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RAM preview fails

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paulos
RAM preview fails
on Dec 9, 2007 at 10:26:50 pm

Hey there

I have a 35 sec comp with a 3D camera orbiting around the scene.

when i try to ram preview the comp it works up until around 20sec and then stops playing back the comp from the first frame.

the other strange behaviour is that in a copy of this comp when i ram preview and the green bar approaches the 20 sec mark, instead of continuing the green bar, the green bar goes forward after the twenty second mark but at the same time starts removing the green bar from earlier in the comp.

feels like some kind of corruption going on here...i have trashed the prefs but still no luck.

any ideas?

Macpro Duel core 3Ghz
4.0G RAM
OS 10.4.10
QT 7.2
FCP 6.0.1
AE CS3
BMD Decklink HD Extreme 6.6
PAL Land


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jkl_editor
Re: RAM preview fails
on Dec 9, 2007 at 11:44:21 pm

Hi Paulos.

Sounds like you've run out of ram to me. After Effects will ram preview as much of the work area as it can. When it runs out it loops back to the beginning and plays out as much as its been able to cache.

The green line issue you have there is the cached ram dropping itself out and being replaced by the new part of the comp that you are previewing on the fly.

I'd recommend droping the ram preview resolution down if you haven't already and maybe try changing your layer quality settings to draft, or setting your 3d settings to draft 3d if its a comp with lights.

Hope this helps,

Cheers,

Ben


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paulos
Re: RAM preview fails
on Dec 10, 2007 at 1:07:44 am

Ben

sounds like you hit it there....i wondered about cache and RAM and surprise surprise it previews fine in lower rez (there are several lights in the comp as well).....my mac has 4gb of RAM, how much RAM can AE CS3 actually use these days? FCP and company can only currently access 4gb.

thanks again




Macpro Duel core 3Ghz
4.0G RAM
OS 10.4.10
QT 7.2
FCP 6.0.1
AE CS3
BMD Decklink HD Extreme 6.6
PAL Land


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Glyn Holmes
Re: RAM preview fails
on Dec 10, 2007 at 1:20:47 am

Are you giving AE access to all your ram? Try bringing the accessible amount of ram up to 95%, and make sure you're not running anything else besides AE.


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Steve Roberts
Re: RAM preview fails
on Dec 10, 2007 at 2:04:07 am

Did you try previewing with the Comp window at half- or quarter-res? Also using the shift-RAM preview options to preview every other frame?


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paulos
Re: RAM preview fails
on Dec 10, 2007 at 4:38:43 am

yeah lower rez seems to working ok.

i assume you assign more ram in the memory and cache settings menu.

it is currently set at 120% = 3.0GB
max ram cache size is 60% = 1.8GB

disk cache is disabled.

do these settings sound right?

Macpro Duel core 3Ghz
4.0G RAM
OS 10.4.10
QT 7.2
FCP 6.0.1
AE CS3
BMD Decklink HD Extreme 6.6
PAL Land


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beenyweenies
Re: RAM preview fails
on Dec 10, 2007 at 6:35:05 pm

Messing with "Max RAM cache size" can have completely unintended consequences, and generally Adobe doesn't recommend tweaking that setting unless you are experiencing problems this setting specifically addresses.

Your best bet is to:

1. Increase your RAM. After Effects CS3 can easily utilize up to 8GB RAM for previews and rendering. Any less and it will use fewer and fewer processor cores, because it needs about 2GB RAM per CPU core to use them. Go into your Preferences>Multiprocessing tab (make sure multiprocessing is turned on) and it will show you how many cores it is currently taking advantage of. With 4GB RAM I bet it's only using 2-3 of them.

2. Add a fast hard drive to your system and dedicate it to the Disc Cache for all of your programs. A very small (50GB or something) 10,000RPM drive is perfect for this task, because the system needs to access it as fast or faster than RAM in order for it to be useful. By adding this drive, enabling disc cache and giving AE about 4GB for Cache, you should be able to greatly extend your previews without having to reduce quality.


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