Patent ID: 8599981
Filing Date: 2013-12-03
Classification: G10L

Abstract:
1. A post filter that comprises a zero filter and a pole filter and suppresses quantization noise of a decoded speech signal which is subjected to layer coding by a coding scheme comprised of a plurality of layers, the post filter comprising: a buffer that stores a predetermined value as a default value of a first control parameter; a control parameter selector that, based on layer information showing layers included in a speech signal subjected to the layer coding, selects a second control parameter corresponding to the layer information; a detector that detects switching of the layers; a smoother that sets a smoothed control parameter to be used for filtering processing such that, when the detector detects the switching of the layers, the smoothed control parameter shifts in a multistep fashion from the first control parameter stored in the buffer to the second control parameter selected by the control parameter selector, and updates the buffer by the smoothed control parameter; and a first filtering processor that performs the filtering processing with respect to the decoded speech signal using the smoothed control parameter set by the smoother.