1. 从文件夹中读取图片文件，这步可以结合ffmpeg来完成，将视频流切图命令为（但需要再写个脚本定期清理旧图片，比如10分钟前）：

ffmpeg -i myfile.avi -r 1000 -f image2 image-%07d.png

2.读取图片并圈出识别出的物体：

import os
import glob

import dlib

# Path to the video frames
video_folder = os.path.join("./video_frames")

# Create the correlation tracker - the object needs to be initialized
# before it can be used
tracker = dlib.correlation_tracker()

win = dlib.image_window()
# We will track the frames as we load them off of disk
for k, f in enumerate(sorted(glob.glob(os.path.join(video_folder, "*.jpg")))):
    print("Processing Frame {}".format(k))
    img = dlib.load_rgb_image(f)

    # We need to initialize the tracker on the first frame
    if k == 0:
        # Start a track on the juice box. If you look at the first frame you
        # will see that the juice box is contained within the bounding
        # box (74, 67, 112, 153).
        tracker.start_track(img, dlib.rectangle(74, 67, 112, 153))
    else:
        # Else we just attempt to track from the previous frame
        tracker.update(img)

    win.clear_overlay()
    win.set_image(img)
    win.add_overlay(tracker.get_position())
    dlib.hit_enter_to_continue()