Multimode speech coding apparatus and decoding apparatus

• US 20070088543A1
• Filed: 12/12/2006
• Published: 04/19/2007
• Est. Priority Date: 01/11/2000
• Status: Active Grant

• Current Assignee: III Holdings 12, LLC (Intellectual Ventures LLC)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Ehara, Hiroyuki
• Granted Patent: US 7,577,567 B2
• Time in Patent Office: Days
• US Class Current: 704/223
• CPC Class Codes: G10L 19/07 Line spectrum pair [LSP] vocoders
• CPC Class Codes: G10L 19/18 Vocoders using multiple modes
• CPC Class Codes: G10L 2025/783 based on threshold decision

Abstract

Square sum calculator 603 calculates a square sum of evolution in smoothed quantized LSP parameter for each order. A first dynamic parameter is thereby obtained. Square sum calculator 605 calculates a square sum using a square value of each order. The square sum is a second dynamic parameter. Maximum value calculator 606 selects a maximum value from among square values for each order. The maximum value is a third dynamic parameter. The first to third dynamic parameters are output to mode determiner 607, which determines a speech mode by judging the parameters with respective thresholds to output mode information.

Claims

1. A multimode speech decoding apparatus comprising:

first decoding means for decoding at least one type of parameter indicative of vocal tract information contained in a speech signal;

second decoding means for being capable of decoding said at least one type of parameter indicative of vocal tract information contained in the speech signal with a plurality of decoding modes;

mode determining means for determining a mode based on a dynamic characteristic of a specific parameter decoded in said first decoding means; and

synthesis means for decoding the speech signal using a plurality of types of parameter information decoded in said first decoding means and said second decoding means,

wherein said mode determining means comprises;

means for calculating an evolution of a quantized LSP parameter between frames;

means for calculating an average quantized LSP parameter on a frame where the quantized LSP parameter is stationary; and

means for calculating a distance between the average quantized LSP parameter and a current quantized LSP parameter, and detecting a predetermined amount of a difference in a particular order between the quantized LSP parameter and the average quantized LSP parameter.

2. A mode determining apparatus comprising:

first decoding means for decoding at least one type of parameter indicative of vocal tract information contained in a speech signal;

second decoding means for being capable of decoding said at least one type of parameter indicative of vocal tract information contained in the speech signal with a plurality of decoding modes; and

mode determining means for determining a mode based on a dynamic characteristic of a specific parameter decoded in said first decoding means.

3. A multimode speech coding apparatus comprising:

first coding means for coding at least one type of parameter indicative of vocal tract information contained in a speech signal;

second coding means for being capable of coding said at least one type of parameter indicative of vocal tract information contained in the speech signal with a plurality of modes;

mode determining means for determining a mode of said second coding means based on a dynamic characteristic of a specific parameter coded in said first coding means; and

synthesis means for synthesizing an input speech signal using a plurality of types of parameter information coded in said first coding means and said second coding means,

wherein said mode determining means comprises;

means for calculating an evolution of a quantized LSP parameter between frames;

means for calculating an average quantized LSP parameter on a frame where the quantized LSP parameter is stationary; and

means for calculating a distance between the average quantized LSP parameter and a current quantized LSP parameter, and detecting a predetermined amount of difference in a particular order between the quantized LSP parameter and the average quantized LSP parameter.