Variable rate vocoder

Patent 5414796 Issued on May 9, 1995. Estimated Expiration Date:

January 14, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

32580

3633107

System for transmitting a coded voice signal
Patent #: 4012595
Issued on: 03/15/1977
Inventor: Ota

Signal synthesizer spectrum contour scaler
Patent #: 4076958
Issued on: 02/28/1978
Inventor: Fulghum

Method and apparatus for speech synthesizing
Patent #: 4214125
Issued on: 07/22/1980
Inventor: Mozer , et al.

Speech processor having speech analyzer and synthesizer
Patent #: 4360708
Issued on: 11/23/1982
Inventor: Taguchi , et al.

Method of and means for variable-rate coding of LPC parameters
Patent #: 4379949
Issued on: 04/12/1983
Inventor: Chen , et al.

Adaptive bit allocator
Patent #: 4535472
Issued on: 08/13/1985
Inventor: Tomcik

Voice encoding and decoding device
Patent #: 4610022
Issued on: 09/02/1986
Inventor: Kitayama , et al.

Voice activity detection process and means for implementing said process
Patent #: 4672669
Issued on: 06/09/1987
Inventor: DesBlache , et al.

More ...

Inventors

Application

No. 004484 filed on 01/14/1993

US Classes:

704/221, Pattern matching vocoders704/201, For storage or transmission704/222, Vector quantization704/224, Normalizing704/500AUDIO SIGNAL BANDWIDTH COMPRESSION OR EXPANSION

Examiners

Primary: MacDonald, Allen R.
Assistant: Hafiz, Tariq R.

Attorney, Agent or Firm

Miller; Russell B., English; Sean

International Class

G10L 003/02

Abstract

An apparatus and method for performing speech signal compression, by variable rate coding of frames of digitized speech samples. The level of speech activity for each frame of digitized speech samples is determined and an output data packet rate is selected from a set of rates based upon the determined level of frame speech activity. A lowest rate of the set of rates corresponds to a detected minimum level of speech activity, such as background noise or pauses in speech, while a highest rate corresponds to a detected maximum level of speech activity, such as active vocalization. Each frame is then coded according to a predetermined coding format for the selected rate wherein each rate has a corresponding number of bits representative of the coded frame. A data packet is provided for each coded frame with each output data packet of a bit rate corresponding to the selected rate.

Other References

W. Bastiaan Kleijn, Daniel J. Krasinski, and Richard H. Ketchum, "Fast Methods for the CLEP Speech Coding Algorithm". IEEE Transaction on Signal Processing vol. 38, No. 8 Aug. 1990
Richard C. Rose, Thomas P. Barnwell, III, "Design and Performance of an Analysis-by-Synthesis Class of Predictive Speech Coders". IEEE Transactions on Signal Processing, vol. 38, No. 9 Sep. 1990
Ioannis S. Dedes, Dhadesugoor R. Vaman, and Cadathur V. Chakravarthy, "Variable Rate Adaptive Predictive Filter". IEEE Transactions on Signal Processing. vol. 40, No. 3 Mar. 1992
"DSP Chips can Produce Random Numbers Using Proven Algorithm" by Paul Menner, EDN, Jan. 21, 1991, pp. 141-145
"Variable Rate Speech Coding: A Review" by N. S. Jayans, 1984 IEEE
"Variable Rate Speech Coding with Onling Segmentation and Fast Algebraic Codes" by R. DiFrancesco et al, 1990 IEEE pp. 233-236
"Finite State CELP for Variable Rate Speech Coding" by Saeed V. Vaseghi, 1990 IEEE, pp. 37-40
"Variable Rate Speech Coding for Asynchronous Transfer Mode" by Hiroshi Nakada et al., 1990 IEEE Transaction on Communications, vol. 38, No. 3, Mar. 1990, pp. 277-284
"A 4.8 KBPS Code Excited Linear Predictive Coder" by Thomas E. Tremain et al., Proceedings of the Mobile Satellite Conference, 1988
"Stochastic Coding of Speech Signals at Very Low Bit Rates" by Bishnu S. Atal, et al., 1984 IEEE
Taniguchi et al, "Combined source and channel coding based on multimode coding"; ICASSP 90: 1990 Inter. Conf. on Acoustics, Speech and Signal Processing; 3-6 Apr. 1990, pp. 477-480 vol. 1
Swaminathan et al, "Half Rate CELP codec candidate for North American digital cellular systems"; 1992 IEEE Inter. Conf. on Selected Topics in Wireless Communications; pp. 192-194
Taniguchi et al, "ADPCM with a multiquantizer for speech coding"; IEEE Journal on Selectid Areas in Communications; Feb. 1988, pp. 410-424, vol. 6 iss. 2
Atal et al. "Adaptive Predictive Coding of Speech Signals", The Bell System Technical Journal, Oct. 1970, pp. 229-238
Schroeder et al. "Stochastic Coding of Speech Signals at Very Low Bit Rates: the Importance of Speech Perception," Speech Communication 4 (1985), pp. 155-162
Schroeder et al. "Code-Excited Linear Prediction (CELP): High-Quality Speech at Very Low Bit Rates," 1985 IEEE Communications, pp. 9370940 (25.1.1-25.1.4)
Bishnu S. Atal. "Predictive Coding of Speech at Low Bit Rates", IEEE Transactions on Communications, vol. Com-30, No. 4, Apr. 1982, pp. 600-614
Shinghai et al. "Improving Performance of Multi-Pulse LPC Coders at Low Bit Rates", IEEE Transactions on Communications, 1984, pp. 1.3.1-1.3.4
Atal et al. "Stochastic Coding of Speech Signals at Very Low Bit Rates," 1984 IEEE
Wang et al. "Phonetically-Based Vector Excitation Coding of Speech at 3.6 kbps," 1989 IEEE, pp. 49-5