Audio Library
for TMS320C3x/'C4x
by DSP Software Engineering, Inc.

Software Overview

The Audio Library software is a package of audio utilities for the TMS320C3x. These utilities are 
intended for voice-storage-type applications. The following package modules operate on linear PCM 
samples:
Automatic Gain Control (AGC): Adaptively controls the dynamic range of a signal. If used with the 
VAD module, AGC controls the dynamic range of speech without amplifying the noise between words.
Voice Activity Detection (VAD): Detects short-term and long-term speaker activity.
Loudness Measurement (LDN): Generates a loudness measure for any speech signal.
VAD and Loudness Control (VLD): Provides an integration of the VAD and LDN modules.
Volume Control (VOL): Controls gain of an I/O signal; typically coupled with user instrumentation.

Features and Benefits

•	User-selectable processing frame sizes
•	Independent, C-callable, object-based functions
•	Sample-rate independent
•	SPOX compatible
•	Configurable control for VAD sensitivity, gain correction, dynamic range, and tracking rate

Processor and System Requirements

•	Devices supported: TMS320C3x, TMS320C4x
•	Algorithm category: Telecommunications
•	Requirements:
All memory requirements are in units of 32-bit words. The MIPs ratings presented require the listed 
amounts of on-chip, zero-wait-state program and data memory, and a processing frame size of 160 
samples. All measurements were made using an executable demonstration built for a third-party PC 
plug-in board.
Function
MIPS
Chip RAM
Data
Program
AGC
0.15
0
50
300
LDN
0.07
0
25
150
VAD
0.04
0
75
350
VLD
0.11
0
125
750
VOL
0.02
0
10
100

User Functions

The Audio Library implementation consists of five independent, C-callable functions that perform 
various audio-processing operations. It also includes functions that reflect the implementation's 
object-based interface. The Audio Library functions interface with arrays of linear PCM samples.
AUDLIB Processing Functions
AGC_update (...)
Update gain measurement and (optionally) gain correct the input
LDN_update (...)
Update signal-loudness measurement
VAD_detect (...)
Return voice-activity-detection status
VLD_detect (...)
Return VAD status and loudness measurement
VOL_update (...)
Update volume level of the input data
Interface Functions (general form)
XXX*_create (...)
Dynamically allocates and initializes data memory for the software object
XXX*_delete (...)
Frees object's usage of dynamically-allocated data memory
* The XXX is the mnemonic for each module (AGC, LDN, VAD, ...)

Company Background and Contact Information

DSP Software Engineering, Inc (DSPSE), founded in 1989, is a leading provider of highly-complex 
digital-signal-processing software used in telecommunications and multimedia applications such as 
computer telephony, digital wireless, PSTN, and satellite communications, and videoconferencing.
Contact:	DSP Software Engineering, Inc
		175 Middlesex Turnpike
		Bedford, MA 01730  USA
		(617) 275-3733
		Fax: (617) 275-4323
		e-mail:  info@dspse.com
		www:  http://www.dspnet.com