audio - Detect and record a sound with python

Question

I'm using this program to record a sound in python:

Detect & Record Audio in Python

I want to change the program to start recording when sound is detected by the sound card input. Probably should compare the input sound level in chunk, but how do this?

Answer 1

You could try something like this:

based on this question/answer

# this is the threshold that determines whether or not sound is detected
THRESHOLD = 0

#open your audio stream    

# wait until the sound data breaks some level threshold
while True:
    data = stream.read(chunk)
    # check level against threshold, you'll have to write getLevel()
    if getLevel(data) > THRESHOLD:
        break

# record for however long you want
# close the stream

You'll probably want to play with your chunk size and threshold values until you get the desired behavior.

Edit:

You can use the built-in audioop package to find the root-mean-square (rms) of a sample, which is generally how you would get the level.

import audioop
import pyaudio

chunk = 1024

p = pyaudio.PyAudio()

stream = p.open(format=pyaudio.paInt16,
                channels=1,
                rate=44100,
                input=True,
                frames_per_buffer=chunk)

data = stream.read(chunk)

rms = audioop.rms(data, 2)  #width=2 for format=paInt16