Remove the same or similar frame in a video|Python opencv

Basic Grammars of OpenCV: Karobben Blog

So, the situation is, after you recorded a video, there are lots of nonsense frames when you are doing something else, drinking water for instance. By calculating the difference between each frame with the previous frame, we can get a list of numbers and tossing the frame with low value by looking into this list.

import library

Python

import cv2
import matplotlib.pyplot as plt

Reading Video

With the Code below, you can load and show the video on window “video”

Python

Video = "test2.mp4"
cap=cv2.VideoCapture(Video)
while (True):
   ret,frame=cap.read()
   cv2.imshow("video",frame)
   # 在播放每一帧时，使用cv2.waitKey()设置适当的持续时间。如果设置的太低视频就会播放的非常快，如果设置的太高就会播放的很慢。通常情况下25ms就ok
   if cv2.waitKey(1)&0xFF==ord('q'):
       cv2.destroyAllWindows()
       break

Calculate the different of each frame

Calculate the difference of the images

def Diff_img(img0, img):
  '''
  This function is designed for calculating the difference between two
  images. The images are convert it to an grey image and be resized to reduce the unnecessary calculating.
  '''
  # Grey and resize
  img0 =  cv2.cvtColor(img0, cv2.COLOR_RGB2GRAY)
  img =  cv2.cvtColor(img, cv2.COLOR_RGB2GRAY)
  img0 = cv2.resize(img0, (320,200), interpolation = cv2.INTER_AREA)
  img = cv2.resize(img, (320,200), interpolation = cv2.INTER_AREA)
  # Calculate
  Result = (abs(img - img0)).sum()
  return Result

Python

Video = "test2.mp4"
cap=cv2.VideoCapture(Video)
ret,frame0 = cap.read()

Result = []
Num = 0
while (True):
   ret,frame=cap.read()
   #cv2.imshow("video",frame)
   if Num > 0:
    Result += [Diff_img(frame0, frame)]
    frame0 = frame
   Num += 1
   if cv2.waitKey(25)&0xFF==ord('q'):
       cv2.destroyAllWindows()
       break

Write result

Video = "test.mp4"
cap=cv2.VideoCapture(Video)
ret,frame0 = cap.read()

fps_c = cap.get(cv2.CAP_PROP_FPS)
Video_h = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
Video_w = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))

fps = fps_c
size = (Video_w,Video_h)
fourcc = cv2.VideoWriter_fourcc('M','J','P','G')
videowriter = cv2.VideoWriter("output.avi",fourcc,fps,size)



Result = []
Num = 0
while (True):
  ret,frame=cap.read()
  #cv2.imshow("video",frame)
  if Num > 0:
    Diff = Diff_img(frame0, frame)
    Result += [Diff]
    frame0 = frame
    if Diff > 10000:
      videowriter.write(frame0)
  Num += 1
  print(round(Num /237450 * 100, 3))

videowriter.release()

The compare of the video before (left) and after (right) processing.

digraph F { rankdir = UD; readV [label = "Reading Video"] readV -> B }