Speech coding system to improve packet loss repairing quality

Abstract

A method of significantly reducing error propagation due to voice packet loss, while still greatly profiting from long-term pitch prediction, is achieved by adaptively limiting the maximum value of the pitch gain for the first pitch cycle within one frame. A speech coding system for encoding a speech signal, wherein said a plurality of speech frames are classified into said a plurality of classesdepending on if the first pitch cycle is included in one subframe or several subframes. The pitch gain is set to a value significantly smaller than 1 for the subframes covering first pitch cycle; wherein the pitch gain reduction is compensated by increasing the coded excitation codebook size or adding one more stage of excitation for the subframes covering the first pitch cycle.

Description

technical field [0001] The present invention belongs to the field of signal coding. Specifically speaking, the field of speech coding; especially for improving the compensation of performance after packet loss during speech packet transmission. Background technique [0002] Traditionally, all parametric speech coding methods often use the redundancy of the speech signal itself to reduce the amount of information that must be transmitted and estimate the parameters of the speech signal in a short period of time. This redundancy is firstly caused by the periodic repetition of the speech waveform and the slow change of the spectrum envelope. [0003] The redundancy of different forms of speech waveforms corresponds to different types of speech signals, such as voiced and unvoiced. In the case of voiced speech, the speech signal is essentially periodic; however, this periodicity varies within speech segments, and the periodic waveform varies slowly between speech segments. Sp...

AI Technical Summary

Problems solved by technology

Although this method solves the problem of error propagation, it also sacrifices the quality when there is no packet loss, or can only compensate for the loss of quality at a higher bit rate.

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