Capture video from web cam on Mac

capture.py

import cv2
from time import sleep

CLASSES = ['SAFE', 'DANGER']
NEG_IDX = 0
POS_IDX = 1
FRAMES_PER_VIDEO = 100
VIDEOS_PER_CLASS = 2

def capture(num_frames, path='out.avi'):
    
    # Create a VideoCapture object
    cap = cv2.VideoCapture(0)

    # Check if camera opened successfully
    if (cap.isOpened() == False): 
        print("Unable to read camera feed")

    # Default resolutions of the frame are obtained.The default resolutions are system dependent.
    # We convert the resolutions from float to integer.
    frame_width = int(cap.get(3))
    frame_height = int(cap.get(4))

    # Define the codec and create VideoWriter object.The output is stored in 'outpy.avi' file.
    out = cv2.VideoWriter(path, cv2.VideoWriter_fourcc('M','J','P','G'), 10, (frame_width,frame_height))

    print('Recording started')
    for i in range(num_frames):

        ret, frame = cap.read()

        if ret == True:     
            # Write the frame into the file 'output.avi'
            out.write(frame)


    # When everything done, release the video capture and video write objects
    cap.release()
    out.release()
    
for take in range(VIDEOS_PER_CLASS):
    for cla in CLASSES:
        path = 'data/{}{}.avi'.format(cla, take)
        print('Get ready to act:', cla)
        # Only works on Mac
        subprocess.call(['say', 'get ready to act {}'.format(cla)])
        capture(FRAMES_PER_VIDEO, path=path)