System of encoding and decoding speech signals

• US 20030200092A1
• Filed: 04/08/2003
• Published: 10/23/2003
• Est. Priority Date: 09/22/1999
• Status: Active Grant

• Current Assignee: Wi-LAN Inc.
• Original Assignee: Mindspeed Technologies Inc. (MACOM Technology Solutions Holdings, Inc.)
• Inventors: Shlomot, Eyal, Gao, Yang, Thyssen, Jes, Su, Huan-Yu, Benyassine, Adil
• Granted Patent: US 6,735,567 B2
• Time in Patent Office: Days
• US Class Current: 704/258
• CPC Class Codes: G10L 19/00 Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H
• CPC Class Codes: G10L 19/167 Audio streaming, i.e. formatting and decoding of an encoded audio signal representation into a data stream for transmission or storage purposes
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding
• CPC Class Codes: H03G 3/00 Gain control in amplifiers or frequency changers

Abstract

A speech compression system capable of encoding a speech signal into a bitstream for subsequent decoding to generate synthesized speech is disclosed. The speech compression system optimizes the bandwidth consumed by the bitstream by balancing the desired average bit rate with the perceptual quality of the reconstructed speech. The speech compression system comprises a full-rate codec, a half-rate codec, a quarter-rate codec and an eighth-rate codec. The codecs are selectively activated based on a rate selection. In addition, the full and half-rate codecs are selectively activated based on a type classification. Each codec is selectively activated to encode and decode the speech signals at different bit rates emphasizing different aspects of the speech signal to enhance overall quality of the synthesized speech.

Claims

1. A speech compression system for encoding and decoding frames of a speech signal to generate synthesized speech comprising:

a full-rate codec operable to encode and decode the frames, the full-rate codec being selectively activatable based on a rate selection and a type classification of each frame;

a half-rate codec operable to encode and decode the frames, the half-rate codec being selectively activatable based on the rate selection and the type classification of each frame;

a quarter-rate codec operable to encode and decode the frames, the quarter-rate codec being selectively activatable based on the rate selection; and

an eighth-rate codec operable to encode and decode the frames, the eighth-rate codec being selectively activatable based on the rate selection.