Streaming Media Metafiles

It’s good to note here that the "version="3.0"" attribute of the .ASX tag refers to the version of the .ASX tagging language itself and not the version of Windows Media Player that will read it. As with any XML format, you can add comments to the file by using the familiar comment tags that work in HTML. Unlike XML, the tags are not case-sensitive.

If we want to make this example equivalent to our previous .RAM file example, we need to add a start time, duration, and a title to our clip. This example will begin playback five minutes into the clip and play for three minutes. Remember, using start times to begin playback some minutes into a video file really only applies if you’re streaming from a genuine streaming media server. If you’re serving this from a web server, the only way to begin playback five minutes into the file is to download the entire first five minutes first.

My Video Title

The Windows Media metafile language has some other useful features, too. Window Media Player can display a 32x194 banner centered below the video display. A banner can appear for the entire presentation, or you can have a different one for each entry in a playlist. Titles can also work this way. The TITLE elements that you place within ENTRYs will appear as a playlist, a clickable navigation menu, on the right-hand side of the Windows Media Player. What’s more, you can add ToolTips (the text that appears when you hover the mouse over the title) to TITLEs and other elements by using the ABSTRACT tag. This example includes those features.

Backyard outtakes
Outtakes of a lazy backyard day

Click here to see this asx source code



Swingin’ on a hammock
Watching the wildlife float by




Ducks and geese
Goin’ for a swim


Click on this grayscale banner to see the source code

There is an interesting quirk to .ASX playlists. Windows Media Player will display the individual entry titles as a playlist if you are streaming the clips from a media server or if you’re playing from your local hard disk. It’s odd, however, that if you serve your media files from a web server, the playlist will only display the title of the full presentation rather than the individual entries within it. Since all the title and abstract data is there in the .ASX file, it shouldn’t matter where the media files are coming from. But it’s really no surprise that it does matter. There are lots of peculiarities like this you’ll discover when delivering media files from anything other than a streaming media server. Using streaming servers to deliver your content is really the best way to avoid a lot of caffeine-induced late-night insomnia shortly before your deadline.

Helix Asxgen
If all you need is a bare-bones metafile that contains just a streaming server URL for the Windows Media Player to connect to, and you happen to be using the RealNetworks Helix Universal Server to deliver your Windows Media content, then you don’t need separate metafiles for all your video links. Like ramgen, described in the first part of this series, asxgen generates an .ASX file on the fly so you don’t have to:

http://myserver.com:8080/asxgen/myvideofile.wmv

A complete reference to Windows Media metafiles can be found at Microsoft’s MSDN website for Windows Media (http://msdn.microsoft.com/windowsmedia/). There you’ll find references to other useful .ASX file elements, such as for inserting ads into your streams and for having your content play again and again and again.