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• Anomalie #3620 : Token de prévisualisation inconsistant selon que l’article est en cours de rédact...

  17 décembre 2015, par realet RealET

  C’est dans ecrire/base/objets.php ligne 182 que l’on trouve :
  ’previsu’ => ’publie,prop,prepa/auteur’

  Et dans ecrire/inc/autoriser.php ligne 375 que l’on trouve :
  if (in_array($opt[$champ] . "/auteur", $previsu))

  Donc, on se retrouve à n’autoriser la prévisualisation que par l’auteur qui prépare l’article.

• YUV420p to other formats, color shift problems

  1er juin 2013, par Sam

  So I'm writing a color detection application using an AR Drone. The drone sends my python/opencv socket server an image from its camera in YUV420p format.

  What I do to access the image as an opencv IPLImage is the following (and yes this is inefficient but I didn't / don't want to have to write new conversion tools myself) :

  1. Save the yuv image to a file (some_image.yuv)
  2. subprocess.call(insert ffmpeg call here)
  3. Read the resultant file (bmp, png, it doesn't matter) back in using cv.LoadImage

  My problem right now is a very noticable color shift. I'm waving a red felt sheet in these pictures. The first one shows a heavy yellow tint. The second isn't as bad but is very rare — mostly when I have the red sheet it's heavily tinted.

  • Tinted image : http://i.stack.imgur.com/BQikM.png
  • Less-tinted image : http://i.stack.imgur.com/ezHyy.png

  I'm wondering both of these things :

  1. if there's either a better way to do this
  2. If the color tinting issue can be resolved

  My ffmpeg conversion line looks something like

  ffmpeg -s 640x480 -vcodec rawvideo -f rawvideo -pix_fmt yuv420p -i image.yuv -vcodec bmp -f image2 output.bmp

  I've also tried :

  ffmpeg -f rawvideo -s 640x480 -pix_fmt yuv420p -vf colormatrix=bt709:bt601 -i image.yuv -f image -vcodec png output.png

  The color shift is always there, unfortunately !

  The color shift is my big problem right now as I later convert the image to HSV and use thresholding to choose a color range that works for me.

• Using libav (ffmpeg), how to decode a video file directly to a GPU texture ?

  15 janvier 2023, par GaryO

  I'm using ffmpeg's libav to decode video files on Mac. For supported codecs, it says it can use the Mac VideoToolbox framework to hardware-accelerate the decoding.&#xA;Can I get the result of that decode directly as a Metal or CoreVideo buffer or texture, in GPU memory ? My plan is to process it with compute shaders before sending it to the screen and I'd like to maximize framerate by removing CPU<->GPU transfers.

  &#xA;

  Is there an example of doing this anywhere ?

  &#xA;