ITU G.726 is the most used speech-compression algorithm in telecommunications due to its high perceived speech quality and low resource requirements. It compresses 64-K speech to 40-, 32-, 24-, or 16-K BPS using adaptive differential pulse-code modulation (ADPCM). Mean Opinion Scores (MOS) for G.726 at the 32K rate are considered to be toll quality; the 24K rate is near toll quality. G.726 is used in applications where high-quality, low DSP MIPS, and low algorithmic delay are desired.
Commetrex offers G.726 in a C-coded reference design, as well as versions optimized for the Texas Instruments TMS320C6000 and TMS320C5400. Commetrex’ implementations are extremely resource-frugal. The ‘C6000 version requires only 1.55 mega-cycles per second in the dual-channel version where two samples are processed simultaneously. On the 200-MHz TI ‘C6201, this yields 120 channels per DSP. When the execution is optimized for single-channel operation the ‘C6000 version requires 2.77-MCPS, or over 60 channels per DSP.
G.726 is eXpress DSP Compliant (http://dspvillage.ti.com/docs/express_dsp/expressdsphome.jhtml). The TMS320DSP Algorithm Standard is directly supported by the MSP Consortium M.100 specification (http://www.msp.org) so it is compatible with any MSP-conforming media-processing system.