🎬 OpenMotion

Free, open-source motion graphics editor — built to run anywhere, starting with the engine.

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✨ What is OpenMotion?

OpenMotion is a cross-platform motion graphics editor in progress, in the spirit of Alight Motion. It is GPL v3 and built around an open, documented project format (.omproj, JSON-based) so your work is never locked inside one app.

Status: Pre-Alpha. Only the engine exists so far. There is no UI yet — the current way to use it is the om-render command-line tool, which turns a .omproj file into an .mp4. Everything below describes what the code in packages/openmotion_core/ does today, and nothing more.

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🎯 Why OpenMotion?

Problem	OpenMotion's answer
Good motion tools are often closed and platform-locked	Open source, and the core engine is plain C++17 + CMake
Closed formats lock your work away	Open, documented .omproj format (JSON)
You can't see how it works	The full source is here, under GPL v3

The software is free. Selling convenience builds — installers, store listings, support — is fine. Hiding how it works is not.

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✅ What works today

The engine (packages/openmotion_core/) currently does:

• Project format — load, validate and save .omproj (JSON, format version 1), with ProjectError reporting instead of exceptions.
• Keyframe evaluation — constant and animated properties with the easing curves linear, ease_in, ease_out, ease_in_out and hold, looked up by binary search.
• Layers — solid, rect, image and video layers are rendered by a software rasterizer; audio layers are mixed into the exported audio.
• Images — decoded through the external ffmpeg/ffprobe executables, with bilinear filtering in premultiplied alpha and a size cap.
• Video — decoded by streaming raw frames from an ffmpeg child process, resampled to the project frame rate; the last frame is held past the clip end.
• Audio — audio layers are delayed, gained and mixed with an ffmpeg filter graph, then encoded as AAC (192 kbit/s).
• Output — an MP4 encoded by ffmpeg (the codec is ffmpeg's default for the mp4 muxer), tagged BT.709.
• om-render CLI — renders a project to an MP4.

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🔲 Not yet

These are not implemented — listed so the roadmap is honest:

• A graphical UI (timeline, preview, inspector).
• Text rendering, and Arabic shaping in particular. text layers are parsed but not drawn.
• Effects (the effects module is an empty placeholder).
• Anti-aliasing — the rasterizer uses hard pixel-centre coverage.
• Rotation-tag (EXIF orientation) support — images are decoded with -noautorotate, so a rotation tag is ignored rather than applied.
• An Alight Motion XML importer (see docs/AM_XML_NOTES.md).
• Audio from video layers — video layers stay muted.
• Real-time preview / playback.

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🛠️ Tech stack

Layer	Technology
Language	C++17
Build	CMake
JSON	nlohmann/json (fetched by CMake)
Tests	Catch2 v3 (fetched by CMake)
Media	External ffmpeg and ffprobe executables
License	GPL v3

There is no Rust, Flutter, wgpu or FFmpeg library linkage. FFmpeg is used only by running the ffmpeg and ffprobe programs as child processes.

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📦 Build and run

Requirements:

• A C++17 compiler and CMake (3.16 or newer).
• ffmpeg and ffprobe on your PATH — needed to load images/video and to export. Builds and the offline tests work without them; tests that need them are skipped.
• Network access on the first configure, to fetch nlohmann/json and Catch2.

cd packages/openmotion_core

# Configure (Debug enables AddressSanitizer + UndefinedBehaviorSanitizer)
cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug

# Build the engine, the om-render CLI and the tests
cmake --build build

# Run the tests
ctest --test-dir build

Render the bundled example:

./build/om-render examples/hello.omproj hello.mp4

om-render takes exactly two arguments, <input.omproj> <output.mp4>, and resolves relative source paths against the directory of the input file.

See docs/ARCHITECTURE.md for the module map and docs/OMPROJ_FORMAT.md for the project format.

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🤝 Contributing

OpenMotion is community-driven from day one.

git clone https://github.com/YOUR_USERNAME/OpenMotion
cd OpenMotion/packages/openmotion_core
cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug
cmake --build build
ctest --test-dir build

The Debug build is sanitizer-clean by design (-fsanitize=address,undefined), and the code is compiled with -Wall -Wextra -Wpedantic -Werror, so a warning fails the build. Please keep it that way.

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📄 License

OpenMotion is licensed under the GNU General Public License v3.0.

You are free to use, study, modify, and distribute this software. If you distribute a modified version, you must keep it under GPL v3.

See LICENSE for the full terms.

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💙 Support the project

The software is free. The developer still needs coffee. ☕

• ⭐ Star this repo
• 🐛 Report bugs and request features via Issues
• 📢 Share OpenMotion with your Linux and FOSS communities

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🗺️ Long-term ideas (not started)

Nothing here is implemented or scheduled. It is a direction, not a promise.

Possible distribution channels (all still just ideas):

Platform	Price idea	Notes
GitHub Releases	Free	Executable + source — always
Flathub	Pay what you want	Linux first-class citizen
F-Droid	Free	FOSS Android store
Microsoft Store	Convenience pricing	Paid convenience build
Steam	Convenience pricing	Auto-updates
Google Play	Convenience pricing	Android mainstream
Itch.io	Pay what you want	Indie community

The source code is always free. You would pay for convenience — never for the software itself.

Rough milestone sketch (no dates, nothing started):

• M1 — Engine skeleton. Software renderer, project format, keyframe evaluation, om-render CLI. (Largely what exists today.)
• M2 — Editing. Timeline, trim/split/move, basic text overlay.
• M3 — Motion graphics core. Easing-curve editor, layer blending modes.
• M4 — Effects and presets. Built-in effects library, JSON presets, an Alight Motion XML preset importer.
• M5 — Community launch. Packaging for desktop platforms, documentation.

Built by the community, for the community.