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ITU-T G.729 Annex A Speech Coder for the TMS320C55x Generation

[eXpressDSP Compliant]

Description

The ITU-T G.729 Annex A fixed-rate speech coder provides toll quality at very low bandwidth. G.729 compresses narrowband linear speech signals at a sample rate of 8kHz to 8kbps, using Conjugate-Structure, Algebraic Code-Excited Linear Prediction (CS-ACELP). The encoder extracts the parameters of the CELP coding model from 10-msec frames. G.729 Annex A is a less mathematically complex version of G.729. It requires roughly one half the cycles of G.729, yet is interoperable with it, with barely any loss of fidelity.

G.729 Annex A encoder is widely used in applications that require robust quality, including videoconferencing, internet, multimedia communications, satellite communications, and store/forward.

The G.729 Annex A is part of the DSP Wizard G.729 suite for TMS320C55x, which is comprised of five separate products:

Algorithm Complexity SID Frames Bit-rate
G.729 High No 8.0kbps
G.729 Annex A Low No 8.0kbps
G.729 Annex B High Yes 8.0kbps
G.729 Annex A Annex B Low Yes 8.0kbps
G.729 Annex D Medium No 6.4kbps

Features

DSP Wizard’s G.729 Annex A implementation was designed for low resource requirements without sacrificing quality. It executes at 6.4 mips for worst-case data. The speed is at least 25% faster than any other G.729 Annex A c55x implementation available. While it may seem that many DSP software vendors claim to have the best speeds, we can back up our claim. Please compare us to the competition. A 200 MHz c55x chip can support 30 channels.

Performance

G.729 Annex A Encoder Decoder Full Duplex
Program Code Memory (Kbytes) 10.6 4.6 13.9
Program Table Memory (Kbytes) 0.0 0.0 0.0
Data Table Memory (Kbytes) 5.1 4.3 5.3
Per Channel Data Memory (Kbytes) 1.1 0.8 1.9
Stack Memory (Kbytes) 0.3 0.3 0.3
Interrupt Latency (cycles) 1 1 1
Call Period (ms) 10 10 10
Processor Load: Worst-Case (MHz) 5.3 1.1 6.4

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