#!/usr/bin/python3
# Tonaufnahme mit einem USB-Mikrophon -> WAV-Audiodatei 
import pyaudio, re, wave
from sys import exit

# Start of PyAudio
pa = pyaudio.PyAudio() # pyaudio.PyAudio instance

# Definition of variables
chk = 4096               # 2^12 samples for buffer
fil = "test.wav"         # path to output audio file
frames = []              # list of audio chunks
ndv = 0                  # number of USB Audio cards
re1 = re.compile(r"hw:\d,\d") # reg.expr. for ALSA cards
re2 = re.compile(r"USB.*Audio \(hw:(\d),\d") # reg.expr.
res = pyaudio.paInt16    # 16 bit resolution
sec = 3                  # recording time in seconds
dsr = "defaultSampleRate" # (16000, 44100, 48000)
spr = int(pa.get_device_info_by_index(2)[dsr])
chs = 1                  # number of channels

# Information to the user
pa = pyaudio.PyAudio() # pyaudio.PyAudio instance
print("\nIgnore the above messages from alsa-lib!")
print("\nALSA audio devices\n------------------")
for i in range(pa.get_device_count()):
    dvi = pa.get_device_info_by_index(i).get('name')
    if re1.search(dvi): print(dvi)
    mch = re2.search(dvi)
    if mch:
        ndv = ndv + 1
        dev = mch.group(1)
if ndv != 1:
    pa.terminate()
    exit("\nError in selecting USB sound card!\n")
print("\nWe will use ALSA sound card "+dev+".")
print("The sampling rate is", spr, "Hz.")
print("The duration of recording is", sec, "s.")

#!/usr/bin/python3
# Definition of audio stream
stream = pa.open(
        format = res,
        rate = spr,
        channels = chs,
        input_device_index = int(dev),
        input = True,
        frames_per_buffer = chk,
)

# Recording (append audio chunks to frame list)
n = int( (spr/chk) * sec )
t = str( round(n*chk/spr,1) )
input("Press ENTER to start recording!")
print("\nRECORDING", end=" ")
print("("+t+" s, "+str(n)+" chunks)", end=" ")
for i in range(0, n):
     data = stream.read(chk,
            exception_on_overflow = False)
     frames.append(data)

# Stop of PyAudio
stream.stop_stream()
stream.close()
pa.terminate()
print("finished.")

# Save record to output audio file (WAV format)
out = wave.open(fil,"wb")
out.setnchannels(chs)
out.setsampwidth(pa.get_sample_size(res))
out.setframerate(spr)
out.writeframes(b''.join(frames))
out.close()
print("Audio file",fil,"written.\n")