Two-Minute Tutor

Understanding how Internet radio works just takes a little bit of math. You always hear about “bits per second” as if it’s just technical jargon -- but when you’re talking about music, those seconds actually mean seconds of music.

The first commercial digital music was put on compact discs in the 1980s. CDs use 1,411,200 million bits of digital information to describe every second of music! Another way to say that is about 1.4 megabits per second.

It’s easy for that many bits to move that quickly from a disc in your CD player to your stereo. But moving that much data that fast through the Internet was a problem at first. Early modems could receive just 14 or 28 thousand bits per second. They couldn’t grab information about the music fast enough to play music, without pausing for it to download.

Two things happened. Companies like Real Networks, Microsoft, and Fraunhofer (the developer of MP3) figured out ways to describe audio using far fewer bits, mostly by eliminating redundant digital information. A song that has been run through an MP3 encoder can deliver one second of nearly CD-quality audio using just 128 thousand bits, or 128 kbps. That’s a lot less data to move in order to make beautiful music.

Meanwhile, broadband Internet services like DSL and cable arose, receiving data at speeds of at least 128 kilobits per second. Voila! Now you can click your mouse and begin hearing music immediately. The flow of bits, behind the scenes, is fast enough that each second of music arrives before you hear it, and the music plays without interruption or any “download” waiting time.

On the receiving end (your computer), the “player” software instantly decodes the bits it receives and through the computer’s sound card, turns them back into music. In fact, because digital music transmission involves COding and DECoding the audio, the software that handles this process inside an Internet radio player is called a “codec.”

See also:

• What You Need