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# SPDX-FileCopyrightText: Copyright 2024 Jeff Epler for Adafruit Industries
# SPDX-License-Identifier: MIT
import os
import collections
import io
import random
import board
import keypad
import audiobusio
import audiocore
import audiomp3
import audiomixer
# Configure the pins to use -- earlier in list = higher priority
pads = [
board.GP0, board.GP1, board.GP2, board.GP3,
board.GP4, board.GP5, board.GP6, board.GP7,
board.GP8, board.GP9, board.GP10, board.GP11,
board.GP12, board.GP13, board.GP14, board.GP15
]
# Configure max voices to play at once
# (No matter what, at most 4 MP3 decoders)
# If set this number too high, playback will stutter. use lower bit rates or fewer voices
#
# when the number of active samples being played back exceeds the number of voices,
# the top numbered playing sample is stopped. There is no logic to restore a sample that
# got stopped in this way.
#
# (this may not be the same as the old FX board logic)
max_simultaneous_voices = 2
audiodev = audiobusio.I2SOut(
bit_clock=board.GP16, word_select=board.GP17, data=board.GP18
)
# This is enough to register as an MP3 file with mp3decoder!, allows creating a decoder
# without "opening" a "file"!
EMPTY_MP3_BYTES = b"\xff\xe3"
def exists(p):
try:
os.stat(p)
return True
except OSError:
return False
def random_choice(seq):
return seq[random.randrange(len(seq))]
# There's no notification when something finishes playing. So, first loop over
# all triggers; if they're not playing, then calling force_off() doesn't actually
# stop any audio (it's already stopped) but it DOES mark the voice & decoder as
# available. Otherwise, we might needlessly stop some other sample.
def free_stopped_channels():
for i in triggers:
if i.voice and not i.playing:
print("fst")
i.force_off()
# iterating on reversed triggers gives priority to **lower** numbered triggers
def ensure_available_decoder():
if available_decoders:
return available_decoders.popleft()
for i in reversed_triggers:
i.force_off()
if available_decoders:
break
return available_decoders.popleft()
def ensure_available_voice():
if available_voices:
return available_voices.popleft()
for i in reversed_triggers:
i.force_off()
if available_voices:
break
return available_voices.popleft()
class TriggerBase:
def __init__(self, prefix):
self._decoder = None
self.voice = None
self.filenames = list(self._gather_filenames(prefix))
def _gather_filenames(self, prefix):
for stem in self.stems:
name_mp3 = f"{prefix}{stem}.mp3"
if exists(name_mp3):
yield name_mp3
continue
name_wav = f"{prefix}{stem}.wav"
if exists(name_wav):
yield name_wav
continue
def get_sample(self, path):
if path.endswith(".mp3"):
self._decoder = ensure_available_decoder()
self._decoder.open(path)
return self._decoder
else:
return audiocore.WaveFile(path)
def play(self, path, loop=False):
self.force_off()
free_stopped_channels()
sample = self.get_sample(path)
self.voice = ensure_available_voice()
self.voice.play(sample, loop=loop)
def force_off(self):
print("force off", self)
voice = self.voice
if voice is not None:
print(f"return voice {id(voice)}")
self.voice = None
voice.stop()
available_voices.append(voice)
decoder = self._decoder
if decoder is not None:
print(f"return decoder {id(decoder)}")
self._decoder = None
print(list(available_decoders), end=" ")
available_decoders.append(decoder)
print("->", list(available_decoders))
@property
def playing(self):
return False if self.voice is None else self.voice.playing
@classmethod
def matches(cls, prefix):
stem = cls.stems[0]
name_mp3 = f"{prefix}{stem}.mp3"
name_wav = f"{prefix}{stem}.wav"
return exists(name_wav) or exists(name_mp3)
def __repr__(self):
return f"<{self.__class__.__name__} {self.filenames}{' playing' if self.playing else ''}>"
class NopTrigger(TriggerBase):
"""Does nothing."""
