python使用Opencv实时读取摄像头进行处理之后传到前端

 参考链接：

读取多个(海康\大华)网络摄像头的视频流 (使用opencv-python)，解决实时读取延迟问题：https://zhuanlan.zhihu.com/p/38136322

websockets：

https://github.com/aaugustin/websockets

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流程： 使用opencv采取多进程实时读取网络摄像头， 经过算法之后采用websocket视频流传给摄像头。

关键代码：具体参考第一篇博客。

import multiprocessing as mp
...
img_queues = [mp.Queue(maxsize=2) for _ in camera_ip_l]  # queue
...
q.put(frame) if is_opened else None  # 线程A不仅将图片放入队列
q.get() if q.qsize() > 1 else time.sleep(0.01) # 线程A还负责移除队列中的旧图

服务端代码：

import time
import multiprocessing as mp
import threading
from queue import Queue
import cv2
import numpy as np
import asyncio
import websockets
from websockets import ConnectionClosed


frame = None


def websocket_process(img_dict):
    # 服务器端主逻辑
    async def main_logic(websocket, path):
        await recv_msg(websocket, img_dict)

    # new_loop = asyncio.new_event_loop()
    # asyncio.set_event_loop(new_loop)
    start_server = websockets.serve(main_logic, '0.0.0.0', 5678)
    asyncio.get_event_loop().run_until_complete(start_server)
    asyncio.get_event_loop().run_forever()



async def recv_msg(websocket, img_dict):
    recv_text = await websocket.recv()
    if recv_text == 'begin':
        while True:
            frame = img_dict['img']
            if isinstance(frame, np.ndarray):
                enconde_data = cv2.imencode('.png', frame)[1]
                enconde_str = enconde_data.tostring()
                try:
                    await websocket.send(enconde_str)
                except Exception as e:
                    print(e)
                    return True


def image_put(q, user, pwd, ip):
    rtsp_url = 'rtsp://{0}:{1}@{2}:554/h265/ch1/main/av_stream'.format(user, pwd, ip)
    cap = cv2.VideoCapture(rtsp_url)
    i = 0
    while True:
        ret, frame = cap.read()
        if ret:
            frame = cv2.resize(frame, (500, 500))
            q.put(frame)
            q.get() if q.qsize() > 1 else time.sleep(0.01)


def image_get(q, img_dict):
    while True:
        frame = q.get()
        if isinstance(frame, np.ndarray):
            img_dict['img'] = frame





def run_single_camera(user_name, user_pwd, camera_ip):
    mp.set_start_method(method='spawn')  # init
    # queue = Queue(maxsize=3)
    # threads = [threading.Thread(target=image_put, args=(queue, user_name, user_pwd, camera_ip)),
    #              threading.Thread(target=image_get, args=(queue, )),
    #              threading.Thread(target=websocket_process)]
    #
    # [thread.start() for thread in threads]
    # [thread.join() for thread in threads]

    queue = mp.Queue(maxsize=3)
    m = mp.Manager()
    img_dict = m.dict()
    Processes = [mp.Process(target=image_put, args=(queue, user_name, user_pwd, camera_ip)),
               mp.Process(target=image_get, args=(queue, img_dict)),
               mp.Process(target=websocket_process, args=(img_dict, ))]

    [process.start() for process in Processes]
    [process.join() for process in Processes]


def run():
    run_single_camera('admin', 'admin', '192.168.101.65')



if __name__ == '__main__':
    run()

前端代码：