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• More Windows fixes

  9 février 2016, par Erik de Castro Lopo

  More Windows fixes
  These fixes got lost in an earlier commit.
  Patch-from : lvqcl <lvqcl.mail@gmail.com>
  

  • [DH] include/share/win_utf8_io.h
  • [DH] src/share/win_utf8_io/win_utf8_io.c

• Why does ffmpeg need DNS resolver as its dependencies ?

  20 décembre 2019, par Kshitij

  I was installing FFmpeg and libav today using brew install ffmpeg libav when I noticed unbound in the dependencies list.

  It’s very strange because unbound is DNS resolver and why ffmpeg would need it.

  ❯ brew install ffmpeg libav
  
  ==> Installing dependencies for ffmpeg: aom, frei0r, gmp, libtasn1, nettle, p11-kit, unbound, gnutls, lame, libass, libbluray, libsoxr, libvidstab, libvpx, opencore-amr, opus, libsndfile, libsamplerate, rubberband, sdl2, speex, giflib, leptonica, tesseract, theora, x264, x265 and xvid

  I even checked the info list for ffmpeg but unbound was not present there

  ❯ brew info ffmpeg
  
  ffmpeg: stable 4.2.1 (bottled), HEAD
  
  Play, record, convert, and stream audio and video
  
  https://ffmpeg.org/
  
  /usr/local/Cellar/ffmpeg/4.2.1_2 (287 files, 56.6MB)*
  
  - Poured from bottle on 2019-12-19 at 10:45:56
  
  From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/ffmpeg.rb
  
  ==> Dependencies
  
  Build: nasm ✘, pkg-config ✔, texi2html ✘
  
  Required: aom ✔, fontconfig ✔, freetype ✔, frei0r ✔, gnutls ✔, lame ✔, libass ✔, libbluray ✔, libsoxr ✔, libvidstab ✔, libvorbis ✔, libvpx ✔, opencore-amr ✔, openjpeg ✔, opus ✔, rtmpdump ✔, rubberband ✔, sdl2 ✔, snappy ✔, speex ✔, tesseract ✔, theora ✔, x264 ✔, x265 ✔, xvid ✔, xz ✔
  
  ==> Options
  
  --HEAD
  
      Install HEAD version
  
  ==> Analytics
  
  install: 66,434 (30 days), 280,128 (90 days), 1,079,492 (365 days)
  
  install-on-request: 48,053 (30 days), 203,583 (90 days), 759,254 (365 days)
  
  build-error: 0 (30 days)

  Links for reference

  • https://formulae.brew.sh/formula/ffmpeg
  • https://formulae.brew.sh/formula/unbound

• Writing a Custom Blend for Softlight

  21 mai 2020, par Jonas

  Lately I've been messing around with ffmpeg's blending modes and noticed their algorithms are not entirely the same as in Photoshop. I'm interested in Softlight blend and will use it as an example to illustrate my issue.

  



  First thing's first, I was able to mimic Photoshop's softlight with the blend and geq filters, but it's painfully slow with video inputs. Problem of geq I guess.

  



  ffmpeg -i top.png -i bottom.png -filter_complex "[0]format=rgba[a];[1]format=rgba,split[b][b2];[a][b]blend=all_expr='if(lt(A\,0.5)\,(2*B*A+(B*B)*(1-2*A))/255\,(2*B*(1-A)+sqrt(B)*(2*A-1))/255)':c3_expr=A,geq=a='p(X\,Y)':r='min(255\,p(X\,Y))':g='min(255\,p(X\,Y))':b='min(255\,p(X\,Y))'[tmp];[b2][tmp]overlay[out]" -map [out] output.png


  



  So it occurred to me that I'd be better off building ffmpeg from source adding in the PS softlight blend formula (note that in the formula a is the bottom layer and b is top, while in the code snippets it's the reverse).

  



  

  



  I'm introducing changes to vf_blend.c file, line 263

  



  DEFINE_BLEND8(softlight,  (A > 127) ? B + (255 - B) * (A - 127.5) / 127.5 * (0.5 - fabs(B - 127.5) / 255): B - B * ((127.5 - A) / 127.5) * (0.5 - fabs(B - 127.5)/255))


  



  and making it

  



  DEFINE_BLEND8(softlight,   (A < 127) ? (2*B*A+(B*B)*(127.5-2*A))/255 : (2*B*(127.5-A)+sqrt(B)*(2*A-127.5))/255)


  



  Result was quite close but not exactly what I want (has a green tint on the output). My question is how can I change that line of code to match the above formula and get the desired softlight blend ?