Deinterlace, Reinterlace, Field Order, and 30P Workflow in FCP

Discussion in 'Digital Video' started by Chris7, Feb 5, 2009.

  1. Chris7 macrumors 6502

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    #1
    Hello,

    I’m about to do a video in which I shoot in 30P with a static camera, and do all the zooming and panning in post. It would seem that if I shot in 60i, this would create major problems in post, as every other pixel up or down I move the frame would cause the field order to reverse. I do not want to shoot in 24p, as some older DVD players will not play this.

    1. Since my HF-100 outputs 30P material into 60i, I need to use a “primitive” deinterlacer that simply puts the fields together, and does not lose resolution. (I believe this happens automatically when removing the telecine from 24P footage). Which deinterlace function in FCP does this for30P?

    2. SD anamorphic is 720x480, but I assume the pixels are very rectangular (wide). I’ll be working in 1920x1080 ProRes (square pixels). When I’m zooming in on my subject, what' the minimum ProRes pixels I need so I don’t lose resolution when converting into SD anamorphic (how far can I zoom in)?

    3. Once I’m done working with the footage, what function(s) do I use to reinterlace the footage before compressing it into MPEG-2 for DVD? Should the reinterlacing be done in Compressor or FCP?

    Thanks in advance.
     
  2. LethalWolfe macrumors G3

    LethalWolfe

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    #2
    Most, if not all, Hollywood DVDs are 24p so I wouldn't worry about compatibility.

    In the Sequence settings try setting the Field Dominance to "none."

    If you want to reframe like this you need to be working in an SD sequence. If you have fast enough drives to work in ProRes you can work in an SD ProRes sequence to help maintain quality.

    Use Compressor and just grab the appropriate preset. That's a good place to start.


    Lethal
     
  3. Chris7 thread starter macrumors 6502

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    #3
    I'm not sure what you mean here. I wanted to take advantage of the 1920x1080 to zoom way in on the subject, maintaining the 16:9 ratio, then convert that into SD. (If I converted to 720x480 SD before zooming, I would not be able to zoom without seeing lots of pixels.)

    What I'm wondering is how does the 720x480 anamorphic translate into square pixels, so I know how far in I can zoom. I'm thinking it's 480x853, but not sure.

    Many thanks for the help.

    Wow. That's all there is to combining the fields? Nice.
     
  4. LethalWolfe macrumors G3

    LethalWolfe

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    #4
    853x480 is a typical size used for widescreen, SD material but you don't want to edit in an 853x480 timeline and you don't want to export an 853x480 QT to make a DVD. The only time to use 853x480 is if you are exporting a file for playback on a device that can't correctly playback anamorphic files.

    I understand what you want to do and I'm not saying convert the HD footage to SD first I'm saying you need to edit the HD footage in an anamorphic, SD sequence. Using HD footage in an SD timeline gives you the ability to zoom in and reframe the shot w/o losing image quality.

    30p is a bit of an odd duck format and I've never worked w/it, but from what I understand just setting Field Dominance to "none" does the trick.


    Lethal
     
  5. bimmzy macrumors regular

    bimmzy

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    #5
    Chris7

    Is your camera capable of shooting 24P?

    I'm trying to work out the resistance to shooting that way.


    24P goes in to 60(i) well almost.....

    my point is that 24fps has been transferred to video (ntsc) for years, and the techniques used work and work well.

    failing that just shoot 30P and be done with it.... 30P goes in to 59.95i perfectly! :eek:

    :D
     
  6. Chris7 thread starter macrumors 6502

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    #6
    Many thanks. I am relatively new to FCP and do not have experience with setting my sequence different from my footage. I just tried this suggestion and the video simply zooms in, leaving no room to zoom back out and pan, so I don't think I'm doing it right. In Sequence Settings under the General tab, I set Frame Size to 720x480, Aspect Ratio to Custom, Pixel Aspect Ratio to NTSC - CCIR 601, and checked Anamorphic. When I close the Settings box and reopen it, the Aspect Ratio changes automatically to NTSC - DV. What am I doing wrong here?
    I also tried changing the Field Dominance to "None," without messing around with the format/aspect ratio. Since the Aspect Ratio stayed at "HDTV 1080i", I set it to "Custom" and hit the Advanced tab under QuickTime Settings, and changed this from 1080i to 1080p, and closed the Settings box. When I reopen it, it still defaults to an Aspect Ratio of 1080i. Are the fields locked together (deinterlaced)?

    Lastly, I'm assuming I keep my Render Control setting to Same as Sequence Codec, right?

    Again, many thanks for your help.

    -Chris

    I would shoot in 24P for this but I am afraid that it might not play in some older DVD players. I'm sure it would look much better than 30P into 60i for the ones that it works on, though.
     
  7. LethalWolfe macrumors G3

    LethalWolfe

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    #7
    Try this, open a new sequence, go to Sequence Settings, go to the Load Sequence Preset button (lower left hand corner) and select Apple Pro Res 422 NTSC 48k. Change the Field Dominance to None and check the Anamorphic box. Now add some footage. When a warning box pops up asking if you want to change the sequence settings to match the footage settings say "no."

