import cv2
import os

input_video = 'input_source.mp4'

output_video = 'output_timelapse.mp4'

frame_skip = 15

cap = cv2.VideoCapture(input_video)

if not cap.isOpened():
    print('無法讀取影片檔案')
    exit()

width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

fourcc = cv2.VideoWriter_fourcc(*'mp4v')
out = cv2.VideoWriter(output_video, fourcc, frame_skip, (width, height))

frame_count = 0
while cap.isOpened():
    ret, frame = cap.read()
    if not ret:
        break

    if frame_count % frame_skip == 0:
        out.write(frame)

    frame_count += 1

cap.release()
out.release()
cv2.destroyAllWindows()