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Tuesday, December 13, 2005

Audiophiles Unite

A Music File by Any Other Name

By Michael Calore

Editor's note: This article previously appeared in Wired News' sister publication, Webmonkey.

Finding music on the internet is getting easier by the week as legit and less-than-legit file-trading services show up by the dozens. Given all of the options, the number and variety of file formats can be ultimately confusing for the uninitiated.

Today we'll study the most popular audio formats and the players that support them. We'll look strictly at audio-file formats that utilize lossy compression, because the small file size and ultimate portability of compressed audio files has afforded them huge popularity, not to mention near ubiquity, on the web. We'll also be looking exclusively at downloadable, and not streaming, file types.

Let's start with the basics of audio compression. I'll do my best to give you a simple explanation. If you already know this stuff, or if you just want to know the difference between MP3 and all the other audio formats, feel free to jump ahead to the next page.

The term "lossy compression" is used often when referring to digital audio file formats. Basically, it means that some audio data is thrown out during the process of creating the compressed file. Most compression formats on the internet -- MP3, OGG, AAC and the like -- utilize lossy compression.

Most audio encoders will start the compression process by excising frequencies and sounds outside the range of human hearing. You technically can't hear those sounds, so your ears won't miss them. Next, the data used to shape the audio you actually can hear is reduced. Bits and pieces are taken out of the audio, but the omissions are made intelligently by algorithms that know which small pieces to take out without causing too much damage to the sound quality. The result is a file that still sounds very much like the original uncompressed parent, but is only a fraction of the size. An MP3 encoded at near-CD quality is roughly one-tenth the size of the original audio file.

The amount of compression (and data loss) applied to a file can be determined by its bitrate. In audio compression, the bitrate is a measurement of the amount of data that is sampled per second. Files with higher bitrates are larger in size and generally sound better than files with a lower bitrate. Most music stores selling audio files on the internet sell files with bitrates of 128 Kbps or 160 Kbps. This range is generally regarded as being comparable to CD-quality audio. Some audiophiles or digital music enthusiasts will encode files at bitrates of 256 Kbps or higher. These bitrates result in slightly larger file sizes, but the audio quality is greatly improved, and, in many cases, indistinguishable from the original CD source.

There are several lossless compression formats as well, such as SHN, FLAC, APE and Apple Lossless format. We'll cover those in a future article.

(the rest of the article may be redundant to you addicts, but if you'd like to read more, click the link. ~Dani)


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