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• avcodec/libjxlenc : prevent color encoding from being set twice

  13 avril, par Leo Izen

  avcodec/libjxlenc : prevent color encoding from being set twice
  We currently populate the color encoding bundle and then check to see
  
  if there's an ICC profile to attach, and set the color encoding bundle
  
  in either case. The ICC profile overrides the color encoding bundle, so
  
  we should not calculate enum-based color encoding if we have an ICC
  
  profile present. Fixes several unnecessary warnings from being emitted.
  Signed-off-by : Leo Izen <leo.izen@gmail.com>
  

  • [DH] libavcodec/libjxlenc.c

• Ffmpeg color opacity

  19 janvier 2016, par Sandra

  I tried to rotate a video and keep the unused place due to the rotation transparent, to be able to overlay it later and to do that, I suppose that if the color was transparent is will be right ; and in the official page (https://www.ffmpeg.org/ffmpeg-filters.html#rotate) they said that you can give a color that ffmpeg would use in place of unused place due to the rotation of the video. So I tried, relatively to https://www.ffmpeg.org/ffmpeg-utils.html#Color to put a color with these commands

  ffmpeg -i video.mp4 -vf "rotate=PI/6:fillcolor=red@0.0" -acodec copy output.mp4

  and

  ffmpeg -i video.mp4 -vf "rotate=PI/6:fillcolor=red@0x00" -acodec copy output.mp4

  And it doesn’t work. The color remain opaque, and that whatever the value of the opacity (0.0 to 1.0)

  Any of you can know what is happened ?

• Does FFmpeg video filter(eq filter) color correction work same as function sws_setColorspaceDetails ?

  25 octobre 2019, par Jahwan Oh

  I’m need to use color filter with two different implementation.
  first one is using the function below. with conversion

  double m_brightness = -0.18;
  
  double m_contrast = 1.45;
  
  double m_saturation = 1.2;
  
  SwsContext *swsctx = sws_getCachedContext(NULL, vStreams[1]->codec->width, vStreams[1]->codec->height, vStreams[1]->codec->pix_fmt, dst_width, dst_height, dst_pix_fmt, SWS_BICUBIC, NULL, NULL, NULL);
  
      int *inv_table, srcrange, *table, dstrange, b, c, s;
  
      sws_getColorspaceDetails(swsctx, &inv_table, &srcrange, &table, &dstrange, &b, &c, &s);
  
      b = int((1 << 16) * m_brightness);
  
      c = int(c * m_contrast);
  
      s = int(s * m_saturation);
  
      ret = sws_setColorspaceDetails(swsctx, table, srcrange, inv_table, dstrange, b, c, s);

  and the other one is using FFmpeg -vf eq color correction on command line.

  ffmpeg -i original.jpg -vf "eq=brightness=-0.18:contrast=1.45:saturation=1.2" -c:a copy original_filter.jpg

  the problem is that I need to have a same result(filtered) with this two tools. with just same brightness/contrast/saturation parameters, it showed different result, so I tried to convert these parameter between these two tools.

  I thought these two color correction work same reading the link below. I’ve tried to convert the swscale filter parameter to ffmpeg -vf eq filter parameter based on the link, but it seems it is not a conversion between them.
  but, it is more like a conversion of m_brightness <—> b.(in the code I’ve attached)
  https://github.com/google/sagetv/blob/71d122229105e164cd410fafed2a5e7483869913/third_party/mplayer/libmpcodecs/vf_scale.c#L393

  you can see the each results with different parameter.

  https://drive.google.com/drive/folders/181_LhkvpB4XbEf05_ecuLoy5nSSEcRiX?usp=sharing

  How can I convert the parameters so that it produce same filtered result ? or is it totally different algorithm ?