Myrelith
A private-by-design, browser-native video editor. Your media stays on your
device.
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Current public preview: v0.2.0-alpha.1. The
hosted app tracks current master.
Myrelith is an experimental non-linear editor built with React, TypeScript,
WebCodecs, Mediabunny, Web Audio, and worker-owned Canvas rendering. It can take
a project from local media to a capability-aware MP4 or WebM export without
sending the source files to an application server.
New saves use the .myrelith extension and myrelith-project format marker.
Projects created before the rename with a .webcut filename or
webcut-project marker remain supported and are normalized when opened.
Why Myrelith?
- Local-first: media decoding, preview, editing, and export happen in your
browser. There are no accounts, ads, cookies, or in-app analytics.
- A real editing model: multi-track editing, linked A/V, trim/ripple/slip/
slide/razor tools, markers, snapping, captions, constant-speed retiming, and
speed ramps.
- Portable projects:
.myrelith files contain the edit, not bundled source
media. Collect media copies referenced sources into a chosen local folder with
a versioned manifest. Chrome can remember browser-managed file permissions and
reconnect sources when allowed.
- Honest compatibility: Myrelith inspects media bytes and probes real decoder
and encoder configurations. Unsupported explicit export choices stay blocked
with a reason; the app never quietly swaps in another format.
- Resilient work: recent-project shortcuts, offline sources, relinking, and
bounded local crash-recovery copies help without pretending they are saves.
What works today
| Area | Highlights |
|---|
| Projects | Horizontal 16:9, vertical 9:16, square 1:1, and 4:5 canvases from 720p to 4K; exact common frame and audio rates; Save, Save As, live save, Resume, Recent, recovery, collect-media archives, and workspace presets |
| Media | Video, audio, PNG, JPEG, WebP, and AVIF; byte-level container inspection; searchable virtualized pool; collections; thumbnails, filmstrips, and waveforms; offline relink; optional local editing proxies |
| Timeline | Four video and four audio tracks by default; select, razor, trim, ripple trim, slip, slide, linked editing, track controls, markers, snapping, caption tracks with SRT/VTT, and undo/redo |
| Captions | SRT/VTT/semantic ASS interchange, batch editing, and optional local English/French transcription with editable text/timing review and one-step Apply/Undo |
| Interchange | Bounded OpenTimelineIO JSON 0.17.0 import/export with a staged loss report; missing media stays offline for relink. No adapters, packages, or remote URL fetch |
| Effects | Text overlays, transforms, crop, blend modes, opacity, volume, color correction, masks and chroma key, keyframed animation, dynamic zoom presets, visual crossfades, and synchronized audio fades when valid handles exist |
| Motion | Constant-speed retiming and speed ramps; video stabilization; point and box tracking; manual lens correction when WebGL2 is available |
| Preview | Direct Program Monitor manipulation; Auto/Full/Half/Quarter quality; histogram, waveform, and vectorscope; playback audio meters; command palette |
| Export | Auto, Compatibility MP4/AVC/AAC, Web WebM/VP9/Opus, Modern WebM/AV1/Opus, and explicit HEVC; buffered download or direct-to-file save |
| Plugins | Signed local .myrelith-plugin packages only; review, enable, disable, and fail-closed preview/export. There is no plugin marketplace |
Try it
Myrelith targets current desktop Chromium. Open the
hosted preview, create a project, and choose
local media. The browser may ask for file access; Myrelith receives only the files
or folders you explicitly choose.
Chrome is the primary development target. Chrome 150 and Edge 150 on Windows
have passed the current import, editing, playback, cancellation, and export
gates. Firefox and Safari are not yet verified. Exact codec support still
depends on the browser, operating system, and hardware, so Myrelith probes it each
time instead of relying on file extensions.
Run locally
Requirements: Node.js ^20.19.0 or >=22.12.0, npm, and a current desktop
Chrome or Edge installation.
git clone https://github.com/zyfvhcfh87-rgb/Myrelith.git
cd Myrelith
npm ci
npm run dev
Open http://localhost:5173.
