Sample-by-sample gain adaptive celp coding of wideband audio

This paper presents a high quality wideband audio coder based on a low delay code excited linear predictive (LD-CELP) model where the excitation gain is adapted in a sample-by-sample manner. The proposed coder employs a backward adaptive predictor which introduces no extra delay to the system. A simple gain adaptive control is utilized to perform a sample-by-sample gain adaptive excitation model. In other words, the proposed coder exploits the advantages of the LD-CELP and ADPCM coding. This coder can provide transparent quality audio signals at a bitrate of 1.5 bits/sample.