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Interlacing of Video
I produced a drama on 1 inch video in 1984. We used the a high quality professional Hitachi camera at that time. This year we had it transferred to DVCAM to reedit. After the transfer was completed, we found that everywhere there was an edit in the original production, there was an interlacing of two frames.
In other words, at the end of each edit, the last frame is superimposed on the first frame of the next sequence.
I researched this, and understand that somehow the two fields that make up each frame are being transposed. I tried to correct this in Vegas, as they have some settings that relate to it, but without success. I am wondering what the solution is. Should I try to get the original re-copied from the 1 inch with special settings? Is there a setting in Vegas that will read it properly? Is there software for dealing with this problem?
We tried taking out the bad frames, but it leaves a hole in the music.
Thanks.
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7 Replies
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1-inch tape from 1984?! Jeez… you’re as old as I am!
I have never heard of this problem before. I can only think of one very labor-intensive method that would solve it. That being said, I don’t know if Vegas will do this. This can be done in Avid, Media 100, and perhaps some other edit programs. Maybe in Vegas too; someone else can chime in on that.
The suggestion: Go to every problematic “mixed” frame and use it to make a one-field freeze frame. In the edit systems mentioned above, you can export an individual freeze frame of any frame in a clip and you can specify that the exported freeze frame be composed of only the odd field; or only the even field; or a blend of the two. Find out whether the odd or even field shows the image you want and make a freeze frame using just that field. You can then clip off the bad frame and insert the new freeze frame as a replacement. Depending on how many edits you’re working with, this can take quite a while. Note: this technique duplicates each odd or even field, which means you will have only 50% image resolution for a single frame at the end of each transition but my guess is the eye will never notice it. I use this technique all the time to eliminate drop-outs (which usually occur on only a single field.)
Hope I’ve understood your problem correctly.
–Lee
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Sounds like you need a “fix bad frame” script which will replace a bad frame with the previous or next frame. There’s a free one listed here:
https://www.sonymediasoftware.com/forums/ShowMessage.asp?MessageID=467049&Replies=0That tool is also one of the features in Excalibur. The audio doesn’t have to be changed so you don’t have to worry about that.
Edward Troxel
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Thanks for the info, but how do we compile and run this script in Vegas?
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What does the “bad frame” look like? From your description, it sounds like one field is from the outgoing shot, one from the incoming – is that right?
These single frames – did you spot these while viewing the programme – a 1-frame mix is surely invisible? Or were they only discovered on a frame-by-frame look in the edit suite?
If they don’t present a problem to viewers, why worry? Or are you saying that there is a visible “frame flash” on each cut? If there is on transfer, and there wasn’t on source, then you have a dud transfer… .
Of course in PAL land, video is usually upper field first, except for DV and spinoff, which are lower field first. Could this be related ..?
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Thanks for your insights. We are trying to re-dub this now, because I think the original dub was bad. I finally found another company with a 1 inch machine and am waiting. There are very few where I live (near Portland, Oregon).
The “ghost” images only show up on the edits, because you cannot see them on the regular frames, although they are there. They show up as one field from the previous cut superimposed on one field of the new segment. They flash on the edits, and if nothing else, I will take them out. However, the problem is that this is a feature length drama, and the music is over much of it, leaving a hole in the music. Where the music is, we will just leave it and hope the flash is not too noticeable, as I have no other choice if the new dub does not fix the problem.
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You’re right. The original dub was bad. Better to do what you’re doing — get a new dub done and forget all these efforts to clean it up in post. Let us know how it turns out.
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It turns out that this was not a bad dub. I had it copied at 3 different places. Finally a tech place knew the problem. Previous to 1990, machines read with a field 2 dominance, not field 1. We changed the fields, but then the action went backward between fields. We used Flame, but could not remedy it. I then tried Adobe AfterEffects, but we are not experts with it and could find no solution.
So I am working with it as it is. We cut out the edits in between as much as possible (music and dialogue prevented some) and since it is only 1 frame, it is unlikely most would see it.
Thanks for all the comments and help.
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