Method for coding variable speed audio frequency switching between adjacent high/low speed coding modes

Abstract

The invention relates to a method for coding a variable speed audio frequency switching between adjacent high/low speed coding modes, which belongs to the field of audio coding and is particularly suitable for a multi-speed audio encoder. The method is technically characterized by comprising the following steps of: coding and decoding each frame of audio signals at a high speed, making coding input signals and decoding output signals in various coding modes at the speed pass through a sensing and weighting filter, calculating an average segmentation signal to noise ratio (SNR), and selecting a coding mode with the maximum sensing and weighting average segmentation SNR; selecting a coding mode with the maximum sensing and weighting average segmentation SNR of the coding input signals and the decoding output signals at a low coding speed close to the high speed; and finally, calculating average segmentation SNR of the coding input signals and the decoding output signals relative to the coding modes selected at the high speed and the low speed respectively, if the average segmentation SNR in the low-speed coding mode is greater than the average segmentation SNR in the high-speed coding mode, switching to the low-speed coding mode, otherwise, switching to the high-speed coding mode. By the method, each frame of audio signals are switched among various coding modes at adjacent high/low coding speeds according to distortion of the output signals relative to the input signals, so that high coding quality is kept, and the average coding speed of the audio signals is reduced simultaneously; therefore, the coding efficiency of the multi-speed audio encoder is improved.

Description

technical field [0001] The invention relates to a variable rate audio encoding method for switching between adjacent high and low rate encoding modes, especially suitable for an audio encoder including multiple encoding rates, and belongs to the field of audio encoding. Background technique [0002] The variable-rate audio coding technology is based on the statistical characteristics of the input audio signal, or the quality of the communication link, or the needs of network users to control the information transmission rate, thereby reducing the average bit rate of transmission and improving transmission efficiency. Compared with the traditional fixed The rate coding method can better save the channel bandwidth, and has been widely valued by researchers. Generally speaking, variable-rate speech coding algorithms can be divided into two categories: source-controlled or channel-controlled. The latter can be channel or network-controlled coding rate variable, which is usually ...

AI Technical Summary

Problems solved by technology

The complexity of the open-loop method is low, but it requires a robust speech frame classification algorithm, and the computational complexity of the closed-loop method is high, but the coding mode matching effect is better

VAD voice activity detection technology is a commonly used method in variable rate speech coders. It greatly reduces the overall coding rate by reducing the quantization coding bits of speech silence segments, but it is not applicable to the coding of music signals. Music signals are not like speech signals. There are about 50% silent segments during the call, and VAD technology can be used to reduce the encoding rate of the silent segments

The EVRC enhanced variable rate coder and SMV optional mode vocoder proposed in the 3GPP2 standard are both based on speech frame classification to determine the quantization coding method and coding rate of each frame, so as to reduce the overall coding rate

The AVS-P10 proposed by the AVS digital audio and video coding standard working group in my country is a multi-rate mobile voice and audio mixed codec. It is similar to the codec principle of AMR-WB+. The P10 core module adopts ACELP / TVC (Transform Vector Coding, Transform Vector Coding), both of which have 8 kinds of monophonic coding rates and 16 kinds of stereo coding rates, both of which are channel-controlled variable rates Encoding, but did not use the source control variable rate encoding method, especially for music signals, there is no suitable source control variable rate method

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