webdartc monorepo

A Dart-native WebRTC stack. This monorepo contains the protocol library and its Flutter integration layer.

Packages

Package	Purpose	Status
dart/	Pure-Dart WebRTC library. RFC-compliant protocol state machines (ICE / DTLS / SRTP / SCTP / RTP / SDP) with all network I/O isolated to a single TransportController. Codec backends via FFI (H.264 via VideoToolbox on Apple / Cisco-prebuilt OpenH264 on Linux + Windows, VP8 + VP9 + Opus via vendored libvpx + libopus — source-built on macOS / Linux, downloaded as wrapper DLLs on Windows). Platform-native crypto (CommonCrypto + Security.framework on macOS, OpenSSL on Linux, CNG / bcrypt.dll on Windows).	Implemented
flutter/	Flutter integration on top of dart. Provides a Metal-backed video-rendering Widget on macOS and a PixelBufferTexture-backed renderer on Windows, with Linux GLES support on the roadmap. Depends on dart via path.	macOS + Windows renderers working; other platforms in progress

Layout

.
├── dart/                     # pure-Dart protocol library (Dart SDK ≥ 3.11)
│   ├── hook/build.dart       #   compiles the VideoToolbox C helper (Apple)
│   │                         #   and the vendored libopus + libvpx
│   │                         #   (macOS + Linux); downloads prebuilt
│   │                         #   wrapper DLLs + Cisco OpenH264 (Windows)
│   │                         #   and Cisco OpenH264 (Linux)
│   ├── src/                  #   C sources built by the hook
│   ├── third_party/opus/     #   libopus submodule (statically linked)
│   ├── third_party/libvpx/   #   libvpx submodule (statically linked,
│   │                         #   shared between webdartc_vp8 + webdartc_vp9)
│   ├── lib/                  #   peer_connection, transport, ice, dtls, srtp,
│   │                         #   sctp, stun, rtp, sdp, crypto, media, codec, core
│   ├── test/                 #   unit + fuzz + e2e (Chrome / Firefox)
│   └── example/             #   video_sender / video_receiver / audio_send /
│                             #   audio_receive / signaling (for Flutter pairing)
├── flutter/                  # Flutter integration (requires Flutter SDK)
│   ├── lib/render/           #   VideoRenderer / ShaderVideoRenderer / widget
│   ├── macos/Classes/        #   Swift FlutterTexture plugin
│   └── example/              #   runnable macOS demo app
├── .github/workflows/ci.yaml # Linux + macOS + Windows CI
│                             # (analyze, unit, E2E, flutter test + build)
├── CLAUDE.md                 # agent guidance for this repo
└── README.md

Working in this repo

This repo is configured as a pub workspace: a single resolution covers both packages.

git clone --recurse-submodules <repo-url> webdartc
cd webdartc
flutter pub get        # resolves dart + flutter together

If you cloned without --recurse-submodules, run git submodule update --init --recursive before building — dart/third_party/opus/ and dart/third_party/libvpx/ are submodules that the build hook needs.

Flutter SDK is required at the repo root because the flutter package depends on the Flutter SDK. Use flutter pub get (not dart pub get) from the workspace root. If you only need the pure-Dart library, depend on webdartc from your own project — you do not need to clone this repo.

Once resolved, each package is worked on from its own directory:

# Protocol library
cd dart
dart test                      # unit tests (runs the build hook on macOS / Linux / Windows)
dart test test/e2e/            # e2e (Chrome / Firefox auto-downloaded)
dart analyze

# Flutter integration
cd flutter
flutter test                   # widget tests with a mock MethodChannel
flutter analyze

# Flutter macOS demo (full Flutter ↔ browser WebRTC peer)
cd flutter/example
flutter run -d macos           # pair with dart/example/signaling (Ayame) + Chrome

The flutter package depends on dart via a local path: reference, so changes in dart/ are picked up without republishing.

Codec matrix

All backends are software (SW) except VideoToolbox on macOS, which is hardware-accelerated.

Codec	macOS	Linux	Windows
H.264	VideoToolbox (HW)	OpenH264 (Cisco prebuilt)	OpenH264 (Cisco prebuilt)
VP8 / VP9	libvpx (submodule source-built)	libvpx (submodule source-built)	libvpx (prebuilt wrapper DLL; source-build opt-in)
Opus	libopus (submodule source-built)	libopus (submodule source-built)	libopus (prebuilt wrapper DLL; source-build opt-in)

registerH264Codec() / registerVp8Codec() / registerVp9Codec() / registerOpusCodec() each pick the right backend for the current platform automatically. dart/hook/build.dart drives every native asset: it compiles the VideoToolbox C shim on macOS, source-builds libopus + libvpx from submodules on macOS / Linux, downloads our prebuilt wrapper DLLs on Windows (webdartc-lib{vpx,opus}-prebuilt-* release assets — set hooks.user_defines.webdartc.lib{vpx,opus}_source_build=true in the workspace-root pubspec.yaml to opt into a local MSVC + vcpkg build), and downloads Cisco's OpenH264 binary from ciscobinary.openh264.org (version + SHA-256 pinned) on Linux + Windows. See dart/README.md#codec-backends for the full per-OS breakdown and the symbol-hiding rationale, and https://www.openh264.org/ for OpenH264's upstream distribution terms.

Native library requirements

• macOS: Xcode (for CoreMedia / VideoToolbox frameworks) and CMake (brew install cmake). dart pub get + dart test handle the rest.
• Linux: sudo apt-get install cmake clang yasm libssl-dev (CMake + clang to build bundled libopus, yasm for libvpx's x86_64 SIMD, OpenSSL for crypto). VP8 / VP9 / Opus are vendored; OpenH264 is downloaded by the build hook on first run — no system codec packages needed.
• Windows: nothing to install for the default path — dart pub get downloads the prebuilt wrapper DLLs for VP8 / VP9 / Opus + the Cisco OpenH264 binary, and the OS-built-in CNG (bcrypt.dll) provides the crypto primitives. The source-build opt-in requires MSVC + vcpkg.

Scope of flutter

Responsibilities this package owns (and dart deliberately does not):

• Rendering — a VideoRendererWidget backed by Flutter's Texture. On macOS the plugin converts decoded I420 frames to NV12 CVPixelBuffer; Flutter's Metal compositor samples it with its built-in YUV→RGB shader.
• Capture / playback — camera, microphone, and speaker integration (roadmap; platform-native where possible via FFI, Flutter plugin where not).

The dart package remains free of dart:ui, Flutter, and platform capture/playback dependencies.

License

See dart/LICENSE.txt.