BANDWIDTH COMPRESSION OF PARAMETRIC SOUNDFIELD REPRESENTATIONS FOR TRANSMISSION AND STORAGE

摘要

The invention relates to the coding and subsequent decoding of parametric representation of soundfields. The spatially and temporally sampled pressure field in a compact three-dimensional target area can be parameterised primarily by decomposition onto orthogonal basis functions and secondarily by taking advantage of spatial and temporal correlations between the first set of primary parameters. Both primary and secondary parameters are subsequently coded using perceptual psychoacoustic thresholds. Additionally, spatial and information theoretic analysis of the parameters provide an optimal updating rate of the parameters as well as the maximal order required. The signal dependent order and update rate of the parametric representation forms part of the encoded bitstream. The psychoacoustic thresholds are a function of both the spatial distribution of acoustic energy (outside of the target area) as well as the frequency distribution of the sound impinging on the ear of a listener inside the target listening area. The calculated psychoacoustic thresholds reflect the precision required to represent the primary and/or secondary parameters for transparent perception of both sounds and their spatial location. This facilitates various quantization techniques to encode the parameters. The coded parameters may be stored or transmitted to a receiver unit. At the receiver unit, the coded parameters are dequantized and an adaptive synthesis system generates loudspeaker feeds to allow the reconstruction of a perceptually transparent acoustic field. The decoder is able to adjust to the differing and time-varying update rates as well as as the time-varying order of the parametric representation. The synthesis system adapts to the number and geometric configuration of the loudspeakers at the receiver location.