Python • Raspberry Pi audio recording works alone, but not when recording video at the same time

Code:

import subprocessimport threadingimport osaudio_process = Nonestop_recording_flag = Falseaudio_filename = "test.wav"def record_audio():    global audio_process, stop_recording_flag    env = os.environ.copy()    env["HOME"] = os.path.expanduser("~")    print("Recording... Type 'stop' and press Enter to stop.")    audio_process = subprocess.Popen([        "arecord", "-D", "dmic_sv", "-c", "2", "-r", "48000",        "-f", "S32_LE", "-t", "wav", audio_filename    ], env=env)    # Wait until user types 'stop'    while not stop_recording_flag and audio_process.poll() is None:        pass    if audio_process.poll() is None:        print("Stopping recording...")        audio_process.terminate()        try:            audio_process.wait(timeout=5)        except subprocess.TimeoutExpired:            audio_process.kill()    print(f"Recording saved to {audio_filename}")def monitor_input():    global stop_recording_flag    while True:        command = input().strip().lower()        if command == "stop":            stop_recording_flag = True            breakif __name__ == "__main__":    t1 = threading.Thread(target=record_audio)    t2 = threading.Thread(target=monitor_input)    t1.start()    t2.start()    t1.join()    t2.join()

Code:

video_selected_index = 0is_recording = Falseframerate = 30video_filename = "/home/pi/video.h264"audio_wav_filename = "/home/pi/audio.wav"final_filename = ""picam = Noneaudio_process = Noneaudio_thread = Nonevideo_thread = Nonedef record_audio():    global audio_process, is_recording    try:        print("  [record_audio] Starting audio capture, Sir.")        env = os.environ.copy()        env["HOME"] = os.path.expanduser("~")        audio_process = subprocess.Popen([            "arecord", "-D", "dmic_sv", "-c", "2", "-r", "48000",            "-f", "S32_LE", "-t", "wav", audio_wav_filename        ], env=env)        # Wait for is_recording to turn False        while is_recording:            time.sleep(0.1)        if audio_process.poll() is None:            print("  [record_audio] Terminating arecord…")            audio_process.terminate()            try:                audio_process.wait(timeout=5)            except subprocess.TimeoutExpired:                audio_process.kill()        print(f"  [record_audio] Audio saved to {audio_wav_filename}, Sir.")    except Exception as e:        print(f"  [record_audio] Exception, Sir: {e}")def start_recording(config):    """    Launch audio + video threads (non-daemon), with a slight stagger.    """    global is_recording, audio_thread, video_thread    is_recording = True    # Start UI updater thread (could remain daemon)    threading.Thread(target=recording_ui_updater, daemon=True).start()    # Create *non-daemon* threads for audio & video so they run fully    audio_thread = threading.Thread(target=record_audio, daemon=False)    video_thread = threading.Thread(target=record_video, args=(config,), daemon=False)    # Start audio first, give it time to initialize DMIC    audio_thread.start()    time.sleep(0.1)    # Now start video capture    video_thread.start()def stop_recording():    """    Signal both threads to finish, then join.    """    global is_recording    is_recording = False    print("  [stop_recording] Signaled threads to stop.")    recording_status("Muxing...")    if audio_thread:        audio_thread.join()    # Give time for OS to flush file buffers    time.sleep(0.5)  # Crucial    if video_thread:        print("  [stop_recording] Joining video thread…")        video_thread.join()    print("  [stop_recording] Threads joined, proceeding to mux.")    mux_audio_video()def show_take_video_menu():    global video_selected_index, is_recording, picam    try:        picam = Picamera2()        picam.configure(picam.create_still_configuration())        picam.start()        time.sleep(2)  # Camera warm-up    except Exception as e:        print(f"Camera initialization failed: {e}")        return    while True:        if not is_recording:            # Draw resolution menu            img = Image.new("RGB", (160, 80), "black")            draw = ImageDraw.Draw(img)            title = "Take Video"            title_width = draw.textlength(title, font=font)            draw.text(((160 - title_width) // 2, 2), title, font=font, fill="red")            for i, (label, _) in enumerate(video_resolutions):                prefix = "> " if i == video_selected_index else "  "                draw.text((10, 18 + i * 14), prefix + label, font=font, fill="red")            display.display(img)        # Button controls        if GPIO.input(21) == GPIO.LOW:  # UP            wait_for_button_release(21)            video_selected_index = (video_selected_index - 1) % len(video_resolutions)        elif GPIO.input(12) == GPIO.LOW:  # DOWN            wait_for_button_release(12)            video_selected_index = (video_selected_index + 1) % len(video_resolutions)        elif GPIO.input(16) == GPIO.LOW:  # SELECT            wait_for_button_release(16)            label, config = video_resolutions[video_selected_index]            if is_recording:                stop_recording()                continue            if label.lower() == "return":                if is_recording:                    stop_recording()                print("Exiting video menu.")                picam.close()                return            if config:                start_recording(config)        time.sleep(0.1)  # Input debounce delaydef mux_audio_video():    global final_filename, framerate    timestamp = time.strftime("%Y%m%d_%H%M%S")    final_filename = f"/home/pi/Videos/recording_{timestamp}.mp4"    subprocess.run([        "ffmpeg", "-y",        "-framerate", str(framerate),        "-i", video_filename,        "-i", audio_wav_filename,        "-metadata:s:v", "rotate=270",        "-c:v", "copy",        "-c:a", "aac",        "-shortest", final_filename    ], check=True)    print(f"Muxed to {final_filename}")