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• YUV8_420P - AVFrame conversion hazard (only Y plan)

  4 mai 2017, par Flow

  I’m working on a FFMPEG application. The goal is to convert a picture (YUV input format) to an AVFrame to be able to process it (by applying a specific filter) and then realize the invert conversion to redirect it to the output.

  Although some filters as drawgrid or noise are perfectly working, filters which apply some "space transformation" (as a "crop" or a "hflip") seem to affect only over the Y component. The colors of the output pictures aren’t filtered which leads to an unsatisfying result.

  I’m asking myself why I have such a result but I didn’t reach to find the problem origin.

  Here is the part of cod which convert the YUV picture to an AVFrame :

  unsigned int i = 0;
  
  int number_common_channels = MIN(IMAGEFORMAT_COMPONENTS, AV_NUM_DATA_POINTERS);
  
  
  
  // Transfer the image informations (width, height, pitch and data)
  
  if ((av_im->width = yuv_im->width[0]) <= 0)
  
  {
  
      cu_printf(ERROR, "Width of destination picture null or negative");
  
      return -1;
  
  }
  
  if((av_im->height = yuv_im->height[0]) <= 0)
  
  {
  
      cu_printf(ERROR, "Height of destination picture null or negative");
  
      return -1;
  
  }
  
  for (i=0; i < number_common_channels; i++)
  
  {
  
      av_im->linesize[i] = yuv_im->pitch[i];
  
      av_im->data[i] = yuv_im->data[i];
  
  }

  If necessary, I can transmit you other parts of the cod where the problem could be. Thanks for your cooperation.

  Flow.

  EDIT 1 : After some researches, it would be possible the problem came from my function which initializes the filter graph. Actually, I used the FFMPEG example given on their website to make it and I deleted the options to the pixel format list because I thought it was useless. It’s possible this function and more precisely the av_opt_set_int_list could be the key, but I don’t reach to find a good example using it. Also, another function, av_opt_set_pixel_fmt was created in the last FFMPEG versions and this could be well to try using it, but I don’t know how to do. So please if someone has a good example with that, I’ll took it with hapiness.

  EDIT 2 : The problem came from the way I copied my data back after the filter was applied. Closed.

• Evolution #4828 : Intégrer tous les objets au plan du site

  22 juin 2021, par b b

  À déplacer sur le projet https://core.spip.net/projects/plan ?

• Evolution #4828 : Intégrer tous les objets au plan du site

  22 juin 2021

  @b_b Ah oui flûte, je déplace