在 python 中使用 opencv 流式传输的视频的异步列表

Question

Trying to Run the list of videos through OpenCV using python while going through the blog I was able to run for Webcam but I am trying run it for list of cameras for which I am not able to make it work,

import threading
import cv2
import time

class VideoCaptureAsync:
    def __init__(self, src=0, width=640, height=480):
        self.src = src
        self.cap = cv2.VideoCapture(self.src)
        self.cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
        self.cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
        self.grabbed, self.frame = self.cap.read()
        self.started = False
        self.read_lock = threading.Lock()

    def set(self, var1, var2):
        self.cap.set(var1, var2)

    def start(self):
        if self.started:
            print('[!] Asynchroneous video capturing has already been started.')
            return None
        self.started = True
        self.thread = threading.Thread(target=self.update, args=())
        self.thread.start()
        return self

    def update(self):
        while self.started:
            grabbed, frame = self.cap.read()
            with self.read_lock:
                self.grabbed = grabbed
                self.frame = frame

    def read(self):
        with self.read_lock:
            frame = self.frame.copy()
            grabbed = self.grabbed
        return grabbed, frame

    def stop(self):
        self.started = False
        self.thread.join()

    def __exit__(self, exec_type, exc_value, traceback):
        self.cap.release()

def test(n_frames=500, width=1280, height=720, async=False):
    if async:
        cap = VideoCaptureAsync(0)
    else:
        cap = cv2.VideoCapture(0)
    cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
    cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
    if async:
        cap.start()
    t0 = time.time()
    i = 0
    while i < n_frames:
        _, frame = cap.read()
        cv2.imshow('Frame', frame)
        cv2.waitKey(1) & 0xFF
        i += 1
    print('[i] Frames per second: {:.2f}, async={}'.format(n_frames / (time.time() - t0), async))
    if async:
        cap.stop()
    cv2.destroyAllWindows()


if __name__ == '__main__':
    test(n_frames=500, width=1280, height=720, async=False)
    test(n_frames=500, width=1280, height=720, async=True)

I wanted to run this for multiple IP cameras Any suggestions for running this code for multiple IP cameras will be very helpful

Answer 1

You need to initiate the VideoCaptureAsync multiple times in your test function. Furthermore you don't need to set height and width multiple times as the class you have defined already have that as parameters. I have modified your test function a bit to show an example for running two webcams at the same time:

def test(n_frames=500, width=1280, height=720, async_flag=False):
    if async_flag:
        cap = VideoCaptureAsync(src=0, width=width, height=height) #<----Change src to ip camera
        cap1 = VideoCaptureAsync(src=1, width=width, height=height) #<----Change src to ip camera 2
    else:
        cap = cv2.VideoCapture(0)
    if async_flag:
        cap.start()
        cap1.start()
    t0 = time.time()
    i = 0
    while i < n_frames:
        _, frame = cap.read()
        _, frame1 = cap1.read()
        cv2.imshow('Frame', frame)
        cv2.imshow('Frame 1', frame1)
        cv2.waitKey(1) & 0xFF
        i += 1
    print('[i] Frames per second: {:.2f}, async={}'.format(n_frames / (time.time() - t0), async_flag))
    if async_flag:
        cap.stop()
        cap1.stop()
    cv2.destroyAllWindows()


if __name__ == '__main__':
    # test(n_frames=500, width=1280, height=720, async_flag=False)
    test(n_frames=500, width=1280, height=720, async_flag=True)