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• ffmpeg black screen issue for video video generation from a list of frames

  11 mai 2023, par arlaine

  I used a video to generate a list of frames from it, then I wanted to create multiple videos from this list of frames.
I've set starting and ending frames indexes for each "sub video", so for example,
indexes = [[0, 64], [64, 110], [110, 234], [234, 449]], and those indexes will help my code generate 4 videos of various durations. The idea is to decompose the original video into multiple sub videos. My code is working just fine, the video generated.

  


  But every sub video start with multiple seconds of black screen, only the first generated video (so the one using indexes[0] for starting and ending frames) is generated without this black screen part. I've tried changing the frame rate for each sub_video, according to the number of frames and things like that, but I didn't work. You can find my code below

  


  for i, (start_idx, end_idx) in enumerate(self.video_frames_indexes):
    if end_idx - start_idx > 10:
        shape = cv2.imread(f'output/video_reconstitution/{video_name}/final/frame_{start_idx}.jpg').shape
        os.system(f'ffmpeg -r 30 -s {shape[0]}x{shape[1]} -i output/video_reconstitution/{video_name}/final/frame_%d.JPG'
              f' -vf "select=between(n\,{start_idx}\,{end_idx})" -vcodec libx264 -crf 25'
              f' output/video_reconstitution/IMG_7303/sub_videos/serrage_{i}.mp4')


  


  Just the ffmpeg command

  


  ffmpeg -r 30 -s {shape[0]}x{shape[1]} -i output/video_reconstitution/{video_name}/final/frame_%d.JPG -vf "select=between(n\,{start_idx}\,{end_idx})" -vcodec libx264 -crf 25 output/video_reconstitution/IMG_7303/sub_videos/serrage_{i}.mp4


  


• Extract Images from video and rebuild video with these images

  6 mars 2015, par David Zenou

  I have a very interesting question i think, i did a simple test.

  First step : I extract images from a little video (duration : 1 minute and 4 seconds) :

  ffmpeg -i C:\test\video.mp4 -r 30 -s 640x360 -f image2 C:\test\foo-%05d.jpeg

  Second step : I want to rebuild the initial video with these extracted images with same parameters :

  ffmpeg -f image2 -i C:\test\foo-%05d.jpeg -r 30 -s 640x360 C:\test\final.mp4

  Special result : Initial video (video.mp4) duration was 1 minute and 4 seconds and new video generated (final.mp4) duration is 1 minute and 17 seconds : the new video is longer and the new film seems slightly slower than the initial video.

  My question : Is it possible to get exactly the same film like initial (same duration, same speed) rebuilding the video from its exctrated images ?

• convert multivideos from 1080p to 720p and add watermarks with subtitles ?

  20 novembre 2020, par shady melad

  0

  


  i will ask again i have many videos like series (dark - la casa de papel - game of thrones ) all of them without any subtitle or watermark first i burn subtitles with handbrake sec i use ffmpeg to burn watermark with videos by this code

  


  for %i in ("C :\Users\shady\Downloads\convert\01*.mp4") do ffmpeg -i "%i" -i C :\Users\fady\Downloads\convert\shady.png -filter_complex "overlay=main_w-overlay_w-10:10" -codec:a copy "C :\Users\shady\Downloads\convert\new01% ni.mp4"

  


  then i convert it to 720p with this code

  


  for %i in (C :\Users\shady\Downloads\convert\01*.mp4) do ffmpeg -i "%i" -c:a copy -s hd720 "C :\Users\shady\Downloads\convert\new01% ni.mp4"

  


  my question now if i want to burn subtitle for series dark all seasons with my watermark and the final file get out with 720p with subtitle with watermark on top at right

  


  can i do that ?

  


  watermark png subtitle srt movies come with mkv not mp4 ( i want the final file come with mp4 )