This vocoder also encodes speech or other audio signals in frames using linear predictive analysis-by-synthesis coding.It has switchable transmission rates 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-T G.723.1 standard specifies a coded representation that can be used for compressing the speech or other audio signal component of multimedia services at a very low bit rate as part of the overall H.324 family of standards. This coder was optimized to represent high quality speech at the above rates using a limited amount of complexity.
The excitation signal 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).Voice activity detection (VAD) and comfort noise generation (CNG), which are specified in Annex A, are also included in this version.
This vocoder is available for applications such as video phones, audio/video conferencing, media gateways.
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