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Why am I getting black frames at the beginning of my QT layer?

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Sean WorsellWhy am I getting black frames at the beginning of my QT layer?
by on Jan 28, 2011 at 5:47:10 am

I'm dropping a QuickTime mov into the Project window. The QT mov file consists of 20 seconds of HD footage. There is no black in this footage. There was black in the footage before, but I used QT Pro to "trim to selection" thereby creating a new .mov file with no blacks--just image.

So using this "no blacks/image-only" mov file in AE, I drop it into a new AE comp, and I suddenly get about 9 frames of black at the beginning of the layer before the image appears. No matter what I do. I even tried trimming the original QT file with QT Pro so that it was HALF the length of the original. And when I drop it into AE, I get 9 frames of black at the beginning. What gives?


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Cory PetkovsekRe: Why am I getting black frames at the beginning of my QT layer?
by on Jan 28, 2011 at 6:29:19 am
Last Edited By Cory Petkovsek on Nov 5, 2014 at 11:31:17 am

What codec? What system? Our answers are simply guesses without specific information.

What if you look at the first few frames in an NLE?

Why not just use the original footage (pre trimmed from QT Pro) and trim off the black part in AE?

Cory

--
Corporate Video


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Sean WorsellRe: Why am I getting black frames at the beginning of my QT layer?
by on Jan 28, 2011 at 6:53:54 am

Thanks Cory.

Codec: QT PhotoJPEG, 25 fps, 1920x1080, exported from Final Cut (on a mac), and then imported to a PC where After Effects is used.

In an NLE: In Avid (PC), the clip in question does NOT show the black frames, so this is something to do with how AE (PC) is interpreting this footage. I've played with the interp settings to no avail.

Reason I'm not using original, pre-trimmed clip in AE: Because the original clip DOES have "real" blacks in them, which I don't want, and trimming them in AE on the timeline means that when I play with Timewarp and reverse the clip, etc., those blacks come back to haunt me, even if I trim them out on the timeline to begin with. Maybe if I precomp stuff this won't happen.


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Cory PetkovsekRe: Why am I getting black frames at the beginning of my QT layer?
by on Jan 28, 2011 at 11:02:12 am
Last Edited By Cory Petkovsek on Nov 5, 2014 at 11:31:29 am

So your source footage is something, possibly PhotoJPEG. You cut off the black at the beginning in FCP. Then you export with PhotoJPEG to open it up in AE on a PC, and you see black at the beginning of the intermediate file. However you don't see black at the beginning of the intermediate in Avid on the PC. Right?

Ok, why don't you use another codec rather than PhotoJpeg? That should have been your second test, after the NLE. Good cross platform intermediates are Avid's QT LE DNxHD codecs (free) and cineform ($) and they'll probably give you a better quality/size ratio.

Other options to use are QT Animation or PNG Sequence, but they will take a lot of space.

Cory

--
Corporate Video


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Tudor "Ted" JelescuRe: Why am I getting black frames at the beginning of my QT layer?
by on Jan 28, 2011 at 4:21:21 pm

Your idea of precomping the footage is good. Also, when you play with time remap, make sure that you have heads and tails to your clip and those frames contain image information, otherwise you will get strange artifacts. Exporting again to another codec like Cory suggested my be best though.

Tudor "Ted" Jelescu
Senior VFX Artist


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