🧪 The Experiment

Video editing on the web is one of the final frontiers of browser capabilities. OpenCut is an ambitious project to bring non-linear editing (NLE) to the browser.

I forked this repo not just to use it, but to dissect it. I wanted to understand how complex desktop-class software is ported to the single-threaded web environment.

🔬 Technical Exploration

1. The Rendering Pipeline

I spent significant time tracing how video frames are drawn to the canvas:

• Source: decoding MP4s using VideoDecoder (WebCodecs API).
• Composition: Stacking layers (text, video, shapes) and applying blend modes.
• Output: Encoding the final canvas stream back to a video file.

2. State Management at 60FPS

Handling the state of a timeline (clips, transitions, keyframes) requires extreme performance. React's virtual DOM creates too much overhead for the playback loop, so the engine often bypasses React for direct DOM/Canvas manipulation during playback.

3. Timeline Virtualization

Similar to list virtualization, the timeline only renders the clips currently in the viewport. I experimented with optimizing this logic to handle hour-long projects without crashing the browser memory.

🛠️ My Contributions & Tweaks

• Workflow Improvements: Refined the keybinding system for standard NLE shortcuts (J-K-L navigation).
• Performance Profiling: Identified bottlenecks in the waveform generation process using Chrome DevTools Performance tab.
• Type Safety: Improved TypeScript definitions for the plugin system to make expanding the editor easier for new developers.

🌟 Why Open Source?

Reading high-quality, complex code is the fastest way to level up. This project taught me more about browser constraints and memory management than any tutorial ever could.