Patent ID: 7657427

Claim:
An apparatus comprising a variable bit-rate multi-mode wideband codec unit operable with an adaptive multi-rate wideband codec, where in a variable bit-rate multi-mode wideband encoding/adaptive multi-rate wideband decoding case, speech frames are encoded in an adaptive multi-rate wideband interoperable mode of a variable bit-rate multi-mode wideband encoder using one of bit rates corresponding to interoperable-full rate for active speech frames, interoperable-half rate at least for dim-and-burst signaling, quarter rate-comfort noise generator to encode at least relevant background noise frames and eighth rate-comfort noise generator frames for background noise frames not encoded as quarter rate-comfort noise generator frames; and where in another case, said unit responsive to a determination that voice activity is not detected for using eighth rate-comfort noise generator encoding, further responsive to a determination that voice activity is detected, and responsive to a voiced versus unvoiced classification such that in response to a frame being classified as unvoiced, the frame is encoded with one of unvoiced half rate or unvoiced quarter rate encoding, further responsive to a frame not being classified as unvoiced for using a stable voiced classification, and in response to the frame being classified as stable voiced, encoded the frame using voiced half rate encoding, else assuming the frame to likely contain a non-stationary speech segment for using an appropriate full rate encoding, whereas a frame with low energy, and not detected as at least a background or an unvoiced frame, is encoded using generic half rate coding to reduce the average data rate; an unvoiced classification decision being based on at least some of a voicing measure r x , a spectral tilt e t , an energy variation within a frame dE, and a relative frame energy E rel , where decision thresholds are set based at least in part on an operating mode comprising a required average data rate.