OpenCV: how to restart a video when it finishes?

Question

I'm playing a video file, but how to play it again when it finishes?

Javier

Solution 1

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)

Solution 2

You don't need to reopen the current capture. All you need to do is to reset position to the beginning of the file and to continue the cycle instead of breaking it.

if (!frame) 
{
    printf("!!! cvQueryFrame failed: no frame\n");
    cvSetCaptureProperty(capture, CV_CAP_PROP_POS_AVI_RATIO , 0);
    continue;
}  

Nevertheless there is a significant delay as if you were reopened it...

See http://docs.opencv.org/2.4.6/modules/highgui/doc/reading_and_writing_images_and_video.html?highlight=cvqueryframe#videocapture-set

Solution 3

Easiest Way-:

cap = cv2.VideoCapture("path")
while True:
  ret, image = cap.read()
  if ret == False:
         cap = cv2.VideoCapture("path")
          ret, image = cap.read()

Comments

[karlphillip]

C? C++? Java? or what? Improve the tagging please.

[karlphillip]

If this question has been successfully answered, consider selecting the official answer by clicking on the checkbox near it. If not, consider adding your own answer.

[noio]

Weirdly, after the first reset like this, the feed keeps returning the last frame.

[Darky WC]

if anybody is using OpenCV version 4.2.0, just substitute cv2.cv.CV_CAP_PROP_FRAME_COUNT to cv2.CAP_PROP_FRAME_COUNT and cv2.cv.CV_CAP_PROP_POS_FRAMES to cv2.CAP_PROP_POS_FRAMES. This works for me.

[Surya Tej]

If you are using opencv python 4.2 the CAP_PROP_FRAME_COUNT doesn't have a prefix CV_