Digital Audio Effects in the Wavelet Domain
Audio signals are often stored or transmitted in a compressed representation, which can pose a problem if there is a requirement to perform signal processing; it is likely it will be necessary to convert the signal back to a time domain representation, process, and then re-transform. This is timeconsuming and computationally intensive; it is potentially more efficient to apply signal processing while the signal remains in the transform domain. We have implemented a scheme whereby linear processing of the traditional type often instinctively understood by those working in the audio field may be applied to signals stored in a wavelet domain representation. Results are presented which demonstrate that the method produces the same output – to within the limits of machine precision – as timedomain processing, for less computational effort than would be required for the full explicit process through the time domain and back again. The potential benefits for linear effects processing (for example, EQ and sample-level delays and echoes) and also for non-linear processing such as dynamics processing, will be introduced and discussed.