Patent attributes
During mixing of an N-channel input signal to generate an M-channel output signal, the mixed channel signals are equalized (e.g., amplified) to maintain the overall energy/loudness level of the output signal substantially equal to the overall energy/loudness level of the input signal. In one embodiment, the N input channel signals are converted to the frequency domain on a frame-by-frame basis, and the overall spectral loudness of the N-channel input signal is estimated. After mixing the spectral components for the N input channel signals (e.g., using weighted summation), the overall spectral loudness of the resulting M mixed channel signals is also estimated. A frequency-dependent gain factor, which is based on the two loudness estimates, is applied to the spectral components of the M mixed channel signals to generate M equalized mixed channel signals. The M-channel output signal is generated by converting the M equalized mixed channel signals to the time domain.
