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• AVFrame / AVPicture change color component

  26 avril 2014, par RoeeL

  Given a video stream (runs with SDL), I need to somehow make the video’s frames color green only, blue only and red only (depends on input).

  How can I do that ? How can I set the color component to be RED only for instance ? (R = 255, G = 0, B = 0)

  Didn’t manage to find anything on google. would love to get some assistance.

  thanks

• FFMPEG write to openEXR grayscale channel 32 bit float (Z pass)

  31 mars 2022, par Chryfi

  I have a byte buffer with image data, or to be precise, with depth data in floats. If I understand the openEXR specification correctly, it supports 32 bit floats for one pixel, so I create a byte buffer with the size of width * height * 4 which I output to FFmpeg.

  


  I want to export the data to a layer named "Z" in openEXR. These arguments -f rawvideo -pix_fmt grayf32be -s %WIDTH%x%HEIGHT% -r %FPS% -i - -vf %DEFVF% -preset ultrafast -tune zerolatency -qp 6 %NAME%_depth_%d.exr (the %...% get replaced by the programme later) export them to no layer (i.e. default layer) and every programme where I checked the image appears green i.e. the 32 bits are stored in the green channel or some information is missing to let programmes know that it's a one channel layer.

  


  How can I achieve a proper depth pass in openEXR with FFMPEG ?

  


• How to wrap a C library parameter ?(Creating x264 .Net wrapper)

  6 décembre 2016, par Rella

  so in dll we have x264_param_t structure\object and a function for its setting up x264_param_apply_profile. in C we use such code to set it up

  x264_param_t param;
  
  x264_param_default_preset(&param, "veryfast", "zerolatency");
  
  param.i_threads = 1;
  
  param.i_width = width;
  
  param.i_height = height;
  
  param.i_fps_num = fps;
  
  param.i_fps_den = 1;
  
  // Intra refres:
  
  param.i_keyint_max = fps;
  
  param.b_intra_refresh = 1;
  
  //Rate control:
  
  param.rc.i_rc_method = X264_RC_CRF;
  
  param.rc.f_rf_constant = 25;
  
  param.rc.f_rf_constant_max = 35;
  
  //For streaming:
  
  param.b_repeat_headers = 1;
  
  param.b_annexb = 1;
  
  x264_param_apply_profile(&param, "baseline");

  I want to create wrapper for such.. thing. so I have libx264.dll and visual studio 2010 pro.

  How can I create .Net C# wrapper for it ?

  I am a beginner in P\Invoke stuff so I do not get a lot of it...

  what I want to achive is is frame by frame level of working with x264... By now I need only encoding parts... And all needed sample code for doing it in C is in How does one encode a series of images into H264 using the x264 C API ? . So I need to write a wrapper only for stuff mentioned there... So I am asking - how to create a wrapper on Parameter and on Function that sets up thap param. And I would love to see how to call that wrapper back from c#. So if you could provide any code in support I’d be glad to see it.