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• Covert video to frames, then back to video without altering the frames in python

  7 mars 2021, par Rashiq

  I am writing a script in python that converts a video (let this video be X) into frames (X′) and then back into the same video (Y). Now, when I break video Y back into frames (Y′) the images are not equal to X′ frames i.e. they have different hashes. I would expect them to be the same, and if being not the same is the expected behaviour, how can I make them the same ?

  


  Is there a way to go from

  


  `video, X —> frames, X′, —> video, Y, —> frames, Y′, —> video, Z, —> frames, Z′

  


  and so on without changing the output from its previous state such the videos X, Y, Z and frames X′, Y′, Z′ are same to each other in their respective sets ?

  


  I have tried multiple video codecs (mp4, avi, mkv) and image formats (tif, jpeg, png). To my understanding, lossy compression codecs should not work by lossless such as tif are not producing consistent output either.

  


  I have followed these video-to-frame and frame-to-video among other tutorials but to no avail. Any help would greatly be appreciated.

  


• How to get better video quality using Accord.Video.FFMPEG.DLL

  31 juillet 2023, par HighwayRob

  I have developed a Visual Studio Winapp that produces a video file utilizing Accord.Video.FFMPEG.DLL.

  


  The quality the video is less than the original images.
Here is the code and then a sample original image and snapshot of the resulting video.

  


  What can I change to improve the video image ?

  


              VideoFileWriter writer = new VideoFileWriter();
            writer.Open(outfile, width, height, 1, VideoCodec.Mpeg4);
            for (int i = firstrow; i <= testframes; i++)
            {
                Bitmap bitmap = new Bitmap(ffiles[i, 0].ToString());
                writer.WriteVideoFrame(bitmap);
                bitmap.Dispose();
            }


  


  I tried Bitmap image = new Bitmap(width, height, PixelFormat.Format64bppArgb) ;

  


  

  


• ffmpeg transcoding one input video stream and multiple output video streams in the same file

  28 janvier 2020, par user2165262

  I am trying to transcode a single video file with 1 video stream and several audio streams to the file having same video stream in different bitrates/sizes with correct padding at the same time.

  the command I use is :

      ffmpeg -y -ss 600 -t 600 -i "INPUT.mkv" -map_chapters -1 -map 0:0 -c:v libx264 -keyint_min 48 -g 96 -bufsize 350k -b:v 350k -minrate 300k -maxrate 400k -profile:v baseline -level 3.0 -preset slow -vf "scale=iw*min(480/iw\,272/ih):ih*min(480/iw\,272/ih),pad=480:272 :(480-iw)/2 :(272-ih)/2" -map 0:0 -c:v libx264 -keyint_min 48 -g 96 -bufsize 650k -b:v 650k -minrate 500k -maxrate 800k -profile:v baseline -level 3.1 -preset slow -vf "scale=iw*min(640/iw\,360/ih):ih*min(640/iw\,360/ih),pad=640:360 :(640-iw)/2 :(360-ih)/2" -map 0:1 -c:a libfaac -b:a 32k -ar 44100 -f mpegts OUTPUT.m2ts
  

  ffmpeg creates two video streams, however the bitrate and resolution for all of them are taken from the last video arguments - i.e. both streams are 640x360 :

      Output #0, mpegts, to ’OUTPUT.m2ts’ :
      Stream #0:0(eng) : Video : h264, yuv420p, 640x360 [SAR 559:560 DAR 559:315], q=-1—1, 650 kb/s,     Stream #0:1(eng) : Video : h264, yuv420p, 640x360 [SAR 559:560 DAR 559:315], q=-1—1, 650 kb/s, 90k tbn, 23.98 tbc (default)
      Stream #0:2(rus) : Audio : aac, 44100 Hz, 5.1, s16, 32 kb/s (default)
      Stream mapping :
      Stream #0:0 -> #0:0 (h264 -> libx264)
      Stream #0:0 -> #0:1 (h264 -> libx264)
      Stream #0:1 -> #0:2 (aac -> libfaac)
      Press [q] to stop, [?] for help
  

  Is it practically possible to make transcoding to several bitrates to the same file ?