Convert image sequence to video using Moviepy

I found another way to do it:

from moviepy.editor import *

img = ['1.png', '2.png', '3.png', '4.png', '5.png', '6.png',
       '7.png', '8.png', '9.png', '10.png', '11.png', '12.png']

clips = [ImageClip(m).set_duration(2)
      for m in img]

concat_clip = concatenate_videoclips(clips, method="compose")
concat_clip.write_videofile("test.mp4", fps=24)

And from current folder:

import os
import glob
from natsort import natsorted
from moviepy.editor import *

base_dir = os.path.realpath("./images")
print(base_dir)

gif_name = 'pic'
fps = 24

file_list = glob.glob('*.png')  # Get all the pngs in the current directory
file_list_sorted = natsorted(file_list,reverse=False)  # Sort the images

clips = [ImageClip(m).set_duration(2)
         for m in file_list_sorted]

concat_clip = concatenate_videoclips(clips, method="compose")
concat_clip.write_videofile("test.mp4", fps=fps)

This is how I did it using your initial code. The error you were seeing was due to not specifying set_duration for the clips. I also sorted the files in the directory so that the resulting mp4 is sequential (was not the case by default).

import os
from moviepy.editor import *

base_dir = os.path.realpath(".")
print(base_dir)
directory=sorted(os.listdir('.'))
print(directory)

for filename in directory:
  if filename.endswith(".png"):
    clips.append(ImageClip(filename).set_duration(1))

print(clips)
video = concatenate(clips, method="compose")
video.write_videofile('test1.mp4', fps=24)