Efficient coding of overcomplete representations of audio using the modulated complex lapped transform (mclt)

Abstract

An 'Overcomplete Audio Coder' provides various techniques for overcomplete encoding audio signals using an MCLT-based predictive coder. Specifically, the Overcomplete Audio Coder uses unrestricted polar quantization of MCLT magnitude and phase coefficients. Further, quantized magnitude and phase coefficients are predicted based on properties of the audio signal and corresponding MCLT coefficients to reduce the bit rate overhead in encoding the audio signal. This prediction allows the Overcomplete Audio Coder to provide improved continuity of the magnitude of spectral components across encoded signal blocks, thereby reducing warbling artifacts. Coding rates achieved using these prediction techniques are comparable to that of encoding an orthogonal representation of an audio signal, such as with modulated lapped transform (MLT)-based coders. Finally, the Overcomplete Audio Coder provides a true magnitude-phase frequency-domain representation of the audio signal, thus allowing precise auditory models to be applied for improving compression performance, without the need for additional Fourier transforms.