Lucent Digital Radio Announces Enhanced Perceptual Audio Coder (PAC™)
Seattle (October 14, 1998) - Lucent Digital Radio today announced enhancements to the Lucent Perceptual Audio Coder (PAC™), which converts analog audio signals to digital format with the highest-quality audio at the lowest bit rates. PAC now delivers near-CD quality at 96 kilobits per second (kbps), and ongoing research and development is aimed at delivering the same performance at much lower bit rates, approaching 64 kbps.
Designed by Bell Labs, PAC is an audio compression algorithm which models human hearing to provide full range CD-like sound at 96 kbps, achieving a 15-1 compression rate. PAC was recently rated the best performing audio coding technology in a class of five tested in independent trials by Moulton Laboratories. In this test, PAC at 96 kbps outperformed the MPEG-2 Advanced Audio Coder (AAC). At 96 kbps, PAC also outperformed AAC at 128 kbps based on a repeatable statistical score.
Because PAC is the only audio coder designed in conjunction with channel coding schemes to resist radio channel impairments, the audio compression algorithm has been optimized for digital broadcast.
Lucent Digital Radio, a wholly-owned venture of Lucent Technologies (NYSE: LU), uses PAC in its In-Band On-Channel (IBOC) digital audio broadcast (DAB) system.
"Lucent Digital Radio is continuing development of PAC with Bell Labs research to increase its use in broadcast, over-the-air applications," said Suren Pai, president of Lucent Digital Radio. "PAC will make digital broadcasting an affordable reality in the 21st century, delivering high-quality audio over bandwidth-constrained networks."
PAC's variable bit rates and superior audio quality allow the coder to adapt, in real time, to changing network capacities, thereby freeing up bandwidth for other applications.
PAC's multi-streaming capabilities allow it to be used for multicasting or broadcasting applications. Unequal error protection and error concealment, as well as integration with channel coding, allow PAC to deliver audio that survives channel impairments in network applications, such as Internet services or DAB.
Several recent improvements in PAC have pushed its performance levels to new heights:
- PAC's improved quantization and coding, allowing higher quality audio at lower bit rates,
- Improved psychoacoustic modeling from Bell Labs research, and
- Near CD-quality stereo audio at 96 kbps - essential for IBOC systems.
"PAC is now ready for a new generation of digital broadcast applications and PC multimedia applications that can take advantage of its superior characteristics, including high quality at lower bandwidths with low software complexity," said Deepen Sinha, principal engineer for Lucent Digital Radio. "For the end-user, the result will be higher quality audio, at any given bit rate."
PAC allows developers to create solutions that can deliver modular audio rates, in 16 kbps increments. Lucent currently uses PAC in the development of other non-broadcast applications, including Internet music distribution and programmable music players.
"The ongoing development of PAC demonstrates Lucent's commitment to commercialize many of the technical contributions Bell Labs has made to industry," said Sid Ahuja, director of the Bell Labs Multimedia Communications Research Laboratory. "PAC opens up wide doors for digital broadcasters that weren't previously possible."
The coming migration to digital radio presents a sizable opportunity for the consumer electronics industry and will enable radio broadcasters to provide improved services to listeners.
Lucent Technologies and its research and development unit, Bell Laboratories, have been leaders in developing technologies for this industry, including the digital encoding of information used in communications systems. Bell Labs also has been in the forefront of digital audio broadcasting (DAB) technology for the past decade.
Lucent Digital Radio is the second Lucent venture in the digital broadcast market. Lucent Digital Video, announced in January, 1998, markets its industry-leading MPEG-2 encoders to the broadcast, cable, wireless cable, fiber optic and satellite markets.
For more information about Lucent Digital Radio, visit the Web site at www.lucent.com/ldr.
Lucent Technologies, headquartered in Murray Hill, N.J., designs, builds and delivers a wide range of public and private networks, communications systems and software, data networking systems, business telephone systems and microelectronic components. Bell Labs is the research and development arm for the company. For more information on Lucent Technologies, visit the company's web site at www.lucent.com.
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