audiocore – Support for audio samples
Available on these boards
- class audiocore.RawSample(buffer: circuitpython_typing.ReadableBuffer, *, channel_count: int = 1, sample_rate: int = 8000, single_buffer: bool = True)
A raw audio sample buffer in memory
Create a RawSample based on the given buffer of 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
single_buffer (bool) – Selects single buffered or double buffered transfer mode. This affects what happens if the sample buffer is changed while the sample is playing. In single buffered transfers, a change in buffer contents will not affect active playback. In double buffered transfers, changed buffer contents will be played back when the transfer reaches the next half-buffer point.
Playing 8ksps 440 Hz and 880 Hz sine waves:
import analogbufio import array import audiocore import audiopwmio import board import math import time # Generate one period of sine wave. 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)) pwm = audiopwmio.PWMAudioOut(left_channel=board.D12, right_channel=board.D13) # Play single-buffered sample = audiocore.RawSample(sine_wave) pwm.play(sample, loop=True) time.sleep(3) # changing the wave has no effect for i in range(length): sine_wave[i] = int(math.sin(math.pi * 4 * i / length) * (2 ** 15)) time.sleep(3) pwm.stop() time.sleep(1) # Play double-buffered sample = audiocore.RawSample(sine_wave, single_buffer=False) pwm.play(sample, loop=True) time.sleep(3) # changing the wave takes effect almost immediately for i in range(length): sine_wave[i] = int(math.sin(math.pi * 2 * i / length) * (2 ** 15)) time.sleep(3) pwm.stop() pwm.deinit()
- __exit__() None
Automatically deinitializes the hardware when exiting a context. See Lifetime and ContextManagers for more info.
- sample_rate: int | None
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
playagain to change it.
- class audiocore.WaveFile(file: str | BinaryIO, buffer: circuitpython_typing.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, which can prevent memory fragmentation.
Load a .wav file for playback with
audioio.AudioOutoraudiobusio.I2SOut.- Parameters:
file (Union[str, BinaryIO]) – The name of a wave file (preferred) or an already opened wave file
buffer (WriteableBuffer) – Optional pre-allocated buffer, that will be split in half and used for double-buffering of the data. The buffer must be 8 to 1024 bytes long. If not provided, two 256 byte buffers are initially 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) wav = audiocore.WaveFile("cplay-5.1-16bit-16khz.wav") a = audioio.AudioOut(board.A0) print("playing") a.play(wav) while a.playing: pass print("stopped")
- __exit__() None
Automatically deinitializes the hardware when exiting a context. See Lifetime and ContextManagers for more info.