Importing and interpreting footage items

You import source files into a project as the basis for footage items and use them as sources for layers. The same file can be the source for multiple footage items, each with its own interpretation settings. Each footage item can be used as the source for one or more layers. You work with collections of layers in a composition.

You primarily work with footage items in the Project panel. You can use the Footage panel to evaluate footage and perform simple editing tasks, such as trimming the duration of a footage item.

You can import many kinds of files, collections of files, or components of files as sources for individual footage items, including moving image files, still-image files, still-image sequences, and audio files. You can even create footage items yourself within After Effects, such as solids and precompositions. You can import footage items into a project at any time.

When you import files, After Effects does not copy the image data itself into your project but creates a reference link to the source of the footage item, which keeps project files relatively small.

If you delete, rename, or move an imported source file, you break the reference link to that file. When a link is broken, the name of the source file appears in italics in the Project panel, and the File Path column lists it as missing. If the footage item is available, you can reestablish the link—usually just by double-clicking the item and selecting the file again.

To reduce rendering time and increase performance, it is often best to prepare footage before you import it into After Effects. For example, it is often better to scale or crop a still image in Photoshop before you bring it into After Effects rather than scaling and cropping the image in After Effects. It is better to perform an operation once in Photoshop than to force After Effects to perform the same action many times per second—once for each frame in which the image appears.

To save time and minimize the size and complexity of a project, import a source item as a single footage item and then use it multiple times in a composition. It's occasionally useful, however, to duplicate a footage item and interpret each differently. For example, you can use the same footage at two different frame rates.

If you use another application to modify a footage item that is used in a project, the changes appear in After Effects the next time that you open the project or select the footage item and select File > Reload Footage.

To replace the source footage item for a layer with another footage item without affecting changes made to the layer properties, select the layer and then Alt-drag (Windows) or Option-drag (macOS) the new footage item onto the layer in the Timeline panel.

To replace all uses of selected footage items with another footage item, select footage items in the Project panel, and then Alt-drag (Windows) or Option-drag (macOS) the new footage item onto a selected footage item in the Project panel.

When After Effects imports video and audio in some formats, it processes and caches versions of these items that it can readily access when generating previews. This caching dramatically improves preview performance because the video and audio items don't need to be reprocessed for each preview. 

Native encoding and decoding of QuickTime files

After Effects can natively decode and encode QuickTime (.mov) files using the GoPro CineForm codecs on macOS and Windows. This means you don't need to install additional codecs to use and create such files.

In MOV, After Effects has native import support for the following uncompressed formats:

• DV, IMX, MPEG2, XDCAM, h264, JPEG, Avid DNxHD, Avid DNxHR, Apple ProRes, AVCI, and GoPro CineForm

Native export support is available for the following uncompressed formats:

• Avid DNxHD, Avid DNxHR, DV, and GoPro CineForm

Supported import formats

Some filename extensions—such as MOV, AVI, MXF, FLV, and F4V—denote container file formats rather than a specific audio, video, or image data format. Container files can contain data encoded using various compression and encoding schemes. After Effects can import these container files, but the ability to import the data that they contain is dependent on which codecs (specifically, decoders) are installed.

By installing additional codecs, you can extend the ability of After Effects to import additional file types. Many codecs must be installed into the operating system (Windows or macOS) and work as a component inside the QuickTime or Video for Windows formats. Contact the manufacturer of your hardware or software for more information about codecs that work with the files that your specific devices or applications create.

Importing and using some files requires the installation of additional import plug-ins.

Adobe Premiere Pro can capture and import many formats that After Effects can’t import natively. You can bring data from Adobe Premiere Pro into After Effects in many ways. Learn more about working with Adobe Premiere Pro and After Effects.

Import footage items

You can import media files into your project using the Import dialog box or by dragging. The imported footage items appear in the Project panel.

Suppose the Interpret Footage dialog box appears after you import a footage item. In that case, it contains an unlabeled alpha channel, and you must select an alpha channel interpretation method or Guess to let After Effects determine how to interpret it. Learn more about Alpha channel interpretation: premultiplied or straight.

