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• create multiple movie thumbnails using ffmpeg (one at a time) failing

  2 septembre 2013, par Christopher Johnson

  I'm using this small bit of code to create thumbnails of videos being uploaded to my site :

  public static void GetThumbnail(string video, string thumbnail)
  
  {
  
      var cmd = "ffmpeg  -itsoffset -1  -i " + '"' + video + '"' + " -vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 " + '"' + thumbnail + '"';
  
      var startInfo = new ProcessStartInfo
  
      {
  
          WindowStyle = ProcessWindowStyle.Hidden,
  
          FileName = "cmd.exe",
  
          Arguments = "/C " + cmd
  
      };
  
  
  
      var process = new Process
  
      {
  
          StartInfo = startInfo
  
      };
  
  
  
      process.Start();
  
  }

  I'm uploading the videos one at a time asynchronously. The first video thumbnail gets created just fine, but each subsequent one does not get created. I've noticed that if I try to delete subsequent videos from the file system, it says it can not delete them because they are in use by ffmpeg. I can delete the first one that finished processing just fine. I have to kill the ffmpeg process from task manager for all of the others that it's holding open. Why is ffmpeg only working the first time through and then holding the video's open in an open process afterwards ?

  I also tried creating multiple thumbnails one at a time from the command prompt and that worked fine (the process does not stay open either).

  What am I missing in my c# code to make sure the process finishes, and then terminates ?

• how to add watermark and subtitles to multi video in the same time with ffmpeg

  19 novembre 2020, par Fady Sawairas

  hello i am using ffmpeg to add watermark to multi video with this code

  


  for %i in ("C :\Users\fady\Downloads\Fady\new2*.mp4") do ffmpeg -i "%i" -i C :\Users\fady\Downloads\convert\cima2u.png -preset ultrafast -filter_complex "[0]scale=1280:720 :-2[bg] ;[bg][1]overlay=main_w-overlay_w-10:10" -b:v 1000k "C :\Users\fady\Downloads\Fady\new\new2% ni.mp4"

  


  now i want to add subtitles to multi video at the same time
like video1.mp4 with subtitle video1.srt
video2.mp4 with subtitle video2.srt
video3.mp4 with subtitle video3.srt

  


  i am wondering is there any code to make it with ffmpeg one time with all video in one folder or i must make each video alone ?

  


• FFmpeg 6 taking more time than FFmpeg 5 for dash file generation

  9 mars 2023, par QCoder

  I tried to generate a MPD file along with the audio and video stream files using the dash muxer in FFmpeg. This is the command I am using :

  


  ffmpeg -y -i video.mp4 -f dash mpd_file


  


  I tried it on 34 min video. For FFmpeg [5.1.2] it took almost 2min 10 sec to generate everything and for FFmpeg [6.0] it took about 4min 41 sec. Amost double the time.

  


  I tried trimming also and for that also the time comparison was almost same, FFmpeg 6 took double the time than that of FFmpeg 5.

  


  What could be the possible reason for it ? Am I missing some flag for FFmpeg 6 or is there any new addition ? Because when I checked the release notes of FFmpeg 6, there was no new filter which was added related to this particular case.

  


  I tested this comparison on the same machine and it is very unbelievable that FFmpeg 6 is taking so much time, considering this is a new and an advanced version of FFmpeg 5.