Interchange & fidelity (OTIO · Lottie · watermark · real-TeX)

Phase-5 adoption additions.

OpenTimelineIO (.otio)

Export a scene’s timeline (one clip per play()/wait() segment, frame-exact) to OTIO JSON — round-trips to DaVinci Resolve / Premiere / FCPXML / EDL / AAF via OTIO’s adapters.

import { sceneToOtioString, sceneToOtio, toOtioJSON, fromOtioJSON } from "ecmanim";
writeFileSync("out.otio", sceneToOtioString(scene, { name: "demo", mediaUrl: "out.mp4" }));

RationalTime {value, rate} keeps everything frame-exact (no float drift). The JS/WASM OTIO bindings are immature, so the schema is reimplemented in TS.

Limitations: the export is a single video track of clips — no audio tracks, no transition/effect metadata, and every clip references the same flat render (mediaUrl) by frame range. It is a timeline skeleton for conforming in an NLE, not a full project interchange.

Lottie import/export

import { vmobjectToLottieJSON, loadLottie } from "ecmanim";
const doc = vmobjectToLottieJSON(shape, { width: 512, height: 512 });  // -> a .json Lottie
const mob = loadLottie(existingLottieJson);                            // -> a VMobject

Maps VMobject cubic-Bézier subpaths to Lottie’s shape model (v vertices with relative i/o tangents + closed flag c). Lottie is y-down, manim y-up, so y is negated on export/import.

Limitations (read before relying on this):

• Static geometry only — no keyframes. Export captures the mobject’s current shape; nothing you animate with play() appears in the Lottie. Exporting an animated scene gives you a frozen frame, not the animation.
• No fills, strokes, gradients, trim paths, mattes, or text on either direction — geometry only. For high-fidelity import of rich Lottie files, use ThorVG-WASM and rasterize.
• Round-tripping is supported for what’s in scope: loadLottie(vmobjectToLottieJSON(m)) reproduces the geometry.

Watermark

import { render } from "ecmanim/node";
await render(MyScene, { watermark: { text: "@channel", position: "bottom-right", opacity: 0.7 } });
// or an image logo: { image: "logo.png", position: "top-left", opacity: 0.9 }
// or standalone: import { applyWatermark } from "ecmanim/node"; await applyWatermark("v.mp4", {...});

Positions: top-left, top-right, bottom-left, bottom-right, center.

Real-TeX (dvisvgm) backend

For publication-grade LaTeX (full package/align support), the Node backend can shell out to a real TeX toolchain — latex → dvi → dvisvgm → SVG → Béziers — with an on-disk cache, detecting the toolchain and falling back to MathJax when TeX isn’t installed. See texToSVGViaDvisvgm / mathTexDvisvgmOrFallback (ecmanim/node). MathJax remains the zero-dependency default.