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Contents

Playlist Service

Overview

The Playlist service provides access to a list of tracks, which can be played in sequence, starting at any point. ‘Shuffle’ and ‘Repeat’ modes also exist, allowing track order to be randomised and playback to loop.

If a device's Product service reports a source of type "Playlist", then that device is guaranteed to bear the Playlist service. If the Playlist service is available, all its properties and actions must be fully implemented.

Evented Properties

Repeat

By default a playlist plays each track in sequence then stops after playing the final track. Setting the Repeat property changes this behaviour to loop from the last track back to the first, playing it immediately.

By default, Repeat is off.

Shuffle

Tracks are played in random order if the Shuffle property is enabled. As with normal playback, each track is played once then the playlist stops. If Shuffle is enabled mid-way through a playlist, each track in the list is shuffled, including any that have just been played.

When combined with Repeat, each track is played once before any track is played for a second time.

By default, Shuffle is off.

Id

The id of the current track (the track currently playing or that would be played if the Transport.Play action was invoked while this source was active). Or 0 if the playlist is empty.

IdArray

A JSON integer array containing the ids of the tracks currently in the playlist.

For example, [2, 276, 19] describes a playlist containing track ids 2, 276, and 19 in that order.

Contains [0..TracksMax] elements.

TracksMax

The maximum number of tracks a playlist can contain. Set on startup and invariant thereafter.

Actions

SetRepeat

Arguments: (in bool repeat)
Enable or disable repeat mode.

Repeat

Arguments: (out bool repeat)
Report whether repeat mode is enabled.

SetShuffle

Arguments: (out bool shuffle)
Enable or disable shuffle mode.

Shuffle

Arguments: (in bool shuffle)
Report whether shuffle mode is enabled.

Id

Arguments: (out uint id)
Return the value of the Id state variable.

ReadList

Arguments: (in string ids, out string json)
Given a space separated list of track ids, report their associated uri and metadata in the following JSON form: 

   [
       {
           "id": integer_id,
           "uri": "track_uri",
           "metadata": "track_metadata"
       },
       {
           "id": integer_id,
           "uri": "track_uri",
           "metadata": "track_metadata"
       }
   ]

Any ids not in the playlist are ignored.

Insert

Arguments: (in uint afterId, in string uri, in string metadata, out uint newId)
Adds the given uri and metadata as a new track to the playlist.

Set the AfterId argument to 0 to insert a track at the start of the playlist.

Reports a 800 fault code if AfterId is not 0 and doesn’t appear in the playlist.
Reports a 801 fault code if the playlist is full (i.e. already contains TracksMax tracks).

DeleteList

Arguments: (int string ids)
Given a space separated list of track ids, remove the tracks with these ids from the playlist.

If the id to be deleted is currently playing, the next track becomes current.

Any ids not in the playlist are silently ignored.

DeleteAll

Arguments: None
Delete all tracks from the playlist.

Move

Arguments: (in string ids, in uint afterId)
Move a space separated list of ids.

Set AfterId to 0 to move the tracks to the start of the playlist.

Any ids not in the playlist are silently ignored.

AfterId must not also be in the list to be moved.

TracksMax

Arguments: (out uint max)
Return the value of the TracksMax property.

IdArray

Arguments: (out uint token, out string json)
Return the value of the IdArray property. Supports polling implementations by returning a token which can be used with the IdArrayChanged action.

IdArrayChanged

Arguments: (in uint token, out bool changed)
Check to see if IdArray has changed since gathering the specified token. This token must have been previously collected from the IdArray action.

This mechanism is provided specifically for any basic control points unable to partake in standard eventing.

UPnP Service Description

For devices supporting the UPnP protocol, the service description is

name: "Playlist"
domain: "openhome.org.eriskay"
version: "1" 

