Audio: tap.python~

A method process() runs on the signal, in one of two forms chosen by its type hint:

• process(self, x: np.ndarray) -> np.ndarray is called once per signal vector with a numpy array of the input and must return an array of the same length (any numeric dtype, or a list; it is converted). This is the form to use for anything that must run in real time — see python/numpy_gain.py, and python/numpy_allpass.py for a filter with feedback. The input array is reused from one call to the next: copy it if you want to keep it.
• process(self, x: float) -> float is called once per sample — simplest for sketching; the call is cheap, but every line of Python in it runs once per sample (see the performance chapter).

Its parameters are the object's signal inlets and its return hint its outlets: process(self, left: np.ndarray, right: np.ndarray) -> tuple[np.ndarray, np.ndarray] makes an object with two of each (see python/stereo_width.py), and process(self) -> float, with no inputs, a generator — the first inlet is always there, for messages. The inputs are all np.ndarray or all per sample, and a tuple return must say how many values it has (tuple[float, float]). A save that changes how many changes the object's inlets and outlets to match, keeping the patch cords of those that stay. Wrap the object in mc. — [mc.tap.python~ numpy_gain] — to run one instance per channel of a multichannel signal. A class's attributes and messages are each instance's own, so Max's MC wrapper passes them on through its own messages, not as they are: setvalue 2 gain 0.1 to the second instance, applyvalues gain 0.5 0.25 one value to each; a plain gain 0.5 is not understood. Output that is not a number, or not finite (NaN, infinity), is replaced with 0.0 and reported once in the Max console, as is a return with the wrong number of values.

Audio settings

An optional method prepare(self, sample_rate: float, vector_size: int) -> None is called with Max's sample rate and vector size before the object processes any audio, again whenever they change, and on every reload before the new code runs. python/allpass.py uses it to size its delay line.