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PC World

How MP3 works


February 3, 2000
Web posted at: 9:39 a.m. EST (1439 GMT)

by Michael Gowan

(IDG) -- MP3 (MPEG-1, Layer 3): a compression standard that creates relatively small digital audio files with high-fidelity sound.

  • High-quality digital sound.
  • Small file sizes.
  • Most widely accepted digital audio standard.
  • No system for protecting copyrights.

Why drive to a store to buy music when you could fire up your PC and download the music instead? You say you want a revolution, and the digital music format known as MP3 is primed to lead the charge against audio CDs. MP3 is a compression standard that significantly reduces the size of audio files while maintaining good sound quality.

MP3: The new wave

MP3 files start life in a different format; for Windows users, that format is usually a Microsoft .wav file. Uncompressed .wav files are huge: A file with one minute of CD-quality music is typically about 10MB. Their sheer size makes them difficult to move or store.

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That's where MP3 comes in. Compress that same minute of music at 128 kilobits per second using MP3, and it'll occupy about one-tenth the disk space of the original. MP3 encoders create smaller files by getting rid of unnecessary audio information. When you convert .wav files to MP3, an encoder filters out data representing sounds outside the average person's hearing range. Because some of the original audio data is lost, this technique is called lossy compression.

But lossy compression has its downside: The more data the encoder throws out to shrink the file size (a setting you can control), the worse the finished product sounds when you play it back. The result is that not all MP3 files sound alike. For instance, the MP3 industry claims that music encoded at 128 kbps will produce "CD quality" MP3 files -- and at that quality, a one-minute audio file fills about 1MB of disk space. But regular MP3 users disagree, saying that they hear significant distortion unless the file has been coded at 160 kbps, which produces files that take up slightly more space but sound much better. MP3s coded at 96 kbps end up as far smaller files but have considerable noise.

Once you have an encoded MP3 file, you need a decoder or player -- which can be either software or hardware -- to convert encoded MP3 data into something you can listen to. You can download most software MP3 players for free from the Web.

Let the music play

At first, you needed a specialized player -- such as Nullsoft's Winamp -- to play MP3 files. But the latest versions of other digital music players, including Microsoft's Windows Media Player, RealNetworks' RealPlayer, and Apple's QuickTime, can also play MP3s. No matter which player you use, you'll want to make sure it has decent file management tools: As you accumulate more MP3 files, you'll need to organize your collection. MusicMatch Jukebox, a combination encoder/player, features a music library window that tracks MP3 files all over your hard drive and keeps lists of them in a sortable, spreadsheetlike window.

If you want to groove to the beat outside your office cubicle, you'll need a portable MP3 player. Following the release of S3/Diamond Multimedia's Rio 300 (the first widely available player) in late 1998, companies like I-Jam, RCA, Pine Technology, and Creative Labs shipped competing products. You download music into the players from your PC over a parallel or USB cable. The players store the music in flash memory or on removable SmartMedia memory cards, and they look and function like skinny portable stereos.

The first-generation players' limited memory held only about an hour of music, either in built-in memory or on 32MB removable flash memory cards. The second-generation players, such as Diamond's Rio 500, extend removable memory capacity to 96MB and support other digital music formats, such as RealAudio or Liquid Audio. MP3 players for your car and home stereo -- which also use SmartMedia flash memory cards to transfer files between the PC and player -- started shipping in late 1999.

But now that you have your player, what are you going to play? One way to get MP3 content is to create your own files from music CDs. To do this, you'll need an encoder application. Every portable MP3 player includes an encoder utility, and downloadable software players -- such as RealNetworks' RealJukebox and MusicMatch Jukebox -- can also rip, encode, and play MP3s. Free versions of these tools let you create MP3 files at 96 kbps. To create better-quality MP3 files at 128 kbps, you need to buy the full versions of RealJukebox or MusicMatch Jukebox, or you need a stand-alone ripper/encoder such as Xing's AudioCatalyst.

You can also download MP3 files from the Net. Commercial MP3 sites -- including and -- offer free downloads or charge on a per-download basis. On the free download sites, you're most likely to find garage bands and musicians on independent labels. But a few notable rock artists, including Alanis Morrisette and David Bowie, have posted MP3 versions of their music at online sites before their CDs were shipped to stores. In general, the music industry hasn't accepted MP3 as a valid distribution channel and regards as illegal any site that posts copyrighted music in MP3 format. Utilities like Napster make it easy to post your own MP3 collection online and search through others' files, but the music industry has condemned Napster as a nefarious tool for music piracy.

It's not surprising that the music industry is nervous about any technology that makes it easy to transmit CD-quality audio files. Record companies and the music industry's trade group, the Recording Industry Association of America, have opposed MP3 players and distribution sites from the outset, saying both promote piracy. When Diamond Multimedia released the Rio 300 MP3 player, the RIAA filed suit, claiming any product associated with the MP3 format facilitated music piracy. The courts disagreed and permitted Diamond and other companies to continue to sell their players. Now the RIAA is going after Napster and The group filed a lawsuit against Napster in December 1999, saying the software creates "a giant online pirate bazaar," and sued in January to block its Instant Listening Service, which lets consumers listen to MP3s of music they buy through To combat copyright infringement, the RIAA created the Secure Digital Music Initiative, which is charged with developing an antipiracy standard. Some industry analysts believe that MP3 will eventually be used by home enthusiasts and for other noncommercial uses, while a more secure format will emerge as the compression standard for commercial music.

As with any technology, developers are looking for ways to improve on MP3. A possible next step may be MPEG-2 Advanced Audio Coding, which will compress a file at 96 kbps, yet produce the higher fidelity of an MP3 file recorded at 128 kbps. Other existing digital audio formats, including Windows Media Player and Liquid Audio, are also being touted as the next best thing, with small file sizes, good sound quality, and that other very important aspect: copyright protection.

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You say you want a revolution: Music on the Web
(PC World Online)
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Recording industry sues
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MP3 to go
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(PC World Online)
Music trade group sues MP3 start-up Napster
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The Fraunhofer Institute
Secure Digital Music Initiative (SDMI)
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