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Audio Control API

Develop apps to control Sony's latest home audio devices.

How to play a file on a Digital Living Network Alliance (DLNA) media renderer

In this tutorial we will use the following methods provided by the AVTransport service, and we will use cURL to send messages to the renderer.

SetAVTransportURI Sets the file to play and provides the metadata for the file. Play Begins or resumes playback of the content. Stop Stops playback. Pause Pauses playback.

This tutorial covers the following steps.

  1. Find your media renderer.
  2. Set up AVTransport configuration files for cURL.
  3. Give the file information to the renderer.
  4. Play the file on the renderer.

Before you begin

  • Install cURL in your development environment. This tutorial uses cURL to send SOAP messages to the media renderer.
  • Set up a media server and media renderer on your network. One quick way to do this is to add music files to a USB memory stick and plug it in to a Sony home audio or personal audio device. The device will perform both functions.
  • Locate a file to play on the media server, and obtain the file’s metadata. See the ContentDirectory tutorial for information on how to do this.

Source path

DLNA is primarily designed to play files from the local network. On some devices, the device may not correctly resolve the hostname in a URI to a IP address. So, you should always use an IP address and not a hostname.

Note: On occasion, the device may not always send an error message when it cannot properly run a command, and in some cases, a problem in a previous command can result in later commands failing.

Step 1: Discovery - find your media renderer

To find your media renderer, use the UPnP SSDP M-SEARCH method, with a search target of urn:schemas-upnp-org:service:AVTransport:1. The response should contain a list of all the media renderers available for use. Identify the media renderer to use, and record the IP address and port number from media renderer’s LOCATION field.

Next, use the full path from the LOCATION field to download the description file for the media renderer. Locate the AVTransport service; it will have a serviceType element with a value of urn:schemas-upnp-org:service:AVTransport:1. Record the value of the associated controlURL element.

You will use the following transport URL to access the AVTransport service, http://{IP}:{PORT}{controlURL}, where {IP} is the IP address, {PORT} is the port number, and {controlURL} is the controlURL for the AVTransport service on your chosen media renderer. The result should be something like /upnp/control/AVTransport.

Step 2: Setup AVTransport configuration files for cURL

To simplify the use of cURL commands, create the following configuration files with the following contents, One for each of the AVTransport methods we will use. In each of these files, use your transport URL for the url value in the file.

SetAVTransportURI.conf 
url = "/upnp/control/AVTransport"
header = "Content-Type: text/xml; charset=utf-8"
header = "SOAPAction: \"urn:schemas-upnp-org:service:AVTransport:1#SetAVTransportURI\""

Play.conf 
url = "/upnp/control/AVTransport"
header = "Content-Type: text/xml; charset=utf-8"
header = "SOAPAction: \"urn:schemas-upnp-org:service:AVTransport:1#Play\""

Stop.conf 
url = "/upnp/control/AVTransport"
header = "Content-Type: text/xml; charset=utf-8"
header = "SOAPAction: \"urn:schemas-upnp-org:service:AVTransport:1#Stop\""

Pause.conf 
url = "/upnp/control/AVTransport"
header = "Content-Type: text/xml; charset=utf-8"
header = "SOAPAction: \"urn:schemas-upnp-org:service:AVTransport:1#Pause\""

You can include a configuration file in a cURL command using the -K argument.

Step 3: Using cURL to play a file

Before it can play a file, you need to inform the media renderer which file to play and provide the file metadata. For information on how to do this, see the How to browse a Digital Living Network Alliance (DLNA) media server tutorial.

In this example the following is the URI for the music file to play. 

http://192.168.1.119:60151/I_01_05_2_-1_00_00_0_35_0_0

And, the following is the metadata for the music file. This is the escaped XML from the How to browse a Digital Living Network Alliance (DLNA) media server tutorial. This includes information about the file we want to play. 

