount</varname>
                  <parameter>URI</parameter>
                </entry>
                <entry>
                  Mounts the <application>MPD</application> stream in
                  the specified URI.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>user</varname>
                  <parameter>USERNAME</parameter>
                </entry>
                <entry>
                  Sets the user name for submitting the stream to the
                  server.  Default is "source".
                </entry>
              </row>
              <row>
                <entry>
                  <varname>password</varname>
                  <parameter>PWD</parameter>
                </entry>
                <entry>
                  Sets the password for submitting the stream to the
                  server.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>name</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Sets the name of the stream.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>genre</varname>
                  <parameter>GENRE</parameter>
                </entry>
                <entry>
                  Sets the genre of the stream (optional).
                </entry>
              </row>
              <row>
                <entry>
                  <varname>description</varname>
                  <parameter>DESCRIPTION</parameter>
                </entry>
                <entry>
                  Sets a short description of the stream (optional).
                </entry>
              </row>
              <row>
                <entry>
                  <varname>url</varname>
                  <parameter>URL</parameter>
                </entry>
                <entry>
                  Sets a URL associated with the stream (optional).
                </entry>
              </row>
              <row>
                <entry>
                  <varname>public</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Specifies whether the stream should be "public".
                  Default is <parameter>no</parameter>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>encoder</varname>
                  <parameter>PLUGIN</parameter>
                </entry>
                <entry>
                  Chooses an encoder plugin.  Default is <link
                  linkend="vorbis_encoder"><parameter>vorbis</parameter></link>.
                  A list of encoder plugins can be found in the <link
                  linkend="encoder_plugins">encoder plugin
                  reference</link>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>solaris</varname></title>

        <para>
          The "Solaris" plugin runs only on SUN Solaris, and plays via
          <filename>/dev/audio</filename>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>device</varname>
                  <parameter>PATH</parameter>
                </entry>
                <entry>
                  Sets the path of the audio device, defaults to
                  <filename>/dev/audio</filename>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>
    </section>

    <section id="playlist_plugins">
      <title>Playlist plugins</title>

      <section>
        <title><varname>embcue</varname></title>

        <para>
          Reads CUE sheets from the "CUESHEET" tag of song files.
        </para>
      </section>

      <section>
        <title><varname>m3u</varname></title>

        <para>
          Reads <filename>.m3u</filename> playlist files.
        </para>
      </section>

      <section>
        <title><varname>extm3u</varname></title>

        <para>
          Reads extended <filename>.m3u</filename> playlist files.
        </para>
      </section>

      <section>
        <title><varname>pls</varname></title>

        <para>
          Reads <filename>.pls</filename> playlist files.
        </para>
      </section>

      <section>
        <title><varname>xspf</varname></title>

        <para>
          Reads <ulink url="http://www.xspf.org/">XSPF</ulink>
          playlist files.
        </para>
      </section>
    </section>
  </chapter>
</book>