From the course: How Do I Do That in After Effects

How do I include transparency information in a render? - After Effects Tutorial

From the course: How Do I Do That in After Effects

How do I include transparency information in a render?

- When you render, it's possible to include transparency data in the rendered file. This is particularly useful for things like animated logo or text that you might want to drop into an editing program and be able to lay on top of footage. Knowing how to embed transparency data means really taking control over the codec, the format of the file. Let's have a look. Sometimes as you work in After Effects, you're going to create layers that have data that you want stored with them. For example, you see here, we've done some green screen work where we've knocked out the background. Well, that works quite well, but you might find yourself wanting to generate these and have the flexibility of swapping out the backgrounds during the editing stage. So if this is the case, I can mark out the clip with the work area and then choose to embed the transparency data in the file. Simply add the composition to the render queue. Then take a look at the output module. What you want to do here is choose to include the RGB data, that's the color information, plus the alpha channel which is the transparency information. You'll need to be sure to pick a codec, the compressor or decompressor, that supports this. Animation does, but it's quite large. You're going to have equally good results with much smaller file size, looking at Apple ProRes 444. Or GoPro Cineform. I suggest the ProRes for broadest compatibility. You'll notice that with that codec selected I still have the ability to include the RGB plus the alpha channel, as well as millions of colors or more accurate, trillions of colors, for even better transparency data. When you click OK, it's all queued up. And then just take a look at the output name and where you're going to store the file. Now, when you render, it processes the data and puts the transparency information in the exported file. Remember, this is pretty intense, so you may see that it takes a little bit longer to render all of these frames because we're doing a really high quality key here, and working with high resolution material. But the end result is that the chroma key effect has been processed, and now in most video editing tools, this footage would composite in real time over a background, giving you the flexibility to experiment with different layers during the video edit.

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