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RAM Preview problem

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Michael MohrRAM Preview problem
by on Oct 18, 2010 at 9:33:26 pm

I'm having a problem using RAM preview. I've got CS4 and a Matrox RTX2. I'm running 64 bit Vista Business. I've got a composition imported from Premiere. On a number of clips I'm using Keylight to key the footage over a .psd. I'm working in HDV. When I use the RAM preview, it will play the first second or two correctly, then the footage turns into color bars with the file name in the corner. Why is it doing this and is there anyway to have it stop doing this.


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Dave LaRondeRe: RAM Preview problem
by on Oct 18, 2010 at 9:54:32 pm

You're experiencing what EVERYBODY used to experience before the advent of AE 10, namely that the wrong kind of footage will give AE fits. AE 10 solved it, but you're on version 9, and here's what's going on:

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.

I'm a Mac guy, so I like to convert to Quicktime movies in the Animation or PNG codecs; both are lossless. I'll use Apple's Compressor, Adobe Media Encoder or Quicktime Pro to do it.

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


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Michael MohrRe: RAM Preview problem
by on Oct 21, 2010 at 6:07:01 pm

Dave,

Thanks for the information. I ended up using AME to recode the footage (as an MPEG2 believe it or not) and it worked just fine.



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Dave LaRondeRe: RAM Preview problem
by on Oct 21, 2010 at 6:13:07 pm

Now, you're aware that mpeg2 is a lossy codec, which can lead to a big hit in image quality if it's re-rendered, right?

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


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Michael MohrRe: RAM Preview problem
by on Oct 21, 2010 at 6:41:05 pm

I figured as much but I didn't have much time to try and figure out what other codec to use. I've done very little in HDV and this was the first time I needed to really use AE for video compositing. Most of the time it's been motion graphics. It didn't turn out bad though and it got converted to SD widescreen in the end. Now I just have to figure out which codec to use for future productions and how to manipulate the settings (at least until I get CS5)



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