Title:
SIGNAL FORMING TYPE ADAPTIVE CODE BOOK BY INDEX
Document Type and Number:
Japanese Patent JP3206497
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To reduce the probability to generate different sounds by the dissidence of the code books of an encoder and a decoder by reforming an adaptive code width by an excitation signal forming means from the past index information of a certain section.
SOLUTION: An index memory means 101 outputs a fixed code book index before i frame to a fixed code book 102 and an adaptive code book index to an excitation signal memory means 104. The output signal of the fixed code book 102 is subjected to gain regulation by a gain regulator 103 and the output signal of the excitation signal memory means 104 to the gain regulation by a gain regulator 105. These two signals are thereafter synthesized by a synthesizing means 106, by which the excitation signal is formed. The excitation signal memory means 104 is inputted with this excitation signal, by which the internal state of the excitation signal memory means 104 is updated. Similarly, the excitation signal is formed by using the indices from i-1 frame before to 1 frame before from an index memory means 101. The excitation signal is then outputted to the adaptive code book 107 in order for use as the code book of the current frame.
Inventors:
Hideo Sano
Application Number:
JP15817497A
Publication Date:
September 10, 2001
Filing Date:
June 16, 1997
Export Citation:
Assignee:
NEC
International Classes:
G10L19/00; G10L19/08; G10L19/09; G10L19/12; G10L19/125; H03M7/30; H04B14/04; (IPC1-7): G10L19/12; G10L19/00; H03M7/30; H04B14/04
Domestic Patent References:
| JP6175695A | ||||
| JP9134198A | ||||
| JP863200A |
Attorney, Agent or Firm:
Hiroo Suzuki