Method and system for frequency domain active matrix decoding without feedback

An active matrix decoder configured to decode N audio input signals to generate M audio output signals, where M and N are integers and M is greater than N, and N=2, said decoder including:

• an input transform subsystem (10, 11) configured to transform the N input signals from the time domain to the frequency domain, thereby generating N streams of input frequency components in response to the N input signals;
• a control subsystem (17) configured to generate gain control values in response to the streams of input frequency components, by
• generating power ratios (30, 31, 32, 33) in response to the streams of input frequency components, said power ratios including at least one power ratio for each block of the streams of input frequency components for each critical frequency band in a set of critical frequency bands;
• wherein the set of critical frequency bands is determined in accordance with perceptually motivated considerations;
• and
• generating the gain control values (38) from the power ratios including by shaping the power ratios in a nonlinear fashion, wherein the gain control values include subsets, each of the subsets for a different one of the critical frequency bands, and wherein the shaping of the power ratios in nonlinear fashion includes exponentiating at least one value determined from at least one of the power ratios with an exponent at least substantially equal to three;
• an active matrix subsystem (16) coupled to the control subsystem (17) and configured to generate M streams of output frequency components in response to the N streams of input frequency components;
• wherein the control subsystem (17) is configured to assert the gain control values to the active matrix subsystem (16) for steering the active matrix subsystem (16) during generation of the M streams of output frequency components;
• and wherein the active matrix subsystem (16) is configured to apply multiple sets of matrix coefficients to the streams of input frequency components, each set of matrix coefficients for a different one of the critical frequency bands;
• and
• an output transform subsystem (20) configured to transform the M streams of output frequency components from the frequency domain into the time domain, thereby generating the M output signals in response to said streams of output frequency components.