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Bandwidth extension of harmonic audio signals

A bandwidth expansion, audio signal technology, applied in the field of audio signal encoding and decoding, can solve the problems of audio signal inclusion defects, audience annoyance, etc.

Active Publication Date: 2017-03-08
TELEFON AB LM ERICSSON (PUBL)
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  • Description
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Problems solved by technology

[0007] However, the BWE of certain audio signals may cause the audio signal to contain artifacts, which can be annoying to the listener

Method used

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  • Bandwidth extension of harmonic audio signals
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  • Bandwidth extension of harmonic audio signals

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Embodiment Construction

[0023] As mentioned above, bandwidth extension of audio signals is associated with several problems. In a decoder, when flipping or translating the low frequency band (ie the encoded, transmitted and decoded portion of the frequency band) to form the high frequency band, there is no certainty that the spectral peaks will differ from the original signal or the spectrum in the "true" high frequency band The peaks end up in the same frequency band. Spectral peaks from low frequency bands may end up in frequency bands where the original signal has no peaks. It is also possible that the parts of the low frequency signal that do not have peaks (after inversion or translation) end up in the frequency band where the original signal has peaks. figure 1 An example of the harmonic spectrum is provided, figure 2 An illustration of the BWE principle is provided, which will be further described below.

[0024] The effects described above can result in severe degradation of signals with ...

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Abstract

A method and apparatus for supporting bandwidth extension (BWE) of harmonic audio signals in a codec. A method in a decoder portion of a codec includes receiving a plurality of gain values ​​associated with frequency band b and a plurality of adjacent frequency bands of frequency band b. The method also includes determining whether the reconstructed corresponding frequency band b' includes a spectral peak. When the frequency band b' includes a spectral peak, the gain value associated with the frequency band b' is set to a first value based on the received plurality of gain values; otherwise the gain value is set to a second value based on the received plurality of gain values value. The invention makes the gain value consistent with the peak position in the bandwidth expansion frequency domain.

Description

technical field [0001] The present invention relates to encoding and decoding of audio signals, and more particularly, to support bandwidth extension (BWE) of harmonic audio signals. Background technique [0002] Transform-based coding is the most commonly used scheme in today's audio compression / transmission systems. The main steps of this scheme are first to convert short blocks of the signal waveform to the frequency domain by means of a suitable transform, eg DFT (Discrete Fourier Transform), DCT (Discrete Cosine Transform) or MDCT (Modified Discrete Cosine Transform) . The transform coefficients are then quantized, sent or stored and then used to reconstruct the audio signal. This scheme works for general audio signals, but requires a sufficiently high bit rate to create a sufficiently good representation of the transform coefficients. A high-level overview of this transform-domain coding scheme is given below. [0003] Transform the waveform to be encoded to the fre...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G10L21/038
CPCG10L21/0388G10L19/012G10L19/02G10L19/028G10L21/0216G10L21/0232G10L21/0316G10L21/0364G10L21/038G10L19/0204G10L25/21
Inventor 塞巴斯蒂安·内斯隆德沃洛佳·格兰恰诺夫托马斯·詹森·托夫特戈德
Owner TELEFON AB LM ERICSSON (PUBL)