A fast frequency transformation techique for transform audio coders

Technique rapide de transformation de frequences destinee a des codeurs audio a transformee

Abstract

A method for coding digital audio data in which coded Fast Modified Discrete Cosine Transform (FMDCT) coefficients are computed utilising a Fast Fourier Transform (FFT) method. The described method allows a significant reduction in computations as compared to an ordinary DCT coding procedure. Also, pairs of audio channels can be combined to use a single FFT computation, where the selected transform length for the paired channels is the same. In such cases where pairing of identical transform length channels is not possible, a long transform length channel is combined with a short transform length channel and converted in two short transforms. A windowing function is also combined with a pre-processing stage to the transformation, further decreasing computational requireements.
L'invention concerne un procédé de codage de données audio numériques, dans lequel des coefficients codés de transformée cosinus discrète rapide modifiée sont calculés au moyen d'une transformation de Fourier rapide. Le procédé décrit permet une réduction importante des calculs par rapport à une procédure de codage ordinaire par transformée cosinus discrète. De même, on peut combiner des canaux audio pour utiliser un seul calcul de transformée de Fourier rapide, dans lequel la longueur de la transformée choisie et destinée aux canaux en paire est la même. Dans les cas où il n'est pas possible d'établir des paires de canaux à longueur de transformée identique, on combine un canal à longueur de transformée longue avec un canal à longueur de transformée courte et on les convertit en deux transformées courtes. On a également combiné une fonction de fenêtrage à une étape de traitement préalable à la transformation, ce qui diminue encore les nécessités de calcul.

Claims

Description

Topics

Download Full PDF Version (Non-Commercial Use)

Patent Citations (6)

    Publication numberPublication dateAssigneeTitle
    EP-0506111-A2September 30, 1992Mitsubishi Denki Kabushiki KaishaDCT/IDCT processor and data processing method
    EP-0564089-A1October 06, 1993AT&T Corp.Verfahren und Vorrichtung für perceptuelles Kodieren von Audio-Signalen
    EP-0590790-A2April 06, 1994Sony CorporationSystème de transformation d'un signal DCT modifié
    EP-0718746-A1June 26, 1996Laboratoires D'electronique Philips S.A.S., Philips Electronics N.V.Booth multiplier for trigonometric functions
    US-5181183-AJanuary 19, 1993Nec CorporationDiscrete cosine transform circuit suitable for integrated circuit implementation
    US-5592584-AJanuary 07, 1997Lucent Technologies Inc.Method and apparatus for two-component signal compression

NO-Patent Citations (0)

    Title

Cited By (23)

    Publication numberPublication dateAssigneeTitle
    DE-19959156-A1June 28, 2001Fraunhofer Ges ForschungVerfahren und Vorrichtung zum Verarbeiten eines Stereoaudiosignals
    DE-19959156-C2January 31, 2002Fraunhofer Ges ForschungVerfahren und Vorrichtung zum Verarbeiten eines zu codierenden Stereoaudiosignals
    EP-1403854-A2March 31, 2004Microsoft CorporationMulti-channel audio encoding and decoding
    EP-1403854-A3May 10, 2006Microsoft CorporationKodierung und Dekodierung von mehrkanaligen Tonsignalen
    GB-2423451-AAugust 23, 2006Ishce LtdInserting a watermark code into a digitally compressed audio or audio-visual signal or file
    US-7143030-B2November 28, 2006Microsoft CorporationParametric compression/decompression modes for quantization matrices for digital audio
    US-7155383-B2December 26, 2006Microsoft CorporationQuantization matrices for jointly coded channels of audio
    US-7249016-B2July 24, 2007Microsoft CorporationQuantization matrices using normalized-block pattern of digital audio
    US-7260225-B2August 21, 2007Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V.Method and device for processing a stereo audio signal
    US-7299190-B2November 20, 2007Microsoft CorporationQuantization and inverse quantization for audio
    US-7502743-B2March 10, 2009Microsoft CorporationMulti-channel audio encoding and decoding with multi-channel transform selection
    US-7539612-B2May 26, 2009Microsoft CorporationCoding and decoding scale factor information
    US-7680671-B2March 16, 2010Stmicroelectronics Asia Pacific Pte. Ltd.Multi-precision technique for digital audio encoder
    US-7801735-B2September 21, 2010Microsoft CorporationCompressing and decompressing weight factors using temporal prediction for audio data
    US-7831434-B2November 09, 2010Microsoft CorporationComplex-transform channel coding with extended-band frequency coding
    US-7930171-B2April 19, 2011Microsoft CorporationMulti-channel audio encoding/decoding with parametric compression/decompression and weight factors
    US-7953604-B2May 31, 2011Microsoft CorporationShape and scale parameters for extended-band frequency coding
    US-9026452-B2May 05, 2015Microsoft Technology Licensing, LlcBitstream syntax for multi-process audio decoding
    US-9105271-B2August 11, 2015Microsoft Technology Licensing, LlcComplex-transform channel coding with extended-band frequency coding
    US-9305558-B2April 05, 2016Microsoft Technology Licensing, LlcMulti-channel audio encoding/decoding with parametric compression/decompression and weight factors
    US-9349376-B2May 24, 2016Microsoft Technology Licensing, LlcBitstream syntax for multi-process audio decoding
    US-9443525-B2September 13, 2016Microsoft Technology Licensing, LlcQuality improvement techniques in an audio encoder
    US-9741354-B2August 22, 2017Microsoft Technology Licensing, LlcBitstream syntax for multi-process audio decoding