Sync

Sync is Noise Factor's low-latency bridge between browser renderers and native video ecosystems. It carries GPU-rendered RGBA frames over authenticated loopback WebSockets and republishes them through platform-native video-sharing providers, allowing applications such as Noisedeck to appear in existing source pickers without a custom plugin in every downstream host.

Project status

Sync is under active development. This source tree currently includes:

• an independently versioned frame and control protocol;
• a browser SDK with bounded discovery, explicit pairing, and separate control and sender-data sockets;
• a native C++20 loopback daemon with per-origin, revocable authorization;
• bounded sender and connection ownership with non-blocking browser submission;
• a macOS Metal publisher and dynamically discovered Syphon integration;
• a Windows Spout publisher and a cross-platform NDI publisher, both dynamically discovered;
• an Apple Silicon menu-bar companion and a Windows tray companion, each with bounded helper supervision; and
• native, browser, protocol, security-boundary, and real-loopback tests.

Both companions are previews and are not ready for general use. Reverse-direction native sources and automatic updates are not part of the current public implementation.

Providers

Sync publishes through every provider that is available on the running platform, at once: a single named output appears simultaneously as a Spout sender and an NDI source on Windows. Receiving applications pick whichever they support.

Provider	Platform	Runtime	Bundled
Syphon	macOS	Syphon.framework	Yes — see docs/dependencies/syphon.md
Spout	Windows	SpoutLibrary.dll	Yes — see docs/dependencies/spout.md
NDI	Windows, macOS	NDI Runtime	No — the SDK licence forbids redistribution; see docs/dependencies/ndi.md

No provider is ever linked at build time. Each is discovered at run time through its documented public entry point, and a provider whose runtime is absent simply reports itself unavailable rather than failing the daemon.

Building the native daemon

Sync requires CMake 3.21 or newer, a C++20 compiler, OpenSSL 3, and libuv. macOS builds also use the system Foundation and Metal frameworks and locate libuv through pkg-config; Windows builds use MSVC and locate libuv and OpenSSL through a CONFIG package such as vcpkg:

vcpkg install libuv:x64-windows openssl:x64-windows
cmake -S . -B build -A x64 `
  -DCMAKE_TOOLCHAIN_FILE="$env:VCPKG_INSTALLATION_ROOT/scripts/buildsystems/vcpkg.cmake"
cmake --build build --config Release --target syncd
ctest --test-dir build --build-config Release --output-on-failure

MSVC is what CI builds and what the installer ships. The tree also builds and passes its tests under MinGW-w64 (GCC), which needs no administrator rights and is a practical local setup:

pacman -S --needed mingw-w64-x86_64-{gcc,cmake,ninja,openssl,libuv,pkgconf}
cmake -S . -B build -G Ninja && cmake --build build
ctest --test-dir build --output-on-failure

Run the tests from a shell with a Windows-shaped environment. An MSYS2 login shell unsets LOCALAPPDATA and points TMP/TEMP at /tmp, and the pairing store resolves its default path from %LOCALAPPDATA% and refuses a path that is not drive-absolute, so several tests fail there for reasons unrelated to the code.

cmake -S . -B build
cmake --build build --target syncd -j4
ctest --test-dir build --output-on-failure

The daemon binds only to IPv4 and IPv6 loopback. Production mode uses port 53979 unless overridden:

./build/syncd
./build/syncd --port 54000
./build/syncd --list-pairings
./build/syncd --revoke-origin https://visuals.example

Naming no publisher selects every provider the platform offers. Naming one or more restricts the daemon to exactly those, and each accepts an explicit runtime path for development builds:

./build/syncd --publisher spout --publisher ndi
./build/syncd --publisher ndi --ndi-runtime /opt/ndi/lib
./build/syncd --publisher spout --spout-library C:/Spout/SpoutLibrary.dll

See the provider table above for each runtime and license boundary.

Packaging the desktop previews

macOS

Packaging requires macOS 13 or newer, an Apple Silicon build, dylibbundler, librsvg, and a locally built Syphon.framework. The release workflow pins Syphon source revision 71351d4b484cd2d1917867f7846a5cdca724552d; use that same revision for local release-equivalent packages.

cmake -S . -B build-package \
  -DSYNC_PRODUCT_VERSION=0.2.0 \
  -DSYNC_SYPHON_FRAMEWORK_PATH=/absolute/path/to/Syphon.framework
cmake --build build-package --target sync_macos_dmg -j4
SYNC_PACKAGE_DIR=build-package/package \
  node --test test/packaging/macos-package.test.js
scripts/smoke-macos-app.sh "$PWD/build-package/package/Sync.app"

The local target creates an unsigned app and DMG. Developer ID signing, notarization, stapling, and public publication belong to the Noise Factor release workflow so credentials never enter this public repository.

Windows

Packaging requires Windows 10 or newer, an x64 MSVC toolchain, Inno Setup 6 (ISCC on PATH), ImageMagick (magick on PATH), and a locally built SpoutLibrary.dll.

cmake -S . -B build-package -A x64 `
  -DCMAKE_TOOLCHAIN_FILE="$env:VCPKG_INSTALLATION_ROOT/scripts/buildsystems/vcpkg.cmake" `
  -DSYNC_PRODUCT_VERSION=0.2.0 `
  -DSYNC_SPOUT_LIBRARY_PATH=C:\absolute\path\to\SpoutLibrary.dll `
  -DSYNC_WINDOWS_DEPENDENCY_PATH="$env:VCPKG_INSTALLATION_ROOT\installed\x64-windows\bin"
cmake --build build-package --config Release --target sync_windows_installer --parallel 4
$env:SYNC_PACKAGE_DIR = "build-package/package"
node --test test/packaging/windows-package.test.js
./scripts/smoke-windows-app.ps1 -Bundle "$PWD/build-package/package/Sync"

The local target creates an unsigned application directory and installer. Authenticode signing and public publication likewise belong to the Noise Factor release workflow.

Browser SDK

The dependency-free browser modules live in browser/. Passive discovery never initiates pairing; pair() must be called from a deliberate user action, and the host application owns returned token storage. See the browser client guide for the API and loopback Permissions Policy requirements.

import { SyncBridgeClient } from './browser/index.js'

const pairingClient = new SyncBridgeClient()
const { token } = await pairingClient.pair('My visual app')
pairingClient.close()

const sync = new SyncBridgeClient({ token })
await sync.connect()

Tests

npm run test:browser
npm run test:packaging
SYNC_DAEMON_PATH=build/syncd npm run test:integration
ctest --test-dir build --output-on-failure

Security

Unknown origins cannot silently publish. Pairing requires a browser-initiated request and a visible native approval prompt; reusable credentials are scoped to an exact normalized origin and can be revoked. Please report suspected vulnerabilities privately using SECURITY.md.

License

Sync is released under the MIT License. See TRADEMARK.md for the branding boundary. Third-party runtime providers retain their own licenses and are not relicensed by this repository.

Copyright © 2026 Noise Factor LLC