You can preview all or part of your composition as you work, without rendering to final output. Though it is common to speak of rendering as if this term only applies to final output, the processes of creating previews to show in the Footage, Layer, and Composition panels are also kinds of rendering.
Many of the controls for previewing are in the Preview panel.
Note:
For additional keyboard shortcuts for Previews for use on a keyboard without numeric keypads in After Effect CS5.5, and earlier, see Previews (keyboard shortcuts).
RAM preview allocates RAM to play video and audio in the Timeline, Layer, or Footage panel at real-time speed. The number of frames that can be stored for real-time playback depends on the amount of RAM available to the application and the settings in the Preview panel.
In the Preview panel, you can specify two sets of RAM preview options: RAM Preview Options and Shift+RAM Preview Options. For example, you may decide to set RAM Preview Options for full frame rate and full resolution, and set Shift+RAM Preview Options to skip one out of every two frames and preview at half resolution.
In the Layer and Footage panels, RAM previews play untrimmed footage.
Skip
The number of frames to skip between a rendered frame and the next rendered frame. Choose 0 to render all frames.
Resolution
Choose Auto to use the resolution set in the Resolution/Down Sample Factor menu at the bottom of the viewer panel.
Note:
The performance of RAM previews performed with the Render Multiple Frames Simultaneously preference selected may be decreased if antivirus software is running.
Press the asterisk key (*) on the numeric keypad during a RAM preview to place a marker at the currently previewed frame. This is a convenient way to place markers corresponding to important points in an audio track. (See Layer markers and composition markers.)
Press Alt (Windows) or Option (Mac OS) while initiating a RAM preview to preview the specified number of frames up to and including the current frame. The default number of frames previewed with this command is 5. The preference for changing this number is in the Alternate RAM Preview section of the Preview preferences. (See Previews preferences (CS5.5, and earlier) or Previews preferences (CS6).)
Note:
If the current frame is within a backward-propagating Roto Brush span and the Layer panel View menu is set to Roto Brush, then this command in the Layer panel previews the frames including and after the current frame. (See Roto Brush strokes, spans, and base frames.)
After Effects can save RAM previews as uncompressed AVI files (Windows) or MOV files (Mac OS). When saving a RAM preview, keep in mind the following:
After Effects uses the composition frame size and the Resolution setting in the default render settings template to determine the final dimensions in pixels of a saved RAM preview. If the Resolution setting in the render settings template is Current Settings, then the Resolution setting in the Preview panel is used. If the Resolution setting in the Preview panel is Auto, then the Resolution setting in the Composition Settings dialog box is used. The saved RAM preview doesn’t consider the zoom level.
RAM preview doesn’t generate interlaced fields, so a saved RAM preview never contains fields.
Note:
The 3D View of the active composition panel must be set to Active Camera for Save RAM Preview to work, even if the composition doesn’t contain 3D layers.
When you preview only audio, it plays immediately at real-time speed, unless you’ve applied Audio effects other than Stereo Mixer, in which case you may have to wait for audio to render before it plays.
Note:
If audio must be rendered for a preview, then only the amount of audio specified by the Duration setting in the Previews preferences is rendered and played for the preview. The default is 30 seconds.
Set the sample rate for audio for the entire project in the Project Settings dialog box (File > Project Settings). CD-quality sound is 44.1 KHz, 16-bit stereo.
The Audio Hardware and Audio Output Mapping preferences determine the behavior of audio previews. These preferences do not affect final output. The output module settings determine the quality of audio in final output. For best-quality audio previews, choose an ASIO device if one is available in the Default Device menu in the Audio Hardware preferences. Otherwise, choose one of the devices for your system, such as the After Effects WDM Sound device (Windows) or one of the Built-in devices (Mac OS).
Standard preview (commonly called spacebar play) plays video in the active Composition, Layer, or Footage panel from the current time. Standard preview does not play audio.
Standard previews play at a speed as close to the speed of real time as possible. However, for complex compositions, the speed of the preview may be much less than real-time speed.
If you stop moving the current-time indicator while keeping the mouse button depressed, a short section of audio loops.
To manually preview (scrub) only the frames that are already rendered and cached into the RAM cache, press the Caps Lock key before dragging the current-time indicator. This prevents After Effects from trying to render other frames when you drag over or past them. This technique is useful when you want to manually preview some frames that you rendered using RAM preview settings that used an option to skip every other frame.
During previews, the Audio panel volume unit (VU) meter actively displays audio volume levels. At the top of the VU meter, signals indicate when the audio is clipping—a distortion that occurs when the audio signal exceeds the maximum level that the audio device allows.
