VARIABLE BIT RATE SPEECH ENCODER

摘要

A video conferencing system comprises an input signal conditioner (30) for digitizing and filtering the microphone signal; a gain quantizer (35) for generating a gain quantization index; a spectrum estimation module (38) for reducing the frequency coefficient to a smaller set of spectrum frames; a speech detection module (40) for estimating the energy component of the microphone signal; a coefficient quantizer (44) for producing a quantization index I(k); a bit rate estimator (42) for producing a step size Q(k); and a class integer C(j) and a bit stream controller (20) for transmitting the resulting signal over a communications channe (22). The method and apparatus thus allocate tranmission bits for use in transmitting samples of the digitized input signals. The remote device reconstructs the digital signals from the transmitted selected samples and estimation samples.