audio — Audio Module

The audio module is used to record audio samples from a microphone on the Arduino Portenta or the Arduino Nicla.

Functions

audio.init

audio.init(channels: int = 2, frequency: int = 16000, gain_db: float = 24, highpass: float = 0.9883, samples: int = -1) -> None

Initializes the audio module. Must be called first before using the audio module.

channels specifies the number of audio channels. May be 1 or 2. Audio samples are interleaved for two audio channels. Using more than one channel is only possible on boards with more than one mic.

frequency is the sample frequency to run at. Running at a higher sample frequency results in a higher noise floor which means less effective bits per sample.

gain_db is the microphone gain to apply.

highpass is the high pass filter cut-off given the target sample frequency. This parameter is applicable for the Arduino Portenta H7 only.

samples is the number of samples to accumulate per callback. This is typically calculated based on the decimation factor and number of channels. If set to -1, the number of samples will be calculated automatically based on the decimation factor and number of channels.

audio.start_streaming

audio.start_streaming(callback) -> None

Calls the callback that takes one argument pcmbuf automatically forever when enough PCM samples have accumulated based on the audio module settings. You can cast the pcmbuf into an ndarray for processing the audio samples in numpy and then pass the ndarray to a ml.Model object for inference.

pcmbuf is a signed 16-bit array of audio samples who’s sized based on the decimation factor and number of channels, or the number of samples specified in the audio.init() function.

In single channel mode audio samples will be 16-bits each filling up the 16-bit array.

In dual channel mode audio samples will be 16-bits each in pairs filling up the 16-bit array.

audio.stop_streaming

audio.stop_streaming() -> None

Stops audio streaming and the callback from being called.