High-quality vector adaptive transform coding at 4.8 kb/s

A frequency-domain search procedure is presented that requires a computational load of approximately 1.5 MFLOPS, reduces the storage cost, and maintains the speech quality. A vector-excitation-coding (VXC) method in the transform domain called vector adaptive transform coding (VATC) is proposed. VATC provides a general framework for VXC in the transform domain, and the quality for the synthetic speech is close to that obtained in code-excited line prediction (CELP). The major advantages of VATC are the different ways of including information from previous frames, different perceptual distortion measurements, different transformations, efficient search algorithms, and the use of vector predictive quantization techniques so as to have a fully quantized coder at 4.8 kb/s