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Optical Flow at on 10% speed - frames jump backward

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Pat DeFilippo
Optical Flow at on 10% speed - frames jump backward
on Mar 26, 2009 at 3:15:48 am

Hello all,

I just did a search in this Motion forum for "Optical Flow" and couldn't quite find the answer, so sorry if this is a repeated question and I just didn't look up the right terminology.

I transferred a sports shot from DVD to a Quicktime movie via MPEG Streamclip as 720x480 and 10-bit uncompressed.

I brought that into FCP6 and slowed it down to 10%. I then used "open with" on that slowed-down clip and selected Motion.

In Motion, I went to Optical Flow. Overall, Optical Flow (of course) looks a lot cleaner. However, between frames, it appears as though the footage jumps backwards. So, playing back the 10% speed clip in real time, it's pretty jumpy.

I then added a Field filter to try +1 and -1, but that didn't appear to be the problem.

I'm thinking that the original problem might have been in coming out of MPEG Streamclip, but I'm not sure.

Is the real problem that I'm trying to slow this down to 10% and "it is what it is"?

Also, just one quick question - the first time I applied Optical Flow, the little spinner started spinning and it took a while before the 28 second clip finished. The second try, however, did not automatically start the Optical Flow processing when I selected it. Is there some sort of "start" button that I'm overlooking?

As you can probably tell, I don't use Motion much! But that's not due to a lack of desire to - it's just from a lack of work that calls for it often enough!

Thanks in advance for your help,
-Pat

G5 Quad 2.5 Desktop with 4GB Ram, 500GB HD & Fiber Card ~
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AJA Io LA ~
Final Cut Studio 2 ~
Sony UVW-1800 Beta-SP ~
Sony DSR-40 DVCam ~
2.33ghz MacBook Pro 17" (with FCS2) ~~~

P D Post Productions, Inc. ~
TV~DVD~VHS~CD~WEB
for Corporate Communications, Commercials, Infomercials, Television Programs and Family Occasions since 1983 ~
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david bogie
Re: Optical Flow at on 10% speed - frames jump backward
on Mar 27, 2009 at 2:59:02 pm

This suggests the footage originated on film or a 24p source. You're seeing some kind of field mismatch or a pulldown error. A pulldown error can be removed. Maybe. that involves much more research on your part, I've never had to attempt that stuff. but the manuals are full of pulldown references.

Give the pulldown wonks a few more days to drop in while you're doing your own searches.

bogiesan



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Pat DeFilippo
Re: Optical Flow at on 10% speed - frames jump backward
on Mar 27, 2009 at 4:41:26 pm

Thanks, David,

I had meant to follow-up with this post, but handn't got to it.

I back-tracked my stepsto MPEG Streamclip and the original DVD. It occured to me to select DV (720x480) instead of selecting 10-Bit Uncompressed (720x486), since the original is on DVD anyway.

Once I brought the exported QT into FCP6, re-marked in and out points, changed the speed to 10%, sent it to Motion for Optical Flow, waited for the render (!), and then watched it again in FCP6, it worked perfectly.

If there were any frames shifting, they were shifting forward instead of backward and they looked very clear. Just for kicks, I compared it to the original 10% speed change from FCP6 and, of course, there was no comparison!

Optical Flow in Motion is the hands down winner between the two.

Thanks again for your help,
-Pat

G5 Quad 2.5 Desktop with 4GB Ram, 500GB HD & Fiber Card ~
30" Cinema Display & 17" Sony SVGA ~
Swift Data 200 Internal 1.6TB SATA II RAID 0 ~
AJA Io LA ~
Final Cut Studio 2 ~
Sony UVW-1800 Beta-SP ~
Sony DSR-40 DVCam ~
2.33ghz MacBook Pro 17" (with FCS2) ~~~

P D Post Productions, Inc. ~
TV~DVD~VHS~CD~WEB
for Corporate Communications, Commercials, Infomercials, Television Programs and Family Occasions since 1983 ~
E-mail PD@PDPost.com ~
Website http://www.PDPost.com ~
Business/Cell Phone (847) 275-5671


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david bogie
Re: Optical Flow at on 10% speed - frames jump backward
on Mar 30, 2009 at 6:35:18 pm

Great, and thanks for coming back and closing the thread with a solution. Hardly anyone ever does that around here.

bogiesan



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