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Python creates video from images using opencv

I was trying to create a video to show dynamically changing data, for example, just constantly displaying images one by one, so I used images (images that were named only 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 the error was raised:

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

I think I was using the list incorrectly, but I'm not sure. So where am I going wrong?

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2 answers


You write the entire array of frames. Try to save frame by frame:

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


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You can read the frames and write them to the video in a loop. Below is the code with a slight modification to remove the 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 the skvideo library to create a video 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)
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