Intro to TouchDesigner · Audio Analysis
Signal Minus Threshold
The top graph is an RMS signal, always between 0 and 1. The bottom graph is that same signal with a Math CHOP subtracting a threshold, no clamping. Whatever was above the threshold line comes out positive, whatever was below it comes out negative. Drag the slider and watch the balance shift.
threshold0.00
% of signal positive100%
the math, one point on the signal at a time
0.5 − 0 = 0.5
0.5 − 0.3 = 0.2
0.5 − 0.5 = 0.0
0.5 − 1 = −0.5
0.50 − 0.00 = 0.50
above the line, positive
A point on the signal only turns negative once the threshold is subtracted past it. Drag the slider above and watch this same point cross from positive to negative.
RMS signal (0 to 1), with the threshold line overlaid
signal − threshold, unclamped — positive above the line, negative below it
At threshold 0, the whole signal sits at or above the line, almost entirely positive. At threshold 1, almost the whole signal falls below it, negative, except the very tallest peaks.