Taking audio input from PC microphone using python

Question

I am using ubuntu 16.04 and I have to take audio input from my pc microphone. I am using python 3. I used pyalsaaudio. I copied the code from somewhere. Here is the code

import alsaaudio, time, audioop
inp = alsaaudio.PCM(alsaaudio.PCM_CAPTURE,alsaaudio.PCM_NONBLOCK)
inp.setchannels(1)
inp.setrate(8000)
inp.setformat(alsaaudio.PCM_FORMAT_S16_LE)
inp.setperiodsize(160)
while True:
    l,data = inp.read()
    if l:
       print(audioop.max(data, 2))
    time.sleep(.001)

By using this code I am getting an error as

ALSAAudioError: Invalid argument

In line no. 3 inp.setchannels(1)

I am new to this if there is another library for doing this then please suggest that too. Thanks.

Answer 1

As far as I am aware from the pyalsaaudio documentation you seem to be setting it up correct according to their example for recording audio.

The only issue I could see with your program could maybe be the installation process? Did you install it with pip or manually? (I'm guessing pip; maybe you are missing the correct ALSA dependencies?). Maybe it's worth trying the manual install if you want to continue using this library.

---

PyAudio

In my experience, most people tend to use PyAudio for real-time audio IO. It is built ontop of portaudio which uses ALSA during the Linux build process. Since it is widely used, you will find plenty examples like:

• Real-time Blocking mode audio IO
• Real-time Callback mode audio IO
• Playing .wav files
• And here's a website with 50 examples of other PyAudio things...

Just to get you started, here is an example of recording audio from a microphone (blocking i.e. the program waits until the audio is recorded before anything else happens), and writing that data to a .wav file in Python with PyAudio.

import pyaudio # Soundcard audio I/O access library
import wave # Python 3 module for reading / writing simple .wav files

# Setup channel info
FORMAT = pyaudio.paInt16 # data type formate
CHANNELS = 2 # Adjust to your number of channels
RATE = 44100 # Sample Rate
CHUNK = 1024 # Block Size
RECORD_SECONDS = 5 # Record time
WAVE_OUTPUT_FILENAME = "file.wav"

# Startup pyaudio instance
audio = pyaudio.PyAudio()

# start Recording
stream = audio.open(format=FORMAT, channels=CHANNELS,
                rate=RATE, input=True,
                frames_per_buffer=CHUNK)
print "recording..."
frames = []

# Record for RECORD_SECONDS
for i in range(0, int(RATE / CHUNK * RECORD_SECONDS)):
    data = stream.read(CHUNK)
    frames.append(data)
print "finished recording"


# Stop Recording
stream.stop_stream()
stream.close()
audio.terminate()

# Write your new .wav file with built in Python 3 Wave module
waveFile = wave.open(WAVE_OUTPUT_FILENAME, 'wb')
waveFile.setnchannels(CHANNELS)
waveFile.setsampwidth(audio.get_sample_size(FORMAT))
waveFile.setframerate(RATE)
waveFile.writeframes(b''.join(frames))
waveFile.close()

If you were having trouble installing it, then here are the basic dependency installs needed for Ubuntu 16.04 LTS (originally posted here).

sudo apt-get install libasound-dev portaudio19-dev libportaudio2 libportaudiocpp0
sudo apt-get install ffmpeg libav-tools
sudo pip install pyaudio

I hope this helps!

Extra: If you fancied it there are plenty examples on the portaudio website on how to get started with real-time audio IO in C/C++