opencv读取视频和摄像头，写视频

 https://docs.opencv.org/3.0-beta/doc/py_tutorials/py_gui/py_video_display/py_video_display.html

https://zhuanlan.zhihu.com/p/38136322

当我们需要读取网络摄像头的时候，我们可以对 cap = cv2.VideoCapture(括号里面的东西进行修改)，填写上我们想要读取的视频流，它可以是：

• 数字0，代表计算机的默认摄像头（例如上面提及的笔记本前置摄像头）
• video.avi 视频文件的路径，支持其他格式的视频文件
• rtsp路径（不同品牌的路径一般是不同的，如下面举出的海康与大华，详细情况查看 附录的「关于rtsp协议」）

user, pwd, ip, channel = "admin", "admin123456", "172.20.114.26", 1

video_stream_path = 0  # local camera (e.g. the front camera of laptop)
video_stream_path = 'video.avi'  # the path of video file
video_stream_path = "rtsp://%s:%s@%s/h265/ch%s/main/av_stream" % (user, pwd, ip, channel)  # HIKIVISION old version 2015
video_stream_path = "rtsp://%s:%s@%s//Streaming/Channels/%d" % (user, pwd, ip, channel)  # HIKIVISION new version 2017
video_stream_path = "rtsp://%s:%s@%s/cam/realmonitor?channel=%d&subtype=0" % (user, pwd, ip, channel)  # dahua

cap = cv2.VideoCapture(video_stream_path)

 

rtsp视频流

https://blog.csdn.net/hpuhjl/article/details/80685572

大华：

1、地址格式分段含义说明：

1. rtsp://[username]:[password]@[address]:[port]/cam/realmonitor?channel=[id]&subtype=[type]
2. rtsp:// => 协议格式头
3. username => 用户名，例如：admin
4. password => 密码，例如：123456
5. address => IPC设备的网络地址，例如：192.168.1.65
6. port => IPC设备的RTSP输出端口，默认为554，若为默认可不填写
7. id => 通道号，起始为1。例如通道2，则为channel=2
8. type => 码流类型，主码流为0（即subtype=0），辅码流为1（即subtype=1）。

2、示例，拉取大华网络摄像机通道1的RTSP地址：

1. 通道1，主码流：
rtsp://admin:123456@192.168.1.65:554/cam/realmonitor?channel=1&subtype=0
2. 通道1，子码流：
rtsp://admin:123456@192.168.1.65:554/cam/realmonitor?channel=1&subtype=1

---

海康

1、地址格式分段含义说明：

1. rtsp://[username]:[password]@[address]:[port]/Streaming/Channels/[id]?transportmode=[type]
2. rtsp:// => 协议格式头
3. username => 用户名，例如：admin
4. password => 密码，例如：123456
5. address => IPC设备的网络地址，例如：192.168.1.65
6. port => IPC设备的RTSP输出端口，默认为554，若为默认可不填写
7. id => 通道号&码流类型
8. 101：通道1主码流 201通道2主码流
9. 102：通道1子码流 202通道2子码流
10. 103：通道1第三码流
11. 1201：通道17主码流
12. 001：通道0主码流
13. type => 可选参数，拉流模式，默认为unicast，若为默认可以不填写
14. unicast：单播模式拉流
15. multicast：组播模式拉流

将多张图片合成视频

import cv2
import os
from bs4 import BeautifulSoup


def parse_xml(xml_file):
    soup = BeautifulSoup(open(xml_file, "r", encoding="utf-8"), 'xml')
    tags = soup('object')
    lines = []
    width = int(soup.size.width.string)
    height = int(soup.size.height.string)
    for each in tags:
        line = []
        name = each.find('name').string.strip()
        # if name == "boat":
        if name == "boat":
            xmin = int(each.bndbox.xmin.string)
            ymin = int(each.bndbox.ymin.string)
            xmax = int(each.bndbox.xmax.string)
            ymax = int(each.bndbox.ymax.string)
            # Todo: 预测坐标中会有负数
            if (xmax < xmin) or (xmax > width) or (xmin < 0):
                print("xmin, xmax value not valid {} {} in {}".format(xmin, xmax, xml_file))
                # raise Exception("xmin, xmax value not valid {} {} in {}".format(xmin, xmax, xml_file))
            if (ymax < ymin) or (ymax > height) or (ymin < 0):
                print(("ymin, ymax value not valid {} {} in {}".format(ymin, ymax, xml_file)))
                # raise Exception("ymin, ymax value not valid {} {} in xml_file".format(ymin, ymax, xml_file))
            # 处理坐标边界
            xmin = 0 if xmin < 0 else xmin
            xmax = width if xmax > width else xmax
            ymin = 0 if ymin < 0 else ymin
            ymax = height if ymax > height else ymax
            line.append(xmin)
            line.append(ymin)
            line.append(xmax)
            line.append(ymax)
            lines.append(line)
        else:
            print(("Invalid name: {} in file {}".format(name, xml_file)))
            # raise Exception("Invalid name: {} in file {}".format(name, xml_file))
    return lines


def images_to_video():
    fps = 10  # 帧率
    img_width = 1920
    img_height = 1080
    out = cv2.VideoWriter(r'F:\tmp\nanhang_detect.mp4', cv2.VideoWriter_fourcc(*'mp4v'), fps, (img_width, img_height))
    path = r"F:\tmp\temp"
    for file_name in os.listdir(path):
        if file_name.endswith(".jpg"):
            img_file = os.path.join(path, file_name)
            xml_file = img_file.replace(".jpg", ".xml")
            img = cv2.imread(img_file)
            if os.path.exists(xml_file):
                lines = parse_xml(xml_file)
                for line in lines:
                    # print(line)
                    xmin, ymin,xmax, ymax= line
                    cv2.rectangle(img, (xmin,ymin), (xmax, ymax), (0, 255, 0), 2)
            # cv2.namedWindow("img", cv2.WINDOW_NORMAL)
            # cv2.resizeWindow("img", 960, 540)
            # cv2.imshow("img", img)
            # cv2.waitKey(0)
            # cv2.destroyAllWindows()
            out.write(img)
    out.release()

images_to_video()