<DIDL-Lite xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/"
xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/"
xmlns:dlna="urn:schemas-dlna-org:metadata-1-0/"
xmlns:arib="urn:schemas-arib-or-jp:elements-1-0/"
xmlns:av="urn:schemas-sony-com:av">
<item id="I_01_05_2_-1_00_00_0_35_0_0" restricted="1" parentID="35"><dc:title>01 - Overture.mp3</dc:title><upnp:class>object.item.audioItem.musicTrack</upnp:class></item></DIDL-Lite>

To make the metadata easier to read, you can unescape the string. 

<DIDL-Lite xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/"
xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/"
xmlns:dlna="urn:schemas-dlna-org:metadata-1-0/"
xmlns:arib="urn:schemas-arib-or-jp:elements-1-0/"
xmlns:av="urn:schemas-sony-com:av">
  <item id="I_01_05_2_-1_00_00_0_35_0_0" restricted="1" parentID="35">
    <dc:title>01 - Overture.mp3</dc:title>
    <upnp:class>object.item.audioItem.musicTrack</upnp:class>
  </item>
</DIDL-Lite>

File metadata can include additional information, such as the artist, track, and so on. Not all media renderers require metadata to play a file, but some do, and these will not play a file for which the metadata has not been set. Thus, it is best to always include it.

To set the file to play and its metadata, use the SetAVTransportURI command.

The command is sent as a SOAP message. Create the message in a SetAVTransportURI.data file. Set the CurrentURI parameter to the URI of the file to play, and set the CurrentURIMetaData parameter to the escaped file metadata. You will use cURL to send the message.

SetAVTransportURI.data 
      0
      /I_01_05_2_-1_00_00_0_35_0_0
      <DIDL-Lite xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/"
xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/"
xmlns:dlna="urn:schemas-dlna-org:metadata-1-0/"
xmlns:arib="urn:schemas-arib-or-jp:elements-1-0/"
xmlns:av="urn:schemas-sony-com:av">
<item id="I_01_05_2_-1_00_00_0_35_0_0" restricted="1" parentID="35"><dc:title>01 - Overture.mp3</dc:title><upnp:class>object.item.audioItem.musicTrack</upnp:class></item></DIDL-Lite>

To run this command, enter the following in your terminal or command prompt. 

curl -K SetAVTransportURI.conf --data-binary @./SetAVTransportURI.data

On success, the response should resemble what you'll find in the next step of this tutorial.

Step 4: Using cURL to play a file

Play/Resume

To start playing the music, use the Play command. Create a new SOAP message file named Play.data.

Play.data 
<?xml version="1.0" encoding="utf-8"?>
<s:Envelope s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
  <s:Body>
    <u:Play xmlns:u="urn:schemas-upnp-org:service:AVTransport:1">
      <InstanceID>0</InstanceID>
      <Speed>1</Speed>
    </u:Play>
  </s:Body>
</s:Envelope>

Use cURL to run the command. 

curl -K Play.conf --data-binary @./Play.data

Pause

To pause the music, use the Pause command. This command is similar to the Play command. You can resume playback by calling the Play command again. Create a new SOAP message file named Pause.data.

Pause.data 
<?xml version="1.0" encoding="utf-8"?>
<s:Envelope s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
  <s:Body>
    <u:Pause xmlns:u="urn:schemas-upnp-org:service:AVTransport:1">
      <InstanceID>0</InstanceID>
    </u:Pause>
  </s:Body>
</s:Envelope>

Use cURL to run the command. 

curl -K Pause.conf --data-binary @./Pause.data

Stop

To stop playing the music, use the Stop command. This command is also similar to the Play command. Create a new SOAP message file named Stop.data.

Stop.data 
<?xml version="1.0" encoding="utf-8"?>
<s:Envelope s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
  <s:Body>
    <u:Stop xmlns:u="urn:schemas-upnp-org:service:AVTransport:1">
      <InstanceID>0</InstanceID>
    </u:Stop>
  </s:Body>
</s:Envelope>

Use cURL to run the command. 

curl -K Stop.conf --data-binary @./Stop.data