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• 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

• Why is accessing these particular videos with ffmpeg far slower than usual ?

  8 novembre 2017, par user779159

  If I run ffmpeg -ss $TIME -i $URL -frames:v 1 -filter:v $FILTER file.jpg -v trace to get a screenshot of a video from a remote website, it normally runs quite quickly. But videos from a different website are taking much longer to run.

  All videos from one particular website are very slow. I’ve compared two videos that are 3-4MB, one from a website where ffmpeg works almost instantly (0.5 seconds) and another from a website where it works terribly slowly (15 seconds).

  Here’s the trace output for the slow video http://pastebin.pl/view/raw/4df9fb06. And here’s trace output for the fast video http://pastebin.pl/view/raw/4b590932.

  Can you identify any reason why one video is so much slower compared to all the other videos ? The ffmpeg command I ran is the one from above and the same for both videos. How can I speed this up ?

  The slow video downloads a few seconds slower than the fast video, but I don’t think the ffmpeg command should be showing such a major difference between the two files.