OpenCV: how to restart a video when it finishes?

c, c++, opencv, python

Solution

If you want to restart the video over and over again (aka looping it), you can do it by using an if statement for when the frame count reaches `cap.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT)` and then resetting the frame count and `cap.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, num)` to the same value. I'm using OpenCV 2.4.9 with Python 2.7.9 and the below example keeps looping the video for me.

import cv2

cap = cv2.VideoCapture('path/to/video') 
frame_counter = 0
while(True):
    # Capture frame-by-frame
    ret, frame = cap.read()
    frame_counter += 1
    #If the last frame is reached, reset the capture and the frame_counter
    if frame_counter == cap.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT):
        frame_counter = 0 #Or whatever as long as it is the same as next line
        cap.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, 0)
    # Our operations on the frame come here
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    # Display the resulting frame
    cv2.imshow('frame',gray)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()

It also works to recapture the video instead of resetting the frame count:

if frame_counter == cap.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT):
    frame_counter = 0
    cap = cv2.VideoCapture(video_name)

Problem

Original source