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• Apple Automator, Shell Script and batch files - video subtitles

  4 décembre 2020, par Luiz Silveira

  I'm making a Workflow to burn SRT to MP4. It's is working but I want it to go to all files of a folder and didn't find a way even with "Dispense Items Incrementally".

  


  I have the SRT and the MP4 in the same folder, so I need the workflow to filter the results to only try the script with the MP4 files and maybe this is the problem for "Dispense Items".

  


  Because the subtitled file goes to the same directory, the filter also excludes files named with "_SUB".

  


  The image is below if someone has an idea... I'm open to other methods of doing this. I just need to go to a folder with 44 MP4 files (and .SRT with the same name) and batch encode the videos with subtitles.

  


  Thank you,
Luiz

  


  enter image description here

  


• 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 ?

  


• 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