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Best Way to Convert NTSC DV to Square Pixels?

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Jared Peace
Best Way to Convert NTSC DV to Square Pixels?
on Oct 16, 2011 at 4:36:28 pm

Hello. I've been researching this for a few hours on the Cow and Google (and off and on for weeks prior to that) and I honestly can't seem to find a satisfactory answer to what should be a pretty common question.

Which is: What is the best way to convert 720x480 non-square pixels to 640x480 square pixels with the least amount of picture degradation? I've tried various methods in Final Cut, After Effects, and Compressor, but the resolution always seems to take a pretty hard hit. Loss of detail, color shifts, etc. It's possible this is inevitable but perhaps it's avoidable.

Basically my workflow is to take 720x480 non-square NTSC DV, convert it to uncompressed 8-bit in FCP, then export it to Compressor where I can change the frame rate from 60i to 24p, then back to FCP where I can upres it to 720p HDV via an upres plug-in.

Because the original footage is DV, I'm essentially trying to avoid even the smallest amount of generation loss during any of these conversions.

I've looked at this: http://www.lurkertech.com/lg/pixelaspect/ but it seems to focus more on frame aspect ratio and preserving the original size of the recorded footage rather than preserving resolution between square and non-square.

Jared
http://www.jaredpeace.com


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John Pale
Re: Best Way to Convert NTSC DV to Square Pixels?
on Oct 16, 2011 at 5:13:40 pm

"Basically my workflow is to take 720x480 non-square NTSC DV, convert it to uncompressed 8-bit in FCP, then export it to Compressor where I can change the frame rate from 60i to 24p, then back to FCP where I can upres it to 720p HDV via an upres plug-in. "

Good God. Why the hell are you doing this? And where does square pixels enter into this? You do know that HDV does not use square pixels.. This workflow is a complete mess. No wonder it looks bad.

What is your intended final format? Is it 720p HD 23.98 fps?


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Andrew Kimery
Re: Best Way to Convert NTSC DV to Square Pixels?
on Oct 16, 2011 at 6:11:52 pm

That is a very convoluted sounding workflow.

[John Pale] " You do know that HDV does not use square pixels."
1080 HDV uses unsquare pixels but 720p is square pixels.

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Jared Peace
Re: Best Way to Convert NTSC DV to Square Pixels?
on Oct 19, 2011 at 2:23:12 am

Ha ha, yeah I kind of specialize in doing things the convoluted way. But here's the goal. I need to convert 29.97 (60i) to 23.976p. I need to upres from 720x480 DV to 1280x720 HDV. And eventually I need to convert from non-square pixels to square pixels for the web. So those are three very different processes and there are a number of different ways to do them.

I've run many, MANY tests on all of these conversions, and the reason I'm converting to 24p first is because interlaced footage produces a better, smoother result when changing the frame rate and interpolating new frames. Then I'm up-rezing with Magic Bullet's Instant HD Advanced plug-in, which does quite well with progressive frames on input.

But converting from 720x480 nonsquare pixels to 640x480 square pixels is EXTREMELY destructive to the image. It's not totally noticeable at 100% scale, but if you zoom in to 400% or especially 800%, the degradation in the image is... basically so bad it boggles me. Totally unacceptable. I'll maybe post some pictures, if the forum has that option.

I wasn't aware that HDV is nonsquare pixels. I suppose I'm not so much converting to HDV specifically as I am an HDTV format. I'm under the impression that HDTVs and HD projectors all use square pixels, and that if I upres to 720p for HD display, then I want to switch to square pixels. Not so?

Jared
http://www.jaredpeace.com


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David Roth Weiss
Re: Best Way to Convert NTSC DV to Square Pixels?
on Oct 16, 2011 at 5:14:54 pm

What exactly is your final goal Jared?

This seems a rather circuitous route for whatever you're final goal is, and it's not abundantly clear why you're doing things this way or what the actual goal really is.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions, Inc.
Los Angeles
http://www.drwfilms.com

Don't miss my new Creative Cow Podcast: Bringing "The Whale" to the Big Screen:
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Creative COW contributing editor and a forum host of the Business & Marketing and Apple Final Cut Pro forums.


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Steve Eisen
Re: Best Way to Convert NTSC DV to Square Pixels?
on Oct 16, 2011 at 5:45:28 pm

I was going to describe the workflow like a flight on Delta. I prefer non-stop flights.

Steve Eisen
Eisen Video Productions
Vice President
Chicago Final Cut Pro Users Group


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Chris Tompkins
Re: Best Way to Convert NTSC DV to Square Pixels?
on Oct 17, 2011 at 1:53:49 pm

Export your edit of 720x480 using "current settings"

Drop that file into your compression program and choose 640x480 as your output size, choose "maintain aspect ratio by" crop or cut.

Chris Tompkins
Video Atlanta LLC


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Jared Peace
Re: Best Way to Convert NTSC DV to Square Pixels?
on Oct 19, 2011 at 2:33:55 am

Thanks David - I was hoping you might respond; your answers on the forum are always clearly explained, well-informed, and patient.

I described my objectives in another reply in this thread though, and don't want to double-post.

I've spent the last few days experimenting with different conversion methods, and it seems to me that the best way to convert from nonsquare to square is to do it in the up-res process from 480p to 720p. That looks pretty good.

Jared
http://www.jaredpeace.com


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