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GPU ray trace hundreds of times faster than CPU?

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Olly LawerGPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 3:02:47 pm

Hi,

We're about to invest in a new machine. We were advised to go with the following - this is a custom PC for AE work only. 2.5D, so we rarely if ever use Ray Trace 3D.

Case: "E-Series" E200IBE Midi Case (Supermicro® CSE-732D4F-903B) - 900W PSU (No Hotswap)
Mainboard: Supermicro® X9DAi Mainboard (16x DIMM Slots)
Graphics Card(s): NVIDIA GeForce GTX 780 - 3GB (PCI-E 3.0) - (2304 GPU Cores)
Hard Drive (1): Samsung 840 EVO – 1TB - SATA3 - SSD [540MB/s (Read) / 520MB/s (Write)]
CPU(s): 2x Intel® Xeon® Processor E5-2650v2 (8x 2.60GHz / 20MB) [w/ HT]
Memory: 32GB "Major Branded" DDR-3 1866MHz - ECC Registered (PC3-15000) RAM

However, another technical person suggested that we go the GPU route instead of CPU as this would be much, much faster and less expensive. Our tests on our current machine though show a 2 second vs 3 minute render time from 'classic 3D' to 'ray trace 3D'. So essentially ray trace 3D is 100+ times slower... This was with a shape layer with a slight wiggle for 1 second. The machine we did the test on is: 3.4 GHz Intel Core i7, 20GB RAM (10GB reserved for other applications and no multicore render), AMD 6970M 2048 MB.

Also, when we applied Ray Trace 3D to an existing project at quality 3 - box, it looked absolutely horrific. Not sure if Ray Trace 3D actually alters the layout of comps created as classic 3D?

Here's what he said:

"It’s a real pity that the AE raytracer is effecting layout as adopting the raytracing engine for your renders is really hundreds of times faster on the right hardware versus the CPU renderer. Do you think adoption of the raytracer might be a realistic prospect for new projects going forward?"

May concern is that, If you can’t adopt the raytracer, you’ll have to spend a fortune on processors and you still won’t see the kind of performance that GPU acceleration provides."


So a little perplexed as to what direction to go. I was always told that a graphics card didn't have much affect on AE render time and that you only need Ray Trace 3D for true 3D projects (which we use other software for).

Olly Lawer


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Chris EvansRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 3:16:09 pm

Your last sentence is correct. Ray trace render does use the GPU to render, but if you're doing 3D things, it's better to use Element 3D or an actual 3D software. The AE team won't be improving the ray tracing feature because they have since gone the route of C4D integration for 3d stuff. So, other than Ray Tracing, the only thing a better gpu does is improve the viewer rendering speed(and element 3d if you use it), which is nice, but not worth spending a ton on a GPU for. Just get an awesome CPU and you'll be good.


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Olly LawerRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 3:20:03 pm

Thank you. What do you think of the PC spec in the post?

Olly Lawer


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Walter SoykaRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 3:29:56 pm

If your "technical person" is advising you to switch your renderer from Classic 3D to ray-traced and invest in GPUs solely to speed up rendering, your technical person is giving you bad advice.

This isn't too surprising; the ray-tracing renderer and its hardware acceleration seem to be both pretty misunderstood. The ray-tracing renderer works significantly differently than the classic 3D renderer.

From the docs [link]:
Limitations of the Ray-traced 3D renderer

The following features are not rendered by the Ray-traced 3D renderer:
  • Blending modes
  • Track mattes
  • Layer styles
  • Masks and effects on continuously rasterized layers, including text and shape layers
  • Masks and effects on 3D precomposition layers with collapsed transformations
  • Preserve Underlying Transparency


Ray-tracing is not intended as a drop-in replacement for Classic 3D; it's a totally different renderer with different capabilities, and using it well requires a different creative approach.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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Todd KoprivaRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 3:46:43 pm

Chris and Walter are correct.

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Todd Kopriva, Adobe Systems Incorporated
After Effects quality engineering
After Effects team blog
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Olly LawerRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 3:47:26 pm

Thank you Walter - very helpful as always!

Can you advise on the spec we had listed. Happy to pay the price for a fast machine. We had budgeted up to £7k as we were thinking Mac Pro top end, but custom built PC seems a cheaper option at £4k.

Apparently the graphics card doesn't matter so much as it's more about cores and RAM?

Olly Lawer


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Chris EvansRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 4:07:24 pm

Unless you do some extremely complicated, effects-heavy compositions, you shouldn't need any more RAM than you have listed. Your CPU is great also, the thing to remember is that a second CPU doesn't double your power, I have been told that you actually need 4 CPU's to double the power from one (for normal computing, multiple CPU's are great for servers). So, if you can go with maybe a 12 core or one with a faster clock speed, you might come out ahead for roughly the same cost and you can probably get a cheaper motherboard.


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Olly LawerRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 4:13:37 pm

Thanks Chris. Just want to get my head around this so sorry for all the questions...

With our current machines - one was listed in the first post - they take ages with bigger projects. Not only in viewing the comps real time or scrubbing but end render too. I mean 3-4 hours for a 2 minute animation - nothing overly complicated, but I'm sure motion blur is to blame a lot. They are top end 2011 iMacs with 20GB of RAM.

