A higher standard for digital music

Will AAC replace MP3 as the encoding standard of choice? Stay tuned.

COMMENTARY--As the fuss over MP3-trading sites such as Napster continues, new music-encoding standards are slowly creeping onto the scene without attracting much attention. It appears Advanced Audio Coding (AAC) will replace MP3 within the next few years.

MP3 is a first-generation technology based on MPEG-1 Audio Layer 3, named MP3 as a convenient file extension. The audio- and video-compression technologies it employs are crude by today's standards. MPEG-2, the technology used in DVD players, dramatically improves both audio and video.

AAC, part of the MPEG-2 system, was previously referred to as NBC (non-backward-compatible), because it's not backward compatible with MPEG-1 audio formats. Another audio format, MPEG-2 Multi channel, or MPEG-2 BC (backward compatible), is backward compatible with MPEG-1. NBC is better for high-quality music compression. I'm not certain what the point of backward compatibility with MPEG-1 is, anyway.

AAC can include 48 audio channels, 15 low-frequency enhancement channels, and 15 embedded data streams. It also has multilanguage capability. When used to code and decode simple recordings such as those traded on MP3 systems, experts say a 96kbps bit-rate AAC recording is equivalent to a typical 128kbps to 160kbps bit-rate MP3 recording. This means the songs can be compressed 30 percent more and sound as good as or better than MP3. This is not insignificant. Plus, the technologies AAC employs are more advanced than MP3's.

In November 1997, AT&T became the first to commercialize AAC when it rolled out its A2B Music Web site (www.a2bmusic. com). Four years later, you can still go to A2B Music to download free songs and an AAC player. Yet most people have still never heard of AAC. AT&T altered its system enough to make it a secure distribution medium, which means it encrypted the files in such a way that the AAC stream isn't fully MPEG-2 AAC-compliant. About this time, students in Germany and elsewhere began popularizing the MP3 format, and trading Web sites began cropping up. AAC was simply ignored.

MP3 was also operating as a gray-market product, and its users were ignoring the licensing requirements. This boosted its popularity, but now that its licensor, Fraunhofer IIS-A of Germany, is imposing stiff licensing fees, the freeloaders are looking for help from a new public open-source compression scheme called Ogg Vorbis. Its chances are slim. Besides, it's eventually the commercial entities that end up paying the fees.

Until recently, AAC wasn't consolidated enough for any single licensing body to manage the agreements. Management responsibilities were finally handed over to Dolby Labs last year. Within the past few months, Panasonic and Toshiba have come out with devices that play both MP3 and AAC files.

The license fees for AAC are similar to those for MP3. Between the two, AAC should prevail. It has characteristics that allow it to be used for rights management and secure downloads, but these features aren't absolute. You can still encode an AAC file from your CD and swap the file with a friend over the Internet.

You can get an AAC player from a number of sites. Although it's not advertised as such on the home page, the newest player from Liquid Audio is an AAC player. Liquid Audio seems more intent on promoting itself to record companies than to the public; it refers to "FastTrack Security" rather than AAC on its home page. In the future, as AAC becomes more widely known, more players will become known as such. At press time, Microsoft was talking about adding AAC compatibility to its media player.

Rip search
Finding a player will eventually become easy, but finding a ripper or coding software to create AAC files may not. Your best bet is to purchase one of the new Rio-like players from any of the hardware vendors. They cost $250 to $400, but they include software that lets you rip your CDs into AAC files for downloading to the player. The ones I've seen that play AAC files use the new and mostly proprietary SD Memory Cards, which resemble CompactFlash memory cards, but smaller. Use of this format is another drawback, although I suspect players that use standard CompactFlash or SmartMedia will soon emerge.

AAC may not emerge as the audio-compression standard of the 21st century, and MP3 may continue to flourish due to nothing more than momentum. In the technology game, the best doesn't always win. It's even possible something newer could leapfrog AAC before it gets a foothold. But whatever happens, right now AAC is the technology of choice—if you have a choice.