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• avcodec/vvc/refs : Use unsigned mask

  7 juillet 2024, par Michael Niedermayer

  avcodec/vvc/refs : Use unsigned mask
  Not a bugfix, but might fix CID1604361 Overflowed constant
  Sponsored-by : Sovereign Tech Fund
  
  Reviewed-by : Nuo Mi <nuomi2021@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/vvc/refs.c

• imagemagick gradient mask file creation

  6 avril 2016, par lang2

  I’m playing with this creative script here : http://www.fmwconcepts.com/imagemagick/transitions/. The plan is to mimic what happens with the script with ffmpeg and generate video with transition effects between pictures. My current understanding is this :

  1. I have two pictures A and B.
  2. I need in between a couple of pictures (say 15) that are partially A and partially B.
  3. To do that I use the composite -compose src-over A.jpg B.jpg mask-n.jpg out.jpg command.
  4. During the process, the mask-n.jpg gets generated automatically that gradually change from all black to all white.
  5. Depends on the mathematically equations, the way the transition effect looks is different.

  In one of the example, Fred the author gave this :

  convert -size 128x128 gradient: maskfile.jpg

  This will generate a image like this :
  

  This is partially black and partially white. For the transition to work, I’ll need an all white one and an all black one and a couple of others in between. What’s the magical command to do that ?

• Creating a transparent color mask that covers half of every frame in a video with opencv/moviepy/ffmpeg

  24 octobre 2019, par Nyktofob

  I’m doing a pose estimation in rats separated into two compartments of a cage. To make my tracking better I want to put a transparent color mask that covers half of every frame so that one of the rats will appear to the neural net as being of different color, thus making it easier for the net to differentiate those rats. My question is : Is there any easy way to do this using python (moviepy/opencv/ffmpeg) ?

  Bare in mind, I’m completely new to python, so I’d appreciate any recommendation of a tutorial or detailed answer.

  I tried using blender to do this, but failed miserably.

  I expect to be able to modify the video, so that there will be a rectangular transparent mask in some color that covers certain part of every frame (Let’s say video is 1920x1080 pixels, so from pixel 960 on x axis everything to the right is transparently green)