XM Drops PAC for CT-aacPlus

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XM Drops PAC for CT-aacPlus

Apr 24, 2002 12:00 PM

Washington, DC - Apr 18, 2002 - At a press conference held in New York City, XM Satellite Radio unveiled its plans to use a customized CT-aacPlus audio encoding algorithm with neural audio optimization. XM states that the new algorithm will provide superior sound quality that is remarkably close to compact disc.

CT-aacPlus is a third-generation audio encoding technology. CT-aacPlus is the combination of Advanced Audio Coding (AAC), now a global standard combining the work of AT&T, Dolby, Fraunhofer and Sony with Coding Technologies' Spectral Band Replication (SBRM) technology.

Coding Technologies, a developer of perceptual audio compression and inventor of SBR, was formed through a merger between a Swedish group of researchers and experts from the renowned German Fraunhofer Institute, the inventor of MP3.

This combination of AAC and SBR, CT-aacPlus has been tested by high-profile audio professionals from around the world. In a double-blind listening test, AAC alone has historically proven 33 percent more efficient compared to previous generations of competing algorithms. Double-blind listening tests conducted by the BBC, Deutsche Telekom and Robert Bosch GmbH have established that the CT-aacPlus combination is 30 percent more efficient than AAC. Based on test results, CT-aacPlus has been adopted by the International Digital Radio Mondiale (DRM) consortium and accepted by MPEG as the reference model for the upcoming version of MPEG-4.

In addition, the XM sound is further enhanced by Neural Audio, a Seattle-based research lab that pioneered future-generation audio, by merging neural networks with the physics of sound. Neural Audio's proprietary pre-processing software uses neural network computing techniques to implement algorithms that are based on models of the brain's perception of sound.

Neural Audio created a customized version of its process, designed to enhance CT-aacPlus results by optimizing temporal and spectral elements prior to encoding, improving soundstage clarity and increasing intelligibility. The unique combination of CT-aacPlus and Neural Audio algorithms enable XM to deliver a consistent sound experience.

Neural Audio's Stereo Transcoder algorithm preserves the imaging and spatiality of stereo and surround-sound content that XM broadcasts. So XM customers with matrix-style surround sound equipment, including Dolby technology, can receive a full surround sound experience.

XM had previously used the Perceptual Audio Coder algorithm, which was originally developed by Lucent Technologies and licensed to XM by Ibiquity Digital. Ibiquity will use PAC in its IBOC DAB system.