Deinterlace or not

TimPion

TimPion

Member
Hi,

I am currently working on my first "real" filmproduction and learning everything on the way. I started a general topic some time ago: http://www.dvxuser.com/V6/showthread.php?t=169836

But now I have a simple question: "to deinterlace or not to deinterlace"

The movie will be a 60 min production with:

  • Color correction
  • some slow motion
  • some compositing (for blood effects, etc)
  • some flashbacks (with blur effects,...)
All the footage is shot in 50i using a sony FX7E. We are using CineForm as a DI

I know I have to deinterlace before doing effects which will mess up the interlacing-lines (like the flashback for example). But I don't know if general color correction will mess up the interlacing.

As for the output format, I don't know whats best. I know I need to have deinterlaced material for the web, but I can deinterlace just before publishing on the web. I also want to deliver on DVD and there might be a chance to get it on the silver screen. So I really need to get the best quality I can.

So do I need to deinterlace everything with CineForm, so I start working with 25p footage and deliver in 25p?

Or is it better to do general cuts, color correction, dissolves,... with Interlaced material and just deinterlace footage which will go through heavy effects in post? If so, is it best to use CineForm's deinterlacer or deinterlace after the footage is converted with cineform?
Is the CineForm derinterlacer a good choice? Or is it better to use magic bullet or another 3th party software?


Thanks for the help!!

Tim
 
Last edited:
My question is, does your software not support interlaced video handling? I've never dealt with Cineform actually, but any competent post software (whether it be an editor, motion graphics, compositing, etc) should be able to handle interlaced video just fine. If you're outputting to the web, personally, I'd deinterlace *after* editing the whole thing. Color correction usually has little to do with your interlacing (assuming you haven't messed up the color sampling, but again, any good editor should be doing this correctly to begin with), and as for effects... Well, those can often be rendered in interlaced form, but if you're concerned, try to deinterlace using third party software. I can't make an exact recommendation, as I use AVISynth freeware filters, but most NLEs and even After Effects, have god awful deinterlacing.

Hope that helps, but give us some more details.
 
Thanks for your reply. The software (premiere pro and aftereffects) handles interlaced video fine, but the question is whether it would be better to deinterlace before editing or after.

I didnt know effects could be rendered in interlaced form, so thats an interesting idea. However, compositing and resizing must still be done in progressive form i guess.

Why would I want to deinterlace after? what are the advantages and disadvantages?
 
TimPion said:
Thanks for your reply. The software (premiere pro and aftereffects) handles interlaced video fine, but the question is whether it would be better to deinterlace before editing or after.

I didnt know effects could be rendered in interlaced form, so thats an interesting idea. However, compositing and resizing must still be done in progressive form i guess.

Why would I want to deinterlace after? what are the advantages and disadvantages?
Click to expand...

Deinterlacing is a reduction of quality, particularly in temporal resolution (fluidity of motion), so it's good to have the original interlaced form. If you're going to broadcast or put on DVD, keep it interlaced. Internet video is almost exclusively deinterlaced due to progressive displays.... All LCD panels are progressive of course, but only a TV will actually bother to deinterlace video, as it expects interlaced input.

As for rendering in interlaced form... I'm not entirely sure how its handled; however, many stock effects are rendered in 60fps because they can then be cut in half for 60i (30fps interlaced). You cannot make true 60i material out of something that is 30p. 720p/60 is frequently used in shooting because it can easily be converted to 60i if necessary, while maintaining full progressive 60fps masters - essentially the opposite of you maintaining your original interlaced masters (but equally important!).
 
For DVD you will need to deinterlace anyway even if you go with 50i DVD. I would deinterlace now into 540p50 or 720p50 and work with it. Cineform will fill the blanks, and 720p will look pretty nice. Then you will be able to go to all other formats including 50p, 50i and 25p very easily.

Did you say slow motion? Then deinterlace into 25p and add those 50i segments slowed down to 0.5 speed for clean slomo.
 
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