How to add a delay when saving video frames as images

I have a series of videos and I want to save frames from them as images. This is my code:

import os, cv2

current_dir = os.getcwd()
training_videos = '../../Videos/training_videos/'

if not os.path.exists(current_dir + '/training_images/'):
    os.mkdir(current_dir + '/training_images/')

for i in os.listdir(training_videos):

    video = cv2.VideoCapture('../../Videos/training_videos/' + i)

    currentFrame = 0

    while (True):
        # Capture frame-by-frame
        ret, frame = video.read()

        # Saves image of the current frame in jpg file
        name = current_dir + '/training_images/frame' + str(currentFrame) + '.png'
        print('Creating...' + name)
        cv2.imwrite(name, frame)

        # To stop duplicate images
        currentFrame += 1

This code works but unfortunately, it takes a frame at every millisecond. This is not something I want. Instead, I want to save a frame at every 5 or 10 seconds. I thought about adding a time delay but that wouldn’t really work because the videos are not live streams so after 5 seconds, it’ll just take the screenshot right after the previous millisecond.

Answer

There’s likely an more efficient way, but you can do this by using the frame rate of the video and then processing the image every FRAME_RATE * 5 frames.

Your code would look something like this (let me know if this doesn’t work as I haven’t ran this on my PC):

import os, cv2

current_dir = os.getcwd()
training_videos = '../../Videos/training_videos/'

if not os.path.exists(current_dir + '/training_images/'):
    os.mkdir(current_dir + '/training_images/')

for i in os.listdir(training_videos):

    video = cv2.VideoCapture('../../Videos/training_videos/' + i)
    fps = video.get(cv2.CAP_PROP_FPS)

    currentFrame = 0

    while video.isOpened():
        # Capture frame-by-frame
        ret, frame = video.read()

        if (video):
            # Write current frame
            name = current_dir + '/training_images/frame' + str(currentFrame) + '.png'
            print('Creating...' + name)
            cv2.imwrite(name, frame)

            currentFrame += fps * 5
            # Skip to next 5 seconds
            video.set(cv2.CAP_PROP_POS_FRAMES, currentFrame)