Variable-mode filter demo

This patch allows you to try out various filter settings of the biquad~ object, via the filtergraph~ object. For adjusting the parameters you can drag on filtergraph~ with the mouse, or you can send values in its three rightmost inlets for frequency, gain, and Q. The spectroscope~ object tries to draw the spectrum of the signal.

Notify when a certain time has elapsed

When we want to measure how much time something took, we use a stopwatch. We click once at the beginning of the time we want to measure, click once at the end, and get a reading of the elapsed time. When we want a notification that a particular amount of time has elapsed we use a timer. We set the amount of time in the future that we want to be notified, start the timer, and the timer notifies us when that amount of time has passed.