`audiofilters` – Support for audio filter effects

The audiofilters module contains classes to provide access to audio filter effects.

Available on these boards

Adafruit Feather RP2350
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 audiofilters.DistortionMode

The method of distortion used by the audiofilters.Distortion effect.

CLIP: DistortionMode: Digital distortion effect which cuts off peaks at the top and bottom of the waveform.

LOFI: DistortionMode: Low-resolution digital distortion effect (bit depth reduction). You can use it to emulate the sound of early digital audio devices.

OVERDRIVE: DistortionMode: Emulates the warm distortion produced by a field effect transistor, which is commonly used in solid-state musical instrument amplifiers. The audiofilters.Distortion.drive property has no effect in this mode.

WAVESHAPE: DistortionMode: Waveshaper distortions are used mainly by electronic musicians to achieve an extra-abrasive sound.

class audiofilters.Distortion(drive: synthio.BlockInput = 0.0, pre_gain: synthio.BlockInput = 0.0, post_gain: synthio.BlockInput = 0.0, mode: DistortionMode = DistortionMode.CLIP, soft_clip: bool = False, mix: synthio.BlockInput = 1.0, buffer_size: int = 512, sample_rate: int = 8000, bits_per_sample: int = 16, samples_signed: bool = True, channel_count: int = 1)

A Distortion effect

Create a Distortion effect where the original sample is manipulated to create a distorted

sound according to the DistortionMode.

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:

drive (synthio.BlockInput) – Distortion power. Value can range from 0.0 to 1.0.
pre_gain (synthio.BlockInput) – Increases or decreases the volume before the effect, in decibels. Value can range from -60 to 60.
post_gain (synthio.BlockInput) – Increases or decreases the volume after the effect, in decibels. Value can range from -80 to 24.
mode (DistortionMode) – Distortion type.
soft_clip (bool) – Whether or not to soft clip (True) or hard clip (False) the output.
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)

Playing adding a distortion to a synth:

import time
import board
import audiobusio
import synthio
import audiofilters

audio = audiobusio.I2SOut(bit_clock=board.GP20, word_select=board.GP21, data=board.GP22)
synth = synthio.Synthesizer(channel_count=1, sample_rate=44100)
effect = audiofilters.Distortion(drive=0.5, mix=1.0, buffer_size=1024, channel_count=1, sample_rate=44100)
effect.play(synth)
audio.play(effect)

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

deinit() → None: Deinitialises the Distortion.

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

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

drive: synthio.BlockInput: Distortion power. Value can range from 0.0 to 1.0.

pre_gain: synthio.BlockInput: Increases or decreases the volume before the effect, in decibels. Value can range from -60 to 60.

post_gain: synthio.BlockInput: Increases or decreases the volume after the effect, in decibels. Value can range from -80 to 24.

mode: DistortionMode: Distortion type.

soft_clip: bool: Whether or not to soft clip (True) or hard clip (False) the output.

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

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.

class audiofilters.Filter(filter: synthio.Biquad | Tuple[synthio.Biquad] | None = None, mix: synthio.BlockInput = 1.0, buffer_size: int = 512, sample_rate: int = 8000, bits_per_sample: int = 16, samples_signed: bool = True, channel_count: int = 1)

A Filter effect

Create a Filter effect where the original sample is processed through a biquad filter

created by a synthio.Synthesizer object. This can be used to generate a low-pass, high-pass, or band-pass filter.