An Ear to the Web

Webcasting around the World
Imagine sitting and listening to a radio program broadcast from the other side of the world. You can hear about the weather in London, listen to traffic reports in Sydney, practice your Spanish by listening to commercials from Madrid, or just hear the latest music from Moscow.

Impossible? No. All you need is your computer and a connection to the Internet. What is Internet radio, and how does it work?

Maybe you don't have the time, money, or inclination to travel the world. But that doesn't mean you can't get to know the sounds and languages of different countries. Just get on the Internet, and leave your passport behind!

Take a trip to Dublin by visiting Liveireland.com, which features two channels of Internet radio: one for modern and traditional Irish music, and the other for contemporary and Top 40. Or hook up to Radio France, where you can listen to music and other features all in French. You can even listen to some good music while looking at Webcam pictures straight from the Ross Ice Shelf in the Antarctic when you visit Anetstation.com.

You'll find Internet radio stations "Webcasting" from Russia, Japan, Greece, Italy, Sweden, Australia, Israel, Chile, and many more countries. Here are a couple of directories to help you find stations of interest:

• The MIT List of Radio Stations on the Internet is the definitive listing for the United States and worldwide. With links to over 9,000 stations, you can search by location or (for the United States) by station formats (e.g., alternative, hip hop, jazz).
  
  
• Or visit the Internet Radio List, which has a database of nearly 2,000 Internet radio stations worldwide, plus reviews of featured stations.
  
  
• And, of course, there's Yahoo! Broadcast (formerly broadcast.com), which hosts our own Riverdeep.net Webcast events. Some of the most popular radio stations in the country use its servers. Check out its Station of the Day and listings of special events.

Gently Down the Stream
What makes Internet radio possible is an innovation called streaming media. To understand how this process works, you first need to think about what happens when you view a simple Web page on your browser without streaming media.

When you connect to a Web site, your computer — the client — asks the computer on the other end—the server — to send everything needed to display the page. That includes the pictures, the keystrokes that make up the text, and all of the underlying instructions that tell the browser how to display it all. This transaction between the client and server computers happens as quickly as possible.

Then the connection is broken so that the server can be available to send out data to some other client--another person wanting to view that Web page. You don't reconnect to that site and that server until you click on a link to open another page.

Listening to sound files this way was frustrating at best. In order to listen to a song or view a video file, you had to download the whole file before playing it. Media files are usually quite large. What if you spent two hours downloading a song and then found out you didn't like it? You wouldn't be likely to repeat the experience.

The arrival of "streaming" made a big difference. The technology behind it cut down on the size of files by compressing the audio or video. These files also were broken up into much smaller pieces, which could be sent one after the other from the server to the client. Your computer plays the first part while the third part is being downloaded, plays the second part while the fourth part is downloaded, without you even noticing. As far as you can tell, it's as if you are tuned in to a "real" radio station. If you don't like what you are hearing, you know it right away.

Strike Up the Bandwidth
With streaming, the size of files ceases to be an issue for the person listening to or watching them on a computer. However, to the Web site sending the Internet radio broadcast — or Webcast — it is an enormous issue. The problem comes from simultaneous listeners.

An Internet radio station's server may stream data to each listener's computer at a rate of 20Kbps. (Kbps is kilobits per second, which is a unit used in measuring the rate of data transfer. When you hear people talk about having a 56K modem, that refers to the 56Kbps speed at which the modem can send and receive data.) A server can only maintain a certain number of simultaneous connections. When it has reached its maximum number of listeners, you may get a message that you cannot connect.

• Data transmission over the Internet isn't perfect. Data can get lost or damaged. In order to avoid this problem, the Internet radio station may increase its transmission rate by 20% for each listener. What rate in Kbps would that be per listener?
  
  
• Using your revised figure, how many simultaneous listeners can your station have connected if you use a server that can stream data at 8Mbps? (Mbps is megabits per second. 1 Mbps = 1000 Kbps.)
  
  
• The greater this stream, the more expensive it is to run the server. If it costs $1,000 a month to use a server that supports 25 simultaneous listeners at 20Kbps each, how much would it cost per month to use the 8Mbps server above?

For more about how this process works, see Internet Radio Broadcasting 101 at About.com.

Related Resources

• Would you like to see an Internet television report on Internet radio? This report from CNN.com discusses Internet radio startup company, Soundbreak.com, among others. (Requires RealPlayer or Windows Media Player plug-in.)
  
  
• The latest edition of Passport to Web Radio discusses how Internet (or Web) radio works and gives a directory of outstanding stations around the world that you can listen to on your computer.
  
  
• Audio on the Web: The Official IUMA Guide is a reference for techies who want to put audio on their own Web site. It is written by the folks at the Internet Underground Music Archive.