Join Richard Harrington for an in-depth discussion in this video Rendering multiple frames simultaneously, part of After Effects Guru: Faster Previews and Rendering.
We mentioned earlier that you can limit the total number of CPU's used by your computer. Maybe you're rendering a couple of applications at once. Not an ideal workflow but perhaps you've got Cinema4D cranking something out while After Effects is also working. Well it's a good idea to be able to control things. Or maybe Premiere Pro is exporting and you just want to reserve some of those CPU's. Remember, it's also not necessary to use every single CPU in your computer. It's possible that if you don't have an abundance of RAM, or you're doing some things that are a bit intensive, your computer can basically go into a starvation mode.
So, many users to choose to set a hard limit, leaving two or four processing cores leftover. On this machine here, I could choose to render multiple frames simultaneously; however, instead of using all eight cores, I'm going to reserve two cores for other uses. Now when I do that it tells me what's happening here. I currently had 10 gigs of RAM. So 10 gigs of RAM means that at this point, it's only actually only using two cores when I tell it to use all three here.
If I drop this number to say two gigabytes of RAM per core, you see that three CPUs are actually used. And, I can go down to a gig and a half, but I don't really like going much lower than that. This means that each core has 1.5 gigabytes of RAM allocated to it. Well, since that third core is not being used anyways, let me just adjust that there. And we'll set that to three. Alright everything looks about right but there's two important options here. When you render multiple frames simultaneously that has to be turned on.
By default it's off. The reason why this is off is that when you invoke it, it takes a little bit longer to thread everything up. Instead of just spinning up one processing task. It's gotta do a lot of background tasks first. And then it starts to push things out. Well, what you need to realize is that that takes a little bit longer when you first click Go, whether that go be the render button or the RAM preview button. So a lot of users were not turning this feature on Fortunately, you have another level of control, you could say only do this for the render queue, not the RAM preview.
And this is usually good because it will start things running quicker. Now for illustrative purposes I'm going to uncheck that just so you can see this in the timeline. All right, when I go to preview this notice it's saying incompatible renderer. Well, that's because this was set to the ray trace 3D renderer. So not only does multi-processing require you to use the older classic 3D renderer, you have several options that you have to double-check. So now that we've got that set, this should work.
I'm in a classic 3D renderer and let's invoke it. And watch what happens. It warns me that this is going to take a while. It had to do the initial background tasks, but now you can see that it's actually rendering faster. In fact, that whole composition previewed much more quickly than we were seeing before. Let's purge that and start over for a second. And you see that it's rendering multiple frames. It says mp. And now it's jumping several frames at a time. Now you see it got through multiple frames simultaneously, very quickly there, because it was using multiple processing.
Now for comparison, let's turn that back off. There we go. And I'll purge that memory and my disk cache, and let's invoke a preview. Now didn't do bad, but it wasn't super fast either. So, it's really subjective. What I generally recommend for most users is under those preferences, turn on Multiple Frames Simultaneously. But leave that off for the render queue. Now if I click okay for a second here and bring back up the task manager.
Let's just clear out all of those frames. We'll purge the memory and the disk cache and let's go at full quality so we really see that work hard. If we look at that you see it spun up pretty well and all of those threads are working pretty efficiently, albeit not totally evenly and that's okay. What's happening here is that each CPU is processing individual frames more quickly and then it's assembling them back together. It still went pretty quick though to pull all of that in at full quality.
On the other hand, if we turn that off. And I purge and start over. It's going through but the usage is not spread out as evenly across all of the frames. You see there that it, is using some more heavily than others. So really up to you, but I would at least recommend that you experiment with the option. Try the memory multi-processing. Tell it to render multiple frame simultaneously. But generally speaking, leave the option checked, to only use it for the render cue and not the RAM preview.
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- Creating render settings templates
- Using multiple output modules
- Setting processor usage
- Rendering multiple frames simultaneously
- Purging RAM
- Controlling your disk and media cache
- Creating and saving previews
- Controlling composition settings