Speech gain quantization strategy

• US 20070255559A1
• Filed: 07/12/2007
• Published: 11/01/2007
• Est. Priority Date: 05/19/2000
• Status: Active Grant

• Current Assignee: DigiMedia Tech, LLC (IP Investments Group LLC)
• Original Assignee: Mindspeed Technologies Inc. (MACOM Technology Solutions Holdings, Inc.), Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Gao, Yang, Benyassine, Adil
• Granted Patent: US 7,660,712 B2
• Time in Patent Office: Days
• US Class Current: 704/225
• 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 19/083 the excitation function being an excitation gain G10L25/90 takes precedence
• 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 19/18 Vocoders using multiple modes
• 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 encoder that analyzes and classifies each frame of speech as being periodic-like speech or non-periodic like speech where the speech encoder performs a different gain quantization process depending if the speech is periodic or not. If the speech is periodic, the improved speech encoder obtains the pitch gains from the unquantized weighted speech signal and performs a pre-vector quantization of the adaptive codebook gain G_P for each subframe of the frame before subframe processing begins and a closed-loop delayed decision vector quantization of the fixed codebook gain G_C. If the frame of speech is non-periodic, the speech encoder may use any known method of gain quantization. The result of quantizing gains of periodic speech in this manner results in a reduction of the number of bits required to represent the quantized gain information and for periodic speech, the ability to use the quantized pitch gain for the current subframe to search the fixed codebook for the fixed codebook excitation vector for the current subframe. Alternatively, the new gain quantization process which was used only for periodic signals may be extended to non-periodic signals as well. This second strategy results in a slightly higher bit rate than that for periodic signals that use the new gain quantization strategy, but is still lower than the prior art'"'"'s bit rate. Yet another alternative is to use the new gain quantization process for all speech signals without distinguishing between periodic and non-periodic signals.

Claims

1-76. -76. (canceled)

77. A speech encoding system that receives a speech signal, the speech encoding system comprising:

a frame processor for processing a frame of the speech signal, the frame processor including;

a pitch gain generator that derives unquantized pitch gains; and

a first vector quantizer that receives the unquantized pitch gains and generates quantized pitch gains;

a subframe processor that begins subframe processing after the pitch gain generator has derived the quantized pitch gains and the first vector quantizer has generated the quantized pitch gains.