`audiodelays` – Support for audio delay effects

The audiodelays module contains classes to provide access to audio delay effects.

Available on these boards

Adafruit Feather RP2350
Adafruit Fruit Jam
Adafruit Metro RP2350
Challenger+ RP2350 BConnect
Challenger+ RP2350 WiFi6/BLE5
Cytron IRIV IO Controller
Cytron MOTION 2350 Pro
Datanoise PicoADK V2
Music Thing Modular Workshop Computer
Pimoroni PGA2350
Pimoroni Pico Plus 2
Pimoroni Pico Plus 2 W
Pimoroni Plasma 2350
Pimoroni Plasma 2350W
Pimoroni Tiny 2350
RP2350 Stamp
RP2350 Stamp XL
Raspberry Pi Pico 2
Raspberry Pi Pico 2 W
Seeeduino XIAO RP2350
SparkFun Pro Micro RP2350
SparkFun Thing Plus RP2350
W5100S-EVB-Pico2
Waveshare RP2350-GEEK
Waveshare RP2350-LCD-0.96
Waveshare RP2350-LCD-1.28
Waveshare RP2350-One
Waveshare RP2350-Plus
Waveshare RP2350-TOUCH-LCD-1.28
Waveshare RP2350-Tiny
Waveshare RP2350-Zero

class audiodelays.Echo(max_delay_ms: int = 500, delay_ms: synthio.BlockInput = 250.0, decay: synthio.BlockInput = 0.7, mix: synthio.BlockInput = 0.5, buffer_size: int = 512, sample_rate: int = 8000, bits_per_sample: int = 16, samples_signed: bool = True, channel_count: int = 1)

An Echo effect

Create a Echo effect where you hear the original sample play back, at a lesser volume after

a set number of millisecond delay. The delay timing of the echo can be changed at runtime with the delay_ms parameter but the delay can never exceed the max_delay_ms parameter. The maximum delay you can set is limited by available memory.

Each time the echo plays back the volume is reduced by the decay setting (echo * decay).

The mix parameter allows you to change how much of the unchanged sample passes through to the output to how much of the effect audio you hear as the output.

Parameters:

max_delay_ms (int) – The maximum time the echo can be in milliseconds
delay_ms (synthio.BlockInput) – The current time of the echo delay in milliseconds. Must be less the max_delay_ms
decay (synthio.BlockInput) – The rate the echo fades. 0.0 = instant; 1.0 = never.
mix (synthio.BlockInput) – The mix as a ratio of the sample (0.0) to the effect (1.0).
buffer_size (int) – The total size in bytes of each of the two playback buffers to use
sample_rate (int) – The sample rate to be used
channel_count (int) – The number of channels the source samples contain. 1 = mono; 2 = stereo.
bits_per_sample (int) – The bits per sample of the effect
samples_signed (bool) – Effect is signed (True) or unsigned (False)
freq_shift (bool) – Do echos change frequency as the echo delay changes

Playing adding an echo to a synth:

import time
import board
import audiobusio
import synthio
import audiodelays

audio = audiobusio.I2SOut(bit_clock=board.GP20, word_select=board.GP21, data=board.GP22)
synth = synthio.Synthesizer(channel_count=1, sample_rate=44100)
echo = audiodelays.Echo(max_delay_ms=1000, delay_ms=850, decay=0.65, buffer_size=1024, channel_count=1, sample_rate=44100, mix=0.7, freq_shift=False)
echo.play(synth)
audio.play(echo)

note = synthio.Note(261)
while True:
    synth.press(note)
    time.sleep(0.25)
    synth.release(note)
    time.sleep(5)

deinit() → None: Deinitialises the Echo.

__enter__() → Echo: No-op used by Context Managers.

__exit__() → None: Automatically deinitializes when exiting a context. See Lifetime and ContextManagers for more info.

delay_ms: synthio.BlockInput: Delay of the echo in milliseconds. (read-only)

decay: synthio.BlockInput: The rate the echo decays between 0 and 1 where 1 is forever and 0 is no echo.

mix: synthio.BlockInput: The rate the echo mix between 0 and 1 where 0 is only sample and 1 is all effect.

freq_shift: bool: Does the echo change frequencies as the delay changes.

playing: bool: True when the effect is playing a sample. (read-only)

play(sample: circuitpython_typing.AudioSample, *, loop: bool = False) → None

Plays the sample once when loop=False and continuously when loop=True. Does not block. Use playing to block.

The sample must match the encoding settings given in the constructor.

stop() → None: Stops playback of the sample. The echo continues playing.

class audiodelays.PitchShift(semitones: synthio.BlockInput = 0.0, mix: synthio.BlockInput = 1.0, window: int = 1024, overlap: int = 128, buffer_size: int = 512, sample_rate: int = 8000, bits_per_sample: int = 16, samples_signed: bool = True, channel_count: int = 1)

A pitch shift effect

Create a pitch shift effect where the original sample play back is altered to change the

the perceived pitch by a factor of semi-tones (1/12th of an octave). This effect will cause a slight delay in the output depending on the size of the window and overlap buffers.