This allows audioi2sin.I2SIn to be used in effects chains with various audio modules, and to be piped to an output source like AudioOut or USBMicrophone. Prior to this change I2SIn has only a simple record() API.

I tested with this basic code that passes audio from the I2S mic to USB as a microphone to the host computer, turning the MCU into a functional USB microphone.

import board
import audioi2sin
import usb_audio

usb_mic = usb_audio.usb_microphone

with audioi2sin.I2SIn(board.D5, board.D6, board.D9,
                      sample_rate=16000, bit_depth=16) as i2s_mic:

    usb_mic.play(i2s_mic)

    try:
        while True:
            pass
    except KeyboardInterrupt:
        pass

I also successfully tested a version with a handful of effects between the input and output so the device acts as a voice changer. I verified the original record API .wav file example works as expected as well.