ITU G.729a/b Vocoder

Commetrex’ 60095-2 speech codec is a resource- efficient implementation of the ITU G.729a/b on the Texas Instruments TMS32C6000 family of DSPs. G.729a/b is widely deployed in conferencing systems and PSTN-IP gateways where high-quality speech and low-bandwidth utilization are requirements.

G.729 specifies a coding scheme that compresses 64-KBPS PCM speech to 8-KBPS using a conjugate structure algebraic-code- excited linear-prediction (CS-ACELP) algorithm. The coder is designed to process frames of 80 samples, or 10-milliseconds of speech data. A 5-millisecond “look ahead” is required, so the total delay is 15-milliseconds. G.729A is a reduced-complexity version of G.729. Since complexity reduction is due to internal computational simplifications, G.729 and G.729 Annex A are bit-by-bit interoperable. 60095-2 also includes the voice- activity detection and silence removal (VAD) and comfort-noise generation (CNG) specified in G.729 Annex B, hence G.729a/b.

60095-2A is Texas Instruments eXpress DSP Compliant. See ( essdsphome.jhtmll). The 60095-2B conforms to the MSP Consortium M.100 specification (, so it is compatible with any MSP-conforming media-processing system.


  • Low resource utilization
  • C-callable interface
  • Does not disable interrupts
  • TMS320DSP Algorithm Standard compliant
  • MSP Consortium M.100 compatible


  • High densities
  • Low power
  • Low implementation cost

‘C62xx Resource Utilization

Encoder: 7.41 MCPS (with VAD)
Decoder: 2.12 MCPS (with CNG)
Program Memory (full duplex): 74,656 bytes
Tables: 8,928 bytes
Per-Instance Memory:
Encoder: 1984 bytes
Decoder: 1680 bytes

License Options

  • Limited-Use Paid-Up Source Code
  • Royalty with Reduced Up-Front
  • Object Code with Runtime Licenses

Ordering Information

60095-2A G.729a/b for the TI TMS320C6000 XDAIS package
60095-2B G.729a/b for the MSP Consortium M.100 package