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Audio signal encoding and decoding method

An audio signal encoding and decoding method technology, applied in the field of audio signal processing, can solve the problems of affecting sound quality, affecting auditory experience, low cut-off frequency, etc., and achieve the effect of ensuring encoding sound quality, reducing encoding bit requirements, and wide and universal applicability

Inactive Publication Date: 2008-06-11
昆山杰得微电子有限公司
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Problems solved by technology

However, if the cut-off frequency is already very low (such as 3Khz or lower) when the sub-band coding method is used for coding in the case of low bit rate (such as below 10kbps), if the method of reducing the cut-off frequency is still used, the coding will be seriously affected The post-auditory experience directly affects the final encoded sound quality

Method used

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Embodiment

[0026] Take the following situation as an example to specifically illustrate the process of implementing the present invention: (1) the spectrum index number corresponding to the high-frequency start frequency point is 200, (2) the spectrum index number corresponding to the cut-off frequency is 400, (3) downsampling The multiple is doubled.

[0027] Then the encoding side:

[0028] 1) Obtain 400 spectrum values ​​below the cutoff frequency through normal time-domain to frequency-domain signal conversion, a total of 400;

[0029] 2) Take the average value of every two frequency points in turn to obtain a spectrum value at a low frequency resolution, a total of 100;

[0030] 3) 200 values ​​in the low frequency band and 100 values ​​in the low frequency resolution form a mixed frequency resolution spectrum (300 values);

[0031] 4) Perform normal spectral coding according to the mixed frequency resolution spectrum to form a final coded code stream.

[0032] Decoder:

[0033]...

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Abstract

The invention discloses a method for coding and decoding an audio signal, which comprises a coding step and a decoding step. The method adopts a policy of mixed resolution coding of different frequency resolutions of high and low frequency ranges, so that higher cut-off frequency can be acquired based on not changing the prior broadband frequency spectrum coding framework; because only the high frequency part corresponding to the audio signal is conducted with a processing of reducing the frequency resolution, the coding tone can be furthest guaranteed on the premise of reducing requirement of coding bit, so that the tone effect which is difficult to fulfill for general parameter coding can be received. The invention can be completely applied without changing the coding / decoding architecture, so the invention has the widest general applicability.

Description

technical field [0001] The invention relates to the technical field of audio signal processing, in particular to an audio signal encoding and decoding method. Background technique [0002] Current audio coding methods can be broadly classified into parametric coding and subband-based spectral coding. Parameter-based coding is mainly used for low bit rates, while subband-based spectral coding is mainly used for medium or high bit rates. Although parametric encoding can be encoded at a lower bit rate, the sound quality is significantly lost after encoding / decoding. The sub-band spectrum coding method can code a bit stream with higher sound quality, but it needs to occupy a higher bit rate. Since the number of bits (bits) generated by spectral coding accounts for the largest proportion in the wideband coding process, in order to significantly reduce the coding bit occupation, it is most possible to reduce the coding occupancy rate of the spectral coding part, and it is also t...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03M7/30G10L19/02G10L19/20
Inventor 周毅欧阳合邹艳
Owner 昆山杰得微电子有限公司
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