    If you change the sequence settings w/footage in the sequence you'll screw up the footage. And if you change sequence settings w/o understanding the consequences of what you are changing you'll screw things up. 9 times out of 10 there is no reason at all the mess w/the default sequence settings so if you are having problems the last thing you want to do is start 'rolling your own' sequence settings 'cause odds are that will do more harm than good.


    Like I said before, don't worry about shooting in 24p. It is part of the DVD spec.


    Lethal
     
  8. Chris7 thread starter macrumors 6502

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    #8
    Thanks so much for your help. I followed this and it's worked perfectly so far. Will the fact that it's 720x486 rather than 720x480 create a problem when I compress it into 720x480 MPEG-2 for DVD? Should I change it to 720x480 in Sequence Settings?
     
  9. LethalWolfe macrumors G3

    LethalWolfe

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    #9
    720x486 is the size typically used for uncompressed SD so it's fine. When you use Compressor to make the MPEG2 file for DVD Studio Pro it will properly make a 720x480 file.


    Lethal
     
  10. Chris7 thread starter macrumors 6502

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    #10
    I assumed that the reason you suggested editing in a SD timeline is so that when I'm "panning" and "zooming" in post, FCP knows what pixel to go to, and doesn't have to do as much guessing later when transferring from square to horizontal pixels, resulting in better image quality. Is this correct? If not what's the reason? (I didn't ask earlier because I didn't want to take up too much of your time.)

    You suggest I do the project in 24P. If I do this, would you still recommend I edit in a SD Sequence (if I know I'm going to SD DVD)?

    Thanks again,
    Chris
     
  11. LethalWolfe macrumors G3

    LethalWolfe

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    #11
    You can only pan/zoom in post and not lose image quality if your footage is bigger than your timeline. For example, editing 1080 footage in a 1080 timeline doesn't give you an room to pan/zoom because the footage is already at 100%. If you zoom in you start to lose image quality. But if you put 1080 footage in an SD timeline you have room to pan/zoom because the footage gets scaled down to around 50%.

    Since the footage is already in 30p just stick w/30p. In the future though if you use 24p and want to pan/zoom in on the footage you should do so in an SD timeline.


    Lethal
     
  12. Chris7 thread starter macrumors 6502

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    #12
    I'm sure you're correct, but I'm not understanding this. Understanding the logic about how the program "thinks" makes it fun for me, and helps me solve/prevent new problems in the future. Intuitively, from a beginner's perspective, it would seem that as long as I do not zoom in more than a certain amount (whatever amount of square pixels converts into the SD 720x480 anamorphic), it should not matter what setting the timeline is in, if I plan to convert this into SD (Compressor will change the aspect ratio of HD and then compress it into MPEG-2 in one step). What would happen to the footage if I just edited it in a HD timeline, then converted it into SD MPEG-2?

    Was I correct in my initial assumption that panning with interlaced footage is just asking for trouble, as the field dominance would reverse every other pixel the frame moved, causing out of order fields?

    Anyway, I appreciate your time here, and I understand if this is just getting too difficult to explain. Clearly, I know next to nothing about timeline settings, but I hadn't realized there was so much I needed to know. My knowledge of FCS is limited to about 40 hours of Larry Jordan Tutorials, and a little of the Apple Pro Training Series. Do I need to go back to the manual to understand this sort of thing? I also have the Level 1 and 2 FCP Apple Pro Training Series, which I have skipped around in. Do you know if this would tell me what I need to know?

    I have not done the shoot yet. What timeline settings would you suggest for this?

    Thanks again,
    Chris
     
  13. LethalWolfe macrumors G3

    LethalWolfe

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    #13
    I'm thinking of it as an order of operations thing. If you edit in an HD timeline you are enlarging the footage and then shrinking it down to SD size. Where as if you are editing in an SD timeline you shrinking w/o enlarging first. Also, by working in an SD timeline you get a better idea of the final viewing experience because some things that seem crisp and clear in an HD timeline, such as text, gfx, or something off in the distance, can become hard to discern digital blobs in SD.

    Progressive footage can be easier to work w/because you don't have to worry about interlacing artifacts. Interlaced footage can be effectively manipulated you just have to be a little more mindful of what you are doing.

    Reading the manual, while boring, will teach you a lot. Same w/the training series books. Honestly though the best learning experience is just using the program. There are a lot of kinda abstract concepts in editing that can be hard to really grasp until you have practical experience w/them. It's kinda like the difference between reading about sports and playing sports. There's only so much info you can absorb at a time so just stay patient and stay curious.

    Same settings as before expect chose the 24p frame rate instead of 30p. You might have to take the extra step though of having Compressor reverse telecine your footage. As a side note, when people talk about frame rate in whole numbers (24, 30, 60) they are just using short hand. When people talk about 60p they really mean 59.94. When people talk about 24p they really mean 23.98 (or 23.976 for the really exact). When working w/video you never, ever want to 'whole number' frame rates. The lone exception is working w/24.000p in preparation for transferring your footage to film.


    Lethal
     
  14. Chris7 thread starter macrumors 6502

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    #14
    I'm still enjoying FCS -- definitely more fun than frustration. I appreciate your help.
     

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