Python creating video from images using opencv

Question

I was trying to create a video to show the dynamic variation of the data, like just continuously showing the images one by one quickly, so I used images (the images just called 1,2,3,4,.....) and wrote the following code:

import cv2
import numpy as np

img=[]
for i in range(0,5):
    img.append(cv2.imread(str(i)+'.png'))

height,width,layers=img[1].shape

video=cv2.VideoWriter('video.avi',-1,1,(width,height))

for j in range(0,5):
    video.write(img)

cv2.destroyAllWindows()
video.release()

and a error was raised:

TypeError: image is not a numpy array, neither a scalar

I think I used the list in a wrong way but I'm not sure. So where did I do wrong?

Possible duplicate of [Create Video from images using VideoCapture (OpenCV)](http://stackoverflow.com/questions/22765397/create-video-from-images-using-videocapture-opencv) — Jeru Luke, Mar 27 '17 at 14:42

score 27 · Accepted Answer · answered Mar 27 '17 at 14:12

27

You are writing the whole array of frames. Try to save frame by frame instead:

...
for j in range(0,5):
  video.write(img[j])
...

reference

answered Mar 27 '17 at 14:12

Václav Struhár

1,739
13
21

yes I just realized I've made a stupid error... thanks anyway! – Yingqiang Gao Mar 27 '17 at 14:18
You are welcome. Please mark this answer as the solution. Thanks :) ( @YingqiangGao ) – Václav Struhár Mar 27 '17 at 14:19
I'm new to stack overflow, how can I mark your answer as you wanted? – Yingqiang Gao Mar 27 '17 at 14:25
On the left side of the answer, there is a tick symbol. It will mark that your question is correctly answered. ( @YingqiangGao ) – Václav Struhár Mar 27 '17 at 14:29
@Vaclav, does this work only for png files.. im getting the following error reading frames saved as jpeg : 2019-01-21 00:15:25.527 python3[96196:35304132] AVF: AVAssetWriter status: Cannot Save .. any ideas? – E B Jan 21 '19 at 05:17

score 14 · Answer 2 · edited Jul 27 '21 at 14:29

You can read the frames and write them to video in a loop. Following is your code with a small modification to remove one for loop.

  import cv2
  import numpy as np
  
  # choose codec according to format needed
  fourcc = cv2.VideoWriter_fourcc(*'mp4v') 
  video = cv2.VideoWriter('video.avi', fourcc, 1, (width, height))

  for j in range(0,5):
     img = cv2.imread(str(i) + '.png')
     video.write(img)

  cv2.destroyAllWindows()
  video.release()

Alternatively, you can use skvideo library to create video form sequence of images.

  import numpy as np
  import skvideo.io
   
  out_video =  np.empty([5, height, width, 3], dtype = np.uint8)
  out_video =  out_video.astype(np.uint8)
  
  for i in range(5):
      img = cv2.imread(str(i) + '.png')
      out_video[i] = img

  # Writes the the output image sequences in a video file
  skvideo.io.vwrite("video.mp4", out_video)

score 1 · Answer 3 · answered Feb 07 '22 at 06:20

1

You can use this pip package. It provides CLI commands to make video from images.

img_to_vid.py -f images_directory

answered Feb 07 '22 at 06:20

Muhammad Danial Khan

421
8
14

Python creating video from images using opencv

3 Answers3