Elements


The following section provides descriptions of each of the playlist elements.

smil

Identifies child elements as a playlist based upon the SMIL standard. The smil element is the root element of the playlist file. Additionally, a smil element has the same function as a seq element, meaning that its child elements are played sequentially.

Media

Contains a digital media source, such as files on a local computer, streams from a remote computer running Windows Media Encoder or Windows Media Services, other playlist files, ASP pages on Web servers, or digital media files on third-party storage systems. Attributes of a media element provide the locations of digital media sources and can specify how the digital media content plays back or is presented to the client. A media element can refer to any digital media source that can be accessed by a data source plug-in and parsed by a media or playlist parser plug-in.

seq

Specifies that child elements play sequentially, from the first element to the last. The seq element is a time-container element.

switch

Specifies alternative media elements that can be used if one or more of the current media elements fails. The switch element is useful for implementing content rollover in a server-side playlist. To identify a valid element that can be successfully accessed and streamed, the server evaluates the child elements within the switch element in the order they are listed. When the server identifies and streams a valid element, the other elements within the switch element are ignored. After the selected element stops streaming, the server continues to stream the portion of the playlist after the switch element.

excl

Specifies that child elements play back according to their timing attributes. Use an excl element if you want to control when child elements begin based on variable criteria. For example, a child element can be triggered by using either a programmatic event or a begin attribute that explicitly specifies a start time. Unlike child elements of a seq element, which play in order once the seq element has been activated, the child elements of an excl element do not play unless they are started explicitly. An excl element is often used in conjunction with priorityClass elements.

priorityClass

Controls how child media elements interrupt playback of their peer elements. If you simply want to configure one element to interrupt playback of another, you can use an excl or seq element with a begin attribute set to start one element while another element is playing. The priorityClass element, however, enables you to specify whether the interrupted element stops, pauses, or can never be interrupted. If a media element is set to pause when interrupted, it will continue to stream from the point at which it was paused when the element that interrupted it ends. If it is set to stop, it will not stream when the element that interrupted it ends.

Using the priorityClass element, you can also specify whether an interruption is deferred until the current media element finishes or is ignored altogether. Furthermore, the child elements in a priorityClass element and the priorityClass elements contained within an excl element container are prioritized by the order in which they are listed in the playlist. The ability to adjust the priority further enables you to control the behavior of child elements.

clientData

Specifies descriptive text, banner images, and logging information for the parent element. Descriptive text, such as artist name and track title, is then displayed in Windows Media Player 9 Series or a player that uses the Windows Media Player 9 Series ActiveX control. Using the clientData element, you can also display banner images, associated hyperlinks, and ToolTip text.

You can insert a clientData element anywhere in a playlist. It can be a child of any element except another clientData element. The information it contains is sent to the client when the clientData element becomes active.




Microsoft Windows Media Resource Kit
Microsoft Windows Media Resource Kit (Pro-Resource Kit)
ISBN: 0735618070
EAN: 2147483647
Year: 2005
Pages: 258

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net