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AE CS4 Mac Pro multi processor rendering advice

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Andrew CristAE CS4 Mac Pro multi processor rendering advice
by on Sep 29, 2009 at 12:09:30 am


I have a Mac Pro single quadcore 2.93 with 8 gigs of ram.

I was wondering if anyone had any advice for optimum rendering from AE. I've pretty much realised that there is no direct relation between the amount of cores to render time i.e. using 4 doesn't render 4 times faster. But what reduces the overheads? As Using 3 cores with 2 gigs of RAM each tends to rocket along until about 300 frames in when there's an awful lot of disk activity and it slows to take longer than with 2 corese. (I'm rendering to the second hard drive, not my primary one).

Is it better to render out to an image sequence, or does that increase disk activity and so slow the process down? Is rendering to one lossless quicktime file causing the bottleneck?

Does wiping the image cache every x frames in the secret preferences menu have any effect?

Not important but any advice would be good. Also, I AM using only lossless quicktimes so the old H264 thing isn't the problem. (It does seem slower since Snow Leopard though but I have got 9.02 update).

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Mark HollisRe: AE CS4 Mac Pro multi processor rendering advice
by on Sep 29, 2009 at 4:47:26 pm

Your sudden hard disk usage is probably an "out-of-RAM" indication. But here's the real problem: Adobe.

They don't particularly like Mac and they also don't like Quicktime. They released CS4 with a few evolutionary updates on the Mac side and a 64-bit Photoshop (with the evolutionary updates) on the Windows side. Adobe applications for the Mac are written in the Carbon framework and there is some indication that Carbon (which was supposed to be transitionary between Apple's System 9 and before to OS X)will never actually fully support 64-bit. Apple has told software engineers that they should be transitioning to Cocoa for years now. And Apple's Grand Central Dispatch is designed to work with Cocoa applications.

The reason why you experienced a slight slowdown in Snow Leopard may be due to decreased support for Carbon. Certainly, it's time Adobe engineers came in out of the cold and had a nice cuppa Cocoa. They may yet do that, especially if other companies' applications switch to Cocoa and derive massive benefit from that (I'm thinking Quark XPress here).

After Effects and all Adobe applications under OS X are 32-bit applications. They are limited to 4G of system RAM -- perhaps total. So, in that you have 2G of RAM per processor, you have 2G per thread. But wait: Nehalem processor cores can act like two cores, so you may actually have eight threads running through your system at once.

But if After Effects can only see 4G of RAM because it simply cannot manage more (after all, it cannot take advantage of Grand Central Dispatch), each theoretical thread is looking at .5G max. Or, if it's inefficient and cannot take advantage of the Nehalem engine, it's looking at a theoretical 1G max.

Additionally, the multi-processor engine that Adobe developed (mind you, they did this because they were using Carbon and could not use any help from the OS that Apple was building into the Cocoa framework) is rumored to only allow the application to see four processors max.

So I'll bet the UI is taking out one processor. Three processors are rendering. Nobody can see more than 1G of physical RAM no matter how much you stuff into your system, and you're immediately off into "virtual memory landia."

Hard drive starts spinning.

I suppose we could all whine at Adobe and ask them to make their applications more modern.

But pity me!

I bought a Dual-Quad Core system. And under AE, I may only be able to use 3 cores to render. Poor planning on my part, certainly, if all I plan to use are 32-bit Adobe applications.

My last computer lasted 10 years. It was a single-processor G4-400 with a 1GHz processor upgrade and 1.5G of system RAM. Ran CS3 applications just great until I upgraded from Tiger to Leopard. If Adobe won't get out of their own way here, they'll be overtaken by others' applications. If I worked for them, I'd be learning Cocoa now.

What if there were no hypothetical questions?

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Andrew CristRe: AE CS4 Mac Pro multi processor rendering advice
by on Sep 29, 2009 at 4:58:09 pm

Oof! Such bitterness..

Yeah I did experience the problem of AE seeing the virtual hyper-threading cores as real cores but managed to turn off HT with the Xcode thing or whatever it is.

I must say I'm having more luck rendering to image sequences, as I read somewhere that 3/4 processors all adding sequential frames to a 2 gig quicktime file means ridiculous overheads which would explain some of the disk access.

Trouble is that you then have to reimport that sequence and render out a movie file so there's not much saving on time there.

I guess we are in a transition time between OSes and applications. Fingers crossed CS5 sorts it out. I might try CS4 on my boot camped Windows 7 and see if there's any difference.

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Mark HollisRe: AE CS4 Mac Pro multi processor rendering advice
by on Sep 29, 2009 at 7:36:34 pm

I don't think that the Windows side of things will necessarily change things much (other than that AE will be very happy to export an AVI in Windows.

The only application that really takes advantage of a 64-bit RAM space is Photoshop, which ought to run fairly quickly. I have seen some pretty nice speedups with Photoshop under Vista.

Did I sound bitter? Didn't mean to.

Adobe has their hands full writing as fast as they can to make applications for not just one but two operating systems. And the Mac Fanboys get them pretty bent out of shape as they sound like the denizens of Amiga when that platform was dying "but could do everything."

Adobe has a major installed user base on Apple. And part of this is due to the fact that Microsoft never really, truly figured out prepress. So the prepress houses are pretty happy to curse Adobe.

What I was trying to point out is that Apple warned Adobe that Carbon was going away and that it was only to be used as a transition to Cocoa. And you may recall that Carbon was rolled out in 2000. It's almost ten years on and Adobe has introduced a lot of new stuff since 2000 and they have had plenty of time to become Mac-compliant.

So I'm not bitter. Frankly, were I running Adobe at this point, I'd be scared. They did buy up as much of their competition as they could, but Quark is still out there and there is now Open Source that may wind up challenging them. Where they stand tall is in the strength of their suite of applications and how they work well together.

What if there were no hypothetical questions?

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Andrew CristRe: AE CS4 Mac Pro multi processor rendering advice
by on Sep 29, 2009 at 7:40:31 pm

Nah I was joking about the bitterness. The lack of competition certainly doesn't seem to have done them any favours. Is Shake still around and viable? And where does Combustion stand these days?

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Mark HollisRe: AE CS4 Mac Pro multi processor rendering advice
by on Sep 29, 2009 at 7:59:44 pm

Shake got EOLed by Apple -- I think a couple of versions of FCS ago. Apple wants everyone to learn Motion that doesn't really do composite, though it does do text effects.

Having tried to do compositing in FCP and wanting to kill myself while doing that, I'd rather not attempt anything more than 5 layers deep.

Combustion is still out there but it's a lot more $$ than AE.

System I was on is the Avid DS. The DS does do compositing and is also an editor and finisher. Doesn't have all of the pre-done effects that AE has, though you can build your own tools and it has an expressions engine that kinda works. Cheap, too at $60K. PC only, I'm afraid.

So AE is kind of king of the hill until something better comes along at that price point.

What if there were no hypothetical questions?

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Robert FlemateRe: AE CS4 Mac Pro multi processor rendering advice
by on Oct 7, 2009 at 7:06:49 pm

Better to render image sequence. Does it save time? Only if you own a system that never, ever crashes. render a movie and a crash at the last frame sees an entire re-render. Crash on the last frame of an image sequence will see you only re-render that last frame (if it's really worth it) Crash anywhere along the timeline you pick up where the render left off.

Render an image sequence.

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