DAFX: Digital Audio Effects, Second Edition

13.3 Cross-adaptive AM-DAFX

DAFX architectures have been classified by their implementation [Zöl05]: filters, delays, modulators, time-segment processing, time-frequency processing, etc. Similarly, DAFX have also been classified by the perceptual attributes [ABLAV03] which they modify e.g., timbre, delay, pitch, positions or quality. Although these classifications tend to be accurate in many contexts, they are not optimal for understanding the signal-processing control architectures of some more complex effects. More recently, an adaptive digital audio effect (ADAFx) class was proposed [VZA06]. This class uses features extracted from the signals to control the signal-processing process. In terms of their adaptive properties, digital audio effects may be distinguished as follows:

1. Direct user control: Features are not extracted from input signals so they are non-adaptive. A multi-source extension of this approach is the result of unifying the user interface, for example when linking a stereo equaliser. This provides exactly the same equalisation for the left and right channel using a single user panel. Although the user interface is unified, the output signal processing is independent of the signal content.

2. Auto-adaptive: Control parameters are based on a feature extracted from the input source. These include, for example, auto tuning, harmonisers, simple single-channel noise gates and compressors.

3. External-adaptive: The system takes its control processing variable from ...