Saturday, August 12, 2006

Digital Broadcasters|AES Seoul Papers (1)

The 29th AES Conference, "Audio for Mobile and Handheld Devices", all digital, September 2 to 4, 2006 Seoul National, University Campus

Digital Audio Presentations - Part 1

Multichannel Goes Mobile: MPEG Surround Binaural Rendering

Invited speakers:

Jeroen Breebaart Philips Research Laboratories, The Netherlands,

Juergen Herre and Jan Plogsties, Fraunhofer IIS, Germany,

Lars Villemoes and Kristofer Kjörling, Coding Technologies, Sweden,

Craig Jin VAST Audio, Australia

Surround sound is on the verge of broad adoption in consumers' homes, for digital broadcasting and even for Internet services. The currently developed MPEG Surround technology offers bitrate efficient, and mono/stereo compatible, digital transmission of high- quality multi-channel audio. This enables multi-channel services for applications where mono or stereo backwards compatibility is required, as well as applications with severely bandwidth limited distribution channels. This paper outlines a significant addition to the MPEG Surround specification which enables computationally efficient decoding of MPEG Surround data into binaural stereo, as is appropriate for appealing surround sound reproduction on mobile devices, such as cellular phones. The paper sets out to describe the digital audio basics of the underlying MPEG Surround architecture, the binaural decoding process, and subjective testing results.

Bandwidth Extension for Scalable Audio Coding

Invited Speakers:

Miyoung Kim, Eunmi Oh, Dohyung Kim, Junghoe Kim and Sangwook Kim Samsung Advanced Institute of Technology (SAIT), Korea

MPEG-4 BSAC has fine grain scalability functionality that bitstream can be truncated and decoded at any layer from one full bitstream. This fine grain scalability supports adaptive transmission and decoding according to user control, terminal specifications and network environment. In current BSAC scheme, however, as the transmitted layers become less and less, the decoded output loses its high frequency signals and the sound quality becomes degraded.

This paper illustrates a novel way to recover the missing digital frequency signals when the decoded bitrate is lower than top bitrate. It provides full bandwidth at any bitrate below top bitrate and graceful degradation of sound quality in scalable reproduction. It also improves digital audio quality at low bitrate with top layer.

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