To view the VU meter and levels controls in more detail, increase the height of the Audio panel.
Units
Choose whether to display audio levels in decibels or in percentages. 100% equals 0 decibels (0 dB).
With all previewing methods—as with rendering to final output—a layer is only visible in rendered previews if its Video layer switch 
is selected.
Some factors that influence the speed with which previews are rendered include layer switches, Fast Previews settings, preference settings, and composition settings.
One of the simplest and most influential of the preview settings controls is the Resolution/Down Sample Factor setting menu at the bottom of the Composition panel. Choose a value other than Full from this menu to see all previews at a lower resolution. (See Resolution.)
To turn pixel-aspect ratio correction on or off
for previews, click the Toggle Pixel Aspect Ratio Correction button 
at
the bottom of the panel. The quality of the pixel aspect ratio correction
is determined by the Zoom Quality preference. (See Viewer Quality
preferences.)
When possible, preview on the same kind of device that your audience will use to view your final output. For example, you can preview on an external video monitor. To see your composition as it will appear on a mobile device—such as a mobile phone—first render your composition to final output, and then use Adobe Device Central to view the movie.
If you create compositions for mobile devices using Device Central, you can preview the compositions within After Effects with guides and settings that simulate some aspects of the target mobile devices. (See Create compositions for playback on mobile devices.)
If color management is enabled, you can preview a composition, layer, or footage item as it will appear in the output color space. (See Simulate how colors will appear on a different output device.)
Note:
Select Show Rendering Progress In Info Panel And Flowchart (Edit > Preferences > Display (Windows) or After Effects > Preferences > Display (Mac OS)) to see additional information in the Info panel or the project Flowchart panel during rendering, either for previews or for final output.
The most basic way of previewing frames is to manually preview by moving or dragging the current-time indicator (CTI).
The time ruler visually represents the time dimension of a composition, a layer, or a footage item. In a Layer or Footage panel, the time ruler appears near the bottom of the panel. For a Composition panel, the time ruler appears in the corresponding Timeline panel. The time rulers in different panels represent different durations. The time ruler in a Layer or Footage panel represents the duration of the contents of that panel; the time ruler in the Timeline panel represents the duration of the entire composition.
On a time ruler, the current-time indicator indicates the frame you are viewing or modifying.
To go forward or backward one frame, click the Next Frame
or
Previous Frame 
button
in the Preview panel, or press Page Down or Page Up.
To go forward or backward ten frames, Shift-click the Next Frame or Previous Frame button, or press Shift+Page Down or Shift+Page Up.
To go forward a specific period of time or number of frames, click the current-time display, and then enter the plus sign (+) followed by the timecode or number of frames to advance. For example, enter +20 to go forward 20 frames or 1:00 to go forward one second. Precede the value by the minus sign (-) to go backward. For example, enter +-20 to go backward 20 frames or +-1:00 to go backward one second.
To go to the first or last frame, click the First Frame 
or
Last Frame 
button in
the Preview panel, or press Home or End.
To go to the first or last frame of the work area, press Shift+Home or Shift+End.
To go to a specific frame, click in the time ruler; click the current-time display in the Footage, Layer, Composition, or Timeline panel; or press Alt+Shift+J (Windows) or Option+Shift+J (Mac OS). You can also drag the current-time display in the Timeline panel to modify the value.
Shift-drag the current-time indicator to snap to keyframes, markers, In and Out points, the beginning or end of the composition, or the beginning or end of the work area.
Jeff Almasol provides a script that creates a panel with controls for moving the current-time indicator to different times in the composition. The panel provides buttons for jumping a specific number of frames forward or back from the current time, as well as buttons for capturing different times and jumping to them easily. For more information, go to Jeff Almasol’s redefinery website.
You can scroll and zoom in time in the Timeline, Footage, and Layer panels. See Scroll or zoom with the mouse wheel.
or the Zoom Out button 
, or drag the zoom slider between the buttons.
Note:
When you click the Time Navigator in the Timeline panel, the Info panel shows the times of the beginning and end of the Time Navigator duration.
For additional ways to zoom and scroll in time using the mouse scroll wheel, see Scroll or zoom with the mouse wheel.
When zoomed in time, press D to center the time graph on the current time.
Designating a viewer as the default panel to preview is especially useful when you have a Composition viewer that represents your final output and you always want to preview that viewer, even when you’re changing settings in other panels.
The panel that’s set to always preview appears frontmost for the duration of the preview.
Note:
When multiple views are open, previews use the frontmost composition view for 2D compositions and the Active Camera view for 3D compositions. To turn off the Active Camera, deselect Previews Favor Active Camera in the Preview panel menu.
