US 8,620,647 B2 · Selection of scalar quantixation (SQ) and vector quantization (VQ) for speech coding

Abstract

In accordance with one aspect of the invention, a selector supports the selection of a first encoding scheme or the second encoding scheme based upon the detection or absence of the triggering characteristic in the interval of the input speech signal. The first encoding scheme has a pitch pre-processing procedure for processing the input speech signal to form a revised speech signal biased toward an ideal voiced and stationary characteristic. The pre-processing procedure allows the encoder to fully capture the benefits of a bandwidth-efficient, long-term predictive procedure for a greater amount of speech components of an input speech signal than would otherwise be possible. In accordance with another aspect of the invention, the second encoding scheme entails a long-term prediction mode for encoding the pitch on a sub-frame by sub-frame basis. The long-term prediction mode is tailored to where the generally periodic component of the speech is generally not stationary or less than completely periodic and requires greater frequency of updates from the adaptive codebook to achieve a desired perceptual quality of the reproduced speech under a long-term predictive procedure.

Claims16

Dependent claims

A method of coding a speech signal using a multi-rate speech coder having an adaptive codebook, a fixed codebook, and a coding rate selected from a plurality of coding rates including a first coding rate and a second coding rate, the method comprising:

obtaining an adaptive codebook gain;
obtaining a fixed codebook gain;
scalar quantizing the adaptive codebook gain and the fixed codebook gain for coding the speech signal, if the coding rate is the first coding rate, to generate a first quantized adaptive codebook gain and a first quantized fixed codebook gain;
vector quantizing the adaptive codebook gain and the fixed codebook gain for coding the speech signal, if the Coding rate is the second coding rate, to generate a second quantized adaptive codebook gain and a second quantized fixed codebook gain;
converting the speech signal into a first encoded speech using the first quantized adaptive codebook gain and the first quantized fixed codebook gain if the coding rate is the first coding rate;
and
converting the speech signal into a second encoded speech using the second quantized adaptive codebook gain and the second quantized fixed codebook gain if the coding rate is the second coding rate.

4 more elements

Dependencies are inferred from the claim text.

Selection of scalar quantixation (SQ) and vector quantization (VQ) for speech coding

Life of this patent

Selection of scalar quantixation (SQ) and vector quantization (VQ) for speech coding

Life of this patent

Abstract

Claims16