HTTP streaming is an alternative approach to serving RealAudio and RealVideo files on the Web without the added management requirements and expense of server-side streaming software. Although this techniques is not well-suited for high-volume sites serving numerous simultaneous streams, many smaller Web sites can benefit tremendously from this simple and inexpensive approach.
Actually, it's better than inexpensive, it's free.
That's because it relies on HTTP (HyperText Transfer Protocol) which is already used by all Web servers to store and transmit ordinary text and graphics files on the Web. And from the producer's point of view, there's no added effort because RealAudio and RealVideo files prepared for use on an HTTP server are identical to those used with a streaming media server.
There are some important differences however, between the capabilities of HTTP and specialized server software such as RealNetworks' RealSystem Server 8.
For example, you can't automatically detect the user's modem speed using HTTP. Instead, files optimized for each of the various connection speeds must be made available for users to select themselves. Also, the HTTP-based approach does not allow for live streaming audio or video presentations because complete files must be stored on the Web server before they can be accessed. Finally, HTTP does not make efficient use of server resources, and as a result doesn't perform well under heavy server loads.
But for sites serving no more than a handful of simultaneous streams at any given time, this is a great way to add streaming audio and video features to your Web site without incurring extra costs.
The only requirement for HTTP streaming is that your host server must recognize the .ra, .ram, .rm and .rpm mime types, which are standardized file classifications. Many servers already do. If not, it's a relatively simple process to configure your host server for these mime types and you can request that your service provider add this feature for you.
Here are instructions for preparing RealAudio or RealVideo files for use on the Web.
- Copy your encoded files (files with the .ra, .ram, .rm or .rpm extension) to your World Wide Web server.
- Use a text editor (such as Notepad or SimpleText) to create a metafile containing a URL to your file. For example, the contents of your metafile should be in the following form: http://hostname/path, where hostname is the name of your World Wide Web server. For example: www.real.com
- Save your metafile as a text using a .ram file extension.
- In your HTML document, reference the metafile in a hyperlink. For example: <A HREF="filename.ram">
<A HREF="http://hostname/file.rm">You can use relative or complete paths. If you use complete paths, you must include both the hostname and the complete path. For example: <A HREF="http://www.real.com/home/welcome.ram">
- When a user clicks on the link, the streaming file(s) begin to download. The RealPlayer begins playing after a few seconds; it does not need to wait for the entire file to be downloaded.
With HTTP streaming and the right encoding and optimization tools, any Web developer has the ability to create and serve on-demand real-time audio and video.