Perceptual coding of audio signals

a technology of audio signals and perception, applied in the field of time-varying signals, can solve the problem that there is no standard presently available for efficiently coding source information for high-quality audio signals with these devices

Inactive Publication Date: 2000-05-23
LUCENT TECH INC
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

While commercially available CD and DAT systems employ elaborate parity and error correction codes, no standard presently exists for efficiently coding source information for high quality audio signals with these devices.

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  • Perceptual coding of audio signals
  • Perceptual coding of audio signals
  • Perceptual coding of audio signals

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Embodiment Construction

To simplify the present disclosure, copending application, Ser. No. 292,598, filed Dec. 30, 1988, by J. L. Hall II and J. D. Johnston, assigned to the assignee of the present invention; J. D. Johnston, "Transform Coding of Audio Signals Using Perceptual Noise Criteria," IEEE Journal on Selected Areas in Communications, Vol. 6, No. 2, February, 1988; and International Patent Application (PCT) WO 88 / 01811, filed Mar. 10, 1988 by K. Brandenburg are hereby incorporated by reference as if set forth in their entirety herein.

Also incorporated by reference as set forth in its entirety herein is a proposal submitted by the assignee of the present application, inter alia, to the International Standards Organization (ISO) on Oct. 18, 1989 for consideration by the members of that body as the basis for a standard relating to digital coding. This document, entitled "ASPEC" will hereinafter be referred to as "the ISO Document".

Application Ser. No. 292,598 describes a perceptual noise threshold est...

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Abstract

A method is disclosed for determining estimates of the perceived noise masking level of audio signals as a function of frequency. By developing a randomness metric related to the euclidian distance between (i) actual frequency components amplitude and phase for each block of sampled values of the signal and (ii) predicted values for these components based on values in prior blocks, it is possible to form a tonality index which provides more detailed information useful in forming the noise masking function. Application of these techniques is illustrated in a coding and decoding context for audio recording or transmission. The noise spectrum is shaped based on a noise threshold and a tonality measure for each critical frequency-band (bark).

Description

FIELD OF THE INVENTIONThe present invention relates to coding of time varying signals, such as audio signals representing voice or music information.BACKGROUND OF THE INVENTIONConsumer, industrial, studio and laboratory products for storing, processing and communicating high quality audio signals are in great demand. For example, so-called compact disc (CD) digital recordings for music have largely replaced the long-popular phonograph records. More recently, digital audio tape (DAT) devices promise further enhancements and convenience in high quality audio applications. See, for example, Tan and Vermeulen, "Digital audio tape for data storage," IEEE Spectrum, October 1989, pp. 34-38. Recent interest in high-definition television (HDTV) has also spurred consideration of how high quality audio for such systems can be efficiently provided.While commercially available CD and DAT systems employ elaborate parity and error correction codes, no standard presently exists for efficiently codi...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G10L19/00G10L19/02H03M7/30H04B1/66H04B14/04
CPCH04B1/665H03M7/00
Inventor BRANDENBURG, KARLHEINZJOHNSTON, JAMES DAVID
Owner LUCENT TECH INC
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