Run the container
Versioned images publish to GitHub Container Registry under the myrelith
package name for Linux AMD64 and ARM64. The server listens on port 8080 inside
the container.
docker run --rm -p 8080:8080 ghcr.io/zyfvhcfh87-rgb/myrelith:0.2.0-alpha.1
Then open http://localhost:8080. The container serves
the static app; editing remains in the visitor's browser.
Privacy and local storage
Myrelith does not upload selected media or projects. It uses browser storage for
preferences, browser-managed file handles you authorize, and bounded recovery
snapshots that contain project structure and source metadata—but never the
source video, audio, or image bytes. Optional local transcription stores a
verified speech model separately in Cache Storage (96 MiB budget including an
install). Choosing Download contacts Hugging Face and its file-delivery hosts;
selecting the exact local model file avoids that download. Audio and transcripts
are not uploaded. Remove the model in the transcription panel or clear local
site data.
Browser storage is bound to the exact site origin. Moving to the Myrelith
hostname cannot automatically transfer Recents, recovery copies, preferences,
or remembered permissions from the previous hostname; save a portable project
file there and open it in Myrelith when migration is needed.
Cloudflare Pages delivers the hosted app and processes ordinary request and
security metadata. Cloudflare Web Analytics is disabled. Read the full
Privacy Notice or the
public hosted copy.
Known limitations
- Myrelith is an alpha preview, not a production-ready editor. Keep your
source media and exported files backed up.
- Browser and OS codec support varies. Auto tries Modern, then Web, then
Compatibility; HEVC is explicit-only. Unsupported selections are never
silently substituted.
- Direct-to-file export and durable recent-file permissions require secure
context and compatible File System Access APIs. Other browsers use downloads
and manual reconnection.
- Recovery copies are origin-local browser conveniences, not user-owned
.myrelith saves. Multi-tab recovery ownership is not coordinated.
- Local transcription supports English/French and one 1–300 second source
window at a time, with continuous mono/stereo audio at 8–96 kHz. Review model
text and timing; some windows require manual timing, and overlapping windows
may repeat words. Cached speech assets support a loaded app offline; opening
the app can require a connection. Spellcheck and translation are unavailable.
- Local ProRes and AC-3/E-AC-3 extensions cover import only. There is no proxy
converter or local export-encoder fallback. Editing proxies are optional
preview helpers; export always uses the original source.
- Non-1× speed and speed ramps share bounded pitch-preserving audio in preview
and export. Held 0% sections fade to silence, and edge speeds can sound more
granular. Timeline text overlays and caption tracks are separate; text
overlays do not yet have keyframe animation.
- Manual lens correction needs a capable WebGL2 path and can block motion
tracking while it is active. Signed plugins are local packages only and can
block export when they cannot be prepared.
- The bundled AC-3/E-AC-3 decoder includes FFmpeg-derived WebAssembly. Copyright
and patent obligations are separate; this prerelease is not a
patent-clearance certification. See Third-party notices.
Quality and architecture
npm test
npm run build
npm run lint
npm audit --omit=dev --audit-level=high
The app keeps a one-way dependency flow:
ui/ → state/ → domain/
app/ → state/ + engine/ + pipeline/ + workers/
engine/ + pipeline/ + workers/ → domain/
The non-negotiable ownership, timing, and state rules live in
ARCHITECTURE.md. Current implementation status and browser
evidence live in docs/HANDOFF.md; the completed build record
is in docs/PLAN.md.
Contributing and support
Read CONTRIBUTING.md before changing code. Please use
synthetic fixtures rather than private media in reports, follow the
Code of Conduct, and use SECURITY.md for
sensitive vulnerabilities. General support expectations are in
SUPPORT.md.
License
Myrelith is copyright © 2026 Aryel and released under the MIT License.
Bundled dependencies keep their own licenses; see
THIRD_PARTY_NOTICES.md.
