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• Unwarping 180 VR Footage with FFmpeg v360 Filter

  5 avril 2021, par Ted Wilmont

  I am struggling at present. I have searched high and low for days and can't find a command that achieves what we want to do.

  


  We have stereoscopic 180 degrees VR footage in a side-by-side equirectangular format that we want to convert to flat so we can process using further AI software.

  


  We have already split the file in half across the width using FFmpeg so we have a "right" eye and a "left" eye video file.

  


  For each video file, we need to convert the 180-degree equirectangular footage to a flat, unwarped video file using FFmpeg (and the v360 filter).

  


  We've tried the following for example :

  


  ffmpeg -i 2LEFT.mp4 -vf "v360=input=equirect:ih_fov=180:iv_fov=180:output=flat" 2LEFTTEST.mp4


  


  However, this results in a very warped/misaligned video.

  


  Some command examples, tips, suggestions as to convert the now monoscopic 180-degree equirectangular footage to a flat video file will be greatly appreciated.

  


  Thank you for your help in advance.

  


• Record region of screen using FFMPEG ? [closed]

  13 février 2024, par pookie

  I am looking to record a defined area of the screen at as high FPS as possible. I then need to extract the milliseconds for each frame.

  



  I was looking at FFMPEG and found that it has (or had...) an option called x11grab, so I tried the following to record a region of the screen :

  



  ffmpeg -f x11grab -s 1678x1050 -i :0.0+7,53 -r 25


  



  It doesn't work : I get an error Unknown input format: 'x11grab'

  



  I tried with xcbgrab too, but I get the same error of Unknown input format...

  



  I have seen this SO post, but I am using Windows 10, and it did not help me.

  



  Google tells me that this argument is now deprecated. I cannot find an examples of how to record just a part of the screen.

  



  I want to take a partial screenshot because I need as high a FPS as possible and my assumption is that taking a partial capture will be faster than taking a full screen capture. Is that correct ? If not, of course I could take a full screen capture and the crop out region of interest... and if that is the case, does anyone know how to do that ?

  


• avfilter/scale_vulkan : add dynamic crop region and aspect ratio match

  26 novembre 2024, par Koushik Dutta

  avfilter/scale_vulkan : add dynamic crop region and aspect ratio match
  The scale_vulkan filter initializes the shader once, with the crop
  
  region set by the original frame. However, subsequent frames may
  
  specify a different crop region than the first frame. This change
  
  updates the cropping to match the behavior present on the other
  
  hardware frame scale filters.
  The scale filter should also allow negative values
  
  that respect aspect ratio, similar to other scale filters.
  Signed-off-by : Koushik Dutta <koushd@gmail.com>
  

  • [DH] libavfilter/vf_scale_vulkan.c