Import footage items using the Import dialog box

Import footage items by dragging

• To import a single file, drag it from Windows Explorer (Windows) or the Finder (macOS) into the Project panel.

• You can also right-click on any folder in your project and then select Import to import files directly to a specific folder in the Project panel. You can also use the keyboard shortcut Cmd + I or Ctrl + I while the folder is selected. (Currently in beta). Learn more about this in After Effects (Beta) Community.

• To import the contents of a folder as a sequence of still images that appear in the Project panel as a single footage item, drag a folder from Windows Explorer (Windows) or the Finder (macOS) into the Project panel.
  
• To import the contents of the folder as individual footage items that appear in the Project panel in a folder, Alt-drag a folder from Windows Explorer (Windows) or Option-drag a folder from the Finder (macOS) into the Project panel.
• To import a rendered output file from the Render Queue panel, drag the corresponding output module from the Render Queue panel into the Project panel.

Interpret footage items

After Effects uses a set of internal rules to interpret each footage item you import according to its best guess for the source file’s pixel aspect ratio, frame rate, color profile, and alpha channel type. If After Effects guesses wrong, or if you want to use the footage differently, you can modify these rules for all footage items of a particular kind by editing the interpretation rules file (interpretation rules.txt), or you can modify the interpretation of a specific footage item using the Interpret Footage dialog box.

The interpretation settings tell After Effects the following about each footage item:

• How to interpret the interaction of the alpha channel with other channels
• What frame rate to assume for the footage item
• Whether to separate fields and, if so, what field order to assume
• Whether to remove 3:2 or 24Pa pulldown
• The pixel aspect ratio of the footage item
• The color profile of the footage item

Generally, you don't need to change interpretation settings. However, if a footage item isn't common, After Effects may need additional information to interpret it correctly.

You can use the controls in the Color Management section of the Interpret Footage dialog box to tell After Effects how to interpret the color information in a footage item. This step is usually only necessary when the footage item does not contain an embedded color profile.

When you preview the footage in the Footage panel, you'll see the results of the footage interpretation operations.

Interpret a single footage item using the Interpret Footage dialog box

Interpret a proxy using the Interpret Footage dialog box

Apply Interpret Footage settings to multiple footage items

You can ensure that different footage items use the same settings by copying interpretation settings from one item and applying them to others.

Edit interpretation rules for all items of a specific kind

The interpretation rules file contains the rules that specify how After Effects interprets footage items. In most cases, you don’t need to customize the interpretation rules file. When you import a footage item, After Effects looks for a match in the interpretation rules file, and then determines interpretation settings for the footage item. You can override these settings after importing, using the Interpret Footage dialog box.

In most cases, the name of the interpretation rules file is interpretation rules.txt; however, some updates to After Effects install a new interpretation rules file with a name that indicates the updated version number, and the updated application uses this new file. If you’ve made changes to the old interpretation rules file, you may need to apply those changes to the new file, too.

Locations of the interpretation rules file in After Effects:

• Windows: <drive>\Users\<username>\AppData\Roaming\Adobe\After Effects/<version>
• macOS: <drive>/Users/<username>/Library/Preferences/Adobe/After Effects/<version>

Locations of the interpretation rules file in previous versions of After Effects:

• Windows: <drive>\Users\<username>\AppData\Roaming\Adobe\After Effects\<version>
• macOS: <drive>/Users/<username>/Library/Preferences/Adobe/After Effects/<version>

Alpha channel interpretation: premultiplied or straight

Image files with alpha channels store transparency information in one of two ways: straight or premultiplied. Although the alpha channels are the same, the color channels differ.

With straight (or unmatted) channels, transparency information is stored only in the alpha channel, not in visible color channels. With straight channels, the results of transparency aren’t visible until the image is displayed in an application that supports straight channels.

With premultiplied (or matted) channels, transparency information is stored in the alpha channel and also in the visible RGB channels, which are multiplied with a background color. Premultiplied channels are sometimes said to be matted with color. The colors of semitransparent areas, such as feathered edges, are shifted toward the background color in proportion to their degree of transparency.

