Transient Processor
SKAS symbolic sound processing and analysis/synthesis
Prof. Dr. Marlon Schumacher
Intermediate project by Andres Kaufmes
HfM Karlsruhe – IMWI (Institute for Music Informatics and Musicology)
Winter semester 2022/23
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For this interim project, I worked on the implementation of a transient processor in OpenMusic with the help of the OM-Sox library.
A transient processor (also known as a transient designer or transient shaper) can be used to influence the attack/release behavior of the transients of an audio signal.
The first hardware device presented was the SPL TD4, introduced by SPL in 1998, which was available as a 19″ rack device and is still available today in an advanced version.
Transient Designer from SPL. (c) SPL
Transient Designers are particularly suitable for processing percussive sounds or speech. First, the transients must be isolated from the desired audio signal; this can be done using a compressor, for example. A short attack time “ducks” the transients and the signal can be subtracted from the original. The audio signal can then be processed with further effects in the course of the signal chain.
Transient processor patch. FX chain of the two signal paths (left “Transient”, right “Residual”).
At the top of the patch you can see the audio file to be processed, from which, as just described, the transients are isolated using a compressor and the resulting signal is subtracted from the original. Now two signal paths are created: The isolated transients are processed in the left-hand “chain”, the residual signal in the right-hand one. After both signal paths have been processed with audio effects, they are mixed together, whereby the mixing ratio (dry/wet) of both signal paths can be adjusted as desired. At the end of the signal processing there is a global reverb effect.
“Scope” view of the two signal paths. Sketches of the possible signal path and processing.
Sound examples:
Isolated signal:
Residual signal: