Adobe 12040118 - After Effects Standard Tutorial page 538

In general, the reasons for After Effects temporarily disabling Render Multiple Frames Simultaneously multiprocessing fall into these categories:
The rendering of a single frame requires more RAM than is available to the individual background processes.
The project uses OpenGL for rendering of previews or final output. The Render Multiple Frames Simultaneously multiprocessing feature
works by using background processes on multiple CPU processor cores to render frames, whereas rendering with OpenGL works by moving
processing to the GPU. (See GPU features in After Effects CS6.)
The composition uses an effect that relies on GPU processing. These effects are generally effects implemented with Pixel Bender.
The composition contains a live Photoshop 3D layer. (See Using 3D object layers from Photoshop.). Note that live Photoshop 3D layers are
not supported in After Effects CS6.
The composition uses an effect with a temporal component that renders much more quickly when the rendering process has access to a
cache of previous frames. These effects include some effects with a Temporal Smoothing option.
The composition uses an effect with a temporal component that requires frames to be rendered in strictly sequential order.
If a composition uses any of the following effects, the composition will not be rendered with the Render Multiple Frames Simultaneously
multiprocessing feature:
Auto Color
Auto Contrast
Auto Levels
Cartoon
Lens Blur
Particle Playground
Shadow/Highlight
Note: Some third-party effects—such as CC Time Blend and RE:Vision Effects Video Gogh—are also incompatible with the Render Multiple
Frames Simultaneously multiprocessing feature.
If you are working in a ray-traced 3D composition in After Effects CS6, the composition will not be rendered with the Render Multiple Frames
Simultaneously multiprocessing feature.
Memory pool shared between After Effects, Premiere Pro, Encore, and Adobe Media Encoder
After Effects shares a memory pool with Adobe Media Encoder, Premiere Pro, and Encore. This is indicated in the Memory & Multiprocessing
preferences panel by the icons for each of these applications at the top of the panel. The icons are dimmed for the applications that are not
running.
A memory balancer prevents swapping of RAM to disk by dynamically managing the memory allocated to each of the applications. Each
application registers with the memory balancer with some basic information: minimum memory requirements, maximum memory able to be used,
current memory in use, and a priority. The priority has three settings: low, normal, and highest. Highest is currently reserved for After Effects and
Premiere Pro, when it is the active application. Normal is for After Effects in the background or Adobe Media Encoder in the foreground. Low is for
background servers of Premiere Pro or Adobe Media Encoder in the background.
Note: An example of a practical result of the shared memory pool is that starting Premiere Pro will decrease the amount of RAM available to After
Effects for RAM previews; quitting Premiere Pro will immediately free RAM for After Effects and extend the possible duration of RAM previews.
Memory & Multiprocessing Details dialog box
The Memory & Multiprocessing Details dialog box contains additional information about installed RAM and current and allowed RAM usage. It also
includes a multicolumn table listing processes related to Adobe Media Encoder, After Effects, Premiere Pro, and Encore. The table includes
information about each process, such as ID, Application Name, Minimum Needed Memory, Maximum Usable Memory, Maximum Allowed Memory,
Current Memory, and Current Priority.
To open the dialog box, choose Edit > Preferences > Memory & Multiprocessing (Windows) or After Effects > Preferences > Memory &
Multiprocessing (Mac OS), and click the Details button at the bottom of the preferences dialog box.
You can copy the information to the clipboard with the Copy button.
Memory (RAM) requirements for rendering
Memory requirements for rendering of a frame (either for previews or for final output) increase with the memory requirement of the most memory-
intensive layer in the composition.
After Effects renders each frame of a composition one layer at a time. For this reason, the memory requirement of each individual layer is more
relevant than the duration of the composition or the number of layers in the composition when determining whether a given frame can be rendered
with the available memory. The memory requirement for a composition is equivalent to the memory requirement for the most memory-intensive
single layer in the composition.