Communigate Pro AE-List@media-motion.tv Message 64143

Jarie does make an interesting point about the monitors themselves using a certain amount of VRAM. I've done some machine learning work that's very VRAM dependent with a lower RAM card on a Mac (GTX 980 in a cheesegrater) and had to unplug one monitor to free up that little bit of extra VRAM to not run out of VRAM.

I also observed something else - the act of unplugging and replugging a monitors DVI cable "clears out" the currently used VRAM. That is to say, imagine you've been working for a while, have a bunch of programs open and have, say, 1 GB free of VRAM. Unplug the monitors DVI cable, plug it back in, and you'll go back to 3 GB free for that moment.

Using an Nvidia card on a Mac, you can check how much RAM is currently used with this command line utility: https://github.com/micahstubbs/cuda-smi/releases/tag/v1.0

I'd be curious if the machines that were able to render Brendan's VR project at full res only had one monitor? Or perhaps they had more recent versions of the Nvidia web driver or CUDA driver - if they have Nvidia cards, that is.

On Fri, Jun 22, 2018 at 7:37 AM, Stephen van Vuuren <AE-List@media-motion.tv> wrote:

> I guess the VRAM requirements for AE are like the ones for Premiere. Quoting from page 559 in The Cool Stuff in Premiere Pro:

Interesting. But I doubt it's true since the VR Tools cannot work at all with GPU acceleration turned off unlike Premiere's implementation. I suspect they are using the engine differently.

And if it were frame buffer by layer, in AE it's easy to have 5 or 10 layers in a very simple project vs. Premiere. 50 or more layers is still common in AE. You would a graphic card of 50GB+ of VRAM (which don't exist). That would be a fatal, dead on arrival design flaw.

-----Original Message-----
From: After Effects Mail List <AE-List@media-motion.tv>
Sent: Friday, June 22, 2018 7:37 AM
To: After Effects Mail List <AE-List@media-motion.tv>
Subject: Re: [AE] VR Tools GPU/CPU VRAM limitations

Stephen van Vuuren wrote:

> I can find no useful information on:
> * Is there a way to force CPU rendering?
> * How much VRAM is required and can you use SLI to split via
multiple
> cards as 8+ GB VRAM cards are very expensive.
> * What frame sizes does the VR tools support? We have 5600 x 4200
and
> 8000 x 8000 - the weird part is simple projects are fine, but bring in
lots of layers, bitmaps and the errors begin.

I guess the VRAM requirements for AE are like the ones for Premiere. Quoting from page 559 in The Cool Stuff in Premiere Pro:

* The approximate amount of GPU memory needed is Width*Height/13107
* An 8K video frame, 8192 × 4320 pixels, requires approximately 2.7 GB.
* Stills from a Canon EOS 5DS, 8688 × 5792 pixels, require approximately
3.84 GB, so you need a GPU with at least 4 GB video RAM.

8k x 8k requires about 4.9 GB per layer.

This is per layer, so if you blend two layers of that size, double the required amount of VRAM to get real-time playback (with GPU-accelerated effects only). When you run out of VRAM, you'll need to render. The rendering will use both the GPU and the CPU, unless you choose Mercury Software Only in Project Settings.

https://premierepro.net/coolstuff/

Brendan Wrote:
> Weirdly, we had other machines with the same graphics card and
> everything
else that couldn't.

If the screen resolutions were different, that could explain why this happened. The GPU is also responsible for pushing pixels to the screen. One of my clients failed to do the math, and bought lots of laptops that they planned to use with two 4k monitors. They had to lower the resolution of those monitors to HD. There wasn't enough VRAM left for AE and Premiere when they used the 4k resolution.

I have not been able to find any documentation about how much VRAM is used to push pixels to the screen at different screen resolutions. Has anyone seen something like that?

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