Question

我对这里发生的事情感到茫然。我试图运行一个opencv VideoCapture进程来读取帧并放入一个队列供工人处理。

应用程序永远不会运行，因为CameraProcess实例似乎永远不会终止。经过一些调查后，看起来在调用#release（）后相机报告已关闭，但在主进程中被视为打开。

我不应该在Process中创建一个VideoCapture实例吗？

示例应用程序：

import cv2
from multiprocessing import Process, Event
from time import sleep

class CameraProcess(Process):
    def __init__(self, camera_id, *args, **kwargs):
        super(CameraProcess, self).__init__(*args, **kwargs)
        self.shutdown = Event()

        self.camera = cv2.VideoCapture(camera_id)
        sleep(1)
        print('Camera is opened? {}'.format(self.camera.isOpened()))

    def run(self):
        while not self.shutdown.wait(0.05):
            print('Doing camera stuff')
            sleep(1)

        self.camera.release()
        print('Camera is closed? {}'.format(not self.camera.isOpened()))

try:
    camera = CameraProcess(0)
    camera.start()
    sleep(5)
    camera.shutdown.set()
    sleep(2)
    print('Camera is closed? {}'.format(not camera.camera.isOpened()))
except KeyboardInterrupt:
    pass
finally:
    camera.terminate()

应用程序输出：

Camera is opened? True
Doing camera stuff
Doing camera stuff
Doing camera stuff
Doing camera stuff
Doing camera stuff
Camera is closed? True
Camera is closed? False

环境：

Debian stretch
Python：3.5.3
cv2：3.4.0

Answer 1

奇怪的是，它应该被释放。但相机资源仍在被占用。可能是一个错误？或者它可能是新的......

为了正确释放资源，我定义了一个新方法，如下所示。然后就行了。

import cv2
from multiprocessing import Process, Event
from time import sleep

class CameraProcess(Process):
    def __init__(self, camera_id, *args, **kwargs):
        super(CameraProcess, self).__init__(*args, **kwargs)
        self.shutdown = Event()

        self.camera = cv2.VideoCapture(camera_id)
        print('Camera is opened? {}'.format(self.camera.isOpened()))

    def run(self):
        while not self.shutdown.wait(0.05):
            print('Doing camera stuff')
            sleep(1)
        self.camera.release()
        print('[run   ] Camera is closed? {}'.format(not self.camera.isOpened()))

    ## Defind a new method to release the resourse(again).
    def shutup(self):
        self.shutdown.set()
        if self.camera.isOpened():
            self.camera.release()
        print('[shutup] Camera is closed? {}'.format(not self.camera.isOpened()))

try:
    camera = CameraProcess(0)
    camera.start()
    sleep(5)
    camera.shutup()
    sleep(2)
    print('[main  ] Camera is closed? {}'.format(not camera.camera.isOpened()))
except KeyboardInterrupt:
    pass
finally:
    camera.terminate()

现在结果为OK。

Camera is opened? True
Doing camera stuff
Doing camera stuff
Doing camera stuff
Doing camera stuff
Doing camera stuff
[shutup] Camera is closed? True
[run   ] Camera is closed? True
[main  ] Camera is closed? True

如何终止＆＃34; multiprocessing.Process＆＃34;正确使用＆＃34; cv2.VideoCapture＆＃34; （Python OpenCV）？

1 个答案: