Recherche avancée

Sur d’autres sites (7553)

• Video Size different for different frame rate after encoding [duplicate]

  24 décembre 2018, par random_28

  This question already has an answer here :

  • ffmpeg to create a slideshow results in very large file
    
    1 answer
    

  I have a series of 600 frames in a dir. I am trying to encode them into a video using ffmpeg. Following is the command which I am using :

  ffmpeg -r INPUT_FPS -i out%03d.jpg -c:v libx264 -vf "fps=OUTPUT_FPS,format=yuv420p" out.mpeg

  I am unable to understand why changing the INPUT_FPS and OUTPUT_FPS affects the encoded file size.

  For e.g. :
  with INPUT_FPS=30, and OUTPUT_FPS=30 :
  the output file is 20 secs long and 20.7 Mb in size.

  with INPUT_FPS=60, and OUTPUT_FPS=60 :
  the output file is 10 secs long but size gets reduced to 16.7 Mb.

  Given both of the videos has 600 same frames, why this discrepancy in size of the encoded file ?

• create thumbnail from video URL in C#

  23 mai 2016, par Hashem Aboonajmi

  I want to generate thumbnail from a video URL in C#. I have searched a lot to find a neat way but no success. I have used Nreco and MediaToolKit but none of them extract thumbnail image. using ffmpeg also has mumbo jumbos which didn’t worked !

  using NReco :

  var ffMpeg = new NReco.VideoConverter.FFMpegConverter();
  
  string thumbnailJPEGpath = "http://localhost:81882/content/hashem.jpeg";
  
  ffMpeg.GetVideoThumbnail(videoUrl,thumbnailJPEGpath);

  using ffmpeg :

  try
  
          {
  
              System.Diagnostics.Process ffmpeg;
  
  
  
              string video;
  
              string thumb;
  
  
  
              video = Server.MapPath("~/Content/Movies/bye.mp4");
  
              thumb = Server.MapPath("~/Content/frame.jpg");
  
  
  
              ffmpeg = new System.Diagnostics.Process();
  
  
  
              ffmpeg.StartInfo.Arguments = " -i " + video + " -ss 00:00:07 -vframes 1 -f image2 -vcodec mjpeg " + thumb;
  
              ffmpeg.StartInfo.FileName = Server.MapPath("~/Content/ffmpeg.exe");
  
              ffmpeg.Start();
  
              ffmpeg.WaitForExit();
  
              ffmpeg.Close();
  
          }
  
          catch (Exception ex)
  
          {
  
              Response.Write("Error: " + ex.Message);
  
          }

  to consider video files are not local and I have only a direct link to the file :
  e.g. :http://phytonord.com/Film-Series/hana/26.mp4

  does anyone has any solution ? any sample code that works ?

• Generating movie from python without saving individual frames to files

  31 juillet 2022, par Paul

  I would like to create an h264 or divx movie from frames that I generate in a python script in matplotlib. There are about 100k frames in this movie.

  



  In examples on the web [eg. 1], I have only seen the method of saving each frame as a png and then running mencoder or ffmpeg on these files. In my case, saving each frame is impractical. Is there a way to take a plot generated from matplotlib and pipe it directly to ffmpeg, generating no intermediate files ?

  



  Programming with ffmpeg's C-api is too difficult for me [eg. 2]. Also, I need an encoding that has good compression such as x264 as the movie file will otherwise be too large for a subsequent step. So it would be great to stick with mencoder/ffmpeg/x264.

  



  Is there something that can be done with pipes [3] ?

  



  [1] http://matplotlib.sourceforge.net/examples/animation/movie_demo.html

  



  [2] How does one encode a series of images into H264 using the x264 C API ?

  



  [3] http://www.ffmpeg.org/ffmpeg-doc.html#SEC41