The MP3 format and Digital Music

To understand how MP3 technology works we must first look at how music is digitally stored. For example, a CD stores music digitally using an uncompressed and high-resolution format. During the process of creating a CD the original music is sampled at a rate of 44,100 times per second with each sample being 2 bytes or 16 bits long. For stereo tracks separate samples are recorded for the left and right speakers. This means that the CD ends up storing a large  amount of information per second of music in order to retain that high-fidelity sound.

The science bit:
44,100 samples/second * 16 bits/sample * 2 channels = 1,411,200 bits per second This is a huge amount of data, but what does that really mean? Well, if you took a song that was 3 minutes long it would take up 32 MILLION bytes of space on that shiny disc. Back in the day of dial-up internet connection it could take you up to 2 hours to download. This reason alone is why the MP3 format has only really come in to its own since the dawn of DSL.

How does the MP3 format work?

In simple terms it is a method of compression. It is designed to reduce the number of bytes in a track without compromising the quality of the original song. The format was designed to reduce a CD quality song by a ratio of 10 > 14 without the human ear being able to detect a difference. So if we were to take our example track of 3 minutes (which took up 32 million bytes or 32MG on the CD) and compressed it using the MP3 format you would end up with a file size of just 3MG. So much like JPG compression the MP3 format takes the original file and reduces its size by removing certain aspects of the file, this is done using a unique algorithm called perceptual noise shaping. The algorithm takes characteristics from the human ear to ensure that it only compresses parts of the track that we won't miss or need.

So the track suddenly becomes portable, faster to download and easier to store. This revolution heralds the birth of the MP3 player, Napster and the iconic Apple iPod. Chances are that you already own several devices that can store an MP3 track; MP3 Players, Cell Phones, iPhones and Blackberry, Laptops or Desktop PC's or perhaps even a Games Console.


Where does the MP3 name come from?
MPEG is the acronym for Moving Picture Experts Group.