G.729 CS-ACELP
Speech Coder
by Atlanta Signal Processors, Inc.

Software Overview

ITU G.729 CS-ACELP (Conjugate-Structure Algebraic Code-Excited Linear-Predictor) is a speech coding 
and decoding standard that provides 4-kHz speech bandwidth at a bit rate of 8 kbps. The full 
algorithm implementation runs on a single `C31 DSP and has quality similar to the ITU G.728 16-kbps 
coding standard. The implementation passes all the floating-point tests provided by the ITU for 
algorithm verification.
The standard specifies a code-excited linear predictive coder (CELP) that uses an algebraic 
codebook to code the excitation signal. The coder operates on speech frames of 10 ms (80 samples at 
an 8-kHz sample rate), computes the long-term predictor coefficients, and operates in an 
analysis-by-synthesis loop to find the excitation vector that minimizes the perceptually weighted 
error signal.

Features and Benefits

•	Code is C callable and relocateable
•	High-quality 8 kbps
•	Fully compliant with ITU G.729 specifications
•	Full-duplex real-time capability on a single TMS320C3x DSP

Processor and System Specifications

•	Final requirements for TMS320C3x not available at press time.

Usage Limitations or Performance Considerations

•	None

Algorithm Verification

•	The implementation is compatible with all the digital test sequences provided by the ITU for 
algorithm verification.

Availability

•	Available April 1996 from Atlanta Signal Processors, Inc.
•	Object code, source code, and run-time license provided by Atlanta Signal Processors, Inc.

Company Background and Contact Information

Atlanta Signal Processors was founded in 1981 by Ronald W. Schafer, Thomas P. Barnwell III, and 
Russell M. Mersereau, three Professors of Electrical Engineering at the Georgia Institute of 
Technology with over 80 years of experience in the field. The company has focused its efforts on 
developing tools for professional signal-processing design engineers and now offers digital 
signal-processing hardware and software products to DSP designers worldwide.

Contact:	Atlanta Signal Processors, Inc.
		1375 Peachtree St. NE, Suite 690
		Atlanta, Georgia  30309-3115
		(404) 892-7265
		Fax: (404) 892-2512
		e-mail: aspi@aspi.com