US 6,714,907 B2 · Codebook structure and search for speech coding

Abstract

A speech compression system with a special fixed codebook structure and a new search routine is proposed for speech coding. The system is capable of encoding a speech signal into a bitstream for subsequent decoding to generate synthesized speech. The codebook structure uses a plurality of subcodebooks. Each subcodebook is designed to fit a specific group of speech signals. A better way is used to calculate a criterion value, minimizing an error signal in a minimization loop as part of the coding system. An external signal sets a maximum bitstream rate for delivering encoded speech into a communications system. The speech compression system comprises a full-rate codec, a half-rate codec, a quarter-rate codec and an eighth-rate codec. Each codec is selectively activated to encode and decode the speech signals at different bit rates to enhance overall quality of the synthesized speech at a limited average bit rate.

Claims34

Dependent claims

A speech coding system comprising:

a speech processing circuitry disposed to receive a speech waveform,
where the speech processing circuitry comprises a codebook having a plurality of subcodebooks with at least two different subcodebooks,
where each subcodebook comprises a plurality of pulse locations for generation of at least one codevector in response to the speech waveform, and
where the plurality of subcodebooks comprise:
a first subcodebook to provide a first codevector comprising a first pulse and a second pulse;
and
a second subcodebook to provide a second codevector comprising a third pulse, a fourth pulse, and a fifth pulse.

4 more elements

Dependencies are inferred from the claim text.

Codebook structure and search for speech coding

Life of this patent

Codebook structure and search for speech coding

Life of this patent

Abstract

Claims34