path: root/spec/Player_Node.xml

<?xml version="1.0" ?>
<node name="/Player_Node" xmlns:tp="http://telepathy.freedesktop.org/wiki/DbusSpec#extensions-v0">
  <interface name="org.mpris.MediaPlayer2.Player">

    <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
      <p>
        This interface implements the methods for querying and providing basic
        control over what is currently playing.
      </p>
    </tp:docstring>

    <tp:enum name="Playback_Status" tp:name-for-bindings="Playback_Status" type="s">
      <tp:enumvalue suffix="Playing" value="Playing">
        <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
          <p>A track is currently playing.</p>
        </tp:docstring>
      </tp:enumvalue>
      <tp:enumvalue suffix="Paused" value="Paused">
        <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
          <p>A track is currently paused.</p>
        </tp:docstring>
      </tp:enumvalue>
      <tp:enumvalue suffix="Stopped" value="Stopped">
        <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
          <p>There is no track currently playing.</p>
        </tp:docstring>
      </tp:enumvalue>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>A playback state.</p>
      </tp:docstring>
    </tp:enum>

    <tp:enum name="Loop_Status" tp:name-for-bindings="Loop_Status" type="s">
      <tp:enumvalue suffix="None" value="None">
        <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
          <p>The playback will stop when there are no more tracks to play</p>
        </tp:docstring>
      </tp:enumvalue>
      <tp:enumvalue suffix="Track" value="Track">
        <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
          <p>The current track will start again from the begining once it has finished playing</p>
        </tp:docstring>
      </tp:enumvalue>
      <tp:enumvalue suffix="Playlist" value="Playlist">
        <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
          <p>The playback loops through a list of tracks</p>
        </tp:docstring>
      </tp:enumvalue>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>A repeat / loop status</p>
      </tp:docstring>
    </tp:enum>

    <tp:simple-type name="Track_Id" type="o" array-name="Track_Id_List">
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Unique track identifier.</p>
        <p>
          If the media player implements the TrackList interface and allows
          the same track to appear multiple times in the tracklist,
          this must be unique within the scope of the tracklist.
        </p>
        <p>
          Note that this should be a valid D-Bus object id, although clients
          should not assume that any object is actually exported with any
          interfaces at that path.
        </p>
        <p>
          Media players may not use any paths starting with
          <literal>/org/mpris</literal> unless explicitly allowed by this specification.
          Such paths are intended to have special meaning, such as
          <literal>/org/mpris/MediaPlayer2/TrackList/NoTrack</literal>
          to indicate "no track".
        </p>
        <tp:rationale>
          <p>
            This is a D-Bus object id as that is the definitive way to have
            unique identifiers on D-Bus.  It also allows for future optional
            expansions to the specification where tracks are exported to D-Bus
            with an interface similar to org.gnome.UPnP.MediaItem2.
          </p>
        </tp:rationale>
      </tp:docstring>
    </tp:simple-type>

    <tp:simple-type name="Playback_Rate" type="d">
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>A playback rate</p>
        <p>
          This is a multiplier, so a value of 0.5 indicates that playback is
          happening at half speed, while 1.5 means that 1.5 seconds of "track time"
          is consumed every second.
        </p>
      </tp:docstring>
    </tp:simple-type>

    <tp:simple-type name="Volume" type="d">
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Audio volume level</p>
        <ul>
          <li>0.0 means mute.</li>
          <li>1.0 is a sensible maximum volume level (ex: 0dB).</li>
        </ul>
        <p>
          Note that the volume may be higher than 1.0, although generally
          clients should not attempt to set it above 1.0.
        </p>
      </tp:docstring>
    </tp:simple-type>

    <tp:simple-type name="Time_In_Us" type="x">
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Time in microseconds.</p>
      </tp:docstring>
    </tp:simple-type>

    <method name="Next" tp:name-for-bindings="Next">
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Skips to the next track in the tracklist.</p>
        <p>
          If there is no next track (and endless playback and track
          repeat are both off), stop playback.
        </p>
        <p>If playback is paused or stopped, it remains that way.</p>
        <p>
          If <tp:member-ref>CanGoNext</tp:member-ref> is
          <strong>false</strong>, attempting to call this method should have
          no effect.
        </p>
      </tp:docstring>
    </method>

