ITU G.722
SB-ADPCM Waveform Coder
for TMS320C3x/'C4x
by DSP Software Engineering, Inc.

Software Overview

The G.722 SB-ADPCM waveform coder software is an implementation of ITU (formerly CCITT) G.722 for 
the TMS320C3x. G.722 is an international standard for encoding 16-kHz sampled audio signals for 
transmission over 48-, 56-, or 64-kbps channels. G.722 provides 7 kHz of audio bandwidth. G.722's 
processing delay is equal to the processing frame size.
G.722 encodes frames of 15-bit linear PCM samples into frames of 6-, 7-, or 8-bit code words. G.722 
has numerous applications in products that require higher audio frequency bandwidth coding, such as 
videoconferencing, multimedia, and speaker/microphone digital telephony.

Features and Benefits

•	User-selectable processing frame size and decoding rate
•	Independent, C-callable functions
•	Object-based interface
•	SPOX compatible
•	In-band synchronization capable

Processor and System Requirements

•	Devices supported: TMS320C3x, TMS320C4x
•	Algorithm category: Vocoder
•	Requirements:
All memory requirements are in units of 32-bit words. The MIPs ratings presented require the listed 
amounts of on-chip RAM, zero-wait-state program and data memory, and a processing frame size of 10 
samples. All measurements were made using an executable demonstration built for a third-party PC 
plug-in board.
Function
MIPS
Chip RAM
Data
Program
Encoder (half duplex)
5.2
0.3 k
0.04 k
1.4 k
Decoder (half duplex)
5.1
0.1 k
0.05 k
1.3 k
Full Duplex*
10.3
0.4 k
0.1 k
1.9 k
*   Significant portions of read-only program and data are shared by the encoder and decoder.

User Functions

The G.722 implementation consists of two independent, C-callable functions that perform all 
encoding and decoding operations. It also includes functions that reflect the implementation's 
object-based interface. The encoder and decoder interface with arrays of 15-bit linear PCM samples 
and 6-, 7-, or 8-bit code words.
G.722 Encoder
G722E_create (...)
Dynamically allocates and initializes data memory for encoder
G722E_delete (...)
Frees encoder's usage of dynamically-allocated data memory
G722E_encode (...)
Encodes a frame of 15-bit linear PCM samples into a frame of code words
G.722 Decoder
G722D_create (...)
Dynamically allocates and initializes data memory for decoder
G722D_delete (...)
Frees decoder's usage of dynamically-allocated data memory
G722D_decode (...)
Decodes a frame of code words into a frame of 15-bit linear PCM samples

•	Source and object code currently available for licensing.

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