Some software lets you specify the background color with which the channels are premultiplied – otherwise, the background color is usually black or white.

Straight channels retain more accurate color information than premultiplied channels. Premultiplied channels are compatible with a wider range of programs, such as Apple QuickTime Player. Often, the choice of whether to use images with straight or premultiplied channels has been made before you receive the assets to edit and composite. Adobe Premiere Pro and After Effects recognize straight and premultiplied channels, but only the first alpha channel they encounter in a file containing multiple alpha channels.

Setting the alpha channel interpretation correctly can prevent problems when you import a file, such as undesirable colors at the edge of an image or a loss of image quality at the edges of the alpha channel. For example, if channels are interpreted as straight when they are actually premultiplied, semitransparent areas retain some of the background color. If a color inaccuracy, such as a halo, appears along the semitransparent edges in a composition, try changing the interpretation method.

You can use the Remove Color Matting effect to remove the fringes from a layer's semi-transparent areas by unmultiplying it.

Set the alpha channel interpretation for a footage item

Set the default alpha channel preferences

Frame rate

The composition frame rate determines the number of frames displayed per second, and how time is divided into frames in the time ruler and time display. In other words, the composition frame rate specifies how many times per second images are sampled from the source footage items, and it specifies the time divisions at which keyframes can be set.

Composition frame rate is usually determined by the type of output that you are targeting. NTSC video has a frame rate of 29.97 frames per second (fps), PAL video has a frame rate of 25 fps, and motion picture film typically has a frame rate of 24 fps. Depending on the broadcast system, DVD video can have the same frame rate as NTSC video or PAL video, or a frame rate of 23.976. Cartoons and video intended for CD-ROM or the web are often 10–15 fps.

When you render a movie for final output, you can choose to use the composition frame rate or another frame rate. The ability to set the frame rate for each output module is useful when you are using the same composition to create output for multiple media.

Support for high-frame-rate footage

You can set any frame rate field up to a maximum of 999 fps, which lets you use higher frame rates for rendering.

Each motion-footage item in a composition can also have its own frame rate. The relationship between the footage-item frame rate and the composition frame rate determines how smoothly the layer plays. For example, if the footage-item frame rate is 30 fps and the composition frame rate is 30 fps, then whenever the composition advances one frame, the next frame from the footage item is displayed. If the footage-item frame rate is 15 fps and the composition frame rate is 30 fps, then each frame of the footage item appears in two successive frames of the composition. (This assumes, of course, the simple case in which no time stretching or frame blending has been applied to the layer.)

Ideally, use source footage that matches the final output frame rate. This way, After Effects renders each frame, and the final output does not omit, duplicate, or interpolate frames. If, however, the source footage has a frame rate slightly different from what you want to output to (for example, 30-fps footage and 29.97-fps final output), you can make the footage frame rate match the composition frame rate by conforming it.

Conforming the frame rate of a footage item does not alter the original file, only the reference that After Effects uses. When conforming, After Effects changes the internal duration of frames but not the frame content. Afterward, the footage plays back at a different speed. For example, if you conform the frame rate from 15 fps to 30 fps, the footage plays back twice as fast. In most cases, conform the frame rate only when the difference between the footage frame rate and the output frame rate is small.

You can change the frame rate for any movie or sequence of still images. For example, you can import a sequence of ten still images and specify a frame rate for that footage item of 5 frames per second (fps); this sequence would then have a duration of two seconds when used in a composition.

Lower frame rates tend to give the impression of unreality, so many people prefer to work at a lower frame rate such as 24 frames per second for creative work instead of working at the 29.97 frames per second that is standard for NTSC video.

The frame rate of the composition should match the frame rate of the final output format. In most cases, you can simply choose a composition settings preset. In contrast, set the frame rate for each footage item to the frame rate of the original source footage.

Change frame rate for a footage item

Change frame rate for a composition

Pixel aspect ratio and frame aspect ratio

Pixel aspect ratio (PAR) is the ratio of width to height of one pixel in an image. Frame aspect ratio (sometimes called image aspect ratio or IAR) is the ratio of width to height of the image frame.

