Understanding playlist syntax

Playlists are based on Extensible Markup Language (XML). One of the advantages of using the Windows Media Playlist Editor to create and edit playlists is that you do not need to know XML code. After you add all the items to your playlist, the Playlist Editor then automatically transforms your playlist into a Synchronized Multimedia Integration Language (SMIL) 2.0-based XML document. Keep in mind that the changes or additions you make to the playlist do not take effect you save the file.

However, if you are familiar with XML, you can create or modify playlist files by using a text editor such as Notepad. The information in this topic should help you gain the basic knowledge you need to read and edit playlists in a text editor, if the need arises.

The following illustration compares how a sample playlist file, Serverside_Playlist.wsx, appears when opened in a text editor versus how it looks when opened in the Playlist Editor. Serverside_Playlist.wsx is provided by default with Windows Media Services.

After you create a playlist file by using either the Playlist Editor or a text editor, you can assign it as the source of a publishing point. If the playlist is the source of an on-demand publishing point, it starts when a client connects to it. If the playlist is the source of a broadcast publishing point, it starts when you start the publishing point. Although Serverside_Playlist.wsx is a fairly simple playlist, you can create complex playlists that are very long and that contain many complex timing and behavior elements. If you are creating your playlist files by using a text editor, make sure to comply with the following guidelines:

• Elements that contain child elements are defined within a set of start and end tags. Tags are denoted by angle brackets (< and >) that surround the element type. The following is an example of a start tag for a smil element: <smil>. An end tag is denoted by a forward slash (/) preceding the element type, such as </smil>. Everything that follows the start tag and precedes the end tag acts as "instructions" for that element and any elements within it. Elements that do not contain child elements can be written without end tags and within a single pair of angle brackets ending with a forward slash (/), for example <media src="content_clip1.wmv"/>. For a list of all the element types that can be used in a Windows Media playlist file, see Playlist elements.
• Attributes define name-value pairs that correspond to certain properties of the element. Each element supports a different set of attributes. If an element has specified attributes, they will appear after the element in the XML code. For example, in the following line

  <media noSkip="true" role="advertisement" src="C:\WMPub\WMRoot\advert1.asf"/>
  
  

  media is the type of element, and the following attributes and values are specified.

  Attribute	Value
  noSkip	true
  role	advertisement
  src	C:\WMPub\WMRoot\advert1.asf

  
  
• Elements, attributes, and their values are case-sensitive. Make sure that the correct case is used when specifying an attribute value or it will not be recognized during playback. Predefined attribute values, such as begin, end, true, and false should all be specified using lowercase.

The examples used in the playlist reference section depict playlists as they appear in a text editor. Keep in mind that all the examples can also be created or opened using the Playlist Editor.

Related topics

• About creating and editing playlists
• About playlist elements
• Constructing a playlist
• Playlist reference