RealAudio Starting Tips

To set up a file for RealAudio streaming, you must generate an audio file first in the appropriate RealAudio format, and give it the file name extension ".ra". The .ra files can then be accessed via a so-called "metafile" (with the extension .ram) that instructs the browser to feed the one or more RealAudio files to the browser via the RealAudio server.

Before setting up a .ram metafile, let me first clarify the concept of a BaseDirectory. On "jan" the "BaseDirectory" is /home so that any references to RealAudio files are relative to the /home directory on jan. All .ra files must be located in or below the user's home directory (for example, /home/tjk). To provide ready access to these files via the Web, it would probably be best to put .ra files in or below one's public_html subdirectory. Here is an example of how to set up a proper link to a RealAudio file so that it will stream through the server:

If I have a RealAudio file called 144.ra in this location:
    /home/tjk/public_html/144.ra

I would give it 644 (world readable) file permissions to make sure it can be accessed via a Web client. To establish a metafile pointing to it, I would create the file /home/tjk/public_html/test.ram (note the file extension .ram) and give it file permissions 644 (world readable). For use of RTSP (Real Time Streaming Protocol) and SureStream encoding, which are supported on this server, you may refer to a file using a line like this:
    rtsp://jan.ucc.nau.edu/tjk/public_html/144.rm
(NOTE: There is no tilde (~) in the URL !!! Also note that the older "pnm" protocol is deprecated under Helix 11.)

This instructs a RealAudio server to make available the audio stream originating from server jan.ucc.nau.edu and from the file /home/tjk/public_html/144.rm (again, note that the BaseDirectory is /home, so that /home never shows up in the actual path to the RealAudio .rm file!). If I wish to stream more than one RealAudio file in succession, I would add a second line to my test.ram file.

To refer to this via a URL, I would use the following syntax:
    Listen to my RealAudio output, click <A HREF="test.ram">here</A>

or, you can just include the path to the sing;e media file; here is an actual such link: RTSP stream. For more information on linking in RealAudio files, consult this link.

To summarize, use .ram as the suffix to a file that points to the media file, use .ra for regular Real Audio files, and use .rm for Real Media (streaming via the RTSP protocol) files. More information can be found elsewhere on how to define or interpret different MIME types.

Quicktime Support

The Helix 11 server supports embedded Quicktime format. A test is on http://jan.ucc.nau.edu/~wew/qtst.html (click here) and it does the QuickTime movie serve as follows (this is the syntax used in that file):
    <embed src="http://www2.nau.edu/launch.mov" width="320" height="240" qtsrc="rtsp://www2.nau.edu/wew/qtst/realqt.mov">
The odd syntax needed here allows you to trick the client browser into seeing a dummy Quicktime movie (we grabbed a short clip and put it in a standard place so anyone can use it without wasting additional space) and hence launching a Quicktime player as an application. Then, the player sees that it really needs to access the desired Quicktime movie and stream it. It is very important that the movie to be streamed be saved in the "hinted" format (i.e., "hint tracks" are embedded). Without this feature included, the movie will not stream via rtsp. Various Quicktime editors allow saving a Quicktime movie with this attribute turned on. For specific information on Quicktime movie creation and editing, please consult this link and click on the "Hint Tracks" in the 'Delivery Tutorials' sectionnear the bottom of the page.

Note that typically if you only want files to be able to be served in streaming mode, they should not be anywhere under one's public_html area or else anyone can still access them using a standard Web browser via http. The creation of a subdirectory outside of the public_html area precules standard Web access to such files.
The Quicktime movie format is supported under Helix 11, which runs on jan (www2.nau.edu), sapphire (www.nau.edu), and dana.

Streaming MP3 Files

A test is on http://mac9.ucc.nau.edu/~wew/mpgtst.html (click here) and it does the mpg audio stream as follows (this is the syntax used in that file):
    <embed type="audio/mpeg" src="it1-1.mp3" width="310" height="45" controller="true" autostart="true">
The streaming file should be in the same location as the web page file. This code snippet will cause the audio file to be automatically played when the page is accessed. It will also bring up controls so the viewer may turn off the recording.

For additional information on RealAudio and RealVideo, please consult the Progressive Networks technical help pages. "jan.ucc.nau.edu" is running a 60-stream RealAudio/RealVideo Helix 11 server. For details on particular features available with this server, consult this link or this link.

This page last updated: Thursday, 04-Dec-2008 00:30:09 MST