@sequio/engine

A command-style object-graph engine for building video editors on top of PixiJS v8.

You construct a tree of Track / Clip / Effect objects and drive a clock; the engine owns the low-level runtime — decode, composite, audio, export. Persistence, schema, undo, collaboration and UI are intentionally out of scope; they belong to the layer above.

Invariant: render(t) is a pure function of the object graph + t — the same tree and the same t always produce the same frame. That is what makes export reproducible and golden-frame testing possible.

Install

npm install @sequio/engine pixi.js

pixi.js is a peer dependency (bring your own single copy). mediabunny (WebCodecs mux/demux) ships as a runtime dependency.

Quick start

import { Compositor, VisualTrack, TextClip, RealtimeClock } from '@sequio/engine';

const compositor = new Compositor({ width: 1920, height: 1080 });
const track = new VisualTrack();
track.add(new TextClip({ text: 'Hello, sequio', start: 0, duration: 3 }));
compositor.addTrack(track);

// Preview: best-effort prepare + immediate sync render (may drop frames).
await compositor.renderPreview(0.5);

See the architecture guide and the example/ demos for the full surface (video/image/audio sources, effects, transitions, text animation, and the Exporter).

The five contracts

1. Async prepare / sync render split — preview does best-effort prepare(t) then renderSync(t); export awaits prepare(t) and never drops a frame.
2. render(t) is pure in (object graph, t) — no hidden frame-to-frame or wall-clock state.
3. Preview and export share one render core — same resolution and color pipeline (sRGB↔linear, premultiplied alpha).
4. Explicit resource ownership — VideoFrame / Texture / RenderTexture and decoders are disposed explicitly, each with a budget + LRU eviction.
5. Invalidate / dirty-flag — the engine never repaints on its own; mutations mark dirty and the host schedules the repaint.

License

MIT © slightc