Ars Technica just published
a great article all about MP3 compression as part of their ongoing AudioFile series (the original article in the series,
The Basics of Uncompressed Audio, was also quite good). I thought some users here might not have seen it and would enjoy it.
Since its standardization in 1991, MP3 has gone from being a little-known portion of a video file format to the kind of ubiquity that most brands can only dream of having. It's both widespread, with small players flying off the shelves, and controversial, dropping from the lips of politicians and advocates for all sides of the intellectual property debate.
But what is MP3? The usual explanations usually take one of two forms. The long version, available in technical papers, is written in jargon and filled with math. The short version, often used by newspapers and nontechnical periodicals, simply states that the process eliminates parts of sound not normally heard by the human ear. But this one-sentence description raises more questions than it answers for any reasonably tech-savvy reader: how does it find those unheard sounds, and how does it get rid of them? What's the difference between the different bit rates and quality levels? If you're anything like me, you've often wanted to know the mechanics of MP3, but not to the point of writing your own encoder.
This guide attempts to explain the process of MP3 compression in simple terms, without oversimplifying it. Although some parts have been omitted, like the details of stereo encoding schemes and in-depth file composition, it covers the basic theory of turning uncompressed sound files into compressed MP3. In order to tour the MP3 codec without getting overwhelmed by the technical minutiae, we'll take a look at some of the background principles and legacy of MP3, then break the process down into analysis and compression before finally considering the impact that this humble format has had on digital audio.
Check it out!