Most computer monitors use square pixels, but many video formats—including ITU-R 601 (D1) and DV—use non-square rectangular pixels.

Some video formats output the same frame aspect ratio but use a different pixel aspect ratio. For example, some NTSC digitizers produce a 4:3 frame aspect ratio, with square pixels (1.0 pixel aspect ratio), and a frame with pixel dimensions of 640x480. D1 NTSC produces the same 4:3 frame aspect ratio but uses nonsquare pixels (0.91 pixel aspect ratio) and a frame with pixel dimensions of 720x486. D1 pixels, which are always nonsquare, are vertically oriented in systems producing NTSC video and horizontally oriented in systems producing PAL video.

If you display nonsquare pixels on a square-pixel monitor without alteration, images and motion appear distorted; for example, circles distort into ellipses. However, when displayed on a video monitor, the images are correct. When you import D1 NTSC or DV source footage into After Effects, the image looks slightly wider than it does on a D1 or DV system. (D1 PAL footage looks slightly narrower.) The opposite occurs when you import anamorphic footage using D1/DV NTSC Widescreen or D1/DV PAL Widescreen. Widescreen video formats have a frame aspect ratio of 16:9.

If a footage item uses nonsquare pixels, After Effects displays the pixel aspect ratio next to the thumbnail image for the footage item in the Project panel. You can change the pixel aspect ratio interpretation for individual footage items in the Interpret Footage dialog box. By ensuring that all footage items are interpreted correctly, you can combine footage items with different pixel aspect ratios in the same composition.

After Effects reads and writes pixel aspect ratios directly from QuickTime movies. For example, if you import a movie captured as widescreen (16:9 DV), After Effects automatically tags it correctly. Similarly, AVI and PSD files contain information that explicitly indicates the pixel aspect ratio of the images.

If a footage item does not contain information that explicitly indicates the pixel aspect ratio of the image, After Effects uses the pixel dimensions of the footage item frame to make a guess. When you import a footage item with either the D1 pixel dimensions of 720x486 or the DV pixel dimensions of 720x480, After Effects automatically interprets that footage item as D1/DV NTSC. When you import a footage item with the D1 or DV pixel dimensions of 720x576, After Effects automatically interprets that footage item as D1/DV PAL. However, you can make sure that all files are interpreted correctly by looking in the Project panel or the Interpret Footage dialog box.

The pixel aspect ratio setting of the composition should match the pixel aspect ratio of the final output format. In most cases, you can simply choose a composition settings preset. In contrast, set the pixel aspect ratio for each footage item to the pixel aspect ratio of the original source footage.

Upgrade pixel aspect ratios to correct values

After Effects CS3 and earlier used pixel aspect ratios for standard-definition video formats that ignore the concept of clean aperture. By not accounting for the fact that clean aperture differs from production aperture in standard-definition video, the pixel aspect ratios used by After Effects CS3 and earlier were slightly inaccurate. The incorrect pixel aspect ratios cause some images to appear subtly distorted.

The following table provides details about pixel aspect ratio values in After Effects:

This discrepancy is limited to these older, standard-definition formats for which clean aperture differs from production aperture. This discrepancy doesn’t exist in newer formats.

New projects and compositions created in After Effects use the correct pixel aspect ratio values by default.

Projects and compositions created in After Effects CS3 or earlier are upgraded to use the correct pixel aspect ratios when these projects are opened in After Effects CS4 and later.

If you use square-pixel footage items that are designed to fill the frame in a composition with non-square pixels, you may find that the change in pixel aspect ratios causes a difference in behavior. For example, if you previously created 768x576 square-pixel footage items to use in a PAL D1/DV composition, you should now create those items with square-pixel dimensions of 788x576.

Composition settings presets for square-pixel equivalents of standard definition formats have changed as follows:

Change pixel aspect ratio interpretation for a footage item

Change pixel aspect ratio for a composition

Common pixel aspect ratios