how to fix Error while recording data of unknown length?

Question

I am trying to record the audio from my microphone of required duration. I want to control the duration of the file by taking the user input.Based on its decision I have to stop recording and save the file for that duration.

import pyaudio
import wave
from multiprocessing import Process

global flag
global frames

def try_recording(stream,RATE, CHUNK):
    while flag != 1:
        #for i in range(0,int(RATE/CHUNK*DURATION): 
        for i in range(0,int(RATE/CHUNK)):
            data = stream.read(CHUNK)
            frames.append(data)

def scan_input():
    num = input('Enter input number: ')
    if int(num) == 1:
       flag = 1
    else:
       scan_input()

if __name__=='__main__':
    FORMAT = pyaudio.paInt16
    CHANNELS = 2
    RATE = 44100
    CHUNK = 1024

    WAVE_OUTPUT_FILENAME = "file.wav"
    flag = 0

    audio = pyaudio.PyAudio()

    # start Recording
    stream = audio.open(format=FORMAT, channels=CHANNELS,
                    rate=RATE, input=True,
                    frames_per_buffer=CHUNK)
    print("recording...")
    frames = []
    #sys.setrecursionlimit(1500)
    p1 = Process(target=try_recording, args = (stream,RATE,CHUNK))
    p1.start()
    p2 = Process(target=scan_input)
    p2.start()

    #frames = try_recording(stream, RATE, CHUNK)
    print('finished recording')
    # stop Recording
    stream.stop_stream()
    stream.close()
    audio.terminate()

    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()

I am able to record files when I define the time in seconds. Now I want to scan the input from user end when to stop the recording. So I modified the program by adding parallel processing so that two functions run simultaneously. When I got a recursion error, I tried to resolve it by adding sys.setrecursionlimit(1500) but the result doesn't change anything.

How to resolve the issue so that I can record the audio for my required duration.

Update: Error and traceback

recording...
Traceback (most recent call last):
  File "D:/Projects/Trails/try.py", line 14, in try_recording
try_recording(stream,RATE,CHUNK)
  File "D:/Projects/Trails/try.py", line 14, in try_recording
try_recording(stream,RATE,CHUNK)
  File "D:/Projects/Trails/try.py", line 14, in try_recording
try_recording(stream,RATE,CHUNK)
  [Previous line repeated 995 more times]
  File "D:/Projects/Trails/try.py", line 9, in try_recording
     if flag == 1:
  RecursionError: maximum recursion depth exceeded in comparison

If I increase the limit to 44000 sys.setrecursionlimit(44000) the code runs for approx 1 sec and ends with error

 Process finished with exit code -1073741571 (0xC00000FD)

UPDATE2: updated code as suggested by @quamrana.

The two processes are not working simultaneously. Loop doesnt come outside of the process 2 function. testing with print statements I understand that until I press 1 it is looping only in process 1, later it is moving to second process but not able to scan input from first function to end the recordings.

Update 3: updating the Process arguments

Traceback (most recent call last):
File "D:/Projects/Trails/try.py", line 42, in <module>
p1.start()
File "C:\Program Files\Python36\lib\multiprocessing\process.py", line 105, in start
self._popen = self._Popen(self)
File "C:\Program Files\Python36\lib\multiprocessing\context.py", line 223, in _Popen
return _default_context.get_context().Process._Popen(process_obj)
File "C:\Program Files\Python36\lib\multiprocessing\context.py", line 322, in _Popen
return Popen(process_obj)
File "C:\Program Files\Python36\lib\multiprocessing\popen_spawn_win32.py", line 65, in __init__
reduction.dump(process_obj, to_child)
File "C:\Program Files\Python36\lib\multiprocessing\reduction.py", line 60, in dump
ForkingPickler(file, protocol).dump(obj)
TypeError: can't pickle _portaudio.Stream objects
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "C:\Program Files\Python36\lib\multiprocessing\spawn.py", line 105, in spawn_main
exitcode = _main(fd)
File "C:\Program Files\Python36\lib\multiprocessing\spawn.py", line 115, in _main
self = reduction.pickle.load(from_parent)
EOFError: Ran out of input

how to resolve multiprocessing pickle error ?

Answer 1

I assume that you don't actually require try_recording to be recursive, so it can be rewritten like this:

def try_recording(stream,RATE, CHUNK):
    while flag != 1:
        for i in range(0,int(RATE/CHUNK)):
            data = stream.read(CHUNK)
            frames.append(data)

Also you are not starting your processes correctly. They should be:

p1 = Process(target=try_recording, args=(stream,RATE,CHUNK))
p2 = Process(target=scan_input)

And your flag should be a shared variable:

# flag = 0
flag = multiprocessing.Value('i', 0)