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• avfilter : add grayworld video filter

  28 août 2021, par Paul Buxton

  avfilter : add grayworld video filter
  Implements a gray world color correction algorithm
  
  using a log scale LAB colorspace.
  Signed-off-by : Paul Buxton <paulbuxton.mail@googlemail.com>
  
  Signed-off-by : Paul B Mahol <onemda@gmail.com>
  

  • [DH] Changelog
  • [DH] doc/filters.texi
  • [DH] libavfilter/Makefile
  • [DH] libavfilter/allfilters.c
  • [DH] libavfilter/version.h
  • [DH] libavfilter/vf_grayworld.c

• DrawText and crossfade effect - ffmpeg

  22 juillet 2018, par Geek

  I have one video with crossfade effect and i want add text on this video (drawtext).
  However when i add a filter text, he remove a crossfade effect in the final video.

  Command to create video with crossfade effect :

  ffmpeg -i first.mp4 -i second.mp4 -filter_complex 
  
      "[0:v]trim=start=0:end=2,setpts=PTS-STARTPTS[0_clip_1];
  
      [0:v]trim=start=2:end=3,setpts=PTS-STARTPTS[fadeoutsrc_0];
  
      [fadeoutsrc_0]format=pix_fmts=yuva420p,fade=t=out:st=0:d=1:alpha=1[fadeout_0];
  
      [fadeout_0]fifo[fadeoutfifo_0];[1:v]trim=start=1,setpts=PTS-STARTPTS[1_clip_2];
  
      [1:v]trim=start=0:end=1,setpts=PTS-STARTPTS[fadeinsrc_1];
  
      [fadeinsrc_1]format=pix_fmts=yuva420p,fade=t=in:st=0:d=1:alpha=1[fadein_1];
  
      [fadein_1]fifo[fadeinfifo_1];
  
      [fadeoutfifo_0][fadeinfifo_1]overlay[crossfade_1];
  
      [0_clip_1][crossfade_1][1_clip_2]concat=n=3[output];[0:a][1:a] acrossfade=d=1 [audio]" 
  
  -map "[output]" -map "[audio]" videoWithCrossfade.mp4

  Command to add filter text :

  ffmpeg -i videoWithCrossfade.mp4 -filter_complex 
  
      "/Windows/fonts/arial.ttf':text='hello world!':fontcolor=white:fontsize=40:box=1:boxcolor=red
  
      @0.5:boxborderw=10:x=500:y=500"
  
      output.mp4

  this is the link of video : http://www.mediafire.com/file/kw3lvdb2rp1bs6u/videoWithCrossfade.mp4/file
  http://www.mediafire.com/file/iycdzozsqzosq87/output.mp4/file

  Thanks for your help !

• ffmpeg -ss then apply filter then concat producing timestamp errors

  6 août 2020, par Bob Ramsey

  Using ffmpeg, I have split a file into multiple parts using -ss. Then I apply a filter to some of the files, then concat the files back together. When I do that, I get : Non-monotonous DTS in output stream 0:0 ; previous : 341334, current : 340526 ; changing to 341335. This may result in incorrect timestamps in the output file. The output file plays, but there are noticeable skips where the files are joined.

  


  Here's how I am splitting the file :

  


  ffmpeg -i full_source.mp4 -ss 0 -to 14.264250 -c copy  01-plain.mp4
ffmpeg -i full_source.mp4 -ss 14.264250 -to 18.435083 -c copy  01-filtered.mp4

ffmpeg -i full_source.mp4 -ss 18.435083 -to 29.988292 -c copy  02-plain.mp4
ffmpeg -i full_source.mp4 -ss 29.988292 -to 31.865167 -c copy  02-filtered.mp4
...
ffmpeg -i full_source.mp4 -ss 0 -to 14.264250 -c copy  10-plain.mp4
ffmpeg -i full_source.mp4 -ss 234.484203 -to 300.000 -c copy  10-filtered.mp4


  


  Then I apply a different drawtext filter on each of the 10 filtered files and save them with a new name, like :

  


  ffmpeg -hide_banner -loglevel warning -y -i 01-filtered.mp4 -filter_complex "drawtext=fontfile=calibri.ttf:fontsize=24:fontcolor=white:x=300:y=500:text='hello world'" -crf 15 01-filtered-complete.mp4


  


  Finally, I join all of the plain and complete files back together like this :

  


  ffmpeg  -f concat -safe 0 -i mylist.txt -c:a copy -c:v copy  outfile.mp4


  


  And that's where the timing error comes in. I've tried adding -vsync drop in the concat command, but that didn't really work either. Same version of ffmpeg does the split, the filter, and the concat. I've tried different versions, everything from 20170519 to one from May 2020 with the same result. Always making sure that all three steps are done by the same version of ffmpeg.

  


  The only thing I can see is that ffprobe shows a duration of 14.27 for 01-plain.mp4 when it should be 14.264250. All of the other files show a similar rounding difference. The files are 23.98 fps. If I do all of my filters in really long command without splitting the file, I can use the more precise numbers with no problem. It just takes 10 times as long. This is all scripted, it happens a couple of hundred times a day and time is money, so I can't take 10 times as long to do each file.

  


  Any ideas ? Thanks in advance !