After Effects provides several options for previewing that make various tradeoffs between speed and fidelity.
Each preview mode provides a different balance between quality and speed for playback and for updating of images during interactions, such as when you drag a layer in the Composition panel or modifying a property value in the Timeline panel.
Draft 3D and Live Update modes apply to all views of a composition.
Draft 3D
Disables lights, shadows, and depth-of-field blur for cameras.
To turn Draft 3D mode on or off, click the Draft 3D button 
at the
top of the Timeline panel.
Live Update
Updates images in the Composition or Layer panel during interactions. When Live Update is deselected, After Effects displays wireframe representations during interactions. To turn Live Update mode on or off, click the Live Update button 
, at the top of the Timeline panel.
To temporarily toggle Live Update mode, hold Alt (Windows) or Option (Mac OS) while dragging to move a layer, modify a property value, or move the current-time indicator.
You can use a different Fast Previews mode for each view in the Composition panel. For example, in a 4 Views layout, you could use OpenGL for the Active Camera view and Wireframe for Left, Right, and Top views. Click the Fast Previews button 
, at the bottom of the Composition panel to set Fast Previews preferences or choose from the following Fast Previews modes:
OpenGL—Interactive or OpenGL—Always On
OpenGL mode provides high-quality previews that require less rendering time than other playback modes. OpenGL can also be used to speed up rendering to final output. OpenGL features in After Effects rely on OpenGL features of your video hardware. When OpenGL does not support a feature, it simply creates a preview without using that feature. For example, if your layers contain shadows and your OpenGL hardware does not support shadows, the preview will not contain shadows. Select OpenGL-Interactive to use OpenGL only for interactions, such as manually previewing (scrubbing) in the Timeline panel or dragging a layer in the Composition panel. You can tell that OpenGL is engaging by looking at the Fast Previews icon, which lights up. Select OpenGL-Always On to use OpenGL for all previews. In this mode, “OpenGL” appears in the upper-left corner of each view in the Composition panel.
Note:
The Enable OpenGL option in the Fast Previews area of the Preview preferences category must be selected for you to use OpenGL for previews. If you also select Enable Adaptive Resolution With OpenGL, then the preview resolution of layers rendered with OpenGL is decreased when necessary to maintain speed of updating of images during interactions.
To prevent After Effects from updating images in the Footage, Layer, and Composition panels, press Caps Lock. When you make a change that would otherwise appear in a panel, After Effects adds a red bar at the bottom of the panel with a text reminder that image refresh is disabled. After Effects continues to update panel controls such as motion paths, anchor points, and mask outlines as you move them. To resume panel updates and display all changes, press Caps Lock again. Pressing Caps Lock is a good way to prevent views from being refreshed for each frame during rendering for final output.
Note:
When you are using OpenGL to render previews and are previewing on a video monitor, the preview shown on the video monitor doesn’t update as you interact with elements of your composition until you have released the mouse at the end of an interaction. (See Preview on an external video monitor.)
The Fast Previews button works the same way as in previous versions of After Effects, however, the options have been reordered, and the names of the options are new. The menu lists options ranging from higher quality but slower performance (Off), to lower quality but higher performance (Wireframe).
Adaptive Resolution
Attempts to downsample footage while dragging a layer or scrubbing a property value. For the ray-traced 3D compositions, Adaptive Resolution will reduce the ray-tracing quality based on the current adaptive resolution:
You can change the adaptive resolution limit in Edit > Preferences > Previews (Windows) or Premiere Pro > Preferences > Previews (Mac OS).
Fast Draft
When laying out a complex scene, or if you are working in a ray-traced 3D composition, you can use Fast Draft mode for previewing. In ray-traced 3D compositions, Fast draft mode supports for beveled, extruded, and curved 3D layers. When previewing, the scene is downsampled to speed up the loading of textures to the GPU. In Fast Draft mode, each frame of video is still read in to the renderer as needed. The downsample factor is set at 1/4 resolution, and effects and track mattes are on.
Changing the Fast Previews mode to match your workflow is important, especially when working with ray-traced 3D compositions.
| Quality name |
Shortcut |
| Off (Final Quality) | Ctrl+Alt+1 (Windows) / Cmd+Option+1 (Mac OS) |
| Adaptive Resolution | Ctrl+Alt+2 (Windows) / Cmd+Option+2 (Mac OS) |
| Draft | Ctrl+Alt+3 (Windows) / Cmd+Option+3 (Mac OS) |
| Fast Draft | Ctrl+Alt+4 (Windows) / Cmd+Option+4 (Mac OS) |
| Wireframe | Ctrl+Alt+5 (Windows) / Cmd+Option+5 (Mac OS) |
In this video tutorial by Todd Kopriva and video2brain, learn how to use the Fast Previews menu. Look at a complex scene and see how different settings affect your ability to manipulate elements.
