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• Mathematically lossless encoding and decoding of RGB24 image sequence

  25 avril 2013, par curryage

  I am trying to encode a RGB24 image sequence into a mathematically (not merely visually) lossless video. huffyuv was suggested on many online forums so I tried the following.

  ffmpeg -i frames\%06d.png  -vcodec huffyuv test.avi

  The resulting video was then decoded into frames again using ffmpeg

  ffmpeg -i test.avi outframes\%06d.png

  However, the input and output frames are not bit-by-bit identical as promised by huffyuv here. Any idea how I can accomplish this ? My eventual goal is to read the video file using OpenCV but I am willing to cross that bridge later once I obtain a losslessly encoded video file.

  This SO question mentions an attempt to obtain a lossless h264 avi and the summary of responses seems to indicate h264 cannot completely accomplish lossless encoding.

  Once again, to emphasize, I am interested in bit-by-bit identical encoding, not just visually similar. Large file sizes are acceptable as is large compression/decompression time.

• Multiple video sources combined into one

  28 septembre 2011, par Oded

  I am looking for an efficient way to do the following :

  Using several source videos (of approximately the same length), I need to generate an output video that is composed of all of the original sources each running in its own area (like a bunch of PIPs in several different sizes). So, the end result is that all the original are running side-by-side, each in its own area/box.

  The source and output need to be flv and the platform I am using is Windows (dev on Windows 7 64bit, deployment to Windows server 2008).

  I have looked at avisynth but unfortunately it can't handle flv and non of the plugins and flv splitters I have tried worked.

  My current process uses ffmpeg in the following manner :

  1. Use ffmpeg to generate 25 png's per second per video, resizing the original as needed.
  2. Use the System.Drawing namespace to combine each set of frames into a new image, starting with a static background, then loading each frame into an Image and drawing to the background Graphics object - this gives me the combined frames.
  3. Use ffmpeg to combine the generated images to a video.

  All this is very IO intensive (which is my processing bottleneck at the moment) and I feel there must be a more efficient way to reach my goal. I do not have much experience with video processing, and don't know what options are out there.

  Can anyone suggest a more efficient way of processing these ?

• Format ffmpeg command to extract the full klv for an mpg/ts file

  24 décembre 2020, par Andrew Marquez

  I am extracting the KLV data from an mpg file using klvdata and ffmpeg.

  



  Following the readme, I have downloaded the sample "Day Flight.mpg" video file that contains KLV data. Running the quick start command works (I get the exact same result as the readme example for the first 6 frames.)

  



  However, for the life of me I don't know how I can extract the KLV data for the entire video file.

  



  As an experiment, I tried creating the KLV data file from an offset start :

  



  ffmpeg -ss 5 -i Day\ Flight.mpg -map data-re -codec copy -f data - > out.klv


  



  and when I run it through my code with different start times (5, 25, etc.) I do get different results.

  



  This (to me) would suggest that the mpg file does contain KLV data throughout, but I can only access 6 frames at a time.

  



  I would expect to be able to run an ffmpeg command to output the full KLV data. I need help formatting my ffmpeg command to properly provide all the data.

  



  To replicate, download the "Day Flight.mpg" file from the klvdata project page and run the command I posted above. You will note it is less than a page long. It should be many, many pages long. Thank you for your help !