ITU G.722
SB-ADPCM Waveform Coder
for TMS320C5x
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 TMS320C5x. 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

•	CCITT G.722 compliant
•	SPOX compatible
•	7-kHz audio coding switchable at 64, 56, and 48 kbps
•	Re-entrant
•	In-band synchronization capable

Processor and System Requirements

•	Devices supported: TMS320C5x
•	Algorithm category: Vocoder
•	Requirements:
All memory requirements are in units of 16-bit words. The MIPs ratings presented require the listed 
amounts of zero-wait-state program and data memory. All measurements were made using an executable 
demonstration built for a third-party PC plug-in board.
Function
MIPS
Data
Program
Encoder (half duplex)
8.0
0.5 k
3.01 k
Decoder (half duplex)
7.85
0.5 k
3.01 k
Full Duplex*
15.85
0.5 k
3.01 k
*   Significant portions of read-only program and data are shared by the encoder and decoder.

User Functions

The G.722 implementation consists of four  independent, C-callable functions that perform all 
encoding and decoding operations. The encoder and decoder interface with arrays of 15-bit 
linear-PCM samples and 6-, 7-, or 8-bit code words.
G.722 Functions
G722_create (...)	
Initialize the G.722 encoder and decoder memory
G722_encode (...)
Encodes a frame of 15-bit linear-PCM samples into a frame of code words
G722_decode (...)
Decodes a frame of code words into a frame of 15-bit linear-PCM samples
G722_delete (...)	
Delete the G.722 encoder and decoder  memory

Algorithm Verification

•	Call DSPSE for verification details

Availability

•	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. 
DSPSE sells its products to OEMs and directly to manufacturers of telecommunications products. 
DSPSE provides the complete solution to your DSP needs with DSP solution software packages and 
individual DSP software component algorithms and expert service.

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