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• Setting individual pixels of an RGB frame for ffmpeg encoding

  15 mai 2013, par Camille Goudeseune

  I'm trying to change the test pattern of an ffmpeg streamer, Trouble syncing libavformat/ffmpeg with x264 and RTP , into familiar RGB format. My broader goal is to compute frames of a streamed video on the fly.

  So I replaced its AV_PIX_FMT_MONOWHITE with AV_PIX_FMT_RGB24, which is "packed RGB 8:8:8, 24bpp, RGBRGB..." according to http://libav.org/doxygen/master/pixfmt_8h.html .

  To stuff its pixel array called data, I've tried many variations on

  for (int y=0; y/  const double j = y/double(HEIGHT);
  
      rgb[0] = 255*i;
  
      rgb[1] = 0;
  
      rgb[2] = 255*(1-i);
  
    }
  
  }

  At HEIGHTxWIDTH= 80x60, this version yields
  , when I expect a single blue-to-red horizontal gradient.

  640x480 yields the same 4-column pattern, but with far more horizontal stripes.

  640x640, 160x160, etc, yield three columns, cyan-ish / magenta-ish / yellow-ish, with the same kind of horizontal stripiness.

  Vertical gradients behave even more weirdly.

  Appearance was unaffected by an AV_PIX_FMT_RGBA attempt (4 not 3 bytes per pixel, alpha=255). Also unaffected by a port from C to C++.

  The argument srcStrides passed to sws_scale() is a length-1 array, containing the single int HEIGHT.

  Access each Pixel of AVFrame asks the same question in less detail, so far unanswered.

  The streamer emits one warning, which I doubt affects appearance :

  [rtp @ 0x269c0a0] Encoder did not produce proper pts, making some up.

  So. How do you set the RGB value of a pixel in a frame to be sent to sws_scale() (and then to x264_encoder_encode() and av_interleaved_write_frame()) ?

• ffmpeg how to put color overlay over video

  17 novembre 2015, par flieks

  I want to put a color overlay (blue, red or green or hex value) over a video giving it a Instagram filter like effect.

  I think it should be in the lines of :

  ffmpeg -i video.mp4 -i "red.png" -filter_complex "blend=all_mode='screen':all_opacity=0.7" output.mp4

  or maybe with all_mode=overlay

  But I get an error :

  First input link top parameters (SAR 0:1) do not match the corresponding second input link bottom parameters (SAR 1:1).

  I also tried with lutrgb=r=1.5, but that didn’t give it a red color (it takes the red away).

  What am i doing wrong ?

• ffmpeg how to put color overlay over video

  13 mai 2020, par flieks

  I want to put a color overlay (blue, red or green or hex value) over a video giving it a Instagram filter like effect.

  



  I think it should be in the lines of :

  



  ffmpeg -i video.mp4 -i "red.png" -filter_complex "blend=all_mode='screen':all_opacity=0.7" output.mp4


  



  or maybe with all_mode=overlay

  



  But I get an error :

  



  First input link top parameters (SAR 0:1) do not match the corresponding second input link bottom parameters (SAR 1:1).


  



  I also tried with lutrgb=r=1.5, but that didn't give it a red color (it takes the red away).

  



  What am i doing wrong ?