What does ret and frame mean here?

Question

When to use ret and frame? What values do these variables hold? I have just started with image processing, so if there are more changes do let me know.

Thank you

import numpy as np
import cv2
cap = cv2.VideoCapture('Sample Lap HUL_OB_1.56.641_Graphic.mpg')

# Define the codec and create VideoWriter object
# fourcc = cv2.cv.CV_FOURCC(*'MJPG')
out = cv2.VideoWriter('output.mpg',0, 60.0, (640,480))
while(cap.isOpened()):
    ret, frame = cap.read()
    if ret==True:
         # frame = cv2.flip(frame,0)
         # write the flipped frame
        out.write(frame)
        cv2.imshow('frame',frame)
        if cv2.waitKey(1) & 0xFF == ord('q'):
             break
     else:
        break
# Release everything if job is finished
cap.release()
out.release()
cv2.destroyAllWindows()

Answer 1

"Frame" will get the next frame in the camera (via "cap"). "Ret" will obtain return value from getting the camera frame, either true of false. I recommend you to read the OpenCV tutorials(which are highly detailed) like this one for face recognition: http://docs.opencv.org/modules/contrib/doc/facerec/facerec_tutorial.html

Answer 2

ret, frame = cap.read()

1. ret is a boolean variable that returns true if the frame is available.
2. frame is an image array vector captured based on the default frames per second defined explicitly or implicitly