stems = [""]
def on_press(self):
pass
def on_release(self):
pass
class BasicTrigger(TriggerBase):
"""Plays a file each time the button is pressed down"""
stems = [""]
def on_press(self):
self.play(self.filenames[0])
def on_release(self):
pass
class HoldLoopingTrigger(TriggerBase):
"""Plays a file as long as a button is held down"""
stems = ["HOLDL"]
def on_press(self):
self.play(self.filenames[0], loop=True)
def on_release(self):
self.force_off()
class LatchingLoopTrigger(TriggerBase):
"""Toggles playing each time the button is pressed"""
stems = ["LATCH"]
def on_press(self):
if self.playing:
self.force_off()
else:
self.play(self.filenames[0], loop=True)
def on_release(self):
pass
class PlayNextTrigger(TriggerBase):
stems = [f"NEXT{i}" for i in range(10)]
def __init__(self, prefix):
super().__init__(prefix)
self._phase = 0
def on_press(self):
self.play(self.filenames[self._phase])
self._phase = (self._phase + 1) % len(self.filenames)
def on_release(self):
pass
class PlayRandomTrigger(TriggerBase):
stems = [f"RAND{i}" for i in range(10)]
def on_press(self):
self.play(random_choice(self.filenames))
def on_release(self):
pass
trigger_classes = [
BasicTrigger,
HoldLoopingTrigger,
LatchingLoopTrigger,
PlayNextTrigger,
PlayRandomTrigger,
]
def make_trigger(i):
prefix = f"T{i:02d}"
for cls in trigger_classes:
if not cls.matches(prefix):
continue
return cls(prefix)
return NopTrigger(prefix)
# No matter what, at most 4 MP3 decoders
decoders = [
audiomp3.MP3Decoder(io.BytesIO(EMPTY_MP3_BYTES))
for _ in range(min(4, max_simultaneous_voices))
]
print(decoders)
available_decoders = collections.deque(decoders, len(decoders))
print(list(available_decoders))
keys = keypad.Keys(pads, value_when_pressed=False)
triggers = [make_trigger(i) for i in range(len(pads))]
def playback_specs(sample):
return dict(
channel_count=sample.channel_count,
sample_rate=sample.sample_rate,
bits_per_sample=sample.bits_per_sample,
)
def check_match_make_mixer(dev):
all_filenames = []
for i in triggers:
all_filenames.extend(i.filenames)
if not all_filenames:
raise RuntimeError("*** NO AUDIO FILES FOUND ***")
if max_simultaneous_voices == 1:
return [dev]
first_trigger = triggers[0]
mixer_buffer_size = (1152 * 4) * 4
specs = None
for filename in all_filenames:
sample = first_trigger.get_sample(filename)
new_specs = playback_specs(sample)
if specs is None:
specs = new_specs
else:
if specs != new_specs:
print("*** Audio file specs don't match ***")
print("{all_filenames[0]}: {specs}")
print("{filename}: {specs}")
raise RuntimeError("*** WITH POLYPHONY, ALL MUST MATCH ***")
first_trigger.force_off()
print(f"audio specs: {specs}")
samples_signed = specs["bits_per_sample"] == 16
mixer = audiomixer.Mixer(
voice_count=max_simultaneous_voices,
buffer_size=mixer_buffer_size,
samples_signed=samples_signed,
**specs,
)
dev.play(mixer)
return list(mixer.voice)
print(triggers)
print(list(available_decoders))
reversed_triggers = list(reversed(triggers))
voices = check_match_make_mixer(audiodev)
print(list(available_decoders))
available_voices = collections.deque(voices, len(voices))
while True:
if e := keys.events.get():
print("event", e)
print("available decoders", *(id(i) for i in available_decoders))
print("available voices", *(id(i) for i in available_voices))
trigger = triggers[e.key_number]
if e.pressed:
trigger.on_press()
else:
trigger.on_release()
print(triggers)
Upload the Code, Sound Effects and Libraries to the Raspberry Pi Pico 2
After downloading the Project Bundle, plug your Pico 2 into the computer's USB port with a known good USB data+power cable. You should see a new flash drive appear in the computer's File Explorer or Finder (depending on your operating system) called CIRCUITPY. Open up the zipped file, go to the the appropriate folder inside (e.g., circuitpython-audio-fx/polyphonic/CircuitPython 9.x if you are using CircuitPython 9.x) and copy the items in that folder directly onto your CIRCUITPY drive.
Your CIRCUITPY drive should look like this after copying the sound effects and the code.py file.
Page last edited January 22, 2025
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