Playing a URL Involving Server-Side Processing Fails

ID: Q236895

The information in this article applies to:

Microsoft Windows Media Player versions 5.2, 6.0, 6.1, 6.4
Microsoft Windows Media Services version 4.0

SYMPTOMS

When you attempt to play a URL involving server-side processing where the MIME type is generated dynamically (such as an ASP page or a CGI script), the URL may not be opened correctly by Windows Media Player or Internet Explorer.

Different URLs can cause different errors. You may receive the following error message:

Access is denied to the specified resource

-OR-

The file may be fully downloaded before playback, instead of progressively download, during which, playback occurs

CAUSE

In certain dynamically-generated responses, the MIME type does not match the extension for the URL. This would be true of a CGI script returning an ASX file. Normally this MIME type is "video/x-ms-asf." Windows Media Player attempts to verify ownership of a file type before it will support progressive download or streaming of that URL. If Windows Media Player cannot determine if it should play back the file type in question, it will not progressively download the file. If Windows Media Player does not progressively download the file, Internet Explorer may not store the file, resulting in an error message.

WORKAROUND

For clients using Windows Media Player version 6.4 or later, add the following parameter to the URL for the server script:

mswmext=.ext

Where the .ext is the extension for the file type you are using. For example, "http://microsoft.com/sample.asp" would be "http://microsoft.com/sample.asp?mswmext=.asx," if sample.asp was expected to return MIME type "video/x-ms-asf". Similarly, for an HTML form performing a GET request to a Web server, you would add the following to the HTML form:

<input type="hidden" name="mswmext" value=".asx">

STATUS

Microsoft has confirmed this to be a problem in Microsoft Windows Media Services version 4.0.

MORE INFORMATION

Support for the "mswmext" parameter was implemented in Windows Media Player version 6.4. You may need to upgrade to this release in order for this workaround to be effective.

The .ext extension should match the expected MIME type. So if "audio/x-mpegurl" is to be returned, the URL should have "mswmext=.m3u" in it. This is only required for URLs where the MIME type is generated dynamically.

Additional query words: netshow wms wmp

Keywords :
Version : WINDOWS:5.2,6.0,6.1,6.4; :4.0
Platform : WINDOWS
Issue type : kbbug