Bringing Yourself Up to Speed with AAC, MP3, and Digital Audio - What Is MP3? Should You Use It?
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Like AAC, MP3 is a file format for compressed audio. That doesn’t sound like much, but for music enthusiasts, MP3 has been one of the most exciting developments since the sound card, amplifier-inside speakers, or noise-canceling headphones. This is because MP3 allows you to carry a large amount of high-quality audio with you on a small device and enjoy it at the cost of nothing but the device, battery power, and time.
Among Mac users, MP3 has been overshadowed recently by AAC since Apple incorporated the AAC codec in iTunes, QuickTime, and the iPod. But MP3 remains the dominant format for compressed audio on computers running Windows (where its major competition comes from WMA, Microsoft’s proprietary Windows Media Audio format) and computers running Linux.
MP3’s name comes from the Motion Picture Experts Group (MPEG; www.chiariglione.org/ mpeg/—not www.mpeg.org, which you might expect it to be), which oversaw the development of the MP3 format. MP3 is both the extension used by the files and the name commonly used for them. More correctly, MP3 is the file format for MPEG-1 Layer 3—but most people who listen to MP3 files neither know that nor care to know such details.
NOTE: Before you ask, there are also MP1 and MP2 formats (which preceded MP3) as well as an MP4 format (for the MPEG-4 file format, which came later).
MP3 can deliver high-quality music in files that take up as little as a tenth as much space as uncompressed CD-quality files. For speech, which typically requires less fidelity than music, you can create even smaller files that still sound good, enabling you to pack that much more audio in the same amount of disk space.
MP3 Patent and Royalty Rates There’s a widespread perception that MP3 is an open standard that anyone can use, but the reality is a bit different. Although MPEG oversaw the development of MP3, Fraunhofer IIS-A did most of the work.
Fraunhofer and Thomson Corporation (which describes itself as providing “information workflow solutions that help business and professional customers work more productively”) hold patent rights over MP3 audio compression. So anyone who wants to create an MP3 encoder or decoder—whether hardware or software—needs to pay a per-unit royalty to Fraunhofer and Thomson. For example, if you choose to create a hardware MP3 decoder, you need to pay $0.75 per unit; if you create a hardware encoder, the fee is $5 per unit.
You don’t need a license to use MP3 hardware or software, as long as the hardware or software is licensed. You’re also free to stream MP3 audio for “private, non-commercial activities,” such as home entertainment. But you do need a license to stream MP3 audio for commercial purposes— for example, if you’re using MP3 for webcasting. (See www.mp3licensing.com for details.)
For commercial MP3 software, licensing isn’t an issue—whoever developed the software will have paid the licensing fee (and you’ll probably have paid them for the software). But for MP3 freeware, licensing is potentially an issue, although the developers of such software are much more likely to be the targets of patent enforcement than users of the software, because the developers are easier and juicier targets.
How to... Choose Between MP3 and AAC Apple’s current implementation of AAC in iTunes and the iPods has a lot to commend it. AAC delivers high-quality audio, small file size, and enough flexibility for most purposes. But if you want to use the files you rip from a CD on a portable player that doesn’t support AAC, or you need to play them using a software player that doesn’t support AAC, choose MP3 instead. Similarly, if you want to share your music files with other people in any way other than sharing your music library via iTunes, MP3 is the way to go—but remember that you need the copyright holder’s explicit authorization to copy and distribute music. |
 This is chapter three of How to Do Everything with Your iPod & iPod Mini, by Guy Hart-Davis (McGraw-Hill/Osborne, ISBN 0072254521, 2004). Check it out at your favorite bookstore today.
Buy this book now. |
Next: Understand Other Digital Audio Formats >>
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