mirror of
https://github.com/heygen-com/hyperframes.git
synced 2026-09-03 04:38:33 +00:00
## Summary - Audio (and video) sounds broken/choppy on first play in the studio preview, but works fine on second play - Root cause: `<audio>` elements default to `preload="metadata"`, which only fetches enough data to determine duration — not enough for smooth playback. When `el.play()` fires, the browser hasn't buffered the audio data yet - The runtime now eagerly sets `preload="auto"` and calls `load()` during init, ensuring media is fully buffered before the user clicks play - `syncRuntimeMedia` now defers `play()` on unbuffered media by registering a `canplay` listener, instead of silently swallowing the failure ## Testing Verified with agent-browser against a 26s narration composition (soulscape-film): ``` # After fix — audio element state at init: preload: "auto" readyState: 4 (HAVE_ENOUGH_DATA) buffered: 26.07s (entire file) duration: 26.07s ``` Audio is fully buffered before any play attempt, so first-play works identically to subsequent plays. ## Files changed - `packages/core/src/runtime/init.ts` — set `preload="auto"` + `load()` in `bindMediaMetadataListeners` - `packages/core/src/runtime/media.ts` — defer `play()` on unbuffered media via `canplay` listener - `packages/core/src/runtime/media.test.ts` — updated test + added unbuffered media test case
Hyperframe Runtime Engine
This folder owns the runtime that powers preview and producer parity.
Current Direction
- Runtime source of truth is converging on
hyperframe.ts. - Build produces:
dist/hyperframe.runtime.iife.js(browser bootstrap)dist/hyperframe.runtime.mjs(tooling/tests)dist/hyperframe.manifest.json(version + sha256 + artifact map)
- FE owns iframe runtime injection.
- BE persists raw generated HTML without injecting runtime scripts.
- Producer validates pinned runtime checksum from manifest before render.
Runtime Contract (Stable Surface)
Globals:
window.__playerwindow.__playerReadywindow.__renderReadywindow.__timelineswindow.__clipManifest
postMessage:
- parent -> runtime control:
source: "hf-parent"type: "control"- actions:
play,pause,seek,set-muted,set-playback-rate,enable-pick-mode,disable-pick-mode
- runtime -> parent events:
source: "hf-preview"type: "state"andtype: "timeline"
Determinism baseline:
renderSeekis the producer-canonical seek path.- 30fps quantization and readiness gates are correctness requirements.
Build
bun run --filter @hyperframes/core build:hyperframes-runtime
Security Expectations
- Runtime bootstrap URL must be version-pinned and host-allowlisted.
- Iframe bridge payloads must be schema-validated.
- Unsafe URL schemes (
javascript:and unapproveddata:) are rejected. - Fail closed if runtime bootstrap/handshake is not healthy.
Product Editing Model
- Primary mode: prompt + element picking.
- Secondary mode: manual precision controls.
- Avoid timeline-first manual workflows as default product path.