Patent ID: 6714908
Filing Date: 2004-03-30
Classification: G10L,H03M

Abstract:
A modified concealing device for a code-excited linear prediction (LP) decoder that generates excited signals based on frames of received signals and performs an error concealment process in which excited signals are attenuated when an error is found in a received LP signal frame comprising:(a) a codebook that has a renewable internal state (tâˆ’1) according to which the codebook outputs, indexed by parameters in a received LP signal frame (t), a code vector which is processed into an excited signal vector (t), the excited signal vector being used to renew the internal state (tâˆ’1) of the codebook to an internal state (t), where tâˆ’1, t, . . . indicate discrete time series; (b) an amplifier that amplifies the excited signal vector; (c) a switch that selects either the excited signal vector (t) or the amplified excitation signal vector (t) from the amplifier and supplies it to the codebook for renewal of its internal state (tâˆ’1) to an internal state (t); (d) a counter that counts a number of successive error frames that contain an error in received LP signals; and (e) a switch controller that directs the switch, if the number of successive error frames counted by the counter exceeds a predetermined number, to select amplified excitation signal vectors for a time period equal to a predetermined number of frames which time period begins from decoding of a first error-free frame after receiving the successive error frames, whereas otherwise directing the switch to select excitation signal vectors.