Google colaboratory 如何在google colab上访问摄像头并在实时视频中绘制地标，代码如下

单元格1由以下代码组成-

!wget   http://dlib.net/files/shape_predictor_68_face_landmarks.dat.bz2 # DOWNLOAD LINK

!bunzip2 /content/shape_predictor_68_face_landmarks.dat.bz2

datFile =  "/content/shape_predictor_68_face_landmarks.dat"

import cv2
import dlib

cap = cv2.VideoCapture(0)

hog_face_detector = dlib.get_frontal_face_detector()

dlib_facelandmark = dlib.shape_predictor("shape_predictor_68_face_landmarks.dat")

while True:
    _, frame = cap.read()
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    faces = hog_face_detector(gray)
    for face in faces:

        face_landmarks = dlib_facelandmark(gray, face)

        for n in range(0, 68):
            x = face_landmarks.part(n).x
            y = face_landmarks.part(n).y
            cv2.circle(frame, (x, y), 1, (0, 255, 255), 1)


    cv2.imshow("Face Landmarks", frame)

    key = cv2.waitKey(1)
    if key == 27:
        break
cap.release()
cv2.destroyAllWindows()

单元格2由以下代码组成-

!wget   http://dlib.net/files/shape_predictor_68_face_landmarks.dat.bz2 # DOWNLOAD LINK

!bunzip2 /content/shape_predictor_68_face_landmarks.dat.bz2

datFile =  "/content/shape_predictor_68_face_landmarks.dat"

import cv2
import dlib

cap = cv2.VideoCapture(0)

hog_face_detector = dlib.get_frontal_face_detector()

dlib_facelandmark = dlib.shape_predictor("shape_predictor_68_face_landmarks.dat")

while True:
    _, frame = cap.read()
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    faces = hog_face_detector(gray)
    for face in faces:

        face_landmarks = dlib_facelandmark(gray, face)

        for n in range(0, 68):
            x = face_landmarks.part(n).x
            y = face_landmarks.part(n).y
            cv2.circle(frame, (x, y), 1, (0, 255, 255), 1)


    cv2.imshow("Face Landmarks", frame)

    key = cv2.waitKey(1)
    if key == 27:
        break
cap.release()
cv2.destroyAllWindows()

我需要现场视频上的地标，而不是拍摄的图像上的地标。如果可能，请在运行代码后共享您的colab链接