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any cure for this problem footage due to incorrect shutter or "pseudo progressive

Posted by dasha 
any cure for this problem footage due to incorrect shutter or "pseudo progressive
March 04, 2012 03:24PM
I know this is not a strictly compressor issue, and I apologize up front, but some input I've received has suggested compressor as a possible fix. What happened was a cameraman shooting on my SonyPD170, standard def, didn't realize the shutter had shifted to 30 when it should have been on 60. My film is currently at a post house in NY and the colorist (who had upconverted to 1080) wondered why all this footage --from the same camera-- was so fuzzy and zaggy--unlike the rest. Upon further investigation he told me that the camera had shot it progressive (unlike all the rest) I checked the camera menu and it had not been accidentally changed to progressive, so the mystery increased. I played the bad tape back in the camera and set the DATA and that's when I saw what I thought was the real problem-- the shutter at 30! But then I got conflicting analyses on another forum ranging from the crazy camera had shot its form of "pseudo progressive" to that it was the shutter and various combinations. Copied below are two of them. My colorist has already tried what cutter R suggested and it did not improve the look. Cutter D, who analyzed a few clips i sent him, thinks it's not a shutter issue, that it's a fake progressive screwup and wonder if Compressor might have a fix-- thus I've posted here to see if any of you might have a suggestion in compressor or elsewhere. I've got two weeks to get recommendations, before the final post is done. I've copied some of the comments I had received:
Cutter R:
*NO* - I have to disagree on this 1/30 sec shutter notion making video
output automatically progressive. Progressive format is one Z scan per frame (no fields). Interlaced
format is one Z scan per _field_ or 2 offset Z scans per frame.Unless the camera's native sensor scan mode is _really_ progressive, the output will actually be interlaced with a 1/60 second offset - since the sensor was scanned in interlaced mode. A true progressive scan camera may output using an interlaced mode to meet file transfer standards, but
the timing of the two fields will then be identical so theycan be reassembled as one progressive frame.
Slowing the shutter speed to 1/30 sec on a CCD or CMOS camera isn't going to convert one to the other. What it IS going to do is integrate 2 sequential 1/60 second (or 4 sequential 1/120 second in some cases) intervals and output them as one frame.

So the reason your image is soft is that there is a 1/60 second offset
between fields. If there is any motion - the frame will be blurred.
The ONLY way I know of to get rid of the motion blur is to de-interlace,
double one field (throwing away the other field) and reinterlace. The
results will be sharp in X (horizontal) and slightly soft in Y(vertical)
but a lot better than temporally shifted random X,Y offsets.

Cutter D:
Looks like the PD150 went into its half-resolution progressive mode, which shoots a single field and then simply line-doubles it to create a full frame. That's what's causing your "jaggies." You can see the progressive motion as a bit of stuttering when viewed on an CRT (a flatscreen won't show this).
Anyway, simply setting the shutter speed to 1/30 will NOT produce the effect seen in your clips. What it would produce is blurring or streaking motion, which we do not see in your clips.
The PD150 should go into this pseudo-progressive mode ONLY when that mode is chosen in the menu. As I mentioned, I once had the same thing happen with a PD150 for no known reason.As far as I know, the only camera that ever does this is the PD150.
If it had been REAL progressive footage it wouldn't have been an issue. But the PD150's progressive mode is "fake" progressive, which produces those jaggies. So progressive per se isn't the issue.
In this "fake" progressive mode, instead of recording the full 480 horizontal lines that compose the picture, the PD150 records only 240 lines, which it then doubles to produce the full picture. In other words, each of those 240 lines is displayed twice, one above the other. So in effect each horizontal line is twice as thick. That's why diagonals look jagged. 

Reinterlacing won't help, unless it's done on a high-end system that can interpolate every other line intelligently and create intermediate lines that render diagonals properly. But you'd have to do a test first to see if it really gets the job done. There might be a way for Compressor to do this, but I haven't tried.

So any suggestions on how the footage might be improved will be greatly appreciated
thanks! Daria
Re: any cure for this problem footage due to incorrect shutter or "pseudo progressive
March 04, 2012 05:12PM
This problem may not be fixable but I would recommend trying some of the Frame Controls options on a short segment of the file to see if it makes a difference. Pay attention to the Deinterlace, Anti-Alias and Details Level controls in particular.

I wrote up a guide for the various Frame Controls options here:
[www.digitalrebellion.com]

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Thank-you, Jon. I have now run a camera test with multiple options and from what we see, this problem was caused by the incorrect shutter at 30 and compounded by a very contrasty shot--man in black suit, white bg-- but not by a mistaken "quasi progressive setting in the menu. When I tested with progressive, everything got even worse, but the shutter along produced the problem we see in the footage. I don't know if this means nothing can fix it, but I did check your guide. Silly question i'm sure, but where do I find these Frame Controls? When I open Compressor and search around, I don't see that in any menu or in any of the settings. Is this because i have version 3.5.3, not 4?
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