dart_webrtc

dart_webrtc (WebrTC Implementation for The Dart language)

A pure Dart implementation of WebRTC — ICE, STUN, TURN, DTLS, TLS, SRTP, RTP, RTCP, SDP — with no native dependencies. Includes a full ion-style SFU (example/ion_style_sfu/) with sharding, clustering, simulcast, TWCC/REMB, NACK/RTX, audio observer, and Prometheus stats.

Inspired by webrtc-nuts-and-bolts

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✨ Highlights

• Pure Dart end-to-end stack — no libwebrtc / libsrtp / libnice. Easy to embed and audit.
• Ion-style SFU with isolate-based sharding, cluster coordinator, UDP relay transport, leaky-bucket pacer, BWE, jitter buffer, simulcast layer rewriter, and audio-level observer.
• 516 unit tests in the SFU package, 93–100 % line coverage across major files.
• VP8 / VP9 / Opus / PCMA / PCMU, RTX (RFC 4588), NACK, PLI, FIR, REMB, TWCC, audio level (RFC 6464), playout-delay codec.
• Built-in load-test harness and synthetic loss simulator.
• Prometheus metrics + JSON /stats endpoint.

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📦 Installation

clone the repo

Then run:

dart pub get

Requires Dart 3.x or later.

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📚 Documentation (WIP)

• API Reference
• Example usage in the /bin directory

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💡 Examples

GitHub: examples

Ion-style SFU server

dart run example/ion_style_sfu/bin/sfu_server.dart \
  --ip 0.0.0.0 \
  --ws-port 9091 \
  --rtp-base 51000 \
  --announce-ip <your-public-ip> \
  --ice-server stun:stun.l.google.com:19302

Browser demo client:

cd example/ion_style_sfu/web
python -m http.server 8000 --bind 0.0.0.0
# open http://localhost:8000/meet.html

Run the SFU test suite:

cd example/ion_style_sfu
dart test

DTLS server

dart bin/srtp_webrtc.dart
dart bin/dart_webrtc.dart
dart lib/src/dtls/examples/server/psk_ccm8.dart
dart lib/src/dtls/examples/server/psk_ccm.dart

SRTP/DTLS server

dart bin/srtp_webrtc.dart

DTLS client

dart lib/src/dtls3/handshaker/client/dtls_client.dart

STUN Server

dart lib/src/stun3/stun_server7.dart

STUN client

dart lib/src/stun3/stun_client.dart

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STUN/DTLS/SRTP/RTCP multiplexing

This example recieves stun, dtls, rtp packets. It decrypts, encrypts and sends the packets back to the sender. copy the sdp offer from this file:

lib\src\sdp8\sdp_test.dart

Adjust the the fingerprint and ice candidate

cd WebRTC-Simple-SDP-Handshake-Demo
php -S localhost:3000

Navigate to the link in your browser=> localhost:3000 Paste the sdp in the sdp offer box

Run this command

dart bin\srtp_webrtc.dart

In your browser, click create answer

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🎯 Roadmap

✅ Shipped

Signaling & NAT traversal

• x STUN (client + server)
• x SIP
• TURN (UDP)

ICE

• x Vanilla ICE
• x Trickle ICE
• x ICE-Lite (client + server)
• ICE Restart

Security

• x DTLS 1.2 + DTLS-SRTP
  • x Curve25519, P-256
  • x PSK (CCM, CCM-8)
• TLS 1.2

RTP / RTCP

• x RFC 3550 RTP base + header extensions (audio level, playout delay, abs-send-time, TWCC)
• x Payload formats: VP8, VP9, Opus, PCMA, PCMU
• x RTX (RFC 4588), RED scaffolding
• x RTCP: SR/RR, NACK, PLI, FIR, REMB, TWCC
• H264, AV1, SVC

SDP / PeerConnection

• x SDP parsing + generation, m-line reuse
• x PeerConnection API
• x Simulcast (RID + SIM SSRC group, recv + forward)
• x Bandwidth estimation (sender-side TWCC + REMB)

SFU (example/ion_style_sfu/)

• x Session / Peer / Publisher / Subscriber / Router / Receiver / DownTrack
• x Isolate-based session sharding (SessionShard, ShardedSfu)
• x Cluster coordinator + UDP relay transport (cascade between SFUs)
• x Audio observer (RFC 6464) + audio-level forwarding policy
• x Leaky-bucket pacer, byte budget, NACK buffer, RTCP rewrite
• x Synthetic loss simulator + load-test harness
• x Prometheus stats + JSON snapshot, /streams aggregator (Phase B11)
• x WebSocket signalling server (runIonStyleSfuServer)
• x Multi-room cluster snapshot rehydration

Compatibility

• x Chrome / Edge / Firefox
• x webrtc-rs interop
• Pion / aiortc / sipsorcery interop suite

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🔜 Roadmap

• VP9 SVC layer selector
• H264 forwarding
• Insertable streams / SFrame (E2EE)
• Recording (OPUS / VP8 / VP9)
• Published throughput benchmarks + Helm chart
• DataChannel (SCTP)
• TURN (UDP + TCP)
• getStats() browser-compatible API
• ICE Restart

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🔗 References

• aiortc (Python)
• pion/webrtc (Go)
• sipsorcery (C#)
• webrtc-rs (Rust)