    <method name="Previous" tp:name-for-bindings="Previous">
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Skips to the previous track in the tracklist.</p>
        <p>
          If there is no previous track (and endless playback and track
          repeat are both off), stop playback.
        </p>
        <p>If playback is paused or stopped, it remains that way.</p>
        <p>
          If <tp:member-ref>CanGoPrevious</tp:member-ref> is
          <strong>false</strong>, attempting to call this method should have
          no effect.
        </p>
      </tp:docstring>
    </method>

    <method name="Pause" tp:name-for-bindings="Pause">
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Pauses playback.</p>
        <p>If playback is already paused, this has no effect.</p>
        <p>
          Calling Play after this should cause playback to start again
          from the same position.
        </p>
        <p>
          If <tp:member-ref>CanPause</tp:member-ref> is
          <strong>false</strong>, attempting to call this method should have
          no effect.
        </p>
      </tp:docstring>
    </method>

    <method name="PlayPause" tp:name-for-bindings="PlayPause">
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Pauses playback.</p>
        <p>If playback is already paused, resumes playback.</p>
        <p>If playback is stopped, starts playback.</p>
        <p>
          If <tp:member-ref>CanPause</tp:member-ref> is
          <strong>false</strong>, attempting to call this method should have
          no effect and raise an error.
        </p>
      </tp:docstring>
    </method>

    <method name="Stop" tp:name-for-bindings="Stop">
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Stops playback.</p>
        <p>If playback is already stopped, this has no effect.</p>
        <p>
          Calling Play after this should cause playback to
          start again from the beginning of the track.
        </p>
        <p>
          If <tp:member-ref>CanControl</tp:member-ref> is
          <strong>false</strong>, attempting to call this method should have
          no effect and raise an error.
        </p>
      </tp:docstring>
    </method>

    <method name="Play" tp:name-for-bindings="Play">
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Starts or resumes playback.</p>
        <p>If already playing, this has no effect.</p>
        <p>If there is no track to play, this has no effect.</p>
        <p>
          If <tp:member-ref>CanPlay</tp:member-ref> is
          <strong>false</strong>, attempting to call this method should have
          no effect.
        </p>
      </tp:docstring>
    </method>

    <method name="Seek" tp:name-for-bindings="Seek">
      <arg direction="in" type="x" name="Offset" tp:type="Time_In_Us">
        <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
          <p>The number of microseconds to seek forward.</p>
        </tp:docstring>
      </arg>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>
          Seeks forward in the current track by the specified number
          of microseconds.
        </p>
        <p>
          A negative value seeks back. If this would mean seeking
          back further than the start of the track, the position
          is set to 0.
        </p>
        <p>
          If the value passed in would mean seeking beyond the end
          of the track, acts like a call to Next.
        </p>
        <p>
          If the <tp:member-ref>CanSeek</tp:member-ref> property is false,
          this has no effect.
        </p>
      </tp:docstring>
    </method>

    <method name="SetPosition" tp:name-for-bindings="Set_Position">
      <arg direction="in" type="o" tp:type="Track_Id" name="TrackId">
        <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
          <p>The currently playing track's identifier.</p>
          <p>
            If this does not match the id of the currently-playing track,
            the call is ignored as "stale".
          </p>
          <p>
            <literal>/org/mpris/MediaPlayer2/TrackList/NoTrack</literal>
            is <em>not</em> a valid value for this argument.
          </p>
        </tp:docstring>
      </arg>
      <arg direction="in" type="x" tp:type="Time_In_Us" name="Position">
        <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
          <p>Track position in microseconds.</p>
          <p>This must be between 0 and &lt;track_length&gt;.</p>
        </tp:docstring>
      </arg>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Sets the current track position in microseconds.</p>
        <p>If the Position argument is less than 0, do nothing.</p>
        <p>
          If the Position argument is greater than the track length,
          do nothing.
        </p>
        <p>
          If the <tp:member-ref>CanSeek</tp:member-ref> property is false,
          this has no effect.
        </p>
        <tp:rationale>
          <p>
            The reason for having this method, rather than making
            <tp:member-ref>Position</tp:member-ref> writable, is to include
            the TrackId argument to avoid race conditions where a client tries
            to seek to a position when the track has already changed.
          </p>
        </tp:rationale>
      </tp:docstring>
    </method>

