Apple Motion Manual do Utilizador descarregar pdf (Página 19)

xviii Getting Started

In the NTSC example, each of the three layers of video takes up 1.3 MB of memory per

frame. In theory, you need only 3.9 MB of VRAM to draw a frame; but in reality, overhead

is created by other processes, and certain filters and effects will use VRAM over and above

that used for the video layers.

After a single frame is drawn, the VRAM is free to load the objects for the next frame. So

the amount of VRAM affects how many layers and effects can be combined at one frame

of the sequence, not the whole sequence. In other words, the number of frames being pre-

viewed is not affected by how much VRAM you have. The VRAM amount affects only the

number of objects that can be composited in a single frame.

Finally, even when you reach your VRAM limits, Motion has a clever RAM-caching feature

that allows you to render a real-time preview and still manipulate individual objects in

real time using a soloing feature.

CPU Speed

You’ve always been told that a faster CPU is better. That’s also true for Motion, but not

in the way you might think. Because the processor in your graphics card is doing all

the heavy lifting, the CPU doesn’t have much to do with the actual construction of the

composite.

The main system CPU comes into play when Motion uses it to calculate behaviors, par-

ticle trajectories, motion paths, and curves before sending them to the graphics card. So if

you use a lot of complex behaviors in your projects, you’ll definitely benefit from a faster

processor.

Summarizing Hardware Requirements

The good news to be gleaned from the preceding technobabble is that if your system

meets the minimum system requirements, improving Motion’s performance doesn’t nec-

essarily mean buying a faster computer. You may only need to upgrade your graphics card.

Here’s the story in a nutshell:

System RAM determines how many frames of animation you can preview in real

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time; and to some degree, how many objects in a composite you can view in real time

before you have to perform a RAM Preview render.

VRAM (video RAM on the graphics card) determines how many objects in a com-

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posite can be rendered in real time before a RAM Preview render is required. If you

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Apple Motion Manual do Utilizador Página 19