Render does not match RAM preview. Totally baffled…

[Jimmy Brunger]

Hmmm…is Open GL checked in your RENDER settings? Make sure ‘render with open GL’ is off and see if that helps…

AE7 Pro – Nucleo – Mocha v1.2.3 – PS CS3 – FCP 5.1.4
MacPro Quad 3GHz / ATI 1900XT / 8GB RAM / OSX 10.4.11
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———————————
Production Studio CS2 – Combustion 3 – Mocha v1.0.1
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[Ross Newton]

I checked and it’s off. I tried a render with it on just for kicks, but it didn’t help. I get the same result whether it’s on or off.

Does Adobe have a tech support number? And can you get to advanced people who really know the program in and out?

[Ross Newton]

Something else that’s bizarre, I can do a RAM preview using the button in the “Time Controls” and it looks perfect in the Composition window. But when I go to “Save RAM Preview” under the Composition menu, it will reiterate through the whole composition, rendering it out and I can see the frames messing up as it renders.

Basically, ANY kind of export is messed up because it cycles through the render queue process where I can see the frames having issues. But just a plain RAM preview, looks perfect.

[Chris Wright]

remove preference folder should do the trick, they often get corrupted and do weird things to preview windows and templates etc and since you’re using Tiff’s, DO NOT use LZW compression, it is not lossless, uncheck that option and use 32 NOT 24 bits, which is only 8 bits/pixel. 🙂

[Ross Newton]

I cleared both of the preference files, this didn’t work (thanks for trying though).

I can identify the problem layers. So I tried precomposing them and proxy-rendering them ahead of time. Didn’t work.

However I have a new discovery on one of my problem comps with the track that goes out of whack. I thought that the tracked CG element was becoming “untracked” or something in the render, but actually what’s happening is the plate/footage is duplicating a frame, thus throwing the CG element off track. My comp is 224 frames and about four times in the final render, it duplicates a frame.

I’ve seen some posts about this problem, but most of them deal with codecs of imported video files. My plate is a DPX image-sequence set at 23.98fps. And as mentioned, it RAM previews fine and doesn’t duplicate any frames… any ideas?

[Troy Murison]

Hi Ross,

You say your comp settings are at 23.98? If so, try changing them to 23.976, otherwise transformations (ie tracking) may ‘jump around’ when rendered to 23.976 as the keyframes aren’t lining up perfectly with the footage. I have seen this before a long time ago. I can’t remember if we had to redo tracking, etc. or just change the framerate to make it right. We didn’t start the project, we were just rendering it for output and we assumed for a long time that it was a problem on our system vs. the artist’s, so it took a long time to work out. I never found out why the RAM preview didn’t match the render though.

I just re-read your post- our comp’s sources were QT’s not file sequences, so in my mind if you’ve interpreted your file sequence at x fps and rendered at x fps, things should match, but I’ve never tried.

-Troy Murison
Seattle, WA

[Ross Newton]

I just did another test. I tried just rendering the DPX sequence by itself with no other layers in a new comp at 23.98fps. It is rendering fine with no frame doubling.

So maybe there’s a problem in my effects comp, although I’ve double checked its frame rate. I’m going to make a new comp and copy my layers over. I’m also going to replace the existing plate layer in my effects comp for kicks. Will report shortly, I have a meeting now.

[Ross Newton]

Problem solved! Everything looks good. Wow, thanks Dave and Troy. Your suggestions made sense as soon as I read them.

The director of this film, before he gave me DPX images sequences, was giving me QT preview movies and they were all showing as 23.976 fps. We just assumed it was wrong or something because he assured me that the RED camera and Final Cut were showing the plates as 23.98 fps! Funny.

I have two questions then, now that I’ve conformed the plate and CG to 23.976. Should I re-render my CG elements as 23.976? I used Lightwave and I set the frame rate to 23.98. I supposed if it looks good I should leave it alone, but I hate things not being perfect. Second question is, why did the RAM preview show it correctly before!? Does it use a different rendering method?

So now that the tracking-comp is correct, I’m still working on fixing the other comps… I think those may have something to do with rendering at 32bpc… I’m going to play with those.

[Ross Newton]

Yeah conforming the CG elements to 23.976 looks good. I guess I shouldn’t try to fix it if it’s not broken. I was thinking about going back and re-rendering the CG at 23.976… maybe Lightwave assumes 23.98 is 23.976 too, because they look right.

So I figured out what the other issues were that I mentioned in my first post. Basically in a couple of the comps, I pre-comped some Particular layers and rendered proxies for them so I could move them to other AE machines that don’t have Particular installed. So the method I used was to pre-comp the Particular layer, set it to render with Alpha to a TIFF sequence, set to Enable Proxy, then render. Then the proxy automatically worked and looked good in my RAM preview. The alpha layer was working appropriately and only showing the particles. However, in the final render of the comp, the pre-rendered proxies were ALL rendering without any alpha. And they were also using the keyframes (like opacity) of the original Particular layer in the pre-comp. So I had all these layers of color fading in and out and no idea why, because the RAM preview looked perfect!

So to fix it, I just imported the pre-rendered proxy files (the TIFF sequences) and dragged them into the comp where the pre-comped Particular layers were, then I turned off the pre-comped layers. Problem solved and the alpha of the pre-rendered files worked great in the RAM preview and final render.

The question is, why weren’t they working the first way (is my method wrong)? And why was the RAM preview showing them work as they should?

[Troy Murison]

Ross,

Glad to hear you’re in a better place right now! The ‘looking-correct-on-RAM-preview’ issue threw us for a loop too, I never revisited the problem to investigate further. “Moving on!” ‘ya know…

Thanks for updating us!

-Troy Murison
Seattle, WA