Sourcing from playlists

Playlists provide a means of organizing different pieces of digital media content into a single user experience. You can use playlists on a publishing point to accomplish several different goals—for example, to add advertisements, to switch between live and stored streams, or to dynamically respond to a user's demographic information. If you reference your content in a playlist, you can combine different Windows Media files into a single stream. Both client-side playlists and server-side playlists can be used with Windows Media-based content.

  • Client-side playlists. These playlists are created by Windows Media Player or by Web scripts and are saved as Windows Media metafiles with an .asx file name extension. You can create a playlist a client-side playlist that contains your favorite songs, and then shuffle and loop the playlist during playback.

  • Server-side playlists. These playlists are created by content producers, server administrators, or Web page scripts and are saved as Windows Media metafiles with a .wsx file name extension. You can stream multiple pieces of digital media content as you would with a client-side playlist, and use additional attributes to further control the behavior of the content. Windows Media Services includes the Windows Media Playlist Editor, which can be used to create server-side playlists.

You can use a combination of client-side playlists and server-side playlists to provide a high degree of connection reliability for your streaming system. The client-side playlist can direct the Player to the different Windows Media servers that are streaming the content, and the switch element in the server-side playlist on the Windows Media server can reference alternate content sources for the server.

You can provide different user experiences depending on whether you make your playlists available through an on-demand publishing point or a broadcast publishing point.

If you want your users to have control over the content you reference in a playlist, you can post your playlist to an on-demand publishing point. Users can fast-forward the content, skip to different entries in the playlist, and pause playback, thereby controlling the method by which they receive the content. A playlist that is the source of an on-demand publishing point starts when a client connects to it.

In contrast, if you have users connect to a playlist through a broadcast publishing point, they can only receive the stream exactly as dictated by the playlist; they have no control over how they receive content, and they can only start and stop the playback. If users stop the content on their players, the content stream on the broadcast publishing point continues. When a user resumes playing the content by clicking start, the player synchronizes with the playlist that is currently playing, regardless of the point at which the user stopped it. A playlist that is the source of a broadcast publishing point starts when you start the publishing point.

Note

Windows Media playlist files are Extensible Markup Language (XML documents that are based on the Synchronized Multimedia Integration Language (SMIL) 2.0 language specification. For more information about the SMIL 2.0 Specification, W3C Recommendation, see the World Wide Web Consortium (W3C) Web site.

Note

If you have enabled the WMS NTFS ACL Authorization plug-in on either the server or a publishing point, every piece of content streamed by the server is authenticated against the user account. This means that if you are streaming content from a playlist, the user must be authenticated against every item listed in the playlist, not just the playlist file. If a user cannot be authenticated for an item in the playlist, that item is skipped.

Note

If you want to save playlist files to another computer or network drive, you must first grant Write permissions to the Network Services account for that computer or network drive. For more information, see About rights.

Note

If you are using multicast distribution with your playlist file, you should only add content to a currently playing playlist if the content is in a known stream format. If the content is in a stream format that is not identified in the multicast information file, players receiving the multicast stream will be in an indefinite waiting state.

Note

Windows Media Services uses playlist parser plug-ins to translate server-side playlists into content streams that can be sent to clients. By enabling or disabling the playlist parser plug-ins, you can control the ability of the Windows Media server to stream content that is structured in different playlist formats.

Note

Windows Media Services uses playlist transform plug-ins to enable you to control the order that content is streamed from a directory or playlist.

See Also

Concepts

WMS NTFS ACL Authorization Playlist parser Playlist transform

Other Resources

Windows Media Services SDK Playlist Reference