Automatically remove "black frames"

[Bartoloni]

right now after processing a footage with Hybrid .. i need to use a Linux script (FFMPEG + blackdetect  filter) to cut in pieces the clip removing the black frames interruptions (i use a blackmagic intensity PRO that generate BLACK frames when the signal is too much "noised" ) and after that i need to merge all these parts to create an output without any BLACK frame..

is possible to used the "blackdetect" filter or something similar on Hybrid to AUTOMATICALLY remove all black frames from footage? (or maybe <5% black frames)

thank you!

[Selur]

No, Hybrid has no filter which would:
a. remove black frames
and
b. cut the audio to keep the source sync


Cu Selur

[Bartoloni]

thank you Cu Selur 

[Selur]

Cu = see you
Selur <- the Name

[Selur]

Can you share a small sample of such a clip (with the black frames)?
I suspect that one could use something like:

def replace_low_luma_frames(clip, threshold):
    # Calculate average luma for each frame
    luma = core.std.ShufflePlanes(clip, planes=0, colorfamily=vs.GRAY)
    avg_luma = core.std.PlaneStats(luma)

    # Create a mask of frames with luma below the threshold
    low_luma_mask = core.std.Expr(avg_luma, f'x {threshold} <')

    # Get frame before for replacement
    frame_before = core.std.Trim(clip, 0, clip.num_frames - 1)

    # Replace frames with low luma using frame_before
    replaced = core.std.MaskedMerge(clip, frame_before, low_luma_mask)

    return replaced

clip = replace_low_luma_frames(clip, 30)

(code is untested, not totally sure whether it works )
to replace each frame which luma is below 30 (or lower) with the frame before it.
Assuming there are only single black frames in the soure and thus singe duplicates that one could use 'FillDrops' to replace the inserted duplicates with interpolated frames.

Cu Selur

[humanoid86]

try it - pulldown="telecine" or "interpolation"

+ tune: Grain or PSNR or SSIM

[Bartoloni]

OMG very thank you helping me!
here a small interlaced sample: www.wcn.it/black.avi

i have a lot of old footages with these black frames (generated by the blackmagic intensity pro card) (there are more than 1 black consecutive frames BTW.. in the sample maybe not.. but there are)

here there are a lot of black "zones" : www.wcn.it/black2.avi

[Selur]

Okay, here's what you can do.

• Start Hybrid
  
• load clip
  
• set 'Filtering->(De-)Interlace/Telecine->Overwrite input scan type to' to 'top field first'
  
• optional: enable 'Filtering->(De-)Interlace/Telecine->QTGMC Vapoursynth->Bob'.
  
• go to 'Filtering->Vapoursynth->Custom->Insert Before' set it to 'FillDrops', enable the text box below it.
  
• in this custom section you now enter:
  
  # replace a black frames with last frame that was not black
def ReplaceBlackFrames(clip, thresh=0.1, debug=False):
  core = vs.core
  if not isinstance(clip, vs.VideoNode):
      raise ValueError('This is not a clip')
      
  def selectFunc(n, f):
    if f.props['PlaneStatsAverage'] > thresh or n == 0:
      if debug:
        return core.text.Text(clip=clip,text="Org, avg: "+str(f.props['PlaneStatsAverage']),alignment=8)
      return clip
    toReplace = n
    for i in range(n)[::-1]:
      if clip.get_frame(i).props['PlaneStatsAverage'] <= thresh:
        continue
      
      # remove current replace with frame before    
      start = core.std.Trim(clip, first=0, last=n-1)
      r = core.std.Trim(clip, first=i, last=i)
      end = core.std.Trim(clip, first=n+1)
      replaced = start + r + end
      break
    
    if debug:
       return core.text.Text(clip=replaced,text="Replaced, avg: "+str(f.props['PlaneStatsAverage']),alignment=8)
    return replaced
          
  clip = core.std.PlaneStats(clip)
  fixed = core.std.FrameEval(clip, selectFunc, prop_src=clip)
  return fixed

clip = ReplaceBlackFrames(clip, thresh=0.1, debug=False)
  If you now look at the Vapoursynth Preview all black frames should be replaced with the last non-black frame.
  
• optional: if there were no multiple black frames in a row, enable 'Filtering->Vapoursynth->Misc->FillDrops', this will then replace the duplicate with an interpolated version.
  

Cu Selur

[Bartoloni]

OMG!!! very very very thank you!!!

[Selur]

Happy that helped, note that this will only work on clips that do not start with black frames.

Cu Selur