audiocore – Support for audio samples

class audiocore.RawSample(buffer: ReadableBuffer, *, channel_count: int = 1, sample_rate: int = 8000)

A raw audio sample buffer in memory

Create a RawSample based on the given buffer of signed values. If channel_count is more than 1 then each channel’s samples should alternate. In other words, for a two channel buffer, the first sample will be for channel 1, the second sample will be for channel two, the third for channel 1 and so on.

Parameters

  • buffer (ReadableBuffer) – A buffer with samples

  • channel_count (int) – The number of channels in the buffer

  • sample_rate (int) – The desired playback sample rate

Simple 8ksps 440 Hz sin wave:

import audiocore
import audioio
import board
import array
import time
import math

# Generate one period of sine wav.
length = 8000 // 440
sine_wave = array.array("h", [0] * length)
for i in range(length):
    sine_wave[i] = int(math.sin(math.pi * 2 * i / length) * (2 ** 15))

dac = audioio.AudioOut(board.SPEAKER)
sine_wave = audiocore.RawSample(sine_wave)
dac.play(sine_wave, loop=True)
time.sleep(1)
dac.stop()
sample_rate :Optional[int]

32 bit value that dictates how quickly samples are played in Hertz (cycles per second). When the sample is looped, this can change the pitch output without changing the underlying sample. This will not change the sample rate of any active playback. Call play again to change it.

deinit(self) → None

Deinitialises the AudioOut and releases any hardware resources for reuse.

__enter__(self) → RawSample

No-op used by Context Managers.

__exit__(self) → None

Automatically deinitializes the hardware when exiting a context. See Lifetime and ContextManagers for more info.

class audiocore.WaveFile(file: typing.BinaryIO, buffer: WriteableBuffer)

Load a wave file for audio playback

A .wav file prepped for audio playback. Only mono and stereo files are supported. Samples must be 8 bit unsigned or 16 bit signed. If a buffer is provided, it will be used instead of allocating an internal buffer.

Load a .wav file for playback with audioio.AudioOut or audiobusio.I2SOut.

Parameters

  • file (typing.BinaryIO) – Already opened wave file

  • buffer (WriteableBuffer) – Optional pre-allocated buffer, that will be split in half and used for double-buffering of the data. If not provided, two 512 byte buffers are allocated internally.

Playing a wave file from flash:

import board
import audiocore
import audioio
import digitalio

# Required for CircuitPlayground Express
speaker_enable = digitalio.DigitalInOut(board.SPEAKER_ENABLE)
speaker_enable.switch_to_output(value=True)

data = open("cplay-5.1-16bit-16khz.wav", "rb")
wav = audiocore.WaveFile(data)
a = audioio.AudioOut(board.A0)

print("playing")
a.play(wav)
while a.playing:
  pass
print("stopped")
sample_rate :int

32 bit value that dictates how quickly samples are loaded into the DAC in Hertz (cycles per second). When the sample is looped, this can change the pitch output without changing the underlying sample.

bits_per_sample :int

Bits per sample. (read only)

channel_count :int

Number of audio channels. (read only)

deinit(self) → None

Deinitialises the WaveFile and releases all memory resources for reuse.

__enter__(self) → WaveFile

No-op used by Context Managers.

__exit__(self) → None

Automatically deinitializes the hardware when exiting a context. See Lifetime and ContextManagers for more info.