How to get a image in video at particular time by using Python?

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In this post we extract a image at a particular time from a video using the Python OpenCV library. 

Steps

  1. Import OpenCV library
  2. Read the video file using cv2.VideoCapture().
  3. Set the video position to a particular (say 2 seconds) time using vid.set(cv2.CAP_PROP_POS_MSEC,2000).
  4. Read the frame at the set position using vid.read().
  5. Save the frame as an image using cv2.imwrite().
  6. Finally check if the image is successfully saved or not.

Complete Program

In the program below, we extract an image at 2 seconds or 2,000 milliseconds time from a video.  

import cv2
#Read the video
vid = cv2.VideoCapture(r"C:\Users\Public\Videos\Sample Videos\Wildlife.wmv")
# Go to 2 Second Position (2 Sec = 2,000 milliseconds)
vid.set(cv2.CAP_PROP_POS_MSEC,2000)
# Retrieve the frame as an image
success,image = vid.read()
while success:
    time = vid.get(cv2.CAP_PROP_POS_MSEC)
    ret = cv2.imwrite("frame2sec.jpg", image)     # save frame as JPEG file
    if ret:
        print("image is saved successfully at time: ", time)
        break

Output

image is saved successfully at time:  2035.0000000000002

Program Explanation

We read the video using cv2.VideoCapture(). For this we need to create an object of VideoCapture class. We created vid, an object of this class. 

After creating the VideoCapture object, we set the position of the video passing the flag CAP_PROP_POS_MSEC and it's value as 2,000. Here we set position to 2 seconds that is 2,000 milliseconds. 

Next we applied read() method to read the frame. This method returns the next frame of the video. Please notice in the output, we have specified 2,000 milliseconds but it returns the frame at 2035.0000000000002 milliseconds. This method also returns true or false, true if frame successfully read else false.

If the frame is successfully read, we save the frame as a jpeg image using cv2.imwrite() method. It returns true if the frame is successfully saved.

We also compute the frame time using cv2.get() with the same flag CAP_PROP_POS_MSEC.

Finally we print the message of successfully saved frame/ image.   

Further Reading:

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