Time Scaling
by D2 Technologies, Inc.

Software Overview

D2's Time Scaling algorithm module modifies the speaking rate of a voice recording without 
affecting the intelligibility or speaker quality of the voice. Speed-up lets the listener scan 
through the recording quickly without missing any important information. Slow-down allows the user 
to slow the recording to interpret unintelligible information and to aid in recording 
transcription.
Designed to the VP Open interface, the Time Scaling module easily integrates with other VP Open 
modules, runs in real-time concurrently with other VP Open modules, and handles any number of voice 
ports assigned to the DSP. Like all of D2's algorithm modules, Time Scaling consists of robust 
software that is rigorously tested.

Features and Benefits

•	Speeds up voice by ratios of: 2:1, 3:2, and 4:3 without affecting the speaker's voice quality and 
while preserving the intelligibility of the voice
•	Speed-up or slow-down rate can be changed "on the fly"
•	Slows down voice by ratios of: 1:2, 2:3, and 3:4 without affecting the speaker's voice quality 
and while preserving the intelligibility of the voice
•	Accepts telephone band codec or linear data

Processor and System Specifications

•	Devices supported: TMS320C2xx, TMS320C5x
•	DSP resource required:
•	Algorithm category: Audio, Telecommunications
TMS320C2xx (Est.)
TMS320C5x
Program memory
0.7 kwords
0.6 kwords
Data memory/port
1.5 kwords
1.3 kwords
Processor loading
worst case
3.7 MIPS (1:2 slowdown), 
1.9 MIPS (2:1 speed up)
3.4 MIPS (1:2 slowdown), 
1.7 MIPS (2:1 speed up)

Usage Limitations or Performance Considerations

•	The host, voice data input and output, memory allocation, and module to module communication 
interfaces must conform to VP Open as described in the VP Open Software Interface Specification.

Algorithm Verification

D2's Time Scaling algorithm module is validated through the following suite of tests:
•	D2 time scaling unit test with male and female speech samples at different speaking rate that are 
processed and listed to for voice quality and intelligibility
•	VP Open interface validation – the Time Scaling algorithm module is integrated with other VP Open 
modules and tested concurrently in real-time on the D2 VDS50 system for multiple voice ports

Availability

Currently available for the TMS320C5x. A demonstration package is currently available for the TI 
EVM50 DSP board. A demonstration cassette tape or a live over-the-phone demonstration is also 
available. Implementation for the TMS320C2xx will be available 2Q 1996.

Company Background and Contact Information

D2 Technologies, Inc. was founded by David Y. Wong and David M. Lindsay to help companies innovate 
telecommunications and information products with voice processing technology, which include 
telephony and voice algorithms, real-time system software, and development services.
With over 20 years of experience, D2's business model is to develop close partnerships with its 
customers via high levels of service and special engineering to ensure mutual success.
Contact:	D2 Technologies, Inc.
		Attn:  Product Sales
		104 West Anapamu Street
		Suite J
		Santa Barbara,  CA 93101
		(805) 564-3424
		Fax:  (805) 966-2144
		e-mail:  sales@d2tech.com