Re: [Csnd] [EXTERNAL] [Csnd] Real-time transient detection

Victor_Lazzarini1 · August 5, 2025, 6:55pm

You could try to look for rms amplitude changes, if these are large enough then you get a trigger. I would think that would work ok for drums. Generally speaking I would think finding the onset of a sound with a fast attack would be easier than with a slow attack.

What are the problems you are finding?

Oeyvind should also have something to say about this, he has a lot of experience with these kinds of applications.

Prof. Victor Lazzarini
Maynooth University
Ireland

joachim · August 5, 2025, 8:01pm

for onset detection of percussive sounds you can also try this:

github.com

csudo/csudo/blob/master/misc/OnDtct.csd

/****************************************************************************
kOnset, kDb OnDtct aIn [,kDbDiff [,kMinTim [,kMinDb [,iRmsFreq [,iDelComp]]]]]
Detects onsets (attacks). Returns also the dB of the rms at this time.

Onset detection is done via the comparision of the current rms value with the
rms value kDelTim seconds before. If the current rms is lager than kDbDiff decibel
compared to the one kDelTim seconds before, an onset is detected. Further conditions
are that kMinTime has passed since the last detection, and the rms value for the 
onset is larger that kMinDb. The velocity of the rms measurement can be adjusted 
with the iRmsFreq parameter.
Note that the kDb output is "too early" for a good estimation of the onset's 
intensity. As the example below shows, it can be taken a short time later.
written by joachim heintz

aIn - audio input signal
kDbDiff - dB difference to signify an offset (default = 10)
kMinTim - minimum time in seconds between two onsets (default = 0.1)
kMinDb - minimum dB to detect an offset (default = -50)
kDelTim - time in seconds which is compared to the current rms (default = 0.025)
iRmsFreq - approximate frequency for rms measurements (default = 50)

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