In the Previews preferences category, you can choose the quality and speed of color management and zoom operations used in previews. From the Zoom Quality or Color Management Quality menu, choose Faster, More Accurate, or More Accurate Except For RAM Previews.
The More Accurate Except For RAM Previews option uses the more accurate operations for manual previews and standard previews, but uses the faster operations for RAM previews. (See Preview video and audio.)
The Zoom Quality preference affects the quality of scaling performed for pixel aspect ratio correction in the Composition and Layer panels. (See Pixel aspect ratio and frame aspect ratio.)
Note:
When the Show Channel menu is set to an option that shows straight colors ( RGB Straight, Alpha Overlay, or Alpha Boundary), the Viewer Quality preference is ignored, and the preview is created as if the Viewer Quality settings were Faster.
The region of interest (ROI) is the area of the composition, layer, or footage item that is rendered for previews. Create a smaller region of interest to use less processing power and memory when previewing, thereby improving interaction speed and increasing RAM preview duration.
By default, changing the region of interest does not affect file output. You can change the size of your composition and select what portion is rendered by cropping to the region of interest.
Note:
When the region of interest is selected, the Info panel displays the horizontal and vertical distances of the top (T), left (L), bottom (B), and right (R) edges of the region from the top-left corner of the composition.
at the bottom of the Composition, Layer, or Footage panel, and then drag to select a viewable area of the panel.To start over with the marquee tool, hold down Alt (Windows) or Option (Mac OS) and click the Region Of Interest button.
To create the equivalent of a region of interest for a single layer, you can draw a temporary mask around the part of the layer that you are working with. The area outside of the mask will not be rendered. This can make working with a small portion of a large layer much faster. Be careful, though, since not rendering the pixels outside of the mask can change the composition’s appearance significantly. (See Creating masks.)
The work area is the part of the duration of a composition that is rendered for previews or final output. In the Timeline panel, the work area appears in a lighter shade of gray.
To expand the work area to the size of the composition, double-click the center of the work area bar.
When you want to compare one view to another in a Composition, Layer, or Footage panel, take a snapshot. For example, you may want to compare two frames at different times in a movie.
Snapshots taken in one kind of panel can be displayed in another kind. For example, you can take a snapshot of a Layer panel and display the snapshot in a Composition or Footage panel. Displaying a snapshot does not replace the content of the panel. If the snapshot has a different size or aspect ratio than the panel in which you display it, the snapshot is resized to fit the current view.
Snapshots are for reference only and do not become part of the layer, composition, or rendered movie.
A sound is generated when you take a snapshot.
at
the bottom of the panel or press Shift+F5, Shift+F6, Shift+F7, or
Shift+F8. 
at
the bottom of the panel. You can preview the contents of your Layer, Footage, or Composition panel on an external video monitor. Previewing on a video monitor requires additional hardware, such as a video capture card or a FireWire port. If you’re using a video card to connect an external video monitor, follow the directions that came with your video card to connect the monitor for viewing previews. If you’re using a FireWire port, first connect a digital camcorder or similar device to the port; then connect the video monitor to the device. For more information on setting up FireWire previews, see the documentation that came with your digital camcorder, VCR, or other device.
Mirror On Computer Monitor
Displays RAM previews or standard previews simultaneously on the external monitor and on the computer screen. Using this option may slow down the previews.
After choosing an output device in the Video Preview preferences, you can preview the current frame on the output device by pressing the forward slash (/) key on the numeric keypad. Press Ctrl+/ (Windows) or Command+/ (Mac OS) to toggle the preference to Desktop Only or to the output device you specified.
Whether or not color management is enabled for the project, After Effects does not manage the color of previews on an external video monitor. The colors sent to the external video monitor are in the working color space for the project. You can manually enable color management for video previews by nesting your composition and using the Color Profile Converter effect to convert from the working color space for the project to the color space of the video preview device. For more information, see Choose a working color space and enable color management.
Note:
When you are using OpenGL to render previews, the preview shown on the video monitor doesn’t update as you interact with elements of your composition until you have released the mouse at the end of an interaction. (See Preview modes.)
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Include audio in or exclude audio from RAM preview.
in the
Preview panel or press 0 (zero) on the numeric keypad.
Repeatedly plays preview from beginning to end.
Plays preview once.
Repeatedly plays preview, alternating between backward and forward play.
in
the Preview panel, or press the spacebar.
in
the lower-left corner of the panel.