Tried many settings, including multicore processing and whilst we've had some success spreading things up, not much. Tried keeping a lot of system space free too etc.

So....

Would you say a lower core machine with a higher GHz is better or a higher core machine and lower GHz? Either option will have 64GB RAM.

And does Graphics card matter?

Olly Lawer


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Chris EvansRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 4:48:33 pm

Graphics Cards matter, but not as much as CPU's or RAM. The one you have listed is a great choice. My suggestion is just to find a good one that is the best money for what you get. Don't spend excess just to get one that's absolute top of the line. Get a decent Quadro if you can, but don't worry about it too much.

With your current setup, if you've tried things, then it's gonna be what it's gonna be.

After effects is designed to utilize multiple cores and it uses them if you have the multicore enabled or not. The only thing that does is render multiple frames at the same time as opposed to using multiple cores for one frame at a time. (there are advantages to both). More cores and a higher clock speed are both valuable. However, without a LOT of testing on different CPU's it's impossible to tell how many Ghz you should sacrifice to get more cores or vice versa. Just do pricing research and get the best deal you can.

Sorry I can't give you a better answer. I would decide on a rough budget and find the best deals you can get for that money.


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Walter SoykaRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 4:59:58 pm

[Chris Evans] "Get a decent Quadro if you can, but don't worry about it too much."

Quadros are nice, but they have terrible price to performance ratios. You'll get more bang for the buck from a high-spec GeForce card like Olly has above.

I use Quadros for 10b monitoring. If I didn't have a 10b monitor, I'd use GeForce instead.


[Chris Evans] "After effects is designed to utilize multiple cores and it uses them if you have the multicore enabled or not. The only thing that does is render multiple frames at the same time as opposed to using multiple cores for one frame at a time."

I do not agree. Ae does not exploit system resources well without multiprocessing -- and even with multiprocessing, it doesn't really exploit them efficiently. Nonetheless, renders take significantly longer and CPU utilization on big multi-CPU systems is low without MP.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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Walter SoykaRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 4:49:51 pm

[Olly Lawer] "Would you say a lower core machine with a higher GHz is better or a higher core machine and lower GHz? Either option will have 64GB RAM."

I believe you got some good advice on this topic here a little while ago:

http://forums.creativecow.net/thread/2/1045585#1045587

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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EricBowenRe: GPU ray trace hundreds of times faster than CPU?
by on Feb 18, 2014 at 8:28:04 pm
Last Edited By EricBowen on Feb 18, 2014 at 8:31:13 pm

There are so many variables which equate to considerations with a workflow that decide the threading and performance of CPU's and ram with AE. You have to be careful with the information you gather because workflows are as different as flavors of ice cream and that means the ideal specs for you will be different to some extent.

1. CPU is most important factor for AE and remains so regardless of workflow. However what CPU is best for you is based on codecs of media used, FX used, and complexity of the comps. AE does thread very well by itself. However some codecs do not thread as well. Those will use ideally 8 to 12 threads and sometimes 16 and then GHz decides performance from there. Those codecs are normally Mpeg based such as AVC or Mpeg 2. Then codecs such as Red, DNG, AVCIntra, and most sequence of still based formats thread very well and will use almost what ever threads are available. You can sacrifice some GHz here but don't go below 2.6GHz on any CPU. That is where the performance really suffers for any editing application. If you get a 6 Core you want 3.4GHz or higher and preferable 4GHz or higher. 8 Core can normally provide the performance boost at 3.6GHz or higher. Keep in mind Complexity of that comp ie layers and activity will add to the ideal threading requirement. The more complex the comp the more threads you need for ideal performance with ram preview or export. The codec that you export to can and will limit the threading though so keep that in mind if you see an export not thread well. Some FX don't thread well either so if you see a poor threading export check your FX used.

2. Ram - you really want a minimum of 32 GB of ram for AE on most workstations. However you have to provide enough ram per thread to feed the cores the frame data. That normally equates to 2GB of ram per thread but atleast 1.5GB per thread needs to be available. If you get a Dual Xeon system then you absolutely will require more than 32GB of ram because of the amount of threads you have. otherwise you waste all of the extra processing power 2 Xeons give you. So if you get 2x 8 Core Xeons you need bare minimum 32GB of ram just for AE and not counting Windows or Graphic buffering. So that means you want 64GB of ram. Complexity once again raises this amount. The more complex the comp on average the more data per frame that has to be accounted for. That means you may need to raise that 2 GB per thread to 4GB per thread. Only you know how complex your workflow is. To give you an example, my 1 min AE comp with 64 layers takes 56GB of ram just to export with multiprocessing on. That is all 1080 frames as well with nothing in the 2K or higher range. That also raises the ram amount per frame.

I hope this helps with the overall things to consider with specs. The comments on the GPU's having far less effect in AE are absolute. Also Walter is correct on the Quadro card. Don't get that unless you need 10bit color preview and have a 10bit color workflow with monitoring ability. Use the money spent on that to get faster CPU's. Don't get any CPU under 2.6GHz no matter how many cores it has. Also make sure you get enough ram for the CPU you decide on.

Eric-ADK
Tech Manager
support@adkvideoediting.com


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