All-Pass Audio Peak Reduction Without Harmonic Distortion

The patent changes the fundamental parameter of the compression approach from nonlinear to linear. By using a linear all-pass filter with carefully designed impulse response instead of traditional nonlinear clipping or limiting, the system achieves peak reduction without introducing harmonic distortion. The linear operation preserves the spectral content while redistributing energy in time.

The patent replaces the mechanical nonlinear limiting mechanism with an electronic linear filtering approach. Instead of using hard clipping or soft knee limiting that inherently create distortion, the invention uses a linear convolution operation with a pre-computed impulse response that achieves the same peak control goal without spectral contamination.

The patent performs preliminary computation of the all-pass filter impulse response offline or in advance, storing it for repeated use. This pre-computation allows the real-time processing to simply convolve the input signal with the pre-designed impulse response, significantly reducing online computational complexity while maintaining the distortion-free linear processing advantage.

The patent segments the peak reduction problem into two independent parts: (1) designing the all-pass filter impulse response characteristics offline, and (2) applying the filter in real-time through simple convolution. This segmentation allows complex optimization to be done once, while real-time processing remains computationally lightweight.