Less Bits, More Filling?

Dolby Laboratories was demonstrating its new Advanced Audio Coding (AAC) consumer encoder, which the company says complements its professional AAC encoder, at this year's New York AES Convention. Dolby says it will license the encoder to enable "high-quality AAC encoding" for CD-rippers, hard disk–based jukebox products, Internet-based music distribution systems, portable players, and other digital audio products aimed at the consumer market.

According to Dolby, AAC perceptual encoding technology delivers digital audio quality "far superior to MP3" while requiring approximately 30% less bandwidth or data storage space. The company claims that AAC achieves this by eliminating over 90% of the original audio signal "without affecting the perceived sound." Dolby adds that AAC has been designated an international standard as part of the MPEG-2 and MPEG-4 specifications.

The company's Andrew Fischer explains that "to the ear, the sound quality of program material encoded in AAC is as brilliant as the original recording, but it uses only a fraction of the data. The consumer encoder achieves over 13x real-time performance. For example, a 4-minute, 30-second track would encode in 21 seconds on an Intel Mobile Pentium III running at 1.13GHz. With this consumer encoder, AAC licensees will be able to develop very competitive products for PC-based jukeboxes or music-on-the-go portable players."

Dolby says that AAC can provide up to 48 channels of audio and sample rates of up to 96kHz and is being used in a wide array of digital audio applications, including Internet streaming and downloading, portable players, digital radio and television broadcasting, and audio storage and archiving. Companies currently using the AAC compression technology for streaming audio to consumers include BMG, Universal Music Group, and Warner Music Group.

Dolby also announced that Liquid Audio has signed on as the first licensee of the new AAC consumer encoder. Liquid Audio says it plans to implement this new technology in the next version of its Liquid Player software, scheduled to be released early next year. Dolby serves as worldwide patent license administrator for AAC licenses on behalf of the technology's co-developers, which include Dolby, AT&T, Sony, and the Fraunhofer Institute for Integrated Circuits..