pip install opencv-python
pip --default-timeout=100 install opencv-python -i https://pypi.douban.com/simple

import cv2
# subprocess 模块允许我们启动一个新进程，并连接到它们的输入/输出/错误管道，从而获取返回值。
import subprocess
# 视频读取对象
cap = cv2.VideoCapture(0)
# 推流地址
rtmp = "rtmp://192.168.10.225:1935/stream/example"# 推流的服务器地址
# 设置推流的参数
command = ['ffmpeg',
           '-y',
           '-f', 'rawvideo',
           '-vcodec', 'rawvideo',
           '-pix_fmt', 'bgr24',
           '-s', '1280*720',  # 根据输入视频尺寸填写
           '-r', '25',
           '-i', '-',
           '-c:v', 'h264',
           '-pix_fmt', 'yuv420p',
           '-preset', 'ultrafast',
           '-f', 'flv',
           rtmp]
# 创建、管理子进程
pipe = subprocess.Popen(command, stdin=subprocess.PIPE)
size = (int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)), int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)))
# 循环读取
while cap.isOpened():
    # 读取一帧
    ret, frame = cap.read()
    if frame is None:
        print('read frame err!')
        continue
    # 显示一帧
    # fps = int(cap.get(cv2.CAP_PROP_FPS))
    cv2.imshow("frame", frame)
    # 按键退出
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
    # 读取尺寸、推流
    img = cv2.resize(frame, size)
    pipe.stdin.write(img.tobytes())
# 关闭窗口
cv2.destroyAllWindows()
# 停止读取
cap.release()

备注：分辨率要根据本机摄像头支持的分比率设置，不然可能显示不出图像

参考链接：

http://events.jianshu.io/p/4d267a9267a5

https://blog.csdn.net/qq_41876456/article/details/119480972

https://blog.csdn.net/m0_51573312/article/details/124580266