    <method name="OpenUri" tp:name-for-bindings="Open_Uri">
      <arg direction="in" type="s" tp:type="Uri" name="Uri">
        <tp:docstring>
          <p>
            Uri of the track to load. Its uri scheme should be an element of the
            <literal>org.mpris.MediaPlayer2.SupportedUriSchemes</literal>
            property and the mime-type should match one of the elements of the
            <literal>org.mpris.MediaPlayer2.SupportedMimeTypes</literal>.
          </p>
        </tp:docstring>
      </arg>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Opens the Uri given as an argument</p>
        <p>If the playback is stopped, starts playing</p>
        <p>
          If the uri scheme or the mime-type of the uri to open is not supported,
          this method does nothing and may raise an error.  In particular, if the
          list of available uri schemes is empty, this method may not be
          implemented.
        </p>
        <p>Clients should not assume that the Uri has been opened as soon as this
           method returns. They should wait until the mpris:trackid field in the
           <tp:member-ref>Metadata</tp:member-ref> property changes.
        </p>
        <p>
          If the media player implements the TrackList interface, then the
          opened track should be made part of the tracklist, the
          <literal>org.mpris.MediaPlayer2.TrackList.TrackAdded</literal> or
          <literal>org.mpris.MediaPlayer2.TrackList.TrackListReplaced</literal>
          signal should be fired, as well as the
          <literal>org.freedesktop.DBus.Properties.PropertiesChanged</literal>
          signal on the tracklist interface.
        </p>
      </tp:docstring>
    </method>

    <property name="PlaybackStatus" tp:name-for-bindings="Playback_Status" type="s" tp:type="Playback_Status" access="read">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>The current playback status.</p>
        <p>
          May be "Playing", "Paused" or "Stopped".
        </p>
      </tp:docstring>
    </property>

    <property name="LoopStatus" type="s" access="readwrite"
              tp:name-for-bindings="Loop_Status" tp:type="Loop_Status">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>The current loop / repeat status</p>
        <p>May be:
          <ul>
            <li>"None" if the playback will stop when there are no more tracks to play</li>
            <li>"Track" if the current track will start again from the begining once it has finished playing</li>
            <li>"Playlist" if the playback loops through a list of tracks</li>
          </ul>
        </p>
        <p>
          This property is optional, and clients should deal with NotSupported
          errors gracefully.
        </p>
        <p>
          If <tp:member-ref>CanControl</tp:member-ref> is
          <strong>false</strong>, attempting to set this property should have
          no effect and raise an error.
        </p>
      </tp:docstring>
    </property>

    <property name="Rate" tp:name-for-bindings="Rate" type="d" tp:type="Playback_Rate" access="readwrite">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>The current playback rate.</p>
        <p>
          The value must fall in the range described by
          <tp:member-ref>MinimumRate</tp:member-ref> and
          <tp:member-ref>MaximumRate</tp:member-ref>, and must not be 0.0.  If
          playback is paused, the <tp:member-ref>PlaybackStatus</tp:member-ref>
          property should be used to indicate this.  A value of 0.0 should not
          be set by the client.  If it is, the media player should act as
          though <tp:member-ref>Pause</tp:member-ref> was called.
        </p>
        <p>
          If the media player has no ability to play at speeds other than the
          normal playback rate, this must still be implemented, and must
          return 1.0.  The <tp:member-ref>MinimumRate</tp:member-ref> and
          <tp:member-ref>MaximumRate</tp:member-ref> properties must also be
          set to 1.0.
        </p>
        <p>
          Not all values may be accepted by the media player.  It is left to
          media player implementations to decide how to deal with values they
          cannot use; they may either ignore them or pick a "best fit" value.
          Clients are recommended to only use sensible fractions or multiples
          of 1 (eg: 0.5, 0.25, 1.5, 2.0, etc).
        </p>
        <tp:rationale>
          <p>
            This allows clients to display (reasonably) accurate progress bars
            without having to regularly query the media player for the current
            position.
          </p>
        </tp:rationale>
      </tp:docstring>
    </property>

    <property name="Shuffle" tp:name-for-bindings="Shuffle" type="b" access="readwrite">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>
          A value of <strong>false</strong> indicates that playback is
          progressing linearly through a playlist, while <strong>true</strong>
          means playback is progressing through a playlist in some other order.
        </p>
        <p>
          This property is optional, and clients should deal with NotSupported
          errors gracefully.
        </p>
        <p>
          If <tp:member-ref>CanControl</tp:member-ref> is
          <strong>false</strong>, attempting to set this property should have
          no effect and raise an error.
        </p>
      </tp:docstring>
    </property>

