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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 trim and merge using Fluent FFMpeg ?

  29 juillet 2016, par John D.

  Here’s what I want to do with fluent-ffmpeg :

  I have 3 input files. An intro, main, and outro video. I wish to merge the three, while trimming the main video. Here is my code :

  var ffmpegCommand = ffmpeg();
  
  ffmpegCommand.addInput(introVideo);
  
  ffmpegCommand.addInput(mainVideo).seekInput(20).duration(3);
  
  ffmpegCommand.addInput(outroVideo);
  
  ffmpegCommand.on('error', function(err, stdout, stderr){
  
    console.log("FAILED!\n\t"+err+"\n\t"+stdout+"\n\t"+stderr);
  
  });
  
  ffmpegCommand.on('end', function(){
  
    console.log('COMPLETE!');
  
  });
  
  ffmpegCommand.on('start', function(commandLine) {
  
    console.log('Spawned Ffmpeg with command: ' + commandLine);
  
  });
  
  ffmpegCommand.mergeToFile('final.mp4', './vid_files/tmp');

  The program executes fine, but when I ffplay final.mp4, the result is that introVideo plays then the video appears to freeze. According to the fluent-ffmpeg documentation, it states "Each of these [Input options] methods apply on the last input added". So I can’t figure out why that syntax doesn’t seem to work...

  How can I trim the main video to send to mergeToFile ?

  Note that this works fine if I don’t have .seekinput(20).duration(3) on the second addInput.

  Oh, here’s the outputted commandLine value :

  ffmpeg -i ./vid_files/intro.mp4 -ss 20 -i ./vid_files/main.mp4 -i ./vid_files/outro.mp4 -y -filter_complex concat=n=3:v=1:a=1 -t 3 final.mp4

• ffmpeg timelapse resets PTS on frame size change

  19 avril 2024, par Ral

  I have 601 sequential images, they change size and aspect ratio on frame 36 and 485, creating 3 distinct sizes of images in the set.

  


  I want to create a timelapse and shave off the first 200 frames and only show the remaining 401, but if I do a trim filter on the input, the filter treats each of the 3 sections of different sized frames as separate 'streams' with their own reset PTS, all of which start at the exact same time. This means the final output of the below commmand is only 249 frames long instead of 401.

  


  How can I fix this so I just get the final 401 frames ?

  


  ffmpeg \
-framerate 60 \
-i "./%07d.jpg" \
-filter_complex "
 [0]scale=1000:1000[in1];
 [in1]trim=start_frame=200[in2];
 [in2]setpts=PTS-STARTPTS
 " \
-r 60 -y trimmed.webm


  


  Filters like setpts=N/(60*TB) or setpts=PTS-SETPTS after the scale to try and fix the frame times also seem to change nothing.

  


  If I remove the trim and pts reset, the timelapse exports all 601 perfectly.
If I remove the pts reset and leave the trim, it exports 449 frames starting on frame 0.

  


  There's no errors or warning associated with the problem, other than the debug states the input reaches EOF on frame 449. (which is 485-36, the two section lengths, for some reason)

  


  I understand pre-processing the image sizes is a way to fix this, but I'd like to understand why this isn't possible in one command.

  


  version 6.0-6ubuntu1, but also happens on 6.1 and 5.1.

  


  Even if I whittle it down to the bare minimum, it still incorrectly exports 450 frames :

  


  ffmpeg -i "./%07d.jpg" -filter setpts=PTS-STARTPTS -y tpad.webm