Showing content from https://todbot.github.io/CircuitPython_Synthio_Tutorial/4_oscillators_wavetables/code_wavetable.py below:
# 4_oscillators_waveforms/code_wavetable.py # part of todbot circuitpython synthio tutorial # 10 Feb 2025 - @todbot / Tod Kurt # import time import ulab.numpy as np import synthio from synth_setup import synth, keys, knobA import adafruit_wave wave_dir = "/wavetables/" # wavetables from old http://waveeditonline.com/ wavetables = ["BRAIDS01.WAV","DRONE.WAV","SYNTH_VO.WAV","PPG_BES.WAV"] wavetable_num_samples = 256 # number of samples per wave in wavetable wti=0 # index into wavetables list class Wavetable: """ A 'waveform' for synthio.Note uses a WAV containing a wavetable and provides a scannable wave position.""" def __init__(self, filepath, wave_len=256): self.w = adafruit_wave.open(filepath) self.wave_len = wave_len # how many samples in each wave if self.w.getsampwidth() != 2 or self.w.getnchannels() != 1: raise ValueError("unsupported WAV format") self.waveform = np.zeros(wave_len, dtype=np.int16) # empty buf to fill self.num_waves = self.w.getnframes() // self.wave_len self.set_wave_pos(0) def set_wave_pos(self, pos): """Pick which wave to use in the wavetable""" pos = min(max(pos, 0), self.num_waves-1) # constrain samp_pos = int(pos) * self.wave_len # get sample position self.w.setpos(samp_pos) # seek to wavetable location waveA = np.frombuffer(self.w.readframes(self.wave_len), dtype=np.int16) self.waveform[:] = waveA # copy into buf self._wave_pos = pos wavetable1 = Wavetable(wave_dir+wavetables[wti]) # load up wavetable midi_note = 45 # A2 note = synthio.Note(synthio.midi_to_hz(midi_note), waveform=wavetable1.waveform) synth.press(note) # start note sounding pos = 0 # last knob position while True: if key := keys.events.get(): # button pushed if key.pressed: wti = (wti+1) % len(wavetables) # go to next index wavetable1 = Wavetable(wave_dir+wavetables[wti]) # load new wavet note.waveform = wavetable1.waveform # attach to note new_pos = (knobA.value / 65535) * wavetable1.num_waves pos = int((new_pos*0.5) + pos*0.5) # filter knob input wavetable1.set_wave_pos(pos) # pick new wavetable print("%s: wave num:%d" % (wavetables[wti], pos)) time.sleep(0.01)
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