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Do I need to de-interlace an edited video master?
I have a few question regarding getting compressed digibeta SD into FCP.
Here’s the situation:
I have the movie (shot at 24fps on 16 mm film). It was transferred to video via a telecine where it was mixed and color-timed. In other words, the final edit master now lives in a 29.97 video world. On the tape it looks great. You can’t see repeated (4:3 pull down) frames and the cuts are all sharp.Video, as you know is interlaced. When I digitized the movie into FCP, I noticed on many cuts half of 1 frame and half the other. I assumed it was simply due to the progressive nature of Mac monitors dealing with the interlaced video. Everyone said it would go away when I burn a DVD and not to worry about it.
However, I am concerned that by re-editing the movie, I have changed the 4:3 pull down sequence so some of those half frames will make it into the new DVD master and I might see some dupe frames.
Also many people now have progressive monitors so I don’t want them to see the movie with crappy frames. Basically, I want the half-frames gone. If I de-interlace it doesn’t it throw away half the picture information? (which, of course means I have half the resolution).
And, if I do have to de-interlace it, what’s the best way to do it? Do I de-interlace the master file then use that to edit, or do a I throw a de-interlace filter on each clip I used? Or, again, do I even need to de-interlace it? I haven’t ever used cinema tools, so I’m not really sure how that works either.
Also, finally, if I want to re-digitize a file from digibeta into FCP uncompressed I assume I should just have the project setting set to uncompressed NTSC. Then it is pulling in straight 1:1… Or do I need to do something else to get the absolute best image in from the tape I can?
Thanks in advance!
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5 Replies
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So you are going to cut a version from the finished tape? You have no access to the dailies?
This is a problem I have often when cutting reels for, say, costume designers who provide me with a DVD of their feature work. The best way to navigate the problem is to simply cut in such a way that you never use those half/half frames. Deinterlacing will lose you half resolution which will look crappy.
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[Filmcutter] “If I de-interlace it doesn’t it throw away half the picture information? (which, of course means I have half the resolution).”
Not sure where you got the idea that de-interlacing throws away half the picture information??? De-interlacing combines two fields into one progressive frame. If anything, progressive display effectively doubles the resolution, as both fields are displayed simultaneously for a full 30th of a second. Interlaced video displays half resolution at 60th second intervals, never actually displaying both fields simultaneously.
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In NTSC video, no matter whether it’s interlaced or not, you still display one field every 60th of a second. That a field…1/2 the scanlines that make up one half of the frame. If you deinterlace your video, you are basically creating two new FIELDS that are interpolated from the two existing fields. One field fills the even scan lines and the other field fills the odd scan lines. The fields are nearly the same and offset by a single scan line. You do, in fact loose vertical resolution when you deinterlace. The computer tries to “fill in” the missing information when it interpolates the new fields from the two original fields. No matter how you do it, in NTSC, you still have to deal with 2 fields per frame of video. Whether it’s interlaced, with each field slightly different based on movement between frames or deinterlaced with nearly identical, synthesized frames…it’s still going to playback at 60 fields per second.
Tom -
Well Tom, we’re both actually corect on this one. You’re assuming playback on traditional NTSC equipment (CRT from tape or from the timeline) at 1/60th of second, while I am assuming playback from DVD on a monitor with fixed pixel display, capable of displaying true progressive frames at 1/30th of a second. The original post did say that DVD was his goal… So, I think we’re both right… Yes???
DRW
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But that still doesnt really tell me what to do. I obviously want the best possible DVD quality I can get. I have a master on Digitbeta that was shot on film. I need to re-edit certain scenes so I cant just lay the whole piece to DVD. But, if I’m getting those half frames when I digitize it into FCP, do I want to re-edit it in FCP to lose them or are those simply the result of an interlaced medium going to a progressive monitor and thus even cutting them out wont change anything. (I’d prefer not to have to cut them out as the master is already mixed and I dont have access to the original stems so even cutting 1 frame when theres a song playing is noticable…
Sorry if this sounds kinda dumb- the interlaced/deinterlaced/3:2 pulldown stuff kinda confuses me. (Thats why I ask you gurus!)
Thanks.
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