Audio-frequency signal coding method and apparatus

Abstract

The method samples audio signals and divides up the signals into multiple positive and negative half waves. Sounding / not sounding determination is carried out for half wave based on up / low threshold frequency. Sub code books for corresponding dimension are searched respectively for multiple half waves determined as sounding based on number of sampled points contained between two zero points i.e. vector dimension of the half wave. Vector quantization is carried out for the sub code books to form output index. Since length of sub code book corresponding to each half wave is much smaller than length of total code book, the method reduces operation quantity of searching codes in vector quantization without lowering hearing quality of decoded audio signal. The invention also discloses decoding method and devices for executing the encoding and decoding methods.

Description

technical field [0001] The present invention relates to a method for encoding an audio signal, in particular, but not exclusively, to a method and device for encoding a speech signal. Background technique [0002] There are many encoding methods for audio signals. The traditional waveform encoder uses the method of reducing the quantization error to make the reconstructed audio converge towards the original audio signal; the parametric encoder uses the mathematical model of audio generation to extract the characteristic parameters of the audio signal, and according to The model parametrically reconstructs the audio signal. [0003] Compared with the parametric encoder, the waveform encoder has its own advantages and disadvantages. Generally speaking, the waveform encoder has the advantages of good sound quality and low complexity, but the bit rate is high, such as the adaptive differential pulse code with a bit rate of 32Kbit / s Modulation (ADPCM, ITU-T G.726), the complexit...

AI Technical Summary

Problems solved by technology

The vector quantization method can provide performance exceeding scalar quantization at a very low bit rate, but if the number of code vectors contained in the codebook is large, it will increase the number of search operations to find a matching code vector for the input vector, obviously greatly increases the workload of codebook search processing, and also increases the complexity of the corresponding audio signal encoder

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