Patent ID: 8145693

Claim:
A Finite Impulse Response (FIR) filter apparatus comprising: an audio signal storing unit for storing a series of audio signal data arranged along a time axis; an impulse response data storing unit for storing impulse response data including impulse response coefficients, each impulse response coefficient being specified by a value on the time axis and indicating an impulse response characteristic; an impulse response coefficient compensating unit for calculating, based on a cross-fade point specified on the time axis and a loop point specified on the time axis, renewed compensated impulse response coefficients falling in a cross-fade period defined between the cross-fade point and an end point specified on the time axis when impulse response coefficients in a period defined between the loop point and the end point are repeated, and for storing the calculated renewed compensated impulse response coefficients in the impulse response data storing unit, wherein the loop point corresponds to a beginning point of the period in which the impulse response coefficients are repeated, the end point corresponds to a tail end of the impulse response coefficients, and the cross-fade point is specified on the time axis between the end point and the loop point and corresponds to a beginning point of the cross-fade period in which cross-fading is effected; and a product-sum operation unit for reading the audio signal data from the audio signal storing unit and reading from the impulse response data storing unit impulse response coefficients including the compensated impulse response coefficients falling in the cross-fade period, and for multiplying the audio signal data by appropriate impulse response coefficients among the read impulse response coefficients to obtain multiplication data and accumulating the multiplication data to output the accumulated data.