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Three defects in the offline FX path, none of which any test could see. **Float output silently disabled sample-accurate volume automation.** The writer emitted 32-bit IEEE float; the very next mixer step bakes the volume envelope into the samples and accepts only 16-bit PCM, returning null otherwise. So enabling any effect downgraded that track to the ffmpeg expression path — capped at 32 straight segments, quantising a curved envelope, and on a dense one falling back to base volume. It now writes 16-bit PCM, clamped rather than wrapped so a limiter at 0 dB or a resonant filter cannot turn overshoot into a click. A test asserts the baker accepts the writer's own output and actually fades it. **Everything was folded to mono.** `prepareAudioTrack` goes out of its way to emit stereo — its pan filter exists to dodge ffmpeg's 3 dB mono-to-stereo rematrix — and this folded it, then wrote one channel. So adding a single peaking EQ collapsed a bed's width and cost ~3 dB in the render, while preview stayed stereo. Channels now travel as one plane each, through an OfflineAudioContext of the same width, and come back interleaved. **Small results decoded the wrong length.** `new Float32Array(buf.buffer)` discards byteOffset and byteLength, and Node pools small allocations: a 400-byte payload sits at offset 8 inside an 8 KiB pool, so a clip under ~1024 samples decoded as 2048 samples of unrelated memory — and the empty-result guard could not see it. The reader has the mirror-image fix: a float data chunk on an odd boundary (ffmpeg's pcm_f32le writes fmt(18) + fact, landing `data` at 58) now copies instead of throwing RangeError on an unaligned view. The tail limitation is now stated rather than mis-stated: the context is exactly as long as the input, so a reverb or delay still ringing is cut there. The old comment claimed the opposite. How far a tail may run past a clip's end changes the clip's length in the mix, so it is a product decision, not one to make here. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
@hyperframes/core
Types, parsers, generators, compiler, linter, runtime, and frame adapters for the Hyperframes video framework.
Install
npm install @hyperframes/core
Most users don't need to install core directly — the CLI, producer, and studio packages depend on it internally.
What's inside
| Module | Description |
|---|---|
| Types | TimelineElement, CompositionSpec, Asset, canvas dimensions, defaults |
| Parsers | parseHtml — extract timeline elements from HTML; parseGsapScript — parse GSAP animations |
| Generators | generateHyperframesHtml — produce valid Hyperframes HTML from a composition spec |
| Compiler | compileTimingAttrs — resolve data-start / data-duration into absolute times |
| Linter | lintHyperframeHtml — validate Hyperframes HTML (missing attributes, overlapping tracks, etc.) |
| Runtime | IIFE script injected into the browser — manages seek, media playback, and the window.__hf protocol |
| Frame Adapters | Pluggable animation drivers (GSAP, Lottie, CSS, or custom) |
Frame Adapters
A frame adapter tells the engine how to seek your animation to a specific frame:
import { createGSAPFrameAdapter } from "@hyperframes/core";
const adapter = createGSAPFrameAdapter({
getTimeline: () => gsap.timeline(),
compositionId: "my-video",
});
Implement FrameAdapter for custom animation runtimes:
import type { FrameAdapter } from "@hyperframes/core";
const myAdapter: FrameAdapter = {
id: "my-adapter",
getDurationFrames: () => 300,
seekFrame: (frame) => {
/* seek your animation */
},
};
Parsing and generating HTML
import { parseHtml, generateHyperframesHtml } from "@hyperframes/core";
const { elements, metadata } = parseHtml(htmlString);
const html = generateHyperframesHtml(spec);
Linting
import { lintHyperframeHtml } from "@hyperframes/core/lint";
const result = lintHyperframeHtml(htmlString);
// result.findings: { severity, message, elementId }[]
Documentation
Full documentation: hyperframes.heygen.com/packages/core
Related packages
@hyperframes/engine— rendering engine that drives the browser@hyperframes/producer— full render pipeline (capture + encode)hyperframes— CLI