How do I use an external microphone for PyAudio instead of the in-built microphone?

Question

The pyAudio.PyAudio().open() function takes an argument known as "input_device_index", in which, if I gave a certain index number that represents my desired microphone, it would use it. Furthermore, another argument known as "Input" must be "True" as well.

CHUNK = 1024
FORMAT = pyaudio.paInt16
CHANNELS = 2
RATE = 48000
RECORD_SECONDS = 2
WAVE_OUTPUT_FILENAME = "output.wav"
INPUT_DEVICE_INDEX = 3

p = pyaudio.PyAudio()
stream = p.open(format=FORMAT,
                channels=CHANNELS,
                rate=RATE,
                input=True,
                input_device_index= INPUT_DEVICE_INDEX,
                frames_per_buffer=CHUNK)

And I identified the index of my desired device by using:

get_device_info_by_index(i)

in which i is an integer that represents a particular index number. For this case, my 'i' is 3. Which outputs:

{'defaultHighInputLatency': 0.1,
'defaultHighOutputLatency': 0.0126875,
'defaultLowInputLatency': 0.01,
'defaultLowOutputLatency': 0.0033541666666666668,
'defaultSampleRate': 48000.0,
'hostApi': 0,
'index': 3,
'maxInputChannels': 2,
'maxOutputChannels': 2,
'name': 'Scarlett 2i2 USB',
'structVersion': 2}

However, after inputting "input_device_index" in the open() function and running the audio record function, I've encountered an error:

File "<ipython-input-145-166f13e76ff1>", line 1, in <module>
record()

File "/Users/aaron.yong/python_main/audio_test_v5.py", line 56, in   record
frames_per_buffer=CHUNK)

File "/anaconda/lib/python3.6/site-packages/pyaudio.py", line 750, in open
stream = Stream(self, *args, **kwargs)

File "/anaconda/lib/python3.6/site-packages/pyaudio.py", line 441, in        __init__
self._stream = pa.open(**arguments)

OSError: [Errno -9986] Internal PortAudio error

Answer 1

My apologies, after restarting my compiler, the code works after all. I've pasted a snippet of pyaudio.py's init function which shows how it works.

Thanks!

def __init__(self,
             PA_manager,
             rate,
             channels,
             format,
             input=False,
             output=False,
             input_device_index=None,
             output_device_index=None,
             frames_per_buffer=1024,
             start=True,
             input_host_api_specific_stream_info=None,
             output_host_api_specific_stream_info=None,
             stream_callback=None):
    """
    Initialize a stream; this should be called by
    :py:func:`PyAudio.open`. A stream can either be input, output,
    or both.
    :param PA_manager: A reference to the managing :py:class:`PyAudio`
        instance
    :param rate: Sampling rate
    :param channels: Number of channels
    :param format: Sampling size and format. See |PaSampleFormat|.
    :param input: Specifies whether this is an input stream.
        Defaults to ``False``.
    :param output: Specifies whether this is an output stream.
        Defaults to ``False``.
    :param input_device_index: Index of Input Device to use.
        Unspecified (or ``None``) uses default device.
        Ignored if `input` is ``False``.
    :param output_device_index:
        Index of Output Device to use.
        Unspecified (or ``None``) uses the default device.
        Ignored if `output` is ``False``.
    :param frames_per_buffer: Specifies the number of frames per buffer.
    :param start: Start the stream running immediately.
        Defaults to ``True``. In general, there is no reason to set
        this to ``False``.
    :param input_host_api_specific_stream_info: Specifies a host API
        specific stream information data structure for input.