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Removing baked in improper de-interlace scan lines – rendering out exactly what I see in preview monitor?
Alright, here is one for you AE gurus.
THE PROBLEM I’M TRYING TO FIX:
Client delivered a 29.97 progressive QT Uncompressed 10 bit YUV file. However it looks like they imported some clips into their FCP7 project and cut them into their sequence without properly de-interlacing. So randomly through out the quicktime I come across shots like with this one, with horizontal field issue looking thing:
I THINK I SOLVED THE PROBLEM IN AFTER EFFECTS:I import QT into AE, select the clip, interpreted footage. The only thing I change is:
Conform to frame rate 29.97
But if you look at the screen grab below, it looks like all I’ve done is change the frame rate from (29.970 fps) to 29.97. No difference, right? Don’t know what the extra 0 means.
I then right click the QT and make a composition, and to my surprise the problem is gone when I play the composition in the preview window. I have no idea what I changed, but horizontals bad de-interlace lines go away on a progressive scan computer monitor as I play the composition. Even gone when I step frame. In addition, I can play out the composition, SDI, through my Black Magic 4k Extreme card, and record the SDI signal to my Black Magic HyperDeck SSD Drive. I then import the new test Quicktime I recorded, and the lines are gone.
SO WHAT’S THE PROBLEM?:
So why don’t I just play out and record to SSD? AE will not playback the entire file in realtime, even with 40 gigs of ram assigned to AE. So I get stutter, and would have to start and stop all the time for a 30 minute show.
I also cannot render out a file that looks like the preview monitor. Either I get the same interlace issue, or a new interlace issue that looks like this:
Since I don’t think there are fields in the original file, AE must be doing something with shutter angle and/or motion blur.
I have a suspicion that the file plays nicely in the preview monitor because of the motion blur settings available in advanced composition settings:
Are the motion blur settings above only operating in the preview monitor, and do not affect the file when rendered out? I tried various force motion blur effects, but they only had Shutter Angle and Samples Per Frame options, no options for Shutter Phase or Adaptive Sample Limit. I want to render out what I see in the preview monitor and what I see when I play out of my decklink extreme 4K card.In other words, render out exactly what the composition is, how do I make this happen?
Is there anything like render same as comp, or a mixdown feature?
Thanks for reading this far.
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3 Replies
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I haven’t run into this before, but if you are looking to just get smooth, realtime playback that you can record then perhaps you can use Dynamic Link to import the composition to Premiere and render in the timeline. Then it should play back in real time and you could record it. Test it out on a 5 second clip first, as Dynamic Link render times can go pretty high.
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Thanks, I tried a dynamic link, but clip interlacing lines returned in premiere. It turns out the file is in fact interlaced, thought only one app would tell me that. Still confused as to why playing out SDI allowed AE to de-interlace the file, without me telling it to? Again play out was great, if I could have maintained realtime playout. Wondering if it has anything to do with the motion blur settings in the advanced tab of the preview settings?
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have you looked at the rendered file in ae?
it looks like the screen shot you posted was from premiere, and it could be that premiere is trying to deinterlace progressive, which would look bad.
if the rendered file looks good in ae, then you may need to find a premiere setting to have it not deinterlace
Kevin Camp
Art Director
KCPQ, KZJO & KRCW
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