Patent ID: 8891708
Filing Date: 2014-11-18
Classification: G10L,H03H,H04S

Abstract:
1. A method for filtering an input signal representing audio or video information to generate an output signal representing the audio or video information with a specified phase shift that is a non-zero function of frequency, wherein the method comprises: receiving the input signal in a forward direction at an input terminal; applying a forward filter and a backward filter coupled in cascade with one another to the input signal, wherein the forward filter applies its filtering operation to its input in the forward direction and the backward filter applies its filtering operation to its input in a backward direction that is opposite the forward direction; and generating an output signal at an output terminal in response to filtered signals received from the cascade of forward and backward filters, wherein the output signal has the specified phase shift that is a non-zero function of frequency; wherein the filtering operation of the backward filter has a phase shift that is a function of frequency and the filtering operation of the forward filter has the specified phase shift that is a non-zero function of frequency defined relative to the phase shift of the filtering operation of the backward filter, and the backward filter is applied to a series of input segments of its input signal to generate its output signal in a series of output segments, wherein: deriving an amplitude adjustment from amplitudes of: applying the amplitude adjustment to the phase-shifted signal in the subsequent output segment to reduce a difference in amplitude with an end of the phase-shifted signal that is adjacent the look-ahead-interval signal in the specified output segment, wherein the amplitude adjustment is modified so that it converges to zero as it is applied to the phase-shifted signal in the forward direction.