Chapter Fourteen - Real Audio/Video

NOTE: We no longer support RealAudio and RealVideo. However, if you know how to install it yourself you are more than welcome to do so. It is very easy to install and you can obtain full instructions on downloading it and implementing it at Real Networks Site. We have provided the following information as a courtesy.

RealAudio and RealVideo technology utilizes an interactive system between the RealVideo Server and the RealPlayer to enable real-time audio and video delivery over the Internet. When the user clicks on a link on a Web page, the clip buffers and then begins to play, all within a few seconds. This gives the deceiving impression that the file is linked directly to the Web page. In reality, information is passing between the Web server supporting the Web page, the RealVideo Server supporting the file, and the RealPlayer.

How does streaming audio/video work?

The file itself is not linked through the web page, contrary to general belief. Information actually passes between the web server, the RealServer, and the RealPlayer. RealAudio and Video can only be retreived by the RealPlayer. If you have a link to the actual file on your server, the file will be downloaded completely before it can be played by the RealPlayer. There needs to be a go between between the web server and the Real Server. This go between is a metafile. This metafile provides the URL of the file to be played to the RealPlayer.

What is a Metafile and how does it work?

Metafiles are text files which contain the URL location of a RealAudio or RealVideo file. Remember that RealAudio and RealVideo files cannot be referenced directly by the Web page because this would cause them to be downloaded in their entirety before playback. In order for the files to be played in real-time, they must be played through a RealPlayer, and served by a RealVideo Server. Therefore there must be a link between the Web server and the RealVideo Server. The link is contained in the metafile.

I've got RealAudio installed on my site, but it's not streaming. It's downloading the file and then playing it. I didn't want it to do this!

You need to have a metafile call the file itself.

How do I make a metafile?

Let's say you want to play the RealAudio file that is named hello.rm

You make a text file with the following line:

pnm://servername/username/domain-www/file.rm

and save the file as hello.ram

You then call the hello.ram in your HTML code as you would any html document.

Where can I get more information about creating Real Audio/Video files?

You can find this information at Real Networks Site.