b1b3b1c9d1
The existing exporter uses mediabunny, which delegates to the WebCodecs VideoEncoder and AudioEncoder. On browsers where those APIs are not exposed (the same environments that needed the decode fallback in #794), export currently fails with "AudioEncoder is not supported by this browser" before producing any output. This change adds a parallel fallback path in SceneExporter: - New helpers \`isWebCodecsExportSupported()\` and \`detectMediaRecorderSupport()\` live in a tiny dependency-free module so they can be unit-tested without dragging in WASM. - New \`exportWithMediaRecorder\` drives the existing CanvasRenderer at real-time wall-clock, captures the output canvas with \`HTMLCanvasElement.captureStream(fps)\`, mixes the project audio buffer through a \`MediaStreamAudioDestinationNode\`, and records the combined MediaStream with MediaRecorder, producing a WebM blob the same browser can play back natively. - \`SceneExporter.export()\` detects \`!isWebCodecsExportSupported()\` at entry and delegates to the new path. The WebCodecs path is unchanged for capable browsers. Trade-offs of the fallback path: - Output is always WebM (most browsers don't expose an MP4 muxer via MediaRecorder). The user's requested format is honoured best-effort. - Rendering runs at real time, so a 60-second timeline takes roughly 60 seconds to export. mediabunny's WebCodecs path continues to render faster than real-time on capable browsers. - Bitrate is mapped per quality preset to a numeric value compatible with \`MediaRecorder.videoBitsPerSecond\`. Unit tests cover the feature-detection helpers across the four states of \`VideoEncoder\` / \`AudioEncoder\` / \`MediaRecorder\` availability. |
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README.md
|
OpenCutA free, open-source video editor for web, desktop, and mobile. |
Sponsors
Thanks to Vercel and fal.ai for their support of open-source software.
Why?
- Privacy: Your videos stay on your device
- Free features: Most basic CapCut features are now paywalled
- Simple: People want editors that are easy to use - CapCut proved that
Project Structure
apps/web/: Next.js web applicationapps/desktop/: Native desktop app built with GPUI (in progress)rust/: Platform-agnostic core: GPU compositor, effects, masks, and WASM bindings. We're actively migrating business logic here from TypeScript.docs/: Architecture and subsystem documentation
Getting Started
Prerequisites
- Bun
- Docker and Docker Compose
Note: Docker is optional but recommended for running the local database and Redis. If you only want to work on frontend features, you can skip it.
Setup
-
Fork and clone the repository
-
Copy the environment file:
# Unix/Linux/Mac cp apps/web/.env.example apps/web/.env.local # Windows PowerShell Copy-Item apps/web/.env.example apps/web/.env.local -
Start the database and Redis:
docker compose up -d db redis serverless-redis-http -
Install dependencies and start the dev server:
bun install bun dev:web
The application will be available at http://localhost:3000.
The .env.example has sensible defaults that match the Docker Compose config — it should work out of the box.
Desktop setup
Desktop is opt-in. If you're only working on the web app, skip this entirely.
If you want to get ready for apps/desktop, see apps/desktop/README.md. It's a two-step setup: Rust toolchain first, then desktop native dependencies.
Local WASM development
Only needed if you're editing rust/wasm and want the web app to use your local build instead of the published package.
Prerequisites — install these once before anything else:
# Rust toolchain
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
# build the WASM package
cargo install wasm-pack
# reruns the build on file changes, used by bun dev:wasm
cargo install cargo-watch
-
Build the package once from the repo root:
bun run build:wasm -
Register the generated package for linking:
cd rust/wasm/pkg bun link -
Link
apps/webto the local package:cd apps/web bun link opencut-wasm -
Rebuild on changes while you work:
bun dev:wasm
To switch apps/web back to the published package, run:
cd apps/web
bun add opencut-wasm
Self-Hosting with Docker
To run everything (including a production build of the app) in Docker:
docker compose up -d
The app will be available at http://localhost:3100.
Contributing
We welcome contributions! While we're actively developing and refactoring certain areas, there are plenty of opportunities to contribute effectively.
🎯 Focus areas: Timeline functionality, project management, performance, bug fixes, and UI improvements outside the preview panel.
⚠️ Avoid for now: Preview panel enhancements (fonts, stickers, effects) and export functionality - we're refactoring these with a new binary rendering approach.
See our Contributing Guide for detailed setup instructions, development guidelines, and complete focus area guidance.
Quick start for contributors:
- Fork the repo and clone locally
- Follow the setup instructions in CONTRIBUTING.md
- Working on
apps/desktop? Seeapps/desktop/README.mdfor setup - Create a feature branch and submit a PR