FFT-based dynamic range compression

Abstract

Many of the dynamic range compressor (DRC) designs that are deployed in the marketplace today are constrained to operate in the time-domain; therefore, they offer only temporally dependent control of the amplitude envelope of a signal. Designs that offer an element of frequency dependency, are often restricted to perform specific tasks intended by the developer. Therefore, in order to realise a more flexible DRC implementation, this paper proposes a generalised time-frequency domain design that accommodates both temporally-dependent and frequency-dependent dynamic range control; for which an FFT-based implementation is also presented. Examples given in this paper reveal how the design can be tailored to perform a variety of tasks, using simple parameter manipulation; such as frequency-depended ducking for automatic-mixing purposes and high-resolution multi-band compression.