REF Element

Artikel
4/26/2023

[The feature associated with this page, Windows Media Player SDK, is a legacy feature. It has been superseded by MediaPlayer. MediaPlayer has been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer instead of Windows Media Player SDK, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The REF element specifies a URL for digital media content.

<REF
   HREF = "URL"
>
</REF>

Attributes

HREF (required)

URL to any piece of media content supported by Windows Media Player.

Parent/Child Elements

Hierarchy	Elements
Parent elements	ENTRY
Child elements	DURATION, ENDMARKER, PREVIEWDURATION, STARTMARKER, STARTTIME

Remarks

This element specifies a URL for a piece of media content. The URL can point to any media type supported, using any protocol supported by Windows Media Player.

The media types supported include still images such as .gif and .jpg images and Flash files with an .swf file name extension. These media types are useful for including advertising content within a playlist. With image files and Flash files that play in a loop, you must also specify the amount of time to display the media item by including a DURATION element within the REF element. If you want an image to continue displaying while the next entry in the playlist is buffered, include a PARAM element within the ENTRY element, set its name attribute to ShowWhileBuffering, and set its value attribute to true.

To reference content on a CD or a DVD that allows it, the wmpcd and wmpdvd protocols are provided. For example, setting the HREF attribute to "wmpdvd://f/5/3" will play chapter 3 of title 5 on a DVD, but only if the DVD has been authored to allow it.

Applications that open digital media from behind a firewall will have better performance when opening the media items if the address is specified using the domain name server (DNS) name instead of the IP address.

The most common use of this element is for URL rollover. If Windows Media Player is unable to open a piece of media defined in a REF element, it tries the URL in the next REF element. Once Windows Media Player opens media content from a URL defined within the scope of one ENTRY element, it ignores subsequent REF tags within that ENTRY element. After the piece of content is done playing, Windows Media Player moves on to the next ENTRY element, if any.

Important Once Windows Media Player establishes a connection to a referenced piece of content, it ignores all other REF elements in that ENTRY, whether the connection terminates normally or abnormally.

If the media item referenced is an image file, the DURATION element must be used to specify the display time for the image.

Note

Attempting to play Flash media that includes sound with the first frame may yield unexpected results. You should author Flash content to play sound starting no earlier than the second frame.

Examples

<ASX VERSION="3.0">
   <ENTRY>
   <TITLE>Example Clip</TITLE>
      <REF HREF="mms://example.microsoft.com/selection1.asf" />
      <REF HREF="mms://sample.microsoft.com/mirror/selection1.asf" />
   </ENTRY>
</ASX>

Requirements

Requirement	Value
Version	Windows Media Player version 7.0 or later

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