Code excitation linear predictive (CELP) encoder and decoder and code excitation linear predictive coding method
First Claim
1. A code excitation linear predictive coding apparatus comprising:
- excitation codebook means for selectively outputting an excitation code vector as an excitation source information of a speech signal; and
code vector conversion circuit means for converting the excitation code vector selectively output from the excitation codebook means into a frequency characteristic determined at the time of output of said excitation code vector.
1 Assignment
0 Petitions
Accused Products
Abstract
There is provided a code excitation linear predictive (CELP) coding or decoding apparatus in which a code vector, which is transmitted by a codebook such as a stochastic codebook, is converted adaptively in accordance with vocal tract analysis information (LPC) so that a high quality reproduction speech is obtained at a low coding rate. Further, in order to obtain a similar effect, a pulse-like excitation codebook formed of an isolated impulse is provided in addition to the adaptive excitation codebook and stochastic excitation codebook so that either the stochastic excitation codebook or the pulse-like excitation codebook is selectively used to provide a vocal tract parameter as a linear spectrum pair parameter.
-
Citations
22 Claims
-
1. A code excitation linear predictive coding apparatus comprising:
-
excitation codebook means for selectively outputting an excitation code vector as an excitation source information of a speech signal; and code vector conversion circuit means for converting the excitation code vector selectively output from the excitation codebook means into a frequency characteristic determined at the time of output of said excitation code vector. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A code excitation linear predictive decoding apparatus comprising:
-
excitation codebook means for selectively outputting an excitation code vector as an excitation source information of a speech signal; and code vector conversion circuit means for converting the excitation code vector selectively output from the excitation codebook into a frequency characteristic determined at the time of output of said excitation code vector. - View Dependent Claims (8, 9, 10, 11, 12)
-
-
13. A code excitation linear predictive coding apparatus comprising:
-
excitation codebook means for outputting an excitation code vector as an excitation source information of a speech signal; and pulse-like excitation codebook means for storing a pulse-like excitation code vector composed of an unit impulse. - View Dependent Claims (14, 15, 16)
-
-
17. A code excitation linear predictive decoding apparatus comprising:
-
excitation codebook means for outputting an excitation code vector as an excitation source information of a speech signal; and pulse-like excitation codebook means for storing a pulse-like excitation code vector composed of an unit impulse. - View Dependent Claims (18, 19)
-
-
20. A code excitation linear predictive coding method comprising the steps of:
-
selectively outputting an excitation code vector from an excitation codebook as an excitation source information of a speech signal; converting the excitation code vector into a converted code vector having a frequency characteristic; and multiplying the converted code vector by a gain output from a gain codebook. - View Dependent Claims (21, 22)
-
Specification