python - Picamera マルチプロセス

Question

別のプロセスを使用して写真を撮ろうとしています。このコードは、 から に変更されましThreadたmultiprocess(これが機能しない理由です)。このクラスのインスタンスを作成して実行するとobj.start()、ポップアップが表示されthe program is already running, do you want to stop it?て何が間違っているのかわかりません。PS ("GO"出力は画面に表示されません)

# import the necessary packages
from picamera.array import PiRGBArray
from picamera import PiCamera
import multiprocessing


class MultiProcess(multiprocessing.Process):
def __init__(self):

    print("INIT")
    multiprocessing.Process.__init__(self)

    # initialize the camera and stream
    self.camera             = PiCamera()
    self.camera.resolution  = (640, 480) 
    self.camera.framerate   = 32
    self.rawCapture         = PiRGBArray(self.camera, size=(320, 240))
    self.stream             = self.camera.capture_continuous(self.rawCapture, format="bgr", use_video_port=True)

    # initialize the frame and the variable used to indicate
    # if the thread should be stopped
    self.frame      = None
    self.stopped    = False

def start(self):
    # start the thread to read frames from the video stream
    p = multiprocessing.Process(target=self.update, args=())
    print("1")
    p.daemon = True
    print("2")
    p.start()
    print("3")
    p.join()
    print("GO")
    return self

def update(self):
    # keep looping infinitely until the thread is stopped
    for f in self.stream:
        print("NEVER REACH HERE")
        # grab the frame from the stream and clear the stream in
        # preparation for the next frame
        self.frame = f.array
        self.rawCapture.truncate(0)

        # if the thread indicator variable is set, stop the thread
        # and resource camera resources
        if self.stopped:
            self.stream.close()
            self.rawCapture.close()
            self.camera.close()
            return

def read(self):
    # return the frame most recently read
    return self.frame

def stop(self):
    # indicate that the thread should be stopped
    self.stopped = True