An AEP file is commonly the project format for After Effects, acting as a blueprint instead of a playable video by storing compositions, various layer types, animation elements such as motion cues and expressions, effect settings, masks, mattes, plus 3D items like cameras and lights, and it generally holds only links to your source media so the file remains small despite the project relying on large external footage.

Since the AEP relies on external links, After Effects may report "footage not found" whenever source files get moved, renamed, or omitted during a transfer, which is why the Collect Files feature (or manually assembling the AEP and all used media) is the normal way to send a project reliably, and if an AEP refuses to open in After Effects, hints like its source, companion files, Windows associations, or a quick read-only text-editor view can indicate whether it’s truly an AE project or an unrelated format.

When an AEP looks broken on another machine, it’s typically because it’s meant to point to external assets rather than include them, and After Effects stores absolute paths to footage, images, audio, and proxies, so if you move the project to a system with different directory names, drive mappings, or missing files, AE will open the project but show Missing/Offline Media until you relink the content.

Projects may look "broken" even when footage is present if the new computer lacks the proper fonts—causing text to shift—or is missing third-party plugins, which makes certain effects show as unavailable, or if you open the file in an older After Effects version that can’t interpret newer features, and the dependable fix is to move the AEP using Collect Files or copy the full project structure exactly, then relink footage so that once fonts, plugins, and paths match, the project usually fixes itself immediately.

If you enjoyed this write-up and you would certainly like to receive even more details concerning AEP file format kindly see our own website. An AEP file is essentially a small structural database that captures your entire After Effects project without containing the heavy media, storing comp properties like resolution, frame rate, duration, nesting, and background color, every timeline layer and its transforms such as position, scale, rotation, opacity, blending, mattes, parenting, timing, plus all animation instructions like keyframes, easing curves, motion blur, markers, and expressions, along with complete effect configurations and any mask or roto data including shape outlines, feather, expansion, and animated vertices.

When 3D features are active, an AEP contains camera setups, light configurations, 3D layer parameters, and render options, as well as organizational metadata like bins, label colors, interpretation rules, and sometimes proxy info, but it typically excludes the footage—MP4s, MOVs, images, and WAVs are stored separately—so the AEP serves as the design map and the addresses to those assets, meaning misplaced files trigger missing-media prompts.