Abstract: A method, circuit and article of manufacture for restoring high-frequency content in a first signal includes down-sampling the first signal by a factor to give a second signal; up-sampling the second signal by the same factor to give a third signal; low-pass filtering the third signal to give a fourth signal; high-pass filtering the fourth signal to give a fifth signal; and, adding the fifth signal to the first signal.

Abstract: A method for optimizing multiple psychoacoustic effects in a sound system includes synthesizing a high-frequency restored version of a input signal; adding the high-frequency restored version of the input signal to the input signal to create a second signal; synthesizing a third signal having enhanced spatialization from the second signal; synthesizing a fourth signal having virtual bass from the second signal; and, adding the third and fourth signals, or second, third and fourth signals, together to create an output signal.

Abstract: A method for spatialization using stereo decorrelation. The method generates decorrelated left and right signals by filtering the left input channel using an all-pass filter with a first group delay and filtering the right input channel using an all-pass filter with a second group delay; the second group delay being different than that of the first group delay. The decorrelated left signal is subtracted from the decorrelated right signal to create a second left signal and the decorrelated right signal is subtracted from the decorrelated left signal to create a second right signal. The method generates a side signal by adding the filtered left input channel signal and the filtered right input channel signal. The side signal is added to the second left signal to generate a left output signal the side signal is added to the second right signal to generate a right output signal.

Abstract: A method of performing an infinite-impulse response digital filter includes switching address pointers between a first instance of the filter and a second instance of the filter; where the first and second instances represent the same filter. A first instance of the filter executes operations sequentially multiplying a current input data value, and first and second previous input data values, with corresponding ones of a first set of filter coefficients, using a multiplier; and a second instance of the filter executes operations sequentially multiplying first and second previous intermediate data values with corresponding ones of a second set of filter coefficients, using the multiplier. Switching between first and second instances of the filter occurs at each data input value or frame according to an alternating signal.