After Effects AutoCaptions

Automatically generate captions from audio/video and create keyframed text layers in After Effects 2026 (Mac & Windows).

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How it works

1. Export – Renders the active comp to audio (MP3/WAV) or video (MP4)
2. Upload – Sends the file to a local backend
3. Transcribe – Backend runs Whisper and returns timestamps + captions
4. Insert – Plugin creates keyframed caption layers in the comp

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Setup

macOS

python3 install.py
python3 backend/server.py

Windows

python install.py
python backend/server.py

Backend runs at http://localhost:8765.

Open the panel in After Effects

Restart AE if it was open, then: Window > Extensions (Legacy) > AutoCaptions

If the installer fails

See README-macOS.md or README-Windows.md for manual installation steps.

Use it

1. Select a composition in the Project panel
2. Confirm backend URL is http://localhost:8765 (or set in Settings)
3. Click Generate Captions

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Settings

Use the gear icon in the panel to configure:

• Export – Output folder, format (MP3/WAV/video), template override
• Caption Style – Font, size, position, justification, word-for-word toggle
• Backend – URL, Whisper model
• Logs – View and copy logs for debugging

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Architecture

┌─────────────────┐     export comp     ┌─────────────┐
│  After Effects  │ ───────────────────►│  Temp WAV/  │
│  (CEP panel)    │                     │  MP4 file   │
└────────┬────────┘                     └──────┬──────┘
         │                                     │
         │ POST { path }                       │
         ▼                                     ▼
┌─────────────────────────────────────────────────────┐
│  Backend (localhost:8765)                           │
│  - Reads file from path                             │
│  - Extracts audio (ffmpeg) if video                 │
│  - Transcribes with OpenAI Whisper                  │
│  - Returns { captions }                             │
└─────────────────────────────────────────────────────┘
         │
         │ POST response
         ▼
┌──────────────────┐
│  Plugin inserts  │
│  caption layers  │
└──────────────────┘

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Troubleshooting

• "Please select a composition" – Click a composition in the Project panel before generating
• "File not found" – Backend must run on the same machine as AE (or use a shared path)
• Panel not showing – Enable CEP debug mode (install script does this) and restart AE
• Export fails – AE may not have a WAV preset; it will fall back to MP4 (backend extracts audio from video)
• ffmpeg not found – Install ffmpeg: brew install ffmpeg (Mac) or download from ffmpeg.org (Windows)

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Project structure

After Effects AutoCaptions/
├── com.autocaptions.panel/   # CEP extension
├── backend/
│   └── server.py             # Transcription API
├── install.py
├── requirements.txt
├── README.md
├── README-macOS.md           # macOS install (incl. manual)
└── README-Windows.md         # Windows install (incl. manual)