01-envelopes.py - Using break-point function to control an FM synthesis.¶
This example shows how break-point tables can be used to control synthesis/effect parameters at audio rate. Pyo offers many objects to generate break-point function:
LinTable: Construct a table from segments of straight lines.
CosTable: Construct a table from cosine interpolated segments.
ExpTable: Construct a table from exponential interpolated segments.
CurveTable: Construct a table from curve, with tension and bias, interpolated segments.
LogTable: Construct a table from logarithmic segments.
CosLogTable: Construct a table from logarithmic-cosine segments.
These objects implement a graph() method (as well as Linseg and Expseg) which show a graph window with which the user can set the shape of the trajectory.
With the focus on the graph window, the copy menu item (Ctrl+C) saves to the clipboard the list of points in a format well suited to be paste in the code. Useful to experiment graphically and then copy/paste the result in the script.
To play more notes, in the Interpreter field of the Server GUI, call the note(freq, dur) function with the desired frequency and duration.
Note: The wxPython Phoenix graphical library must be installed to use the graph. Infos at:
from pyo import * s = Server().boot() # Defines tables for the amplitude, the ratio and the modulation index. amp_table = CosTable([(0, 0), (100, 1), (1024, 0.5), (7000, 0.5), (8192, 0)]) rat_table = ExpTable( [(0, 0.5), (1500, 0.5), (2000, 0.25), (3500, 0.25), (4000, 1), (5500, 1), (6000, 0.5), (8192, 0.5),] ) ind_table = LinTable([(0, 20), (512, 10), (8192, 0)]) # call their graph() method. Use the "yrange" argument to set the minimum # and maximum bundaries of the graph (defaults to 0 and 1). amp_table.graph(title="Amplitude envelope") rat_table.graph(title="Ratio envelope") ind_table.graph(yrange=(0, 20), title="Modulation index envelope") # Initialize the table readers (TableRead.play() must be called explicitly). amp = TableRead(table=amp_table, freq=1, loop=False, mul=0.3) rat = TableRead(table=rat_table, freq=1, loop=False) ind = TableRead(table=ind_table, freq=1, loop=False) # Use the signals from the table readers to control an FM synthesis. fm = FM(carrier=[100, 100], ratio=rat, index=ind, mul=amp).out() # Call the "note" function to generate an event. def note(freq=100, dur=1): fm.carrier = [freq, freq * 1.005] amp.freq = 1.0 / dur rat.freq = 1.0 / dur ind.freq = 1.0 / dur amp.play() rat.play() ind.play() # Play one note, carrier = 100 Hz, duration = 2 seconds. note(200, 2) s.gui(locals())