Example Pd Patches

See Sec. 2.4.2 - 2.4.3 regarding message passing, infinite loops, and hot and cold inlets.

In plugdata, you can mouse-over inlets and outlets to get information about the type of data that is expected to be input or output to each.
Note the difference in shape between “message” and “object” boxes in Pd.
A message box does nothing until it receives a “bang” or it is clicked.
The “bang” GUI object sends out the “bang” message.
Print objects can take an argument to help distinguish multiple ones from each another.

The metro object sends out “bangs” at a specified rate in milliseconds. It is turned on with a 1 and turned off with a 0.

GUI objects in Pd-Vanilla are limited to bangs, toggles, sliders, number boxes (which can be used like a slider), radio buttons, and VU meters.
Because it has the cyclone library installed, plugdata offers a wider array of GUI objects, including buttons, knobs, a function object, and a virtual keyboard object, similar to what exists in Max/MSP.

Object names that end with a tilde (~) denote objects that produce and/or take audio-rate signals.
Object names that do not have a tilde run at a control rate, which is much slower than the audio sample rate.
osc~ is a basic sinusoidal oscillator. In order to hear the result of an audio process, an audio signal must be sent to a dac~ object.
Sliders can be used to control parameters such as frequency and amplitude.
The line~ object can produce linear line segments at the audio rate, which can be used to ramp up or ramp down the amplitude.
The mtof object peforms control-rate MIDI note number to frequency conversions.
The ftom object performs control-rate frequency to MIDI note conversions.

A few of the objects that can be used to compute and report signal amplitude levels are shown in the Pd patch above (note that many of these objects are not available in Pd-Vanilla).
The sig~ object takes a control-rate float or int value and outputs that value at the audio rate.
The lin2db and db2lin objects convert between linear and dB levels.
The gain~ object provides an interpolating logarithmic signal fader.
The average~ object computes a running average of an input signal over a specified number of samples. It can provide three different average types, “bipolar”, “absolute”, and “rms”.
The avg~ object computes the average of the absolute value of an input signal between bangs.
The vu~ object provides a graphical signal level meter.
The snapshot~ object outputs the current audio sample value when a bang is received.
The peakamp~ object reports the maximum absolute value of audio data between bangs or at regular intervals.
The spike~ object reports intervals of zero to non-zero transitions.
The zerox~ object counts zero-crossings, which can be used to distinguish transients from pitched signals.