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Improved harmonic transposition

A technology for transposing and audio signals, applied in speech analysis, instruments, etc., can solve problems such as signal artifacts and affecting system reliability

Active Publication Date: 2013-10-23
DOLBY INT AB
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Additionally, such measures often affect the reliability of the system, and can introduce signal artifacts when switching signal processing, for example when switching between window sizes

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Embodiment Construction

[0062] The following examples merely illustrate the principles of the present invention for improved harmonic transposition. It should be understood that modifications and variations of the arrangements and details described herein will be apparent to those skilled in the art. It is the intention, therefore, to be limited only by the scope of the appended patent claims and not by the specific details presented by way of description and illustration of the embodiments herein.

[0063] In the following, the principles of harmonic transposition in the frequency domain and the proposed improvements of the present teachings are outlined. The key components of the harmonic transpose are time-extended by preserving the integer transpose factor T of the frequency of the sinusoid. In other words, the harmonic transpose is based on time-expanding the underlying signal by a factor T. A harmonic transpose is performed to preserve the frequency of the sinusoids that make up the input sig...

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Abstract

The present invention relates to transposing signals in time and / or frequency and in particular to coding of audio signals. More particular, the present invention relates to high frequency reconstruction (HFR) methods including a frequency domain harmonic transposer. A method and system for generating a transposed output signal from an input signal using a transposition factor T is described. The system comprises an analysis window of length La, extracting a frame of the input signal, and an analysis transformation unit of order M transforming the samples into M complex coefficients. M is a function of the transposition factor T. The system further comprises a nonlinear processing unit altering the phase of the complex coefficients by using the transposition factor T, a synthesis transformation unit of order M transforming the altered coefficients into M altered samples, and a synthesis window of length Ls, generating a frame of the output signal.

Description

technical field [0001] The present invention relates to transposing signals in frequency and / or expanding / compressing signals in time, and in particular to the encoding of audio signals. In other words, the present invention relates to time scale modification and / or frequency scale modification. More particularly, the present invention relates to high frequency reconstruction (HFR) methods including frequency domain harmonic transposers. Background technique [0002] HFR techniques, such as spectral band replication (SBR) techniques, enable significant improvements in the coding efficiency of conventional perceptual audio codecs. Combined with MPEG-4 Advanced Audio Coding (AAC), it forms a very efficient audio codec that has been used in the XM Satellite Radio System and the Digital Radio Mondiale worldwide, but also in 3GPP, DVD Forum Standardize it in etc. The combination of AAC and SBR is called aacPlus. This is part of the MPEG-4 standard, where it is called the High...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G10L19/022G10L21/04G10L21/038
CPCG10L19/0212G10L19/022G10L21/038G10L21/04G10L19/00G10L19/24
Inventor 佩尔·埃克斯特兰德拉尔斯·法尔克·维尔默斯
Owner DOLBY INT AB