Digital Music Basics

Files and Formats and Quality, Oh My!

A quick rundown of the most basic of basics: Music on CDs is stored in tracks, with each song usually being one track. When you rip, or copy, a CD onto your computer, you get a bunch of files, with one song in each file. Usually the files are named something like britney_spears_09_let_me_be.mp3, from which you can deduce the artist is Britney Spears, and the file contains the song Let Me Be, which is track #9 on the CD, and it's in mp3 format. And just to be clear, this is an example, not my CD. Got that? It's not mine, really.

Ok... mp3 is not only the file type. From mp3-mac.com: "MP3 is a form of compression. In short is stands for MPEG-1 Audio Layer III, which was developed by the Moving Picture Experts’ Group (MPEG) and has been further developed by the Fraunhofer Institute for encoding purposes."

What?

The important thing is that mp3 is a form of compression. It's a way of mathematically analyzing the music and storing it in a file in such a way that some quality gets lost, but the file is much much smaller than if you just copied the files straight from the CD. Usually about 10 times smaller, so the loss of quality, which most people won't notice anyway, is worth it.

Also, you can select just how much quality to trade off, with something known as bit-rate. It is generally accepted that a bit-rate of 128Kbps (Kilo, or thousand, bits per second) is the minimum for music. If the bit-rate is lower than that, the loss of quality tends to be much more noticable.

So what's a good bit-rate?

If space is an issue, then 128kbps is perfectly acceptable. If you're a music buff, then use a higher setting. I tend to use 160kbps for most of my CDs, and I can't usually hear any difference between the ripped file and the original CD.

And then there are other formats too...

Yes, quite a number of different ones. Microsoft is pushing Windows Media Audio (WMA), Apple uses AAC, Sony uses ATRAC3 and some people (in particular Linux users) tend to like one known as Ogg-Vorbis.

Some of these, such as Windows Media, AAC and ATRAC3 incorporate something called "Digital Rights Management", which effectively limits which devices can play your digital audio files, thus keeping you from making copies for all your friends.

Some of these formats also do a better job of compressing than mp3, which means they don't lose as much quality at the equivalent bit-rate.

Anything we're missing? Let us know.

Talk about this topic in the discussion forums.