Extract Voice

We use PyAudio python library to extract voice.

• Step 1, We need to run the following script to get the device index number of 2 Mic pi hat:

sudo pip install pyaudio
cd ~
nano get_index.py

• Step 2, copy below code and paste on get_index.py.

import pyaudio
 
p = pyaudio.PyAudio()
info = p.get_host_api_info_by_index(0)
numdevices = info.get('deviceCount')
 
for i in range(0, numdevices):
        if (p.get_device_info_by_host_api_device_index(0, i).get('maxInputChannels')) > 0:
            print "Input Device id ", i, " - ", p.get_device_info_by_host_api_device_index(0, i).get('name')

• Step 3, press Ctrl + X to exit and press Y to save.
• Step 4, run ‘sudo python get_index.py’ and we will see the device ID as below.

Input Device id  2  -  seeed-2mic-voicecard: - (hw:1,0)

• Step 5, change RESPEAKER_INDEX = 2 to index number. Run python script record.py to record a speech.

import pyaudio
import wave
 
RESPEAKER_RATE = 16000
RESPEAKER_CHANNELS = 2 
RESPEAKER_WIDTH = 2
# run getDeviceInfo.py to get index
RESPEAKER_INDEX = 2  # refer to input device id
CHUNK = 1024
RECORD_SECONDS = 5
WAVE_OUTPUT_FILENAME = "output.wav"
 
p = pyaudio.PyAudio()
 
stream = p.open(
            rate=RESPEAKER_RATE,
            format=p.get_format_from_width(RESPEAKER_WIDTH),
            channels=RESPEAKER_CHANNELS,
            input=True,
            input_device_index=RESPEAKER_INDEX,)
 
print("* recording")
 
frames = []
 
for i in range(0, int(RESPEAKER_RATE / CHUNK * RECORD_SECONDS)):
    data = stream.read(CHUNK)
    frames.append(data)
 
print("* done recording")
 
stream.stop_stream()
stream.close()
p.terminate()
 
wf = wave.open(WAVE_OUTPUT_FILENAME, 'wb')
wf.setnchannels(RESPEAKER_CHANNELS)
wf.setsampwidth(p.get_sample_size(p.get_format_from_width(RESPEAKER_WIDTH)))
wf.setframerate(RESPEAKER_RATE)
wf.writeframes(b''.join(frames))
wf.close()

• Step 6. If you want to extract channel 0 data from 2 channels, please follow below code. For other channel X, please change [0::2] to [X::2].

import pyaudio
import wave
import numpy as np
 
RESPEAKER_RATE = 16000
RESPEAKER_CHANNELS = 2
RESPEAKER_WIDTH = 2
# run getDeviceInfo.py to get index
RESPEAKER_INDEX = 2  # refer to input device id
CHUNK = 1024
RECORD_SECONDS = 3
WAVE_OUTPUT_FILENAME = "output.wav"
 
p = pyaudio.PyAudio()
 
stream = p.open(
            rate=RESPEAKER_RATE,
            format=p.get_format_from_width(RESPEAKER_WIDTH),
            channels=RESPEAKER_CHANNELS,
            input=True,
            input_device_index=RESPEAKER_INDEX,)
 
print("* recording")
 
frames = [] 
 
for i in range(0, int(RESPEAKER_RATE / CHUNK * RECORD_SECONDS)):
    data = stream.read(CHUNK)
    # extract channel 0 data from 2 channels, if you want to extract channel 1, please change to [1::2]
    a = np.fromstring(data,dtype=np.int16)[0::2]
    frames.append(a.tostring())
 
print("* done recording")
 
stream.stop_stream()
stream.close()
p.terminate()
 
wf = wave.open(WAVE_OUTPUT_FILENAME, 'wb')
wf.setnchannels(1)
wf.setsampwidth(p.get_sample_size(p.get_format_from_width(RESPEAKER_WIDTH)))
wf.setframerate(RESPEAKER_RATE)
wf.writeframes(b''.join(frames))
wf.close()