G.728 LD-CELP vocoder

GAO’s G.728 vocoder implements the low delay code-excited linear prediction (LD-CELP) speech compression technique specified in the ITU-T standard and provides approximately 4 kHz of speech bandwidth. The software encodes 5 sample frames of 16-bit linear PCM data into 10-bit code words. GAO’s G.728 software employs backward-adaptive linear predictive coding analysis to achieve a low transcoding delay. Applications for GAO G.728 include digital circuit multiplication equipment, videoconferencing, digital telephony, and multimedia products.

The ITU-T G.728 standard specifies the encoding of 8 kHz sampled speech signals for transmission over a 16 Kbps channel. This recommendation contains the description of an algorithm for the coding of speech signals at 16 Kbps using low-delay code excited linear prediction (LD-CELP).