ITU-T G.723.1 Compliant Vocoder Now Available

Toronto, Canada – GAO Research Inc. ( recommends its latest release of its ITU-T G.723.1 compliant vocoder which performs compression and decompression of 8kHz speech signals. It encodes 16-bit PCM samples into 16-bit code-words yielding 10 or 12 code-words per 240 sample frames for the 5.3Kbps and 6.3Kbps channels respectively, as well as speech or other audio signals. The vocoder has a switchable transmission rate over 5.3Kbps or 6.3Kbps channels providing 4kHz of quality speech bandwidth. The higher bit rate has greater quality; the lower bit rate gives good quality and provides system designers with additional flexibility.
The ITU standard specifies the coded representation that is used for compressing signal components for multimedia services at a very low bit rate as a part of the overall H.324 family of standards. The excitation signals for the high rate coder is Multipulse Maximum Likelihood Quantization (MP-MLQ) and for the low rate coder is Algebraic-Code-Excited Linear-Prediction (ACELP). This coder was optimized to output high quality speech at the above rates with simple operations.Voice activity detection (VAD) and comfort noise generation (CNG), which are specified in Annex A, are included in this version. It is commonly used for applications such as video phones, audio/video conferencing and media gateways.
About GAO Research Inc.
GAO Research Inc. ( is a recognized international leading provider of communications software to telecom and electronics companies and provides the most comprehensive and unique suite of modem, fax, telephony, speech software, VoIP, FoIP, fax relay and fax/modem/voice relay software for embedded applications for DSP and microprocessors.

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