    <property name="Metadata" tp:name-for-bindings="Metadata" type="a{sv}" tp:type="Metadata_Map" access="read">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>The metadata of the current element.</p>
        <p>
          If there is a current track, this must have a "mpris:trackid" entry
          (of D-Bus type "o") at the very least, which contains a D-Bus path that
          uniquely identifies this track.
        </p>
        <p>
          See the type documentation for more details.
        </p>
      </tp:docstring>
    </property>

    <property name="Volume" type="d" tp:type="Volume" tp:name-for-bindings="Volume" access="readwrite">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true" />
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>The volume level.</p>
        <p>
          When setting, if a negative value is passed, the volume
          should be set to 0.0.
        </p>
        <p>
          If <tp:member-ref>CanControl</tp:member-ref> is
          <strong>false</strong>, attempting to set this property should have
          no effect and raise an error.
        </p>
      </tp:docstring>
    </property>

    <property name="Position" type="x" tp:type="Time_In_Us" tp:name-for-bindings="Position" access="read">
        <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="false"/>
        <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
          <p>
            The current track position in microseconds, between 0 and
            the 'mpris:length' metadata entry (see Metadata).
          </p>
          <p>
            Note: If the media player allows it, the current playback position
            can be changed either the SetPosition method or the Seek method on
            this interface.  If this is not the case, the
            <tp:member-ref>CanSeek</tp:member-ref> property is false, and
            setting this property has no effect and can raise an error.
          </p>
          <p>
            If the playback progresses in a way that is inconstistant with the
            <tp:member-ref>Rate</tp:member-ref> property, the
            <tp:member-ref>Seeked</tp:member-ref> signal is emited.
          </p>
        </tp:docstring>
    </property>

    <property name="MinimumRate" tp:name-for-bindings="Minimum_Rate" type="d" tp:type="Playback_Rate" access="read">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>
          The minimum value which the <tp:member-ref>Rate</tp:member-ref>
          property can take.
          Clients should not attempt to set the
          <tp:member-ref>Rate</tp:member-ref> property below this value.
        </p>
        <p>
          Note that even if this value is 0.0 or negative, clients should
          not attempt to set the <tp:member-ref>Rate</tp:member-ref> property
          to 0.0.
        </p>
        <p>This value should always be 1.0 or less.</p>
      </tp:docstring>
    </property>

    <property name="MaximumRate" tp:name-for-bindings="Maximum_Rate" type="d" tp:type="Playback_Rate" access="read">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>
          The maximum value which the <tp:member-ref>Rate</tp:member-ref>
          property can take.
          Clients should not attempt to set the
          <tp:member-ref>Rate</tp:member-ref> property above this value.
        </p>
        <p>
          This value should always be 1.0 or greater.
        </p>
      </tp:docstring>
    </property>

    <property name="CanGoNext" tp:name-for-bindings="Can_Go_Next" type="b" access="read">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>
          Whether the client can call the <tp:member-ref>Next</tp:member-ref>
          method on this interface and expect the current track to change.
        </p>
        <p>
          If it is unknown whether a call to <tp:member-ref>Next</tp:member-ref> will
          be successful (for example, when streaming tracks), this property should
          be set to <strong>true</strong>.
        </p>
        <p>
          If <tp:member-ref>CanControl</tp:member-ref> is
          <strong>false</strong>, this property should also be
          <strong>false</strong>.
        </p>
        <tp:rationale>
          <p>
            Even when playback can generally be controlled, there may not
            always be a next track to move to.
          </p>
        </tp:rationale>
      </tp:docstring>
    </property>

    <property name="CanGoPrevious" tp:name-for-bindings="Can_Go_Previous" type="b" access="read">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>
          Whether the client can call the
          <tp:member-ref>Previous</tp:member-ref> method on this interface and
          expect the current track to change.
        </p>
        <p>
          If it is unknown whether a call to <tp:member-ref>Previous</tp:member-ref>
          will be successful (for example, when streaming tracks), this property
          should be set to <strong>true</strong>.
        </p>
        <p>
          If <tp:member-ref>CanControl</tp:member-ref> is
          <strong>false</strong>, this property should also be
          <strong>false</strong>.
        </p>
        <tp:rationale>
          <p>
            Even when playback can generally be controlled, there may not
            always be a next previous to move to.
          </p>
        </tp:rationale>

