SCALABLE SPEECH AND AUDIO CODEC USING COMBINATORIAL MDCT-SPECTRUM ENCODING

摘要

A scalable speech and audio codec is provided that implements combinatorial spectrum encoding A residua] signal is obtained from a Code Excited Linear Prediction (CELP)-based encoding layer where the residual signal is γ difference between an original audio signal and a reconstructed version of the original audio signal. The residual signal is transformed al a Discrete Cosine Transform (DCT)-type transform layer to obtain a corresponding transform spectrum having a plurality of spectral lines. The transform spectrum spectral lines are transformed using a combinatorial position coding technique. The combinatorial position coding technique includes generating a lexicographical index for a selected subset of spectral lines, where each lexicographic index represents one of a plurality of possible binary strings representing the positions of the selected subset of spectral lines. The lexicographical index represents non-zero spectral lines in a binary string in fewer bits than the length of the binary string.