<?xml version="1.0" encoding="utf-8"?>
<scpd xmlns="urn:schemas-upnp-org:service-1-0">
  <specVersion>
    <major>1</major>
    <minor>0</minor>
  </specVersion>
  <actionList>
    <action>
      <name>SetRepeat</name>
      <argumentList>
        <argument>
          <name>Repeat</name>
          <direction>in</direction>
          <relatedStateVariable>Repeat</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>Repeat</name>
      <argumentList>
        <argument>
          <name>Repeat</name>
          <direction>out</direction>
          <relatedStateVariable>Repeat</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>SetShuffle</name>
      <argumentList>
        <argument>
          <name>Shuffle</name>
          <direction>in</direction>
          <relatedStateVariable>Shuffle</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>Shuffle</name>
      <argumentList>
        <argument>
          <name>Shuffle</name>
          <direction>out</direction>
          <relatedStateVariable>Shuffle</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>Id</name>
      <argumentList>
        <argument>
          <name>Id</name>
          <direction>out</direction>
          <relatedStateVariable>Id</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>ReadList</name>
      <argumentList>
        <argument>
          <name>IdList</name>
          <direction>in</direction>
          <relatedStateVariable>IdList</relatedStateVariable>
        </argument>
        <argument>
          <name>TrackList</name>
          <direction>out</direction>
          <relatedStateVariable>TrackList</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>Insert</name>
      <argumentList>
        <argument>
          <name>AfterId</name>
          <direction>in</direction>
          <relatedStateVariable>Id</relatedStateVariable>
        </argument>
        <argument>
          <name>Uri</name>
          <direction>in</direction>
          <relatedStateVariable>Uri</relatedStateVariable>
        </argument>
        <argument>
          <name>Metadata</name>
          <direction>in</direction>
          <relatedStateVariable>Metadata</relatedStateVariable>
        </argument>
        <argument>
          <name>NewId</name>
          <direction>out</direction>
          <relatedStateVariable>Id</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>Move</name>
      <argumentList>
        <argument>
          <name>AfterId</name>
          <direction>in</direction>
          <relatedStateVariable>Id</relatedStateVariable>
        </argument>
        <argument>
          <name>IdList</name>
          <direction>in</direction>
          <relatedStateVariable>IdList</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>DeleteList</name>
      <argumentList>
        <argument>
          <name>IdList</name>
          <direction>in</direction>
          <relatedStateVariable>IdList</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>DeleteAll</name>
    </action>
    <action>
      <name>TracksMax</name>
      <argumentList>
        <argument>
          <name>TracksMax</name>
          <direction>out</direction>
          <relatedStateVariable>TracksMax</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>IdArray</name>
      <argumentList>
        <argument>
          <name>Token</name>
          <direction>out</direction>
          <relatedStateVariable>IdArrayToken</relatedStateVariable>
        </argument>
        <argument>
          <name>Array</name>
          <direction>out</direction>
          <relatedStateVariable>IdArray</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
    <action>
      <name>IdArrayChanged</name>
      <argumentList>
        <argument>
          <name>Token</name>
          <direction>in</direction>
          <relatedStateVariable>IdArrayToken</relatedStateVariable>
        </argument>
        <argument>
          <name>Value</name>
          <direction>out</direction>
          <relatedStateVariable>IdArrayChanged</relatedStateVariable>
        </argument>
      </argumentList>
    </action>
  </actionList>
  <serviceStateTable>
    <stateVariable sendEvents="yes">
      <name>Repeat</name>
      <dataType>boolean</dataType>
    </stateVariable>
    <stateVariable sendEvents="yes">
      <name>Shuffle</name>
      <dataType>boolean</dataType>
    </stateVariable>
    <stateVariable sendEvents="yes">
      <name>Id</name>
      <dataType>ui4</dataType>
    </stateVariable>
    <stateVariable sendEvents="yes">
      <name>IdArray</name>
      <dataType>string</dataType>
    </stateVariable>
    <stateVariable sendEvents="yes">
      <name>TracksMax</name>
      <dataType>ui4</dataType>
    </stateVariable>
    <stateVariable sendEvents="no">
      <name>IdList</name>
      <dataType>string</dataType>
    </stateVariable>
    <stateVariable sendEvents="no">
      <name>TrackList</name>
      <dataType>string</dataType>
    </stateVariable>
    <stateVariable sendEvents="no">
      <name>Uri</name>
      <dataType>string</dataType>
    </stateVariable>
    <stateVariable sendEvents="no">
      <name>Metadata</name>
      <dataType>string</dataType>
    </stateVariable>
    <stateVariable sendEvents="no">
      <name>IdArrayToken</name>
      <dataType>ui4</dataType>
    </stateVariable>
    <stateVariable sendEvents="no">
      <name>IdArrayChanged</name>
      <dataType>boolean</dataType>
    </stateVariable>
  </serviceStateTable>
</scpd>
Retrieved from "http://wiki.openhome.org/wiki/Av:Developer:Eriskay:PlaylistService"