前言
网络摄像头的视频流解析直接使用通过http的Mjpeg是具有边界帧信息的multipart / x-mixed-replace,而jpeg数据只是以二进制形式发送。因此,实际上不需要关心HTTP协议标头。所有jpeg帧均以marker开头,0xff 0xd8并以结尾0xff 0xd9。因此,上面的代码从http流中提取了此类帧,并将其一一解码。像下面
...(http) 0xff 0xd8 --| [jpeg data] |--this part is extracted and decoded 0xff 0xd9 --| ...(http) 0xff 0xd8 --| [jpeg data] |--this part is extracted and decoded 0xff 0xd9 --| ...(http)
如果图像的获取是从tcp网络中传输到本地进行解析需要对bytes类型数据进行解码
在使用OpenCV直接调用网络摄像头时可能会出现
Cam not found
这时候就需要下面这种办法
代码:
帧解析
import cv2 cap = cv2.VideoCapture('http://localhost:8080/frame.mjpg') while True: ret, frame = cap.read() print(frame) if ret == True: cv2.imshow('Video', frame) if cv2.waitKey(1) == 27: exit(0)
视频流解析
import cv2 import requests import numpy as np r = requests.get('http://192.168.1.xx/mjpeg.cgi', auth=('user', 'password'), stream=True) if(r.status_code == 200): bytes = bytes() for chunk in r.iter_content(chunk_size=1024): bytes += chunk a = bytes.find(b'\xff\xd8') b = bytes.find(b'\xff\xd9') if a != -1 and b != -1: jpg = bytes[a:b+2] bytes = bytes[b+2:] i = cv2.imdecode(np.fromstring(jpg, dtype=np.uint8), cv2.IMREAD_COLOR) cv2.imshow('i', i) if cv2.waitKey(1) == 27: exit(0) else: print("Received unexpected status code {}".format(r.status_code))
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