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• FFMPEG Interframe to intraframe without 'converting' or losing data

  11 août 2017, par Domenick Simpson

  I’m new to this so I apologise I couldn’t find the answer after searching.

  I am just ripping some video content for my film show-reel (specifically the Lego movie bluray) and came across some issues. When using ’makeMKV’ and ’xMedia Recode’ to perform a lossless transfer of the video data into an mp4 container I am getting artifacts in After Effects due to the interframe encoding of this bluray in H264 format. This doesn’t seem to be a problem with the Lego Batman movie bluray for some reason, maybe it uses Interframe. Anyway, some frames have block artifacts etc when editing / cutting shots.

  Is there a way to convert this original MP4 stream into the same format without losing data / into an intraframe mp4 for editing purposes ?

  I have used various re-encoding methods to H264 and prores that don’t result in block artifacts but result in less quality and different colourspace, and, higher file sizes.

  In FFMPEG I also tried exporting the mp4 as a png sequence but I assume due to the conversion of YUV to RGB I am getting quite noticeable differences in reds and gamma. I’d also prefer to keep this as a H264 or single video file if possible. Full disclosure, I tried various conversion types rgb24 etc to retain colour info but this didn’t work either.

• How can I programmatically write and read random video watermarks ?

  13 novembre 2017, par GreenTriangle

  I spent a few minutes trying to think of a clearer way to word my title, but I couldn’t manage it, sorry.

  I want to essentially canary trap video files : I am (hypothetically, this is not real but a personal exercise) offering them up to 5,000 different people, and if one gets leaked, I want to know who leaked it. Metadata is too easily emoved, so what I’d like to do is add a random and subtle watermark to each file, and store information about that in a database.

  For example : on Joe Smith’s copy, a 10x10 pixel 80% transparent red square in the upper left corner for 5 frames. On Diane Brown’s copy, a full-width 5-pixel 90% transparent black bar on the bottom edge for 15 frames. Then, if I find a leaked copy, I could check it against the database.

  I know this still isn’t foolproof : cropping would break co-ordinates, hue/brightness transforms would break colour reading, cutting time would break timestamps. But if I did want to do this anyway, what would be a good strategy for it ?

  My idea was to generate PNG overlays randomly, split the video into parts with mkvtoolnix/ffmpeg, re-encode the middle part with ffmpeg + overlay filter, and then rejoin them. But is this silly when there’s a "proper" way to do it ? And what would I be doing to read the watermarks, which I can’t even really conceive of ?

• python cut portion of video "Fastest way"

  23 mai 2020, par mhndev

  I'm trying to cut out portion of video file using python(3.7.1) and ffmpeg in my flask (1.0.2) application,
this is solution 1

  



      # solution 1
    from moviepy.editor import *
    from moviepy.video.io.ffmpeg_tools import ffmpeg_extract_subclip

    video = VideoFileClip('/app/videos/video.mkv'.subclip(10, 20)
    video.write_videofile('/app/videos/cutted_video.mp4')


  



  and here is result in flower panel screenshot.
as you can see cutting out two videos takes more than two seconds.

and this is solution 2

  



      # solution 2
    from moviepy.editor import *
    from moviepy.video.io.ffmpeg_tools import ffmpeg_extract_subclip


    ffmpeg_extract_subclip(
        '/app/videos/video.mkv',
        10,
        20,
        '/app/videos/cutted_video.mp4'
    )


  



  first solution works pretty well, but It takes about 1-2 seconds to cut the video out.
instead second solution works very fast ( less than 0.5 sec ) but the output video is just audio plus black screen.

  



  what is the fastest way to cut portion of video in python.
If there is any other library which is faster please tell me that.