diff --git a/scripts/preprocess/extract_video.py b/scripts/preprocess/extract_video.py
index 4cb912d..115f4ec 100644
--- a/scripts/preprocess/extract_video.py
+++ b/scripts/preprocess/extract_video.py
@@ -32,7 +32,8 @@ def extract_video(videoname, path, start, end, step):
         if cnt < start:continue
         if cnt >= end:break
         if not ret:continue
-        cv2.imwrite(join(outpath, '{:06d}.jpg'.format(cnt)), frame)
+        if (cnt % step ==0):
+            cv2.imwrite(join(outpath, '{:06d}.jpg'.format(cnt)), frame)
     video.release()
     return base