Motion and the OoO, Part 2

In Part 1 of our exploration of Motion's Order of Operations, or OoO (which you can find here), we looked at a situation where a drop shadow applied to a layer would rotate with the layer because transformations are calculated after effects. Today, we'll look at another common issue that can arise when working with still images.

The scenario: you add several photos to Motion that you took with a digital camera or purchased from a stock photography site. You then add some filters and find that Motion's performance begins to suffer. You are working in a simple 720x480 DV project and so you wonder, what's going on here?

Let's take a look. Here's a photo in the Canvas after importing and adding a gaussian blur filter cranked up to 64:



There are two issues here. The first is the impact of the filter. Even though the blur amount is cranked up as far as you can go in the HUD (tip: you can go higher in the Inspector), the photo isn't blurred much at all. The second issue is performance: without the blur applied, this project plays back at a full 30fps on my MacBook Pro. With the filter active, it plays back at a measly 2fps.

The preview window of the Inspector gives us a hint as to what is going on:



Note that the dimensions of the photo are 3950 x 1244. This is a large photo (although not so large by digital camera standards), and Motion is automatically resizing it to fit the Canvas. Note the Scale parameter in the Properties tab of the Inspector:



Motion has scaled down the image to 16.41% of its original size to fit in the Canvas.

So if you didn't check the Inspector, you may not realize you are working with an image that may be much larger than you need. You may think it shouldn't matter how big the original photo is because you have scaled it down before adding the blur filter, but here's where the Order of Operations will get you: filters are applied before transformations, so the full size photo is loaded into RAM, blurred, and then scaled down. This is why the blur has such little effect - you are blurring a very large image.

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