Speech encoding at variable bit rate
First Claim
1. A speech encoding method for variable-rate encoding a speech signal, comprising the steps of:
- a speech signal is divided into speech frames for speech encoding by frames,a first analysis is made for a divided speech frame in order to form a first product, comprising a number of first prediction parameters for modeling the divided speech frame in a first interval,a second analysis is made for the divided speech frame in order to form a second product, comprising a number of second prediction parameters for modeling the divided speech frame in a second interval, andsaid first and second prediction parameters are presented in digital form, whereinbased upon the first and the second products obtained in the first analysis and the second analysis, the number of bits used for presenting one of the following parameters is determined;
the first prediction parameters, the second prediction parameters and a combination of them, andthe speech signal is encoded by a bit stream comprising a determined number of bits representing said first and said second prediction parameters.
1 Assignment
0 Petitions
Accused Products
Abstract
The invention is related digital speech encoding. In a speech codec according to the invention, for modeling a speech signal (301) both prediction parameters (321, 322, 331) modeling a speech signal in a short term and prediction parameters (341, 342, 351) modeling a speech signal in a long term are used. Each prediction parameter (321, 322, 331, 341, 342, 351) is presented using a certain accuracy, in a digital system with a certain number of bits. In speech encoding according to the invention the number of bits used for presenting prediction parameters (321, 322, 331, 341, 342, 351) is adjusted based upon information parameters (321, 322, 331, 341, 342, 351) obtained from a short-term LPC-analysis (32) and from a long-term LTP-analysis (31, 34, 35). The invention is particularly suitable for use at low data transfer speeds, because it offers a speech encoding method of even quality and low average bit rate.
110 Citations
9 Claims
-
1. A speech encoding method for variable-rate encoding a speech signal, comprising the steps of:
-
a speech signal is divided into speech frames for speech encoding by frames, a first analysis is made for a divided speech frame in order to form a first product, comprising a number of first prediction parameters for modeling the divided speech frame in a first interval, a second analysis is made for the divided speech frame in order to form a second product, comprising a number of second prediction parameters for modeling the divided speech frame in a second interval, and said first and second prediction parameters are presented in digital form, wherein based upon the first and the second products obtained in the first analysis and the second analysis, the number of bits used for presenting one of the following parameters is determined;
the first prediction parameters, the second prediction parameters and a combination of them, andthe speech signal is encoded by a bit stream comprising a determined number of bits representing said first and said second prediction parameters. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A telecommunication system comprising communication means such as mobile stations, base stations, base station controllers, mobile communication switching centers, telecommunication networks and terminal devices for establishing a telecommunication connection and transferring information between said communication means,
said communication means comprise a speech encoder operative with a variable rate of coding, which said speech encoder further comprises means for dividing a speech signal into speech frames for encoding by frames, means for performing a first analysis to a divided speech frame in order to form a first product, which first product comprises prediction parameters modeling the divided speech frame in a first interval, means for performing a second analysis to the divided speech frame in order to form a second product which second product comprises prediction parameters modeling the divided speech frame in a second interval, and means for outputting a coded speech signal by presenting the first and the second prediction parameters in a digital form, wherein said speech encoder further comprises means for analyzing the performance of the first analysis and the second analysis, based upon the first product and the second product, and that said performance analyzing means have been arranged to determine the number of bits used for presenting one of the following parameters: - the first prediction parameters, the second prediction parameters, and a combination of them.
-
7. A communication device comprising means for transferring speech and a speech encoder for speech encoding, which speech encoder is operative with a variable rate of coding and comprises
means for dividing a speech signal into speech frames for speech encoding by frames, means for performing a first analysis to a divided speech frame in order to form a first product, which first product comprises first prediction parameters modeling the divided speech frame in a first interval, means for performing a second analysis to the divided speech frame in order to form a second product, which second product comprises second prediction parameters modeling the divided speech frame in a second interval, and means for outputting a coded speech signal by presenting the first and the second prediction parameters in a digital form, wherein said speech encoder further comprises means for analyzing the performance of the first analysis and the second analysis of the speech encoder based upon the first product and the second product, and that said performance analyzing means have been arranged to determine the number of bits used for presenting one of the following parameters: - the first prediction parameters, the second prediction parameters and a combination of them.
-
8. A speech encoder operative with a variable rate of coding, comprising:
-
means for dividing a speech signal into speech frames for speech encoding by frames, means for performing a first analysis to a divided speech frame in order to form a first product, which first product comprises first prediction parameters modeling the divided speech frame in a first interval, means for performing a second analysis to the divided speech frame in order to form a second product, which second product comprises second prediction parameters modeling the divided speech frame in a second interval, and means for outputting a coded speech signal by presenting the first and the second prediction parameters in a digital form, wherein said speech encoder further comprises means for analyzing the performance of the first analysis and the second analysis of the speech encoder based upon the first product and the second product, and that said performance analyzing means have been arranged to determine the number of bits used for presenting one of the following parameters;
the first prediction parameters, the second prediction parameters and a combination of them.
-
-
9. A speech encoder operative with a variable rate of coding, comprising:
-
generating means for outputting a coded speech signal, and means for receiving speech from a telecommunication connection in form of speech parameters, which speech parameters comprise first prediction parameters for modeling speech in a first interval and second prediction parameters for modeling speech in a second interval, wherein said generating means comprise a mode selector, said speech parameters comprise information parameters, said mode selector has been arranged to select a correct speech decoding mode for the first prediction parameters and the second prediction parameters based upon said information parameters.
-
Specification