      </tp:docstring>
    </property>

    <property name="CanPlay" tp:name-for-bindings="Can_Play" type="b" access="read">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Whether playback can be started using
           <tp:member-ref>Play</tp:member-ref> or
           <tp:member-ref>PlayPause</tp:member-ref>.
        </p>
        <p>
          Note that this is related to whether there is a "current track": the
          value should not depend on whether the track is currently paused or
          playing.  In fact, if a track is currently playing (and
          <tp:member-ref>CanControl</tp:member-ref> is <strong>true</strong>),
          this should be <strong>true</strong>.
        </p>
        <p>
          If <tp:member-ref>CanControl</tp:member-ref> is
          <strong>false</strong>, this property should also be
          <strong>false</strong>.
        </p>
        <tp:rationale>
          <p>
            Even when playback can generally be controlled, it may not be
            possible to enter a "playing" state, for example if there is no
            "current track".
          </p>
        </tp:rationale>
      </tp:docstring>
    </property>

    <property name="CanPause" tp:name-for-bindings="Can_Pause" type="b" access="read">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Whether playback can be paused using
           <tp:member-ref>Pause</tp:member-ref> or
           <tp:member-ref>PlayPause</tp:member-ref>.
        </p>
        <p>
          Note that this is an intrinsic property of the current track: its
          value should not depend on whether the track is currently paused or
          playing.  In fact, if playback is currently paused (and
          <tp:member-ref>CanControl</tp:member-ref> is <strong>true</strong>),
          this should be <strong>true</strong>.
        </p>
        <p>
          If <tp:member-ref>CanControl</tp:member-ref> is
          <strong>false</strong>, this property should also be
          <strong>false</strong>.
        </p>
        <tp:rationale>
          <p>
            Not all media is pausable: it may not be possible to pause some
            streamed media, for example.
          </p>
        </tp:rationale>
      </tp:docstring>
    </property>

    <property name="CanSeek" tp:name-for-bindings="Can_Seek" type="b" access="read">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="true"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>
          Whether the client can control the playback position using
          <tp:member-ref>Seek</tp:member-ref> and
          <tp:member-ref>SetPosition</tp:member-ref>.  This may be different for
          different tracks.
        </p>
        <p>
          If <tp:member-ref>CanControl</tp:member-ref> is
          <strong>false</strong>, this property should also be
          <strong>false</strong>.
        </p>
        <tp:rationale>
          <p>
            Not all media is seekable: it may not be possible to seek when
            playing some streamed media, for example.
          </p>
        </tp:rationale>
      </tp:docstring>
    </property>

    <property name="CanControl" tp:name-for-bindings="Can_Control" type="b" access="read">
      <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="false"/>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Whether the media player may be controlled over this interface.</p>
        <p>
          This property is not expected to change, as it describes an intrinsic
          capability of the implementation.
        </p>
        <p>
          If this is <strong>false</strong>, clients should assume that all
          properties on this interface are read-only (and will raise errors
          if writing to them is attempted), no methods are implemented
          and all other properties starting with "Can" are also
          <strong>false</strong>.
        </p>
        <tp:rationale>
          <p>
            This allows clients to determine whether to present and enable
            controls to the user in advance of attempting to call methods
            and write to properties.
          </p>
        </tp:rationale>
      </tp:docstring>
    </property>

    <signal name="Seeked" tp:name-for-bindings="Seeked">
      <arg name="Position" type="x" tp:type="Time_In_Us">
        <tp:docstring>
          <p>The new position, in microseconds.</p>
        </tp:docstring>
      </arg>
      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>
          Indicates that the track position has changed in a way that is
          inconsistant with the current playing state.
        </p>
        <p>When this signal is not received, clients should assume that:</p>
        <ul>
          <li>
            When playing, the position progresses according to the rate property.
          </li>
          <li>When paused, it remains constant.</li>
        </ul>
        <p>
          This signal does not need to be emitted when playback starts
          or when the track changes, unless the track is starting at an
          unexpected position. An expected position would be the last
          known one when going from Paused to Playing, and 0 when going from
          Stopped to Playing.
        </p>
      </tp:docstring>
    </signal>

  </interface>
</node>
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