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• FFMPEG : Creating a video, which has the maximun value per pixel of n-input videos

  18 décembre 2016, par LighthouseZGZ

  Imagine a collection of short videos, each one showing a shooting star.

  I would like to get a composite video of all shooting stars. Not in sequence, at the same time. The (x,y) pixel of the nth frame in the output video should have the maximum value for that (x,y) pixel of the same frame in all the videos.

  I know how to do that using images and imagemagick :

  magick *.bmp -evaluate-sequence max output.bmp

  I need something similar for video. Frame by frame.

  Any help would be appreciated. Thanks.

• Extracting frames every second of all videos in folder

  20 octobre 2023, par Sparkiepandas

  I am trying to extract a frame every second of a video, while having multiple videos in a folder. I got it working for 1 video like this, but I think I am messing up my loop for all videos. Below is the code for 1 video that works.

  



  import cv2
pathOut = r"C:/Users/Me/Out/"
vidcap = cv2.VideoCapture(r'C:\Me\Desktop\test.mp4');
count = 0
success = True
while success:
    success,image = vidcap.read()
    print('read a new frame:',success)
    if count%30 == 0 :
         cv2.imwrite(pathOut + 'frame%d.jpg'%count,image)
    count+=1


  



  With the loop for all videos I made it up like this.

  



  import os
import cv2
pathOut = r"C:/Users/Me/Out/"
count = 0
success = True
counter = 1
listing = os.listdir(r'C:/Users/Me/videos/train')
for vid in listing:
    vid = r"C:/Users/Me/videos/train/"+vid
    cap = cv2.VideoCapture(vid)
    count = 0
    counter += 1
    while success:
        success,image = cap.read()
        print('read a new frame:',success)
        if count%30 == 0 :
             cv2.imwrite(pathOut + 'frame%d.jpg'%count,image)
        count+=1


  



  My vid loop does not seems to work because it is only taking one video. Then it states false, probably because there are no frames left, but I do not know how to push it forward to the next video. I think I need to do some minor adjustment, does anybody have any idea what exactly ?

  


• How to concatenate two or more videos with different width in FFMpeg and to maintain the same aspect ratio ?

  23 octobre 2019, par Aarwil

  I have five video parts to concat all. Each five videos are in the same width and height. The second part is the hstack of another 2 videos and the third part is the hstack and vstack of another 3 videos. While concat all the five video parts the aspect ratio is not maintaining in the final video. Since I am new to ffmpeg help me to sort out the problem

  I have tried with the command with filter complex and to reduce the size I used frame per second.

  "ffmpeg -i
  RM356ce8c15f47cb07b7af885fd718a39f/final/RM356ce8c15f47cb07b7af885fd718a39f.mp4 -vf scale=1280:480 -filter:v fps=fps=30 E :\test\routes\public\assets\downloads\RM356ce8c15f47cb07b7af885fd718a39f/final/RM356ce8c15f47cb07b7af885fd718a39f.mp4"

  Only ’-vf fps=fps=30’ read, ignoring remaining -vf options : Use ’,’ to separate filters