Vocoders by Adaptive Digital

G.722.2 / AMR Wide Band

G.722.2

ADAPTIVE DIGITAL G.722.2 C55x , C6x

WIDE-BAND AUDIO CODER

The Adaptive Digital Technologies G.722.2 Audio Coder is a real-time implementation of the ITU G.722.2 audio coder also referred to as the Adaptive Multi-Rate Wideband (AMR-WB) codec. Not only does AMR-WB provide advanced voice quality over the existing narrowband standards, but it is also very robust against transmission errors due to multi-rate operation and adaptation. Wideband speech coding is a substantial feature in high-fidelity telephony and in telecommunications processes such as audio teleconferencing and program broadcasting. The G.722.2 audio coder encodes 16 kHz sampled audio signals for transmission, and compresses the signals to a multitude of bit rates ranging from 6.6 kbit/s to 23.85 kbit/s. The G.722.2 coder provides 7 kHz of audio bandwidth.

The ITU-T Recommendation G.722.2, Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB), was approved in July of 2003 by the ITU-T Study Group 16 under the ITU-T Recommendation A.8 procedure. This proved to be a significant event throughout international telecommunications communities, because the same specification was also adopted by the 3 rd Generation Partnership Project (3GPP). The standardization of AMR-WB by both ITU and 3GPP meant that the same algorithms and processing techniques can be deployed on traditional LAN line circuits, as well as wireless communication/radio networks.

The AMR Wide Band codec is based on the Code Excited Linear Prediction (CELP) coding model, allowing the end user network to experience truer voice signals due to the higher bandwidth. Compared to typical narrow band coding, the AMR-WB codec operates at double the sample rate which ultimately leads to more natural sounding voice and music content. The codec also employs other routines that have become characteristic to telephony networks such as Voice Activity Detection (VAD), Discontinuous Transmission (DTX) and Comfort Noise Generation (CNG).

Contributed by Nick Saluzzi
College of Engineering
Villanova University

Data sheet - .pdf

Coding Rate: 6.60, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05 and 23.85 kbps

Sampling Rate: 16 kHz

Delay: 20 msec

FEATURES

  1. Functions are C-callable

  2. Multi–Channel Implementation.

  3. Completely re–entrant (Channel can interrupt any Channel, any time)

  4. The encoder and decoder meet all ITU G.722.2 compliance data files.

  5. Includes Packet Loss Concealment Algorithm

  6. Includes Support for Discontinuous Transmission (DTX)

  7. xDAIS Compliant

  8. C64x xDM Compliant: easy codec implementation and integration for DaVinci™ Technology

AVAILABILITY

ADT G.722.2 is available on the TMS320C6000™ DSP Platform

C64x™DSP Generation

 

SPECIFICATIONS

DaVinci™

G.722.2 C64x

All Memory usage is given in units of byte.

Function
MIPS
Program Memory
Data Memory
Per-Channel Data Memory
Encode 24
140 KB
29,138
2,700
Decode 6
90 KB
24,588
1,550
Encode/Decode 30 150 KB 32,500 4,330

Last update: 04/06/2006

 

G.722.2 C55x

All Memory usage is given in units of byte.

Function
MIPS
Program Memory
Data Memory
Per-Channel Data Memory
Encode/Decode 33 49 k 33 k 4,330

Last update: 11/01/2006

 

APPLICATIONS

Audio and video teleconferencing

Internet applications such as broadcasting and streaming

Digital radio broadcasting

integrated services digital network (ISDN) wide band telephony

VOIP

FUNCTION

InitializeEncoderChannel (…) Initializes the G.722.2 Encode Channel Structure

InitializeDecoderChannel (…) Initializes the G.722.2 Decode Channel Structure

EncodeG722_2 (…) Executes the G.722.2 encoder

DecodeG722_2 (…) Executes the G.722 .2 decoder



PRODUCTS