Coding with noise shaping in a hierarchical coder

摘要

A method is provided for hierarchical coding of a digital audio signal comprising, for a current frame of the input signal: a core coding, delivering a scalar quantization index for each sample of the current frame and at least one enhancement coding delivering indices of scalar quantization for each coded sample of an enhancement signal. The enhancement coding comprises a step of obtaining a filter for shaping the coding noise used to determine a target signal and in that the indices of scalar quantization of said enhancement signal are determined by minimizing the error between a set of possible values of scalar quantization and said target signal. The coding method can also comprise a shaping of the coding noise for the core bitrate coding. A coder implementing the coding method is also provided.

主权项

1. A method of hierarchical coding of a digital audio signal comprising, for a current frame of the input signal:
performing, on a processor, a core coding, delivering a scalar quantization index for each sample of the current frame to at least one enhancement coding layer; and performing, on the processor, at least one enhancement coding delivering indices of scalar quantization for each coded sample of an enhancement signal, wherein the enhancement coding comprises a step of obtaining an enhancement coding error signal by combining the input signal of the hierarchical coding with a signal reconstructed partially based on a coding of a previous coding layer and of the past samples of the reconstructed signals of the current enhancement coding layer, and a step of obtaining a noise shaping filter and filtering the enhancement coding error signal with this noise shaping filter to determine a target signal and the indices of scalar quantization of said enhancement signal are determined by minimizing error between a set of possible values of scalar quantization for each sample of the current frame and said target signal, wherein the noise shaping filter is further modified by adapting memories of the noise shaping filter based on the output of the scalar quantization step corresponding to the determined indices of scalar quantization for each coded sample of the enhancement signal.