Backward Adaptation of Quantizing Resources
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Subband Coding associated with adaptive (or dynamic) allocation of bit resources has been shown to be an efficient approach for digital coding of speech signals. The input signal S(n) sampled at 8 KHz, is split into p subbands. Then each subband signal is quantized by a Block Companded PCM quantizer (BCPCM). The quantizer parameters are updated per block of samples, to take into account the short-term variations of the formant's frequencies and energies. Let S(i, j) denote the j-th sample of the i-th subband, and let us assume the block duration corresponds to N subband samples. For each subband signal S(i,j), for i=1, ...,p, one determines the so-called subband characteristic: (Image Omitted) The characteristic terms are locally used to derive the bit resources which should be allocated to each subband.