Method and system for encoding and decoding audio signal

A technology of audio signal and coding method, which is applied in the direction of binaural system, stereo system, speech analysis, etc., and can solve the problem of sound quality loss and so on

Active Publication Date: 2008-06-18
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method significantly reduces the bit rate, but because it cannot reconstruct spectral details, it also brings a certain loss of sound quality, so it is mainly used for higher frequency sub-bands that are not sensitive to human ears

Method used

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  • Method and system for encoding and decoding audio signal
  • Method and system for encoding and decoding audio signal
  • Method and system for encoding and decoding audio signal

Examples

Experimental program
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Embodiment 1

[0126] Referring to Fig. 1, the embodiment of the present invention provides a kind of coding method of audio signal, specifically comprises the following steps:

[0127] Step 101: Perform time-frequency conversion on the time-domain audio signals of the left and right channels;

[0128] The input is the time-domain audio signal of the left and right channels, and the output is the frequency-domain audio signal of the left and right channels. Here, FFT (FastFlourier Transform, Fast Fourier Transform), MDCT (Modified Discrete Cosine Transform, Modified Discrete Cosine Transform), or PQMF (Polyphase Quadrature Mirror Filterbank, polyphase filter bank) to achieve.

[0129] Step 102: dividing subbands;

[0130] The frequency-domain audio signals of the left and right channels are output as continuous non-overlapping sub-bands divided according to a certain bandwidth. The bandwidth of the sub-bands matches the human auditory characteristics. From low frequency to high frequency, t...

Embodiment 2

[0165] Referring to Fig. 2, an embodiment of the present invention provides a decoding method of an audio signal, which specifically includes the following steps:

[0166] Step 111: Decompose the coded code stream into an audio code stream and a parameter code stream.

[0167] Step 112: Perform entropy decoding and inverse quantization on the audio code stream and the parameter code stream respectively to obtain spectrum data and rotation angles.

[0168] Step 113: According to the stereo encoding mode, perform corresponding sum-difference or intensity stereo decoding to obtain two channels of related sub-band signals.

[0169] Step 114: Perform maximum correlation inverse rotation on the two channels of sub-band signals to output the left and right sub-band signals.

[0170] Step 115: Perform time-frequency synthesis on the left and right sub-band signals to reconstruct the digital audio signals of the left and right channels in the time domain.

[0171] In this embodiment, t...

Embodiment 3

[0174] Referring to FIG. 3 , an embodiment of the present invention provides an audio signal encoding system, including time-frequency analysis units 501 and 502, a maximum correlation rotation transformation unit 503, a sum difference or intensity stereo encoding unit 504, and a quantization entropy encoding unit 505 and 506, and a code stream shaping module unit 507.

[0175] Time-frequency analysis units 501 and 502 are used to perform time-frequency transformation on the signals of the left and right channels respectively, which can be FFT, MDCT, or polyphase filter bank;

[0176] The maximum correlation degree rotation transformation unit 503 is a core unit, through the transformation described in (3) formula, and the rotation angle is determined by (5) formula, to obtain the two-way sub-band signals with the maximum correlation degree under the orthogonal rotation transformation;

[0177] The sum difference or intensity stereo coding unit 504 selects the sum difference o...

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Abstract

The invention discloses a coding method of audio signals and a system thereof and a decoding method and a system thereof, pertaining to the field of processing multimedia signals and source coding. The coding method comprises: orthogonal rotating transforming left-right track audio signals by taking an extremely large related degree rotation angle as a rotating angle; the orthogonal rotating transformed left-right track audio signals are coded. The decoding method comprises: decoding received code stream data and then outputting the decoded audio signals; orthogonal inverse rotating transforming the decoded audio signals by taking an extremely large related degree rotation angle as a rotating angle. The coding system comprise: an extremely large related degree rotation transforming module and a coding module. The decoding system comprises: a decoding module and an extremely large related degree inverse rotation transforming module. The invention records stereo information through a small quantity of parameters of the extremely large related degree rotation angles and can utilize very low code rate to realize the high fidelity compression of the stereo audio signals.

Description

technical field [0001] The invention relates to the fields of multimedia signal processing and information source coding, in particular to an audio signal coding method and system and a decoding method and system. Background technique [0002] Stereo signals come from two main sources, natural recordings with two or more microphones, and artificial mixing in an audio studio. The audio of each channel of the former comes from the same audio scene. Except for the time difference and intensity difference caused by the microphone placement, the audio information recorded by them is basically the same, so there is a strong correlation. The latter strives for a realistic audio scene in most cases and therefore also has a strong correlation between channels. [0003] Using this correlation to reduce the bit rate of stereo coding is an important research topic in the field of audio coding. What was proposed earlier was Sum-difference Stereo. In this method, the left channel L and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G10L19/00H04S1/00G10L19/008
Inventor 张树华窦维蓓
Owner TSINGHUA UNIV
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