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How to remove 'flickering'?


phil_the
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I have seen this thread but my problem is not flickering due to changes in exposure / light levels, but a different type of flickering, so I'm not sure if the same suggestions will be appropriate.

In my case I have been sent a video with quite bad flickering throughout. I assume this is due to a fault in their camera, so not much point in asking them to redo it.

When I use the clip viewer and step through the frames I can see that one or two frames appear to be shifted in the frame and looks like this:

Snapshot - 12.png

Is there a simple way to fix this type of problem? I suppose I could take a snapshot at each frame prior to the faulty frames and overlay this, but this would be extremely tedious to do the whole clip.

Thanks
Phil.

 

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Hi phil

I don't think there is an automatic way to screen out these particular frames within VP apart from, as you say, overlaying the duff ones with a copy of their neighbor or splitting them out, which, if there are a lot will be time consuming and tedious.

A possible deleting option would be to step through the video and  split the clip just before  and after the duff frame(s). Switch into Storyboard mode and then delete all the duff clips which will now be easily seen. As this would disturb the audio, unlink this before you start splitting. It can be re-synched later. Try a couple of duff frames first so you can see exactly where to split.

Have you tried stabilizing the clip? Judging by your image however, this would be a VERY long shot and probably won't work. There are big displacements it seems and Stabilize isn't designed for this sort of thing.  Give it a try anyway

Not much choice I am afraid  :unsure:

Nat

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Thanks for the quick reply.

Another idea I had after posting, was that I could overlay the same clip and shift it by a few frames. Then, all I would need to do is split and remove the affected sections, and the shifted frames would show through. This would still be quite tedious as there are lots of affected frames, but would be easier than creating  lots of snapshots.

I hadn't thought of using stabilisation. As you say though it isn't really designed for such big shifts.

I wonder whether there might be a clever trick by exporting with different frame rates? According to the File properties, this clip is 23.33 fps. 

If I were to export it at say 20fps would this simply drop a few frames every now and then? I would obviously be very lucky if it happened to drop the affected frames, but I wondered if I did this multiple times, shifting the clip on the sequence by a few frames each time, I might get enough useable sections that I can splice together. I might have a play with this and see what happens.

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I just re-read your suggestion about using the Storyboard mode. I haven't used this very much. If I delete a split section from there, would the following section shift to fill the gap or stay in the same place in the timeline? I would need to maintain the time placements in order to re-sync the audio and to keep it synced with the other tracks I am going to be combining this one with.

I'll try it.

or...

rather than splitting the clips, it might be easier to add a transparent effect and switch this between 0 and 100% in the animator.

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Hi phil

Although it may be tedious if there are a lot of faulty images splitting and then removing the bad frames may be the best bet. (See below)

Overlapping to cover up the frames can get complicated as it means using several tracks and bearing in mind that upper tracks cover lower tracks, each time the next bad frame will end up on the lower track....

For the same reason using transparency on paper would work but with many effects VP might begin to struggle in preview.

So try this...

I have a clip that has two yellow (faulty) frames somewhere....This a mock up using blank frames. Normal frames are red and faulty frames are yellow.

  • Save the audio as a separate file (just a precaution)
  • Un-link the audio
  • Step through  or play to the first faulty frame appears. Note that they may not be visible on the timeline as they are very short but the Sequence preview window (stepping frame wise) will reveal it.
  •  
  • aa.jpg
  •  
  •  Split the Track....
  • Step to the right until the next correct frame appears in the sequence preview
  • Split the track a second time.
  • Repeat for the remaining faulty frames.  Note: The faulty frames in your video may not be visible on your timeline.  The splits you made however will be.
  •  
  • dd.jpg
  •  
  • If you zoom in the faulty frames may become visible between the splits but you don't need to do this except out of  interest.
  •  
  • ccc.jpg
  •  
  • Now switch into Storyboard mode. The isolated faulty frames will now be shown as individual slides no matter what their actual length. (In this example the yellow "slides")
  •  
  • ee.jpg
  •  
  • Travel along the timeline in story board mode clicking and deleting each faulty frame. This leaves gaps in the timeline...
  •  
  • ff.jpg
  • .......so as you do this close the gap each time.

You should now have your original video without any faulty frames but nevertheless split at numerous points. (Not a problem) The audio will still be present so play the timeline and see if the synch is good enough despite the missing frames. If the audio is now too long adjust the speed a notch until it is as close as possible.

Nat

 

bb.jpg

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Thanks,

I have done it now. I pretty much did what you said, although I found it OK to stick with the Timeline view and use the >|| button to skip through and identify the clips to delete.

As there were so many glitches, the audio would probably have got out of sync by the end I think, so what I did was do the delete without the ripple so it leaves a gap (I think delete in the Storyboard would have done the same). This leaves blank gaps. So then I overlaid the same track but shifted it by four frames which filled in all the gaps 🙂. I removed the audio from the track that I split, and used the audio from the overlaid track. I unlinked this audio and shifted it back to match the main track, although that probably wasn't necessary as a difference of four frames likely wouldn't have been noticeable.
Thanks both for you help and advice.

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