13.3 How to Export Video From After Effects Using PreRendering

[MUSIC] In this lesson, we're going to continue talking about exporting and explore the idea of pre rendering and see exactly how that can help your workflow. [MUSIC] All right, the final thing that I want to talk about is pre rendering. Now sometimes you'll have a project, that involves a lot of kind of processor intensive things. You can see the scaling on this video, as I scrub it, it's kind of weird. So I'm gonna turn off adaptive resolution, because that drives me nuts. So this particular project uses a lot of kind of, well higher end effects. You can see this looks pretty cool, but I'm using trapcode particular and I have several instances of trapcode particular running like many tens of thousands of sparks in smoke elements. I'm using video co pilots Sabre to do some cool kind of fire on the back of this thing. I'm using video co pilots Element 3D to kind of generate this 3D logo thing here and I'm using After Effects lighting and the virtual camera and a motion blur there's a lot going on in this comp. And this can be really problematic when you are trying to render because right now this is previewing using a pre render. And watch what happens when I take the pre rendered layer off, which is this smoke because I've identified that the smoke layer here is the layer that is causing the most problems in the playback and also in the render. But watch in real time here as After Effects on this pretty fast machine tries to render the smoke particles, you can see for each frame it's taking a couple of seconds. And the reason is this effect here particular, you can see right here there are eight thousand particles visible, and every one of those particles is actually a pre comp called smoke loop 04. In that pre comp there are two video elements. And so when there are eight thousand particles being displayed or however many there are, it's actually double that in terms of the number of video assets that's being displayed. And it's taking a couple of seconds per frame to render but keep in mind that this is only at half resolution. If I kick this up to full resolution, and I were to, you know, look at this at 100% or something, it will take over a minute and I think over two minutes to render one frame just in this preview here. Now if you're trying to kind of work on this or even render it, what you'll find is It'll render nice and fine right up to here and then as soon as it starts generating these particles it's like everything breaks and you'll think that there's something wrong with your computer because it'll be taking several minutes per frame to render this. So there's an intermediate solution here and that is to pre render the smoke particles which is what I did. And you can see, in real time, it's still not rendered the smoke particles yet, it's still taking forever. I'm not gonna make you sit here and wait, but you can take my word for it. It takes a long time. So to pre render just the smoke, what I did is I soloed the smoke and I'll put it back down to half resolution here so that it actually stands a chance of being displayed. And then I came up here to composition and went down to pre render that will add it to the render queue. You can see I've already added one here, but I'll just delete that. And it'll choose some kind of codec, by default on my system, it chooses an AVI container file. I don't even know what the actual codec is inside here. But if we jump in here, usually what I would do is change this from AVI to something like QuickTime and then I would pick the CineForm codec, although you could also use Apple ProRes four, four, four, four? Four, fours? That would also work as well. I believe that the codec that it uses to pre render is lossless. So depending on how long your clip is, that could take up a lot of space. But doing your pre render with a codec that is quote unquote lossy is also okay. That's totally fine to do too, I would probably shut off the audio. So turn the audio output off so it didn't encode audio even though there's no audio in here, it would still take up a tiny bit of space. I click okay and then I hit the render button. Now, I've already done this previously, and then I've re imported that footage. And then I'll just delete the smoke out of here to get the pre render back in here. I just drop it into the comp and then line it up, and then disable my smoke layer here with the effect on it. And now things are back to running the way they should here where I'm actually getting some playback. It's not real time, it's not even close, but it's, it can cache this little clip here in a reasonable amount of time where before it would have been a nightmare to see what is going on. This is especially true when it comes to rendering. What you'll find is when you're rendering this for client preview or whatever, you'll render it, it'll go fast right up until here and then it'll choke until the smoke particles are gone. And then it'll go fast again. The problem is this is not the final render. And you're gonna have to go back in and make more changes. That can become really problematic because it can take forever to render just that one element. So when you encounter kind of renders that are slowing down, if you kinda keep an eye on things that are not going very fast, you may identify some layers that are taking a really long time. And so the solution is to pre render this, put it in the comp, make sure you leave the other layer in case you need to go back and make changes because if I did something where I needed to change the speed of this element going across the screen that pre render wouldn't work anymore. However, if I wanted to make changes to the lighting or the sparks or basically anything else other than the movement, that pre-render would still be totally fine. I could change the texturing and the lighting on this 3D element here. And that pre-render would work for all of those. It's not something that you have to use all of the time. But when you come across a couple of layers that are really slowing your project down, take a look at pre rendering, because it can be a real lifesaver. [MUSIC] So that about wraps it up for this lesson. Make sure to check out the next lesson on masks and cropping. [MUSIC]