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Footage 'bouncing' upon render.

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Callum Whiteley
Footage 'bouncing' upon render.
on Apr 22, 2010 at 11:03:28 pm


In AE CS4 I have a 3D environment containing vector art and footage.

In a RAM Preview the composition plays fine with smooth running footage. Once rendering, however, I can see the clips 'bouncing' slightly every 5 frames or so. The graphics all stay as they should.

The imported footage has been scaled very slightly and has no effects added but a couple of masks.

Here is an FLV sample:

This problem occurs no matter which format I decide to render.

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Tudor "Ted" Jelescu
Re: Footage 'bouncing' upon render.
on Apr 23, 2010 at 6:35:33 am

If your source footage is interlaced ( it looks like DV to me) then make sure you interpret the footage in the project panel - de-interlace ( Fields and Pulldown > Separate fields > Lower field first for DV) and check the Preserve edges.

Tudor "Ted" Jelescu
Senior VFX Artist
Bucharest, Romania

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Dave LaRonde
Re: Footage 'bouncing' upon render.
on Apr 23, 2010 at 1:31:04 pm

[Callum Whiteley] "...I can see the clips 'bouncing' slightly every 5 frames or so...."

That's weird. And when video footage acts weird in AE, a common reason is that it's a certain TYPE of video footage:

Dave's Stock Answer #1:

If the footage you imported into AE is any kind of the following -- footage in an HDV acquisition codec, MPEG1, MPEG2, AVCHD, mp4, mts, m2t, H.261 or H.264 -- you need to convert it to a different codec.

These kinds of footage use temporal, or interframe compression. They have keyframes at regular intervals, containing complete frame information. However, the frames in between do NOT have complete information. Interframe codecs toss out duplicated information.

In order to maintain peak rendering efficiency, AE needs complete information for each and every frame. But because these kinds of footage contain only partial information, AE freaks out, resulting in a wide variety of problems.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA

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