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by mgdlbp 1186 days ago
VLC:

Tools > Effects and Filters > Video Effects > Advanced > Anti-Flickering

Tools > Preferences > Show settings: All > Search: antiflicker

  mpv --vf=deflicker,scale=960x540,pixscope 'https://github.com/apple/VideoFlashingReduction/blob/main/VideoFlashingReduction_Mathematica/Resources/movie.mp4?raw=true'
(generate test video):

  ffplay -f lavfi -i "color=777777[x],color=cccccc,
    [x]framepack=frameseq,settb=AVTB,
    setpts=N/TB/${flickerrate:-12},framerate=${interpolated:-24},
    deflicker=size=5:mode=am,scale=640x480,pixscope"
antiflicker and deflicker are different implementations
1 comments
mgdlbp 1185 days ago
Doh! there's a better filter for this: photosensitivity. It detects local brightness changes that sum to 0, unlike deflicker and apparently the Apple algorithm.

drawgraph can be bodged to convert metadata to frames, and signalstats the opposite. This enables silly things like a self-contained filtergraph mimicking Apple's demo with plots and usable in mpv.

  frames=5
  sensitivity=1.5
  dim_range=2
  dim_intercept=-0.4
  smoothing=10
  smoothtype=am
  decay=0.9
  min_contrast=0.0
  min_brightness=0.0
  min_saturation=0.0
  
  ffplay -vf "split[original],  crop=640:360:0:0,
  split=5[i1][i2][i3][i4][i5];
  [i1]photosensitivity=$frames :$sensitivity,
    drawgraph='bg=black@0 :r=60 :s=1x1 :m1=lavfi.photosensitivity.factor
        :fg1=0x010101*round(0xff*clip(VAL*$dim_range+$dim_intercept,0,1))',
 split[sensedat],  deflicker=$smoothing :$smoothtype,
 negate,  lagfun=$decay,  negate,  split[mit1][mit2];
      [mit1][i2]scale2ref[mask][i2];  [i2][mask]alphamerge[m];
      [mit2]signalstats[mitdat];
  [i3]eq=$min_contrast :$min_brightness :${min_saturation}[a];
    [a][m]overlay,  split[output1][output2];
  [sensedat]drawgraph=lavfi.photosensitivity.badness :0xffff0000
      :bg=white :r=60 :slide=scroll :size=512x256 :min=0 :max=7[bad];
    [bad][i5]scale2ref[badout][reuse];
      [badout]drawtext=fontcolor=2222dd:text='frame     %{metadata\:lavfi.photosensitivity.frame-badness}'[badout];
      [badout]drawtext=fontcolor=0000ff:y=1.2*lh:text='badness %{metadata\:lavfi.photosensitivity.badness}'[badout];
      [badout]drawtext=fontcolor=777700:y=2.4*lh:text='factor      %{metadata\:lavfi.photosensitivity.factor}'[badout];
    [mitdat]drawgraph=lavfi.signalstats.YAVG :0xff00ccdd
        :bg=00000000 :r=60 :slide=scroll :size=512x256 :min=0 :max=255,  vflip[factor];
    [factor][badout]scale2ref[factorout][badout];
      [factorout]drawtext=fontcolor=999900:y=3.6*lh:text='smoothed %{metadata\:lavfi.signalstats.YAVG}'[factorout];
    [badout][factorout]overlay[rplot];
  [i4]signalstats,  drawgraph=lavfi.signalstats.YAVG :0xffff0000
      :bg=white :r=60 :slide=scroll :size=512x256 :min=0 :max=255[lum];
    [lum][reuse]scale2ref[lumout][reuse];
      [lumout]drawtext=fontcolor=ff0000:text='%{pts\:hms} %{pts} %{eif\:n\:d\:5}'[lumout];
      [lumout]drawtext=fontcolor=0000ff:y=1.2*lh:text='avg luma %{metadata\:lavfi.signalstats.YAVG}'[lumout];
  [output1]signalstats,  drawgraph=lavfi.signalstats.YAVG :0xff00ccdd
      :bg=00000000 :r=60 :slide=scroll :size=512x256 :min=0 :max=255[mlum];
    [mlum][lumout]scale2ref[mlumout][lumout];
      [mlumout]drawtext=fontcolor=999900:y=2.4*lh:text='mitigated %{metadata\:lavfi.signalstats.YAVG}'[mlumout];
    [lumout][mlumout]overlay[lplot];
  [reuse][output2][rplot][lplot]xstack=4 :0_0|w0+30_0|w0+30_h0+20|0_h0+20,  [original]hstack" \
  'https://web.archive.org/web/0id_/https://developer.apple.com/accessibility/downloads/video-flashing-reduction-fig12.mp4'
link