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 keyframes 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 minimal despite the project relying on large external footage.

After Effects shows "missing media" when an AEP’s linked assets are moved or excluded during transfer, which is why proper relocation usually involves Collect Files or manually assembling the AEP and every referenced element into one package, and if an AEP doesn’t behave like an AE file, clues like its download source, neighboring files, Windows associations, or a read-only glance in a text editor can confirm whether it’s a real After
Effects project or a different type entirely.
When an AEP appears to fail to load assets on another computer, it’s usually because it works as a blueprint that references outside files rather than storing them internally, meaning After Effects relies on absolute paths to footage, images, audio, and proxies, and once the project moves to a system with different drive letters, folder structures, or missing media, AE can open the project but not the assets, resulting in Missing/Offline Media until everything is relinked.
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AEP file reader check out our own web site. Projects can seem malfunctioning even with all footage available when the new PC doesn’t have the right fonts, causing text to shift unexpectedly, or lacks third-party plugins so effects appear missing, or when an older version of After Effects can’t read newer project elements, and the stable solution is to use Collect Files or duplicate the exact folder structure and then relink, after which matching fonts, plugins, and paths typically restore the project instantly.
An AEP file functions like a lightweight project database for your After Effects project, which is why it can store an entire motion-graphics setup without matching the size of your footage, capturing details about comps—their resolution, frame rate, duration, nesting, and background—along with every timeline layer and its transforms such as position, scale, rotation, opacity, blend modes, mattes, parenting, and timing, plus animation elements including keyframes, easing, motion-blur settings, markers, expressions, and full effect setups, as well as masks or roto shapes with their contours, feather, expansion, and animated points.
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 pointers to those assets, meaning misplaced files trigger missing-media prompts.