webrtc_dart 0.25.3

Pure Dart WebRTC implementation. DataChannels, media streaming, ICE/DTLS/SCTP/RTP. Port of werift-webrtc. No native dependencies - works on any Dart platform.

webrtc_dart

Server-side WebRTC (Web Real-Time Communication) in pure Dart. Build SFUs (Selective Forwarding Units), recording servers, and media pipelines.

What is webrtc_dart?

A server-side WebRTC library for Dart, similar to Pion (Go), aiortc (Python), and werift (TypeScript).

Use cases:

• SFU (Selective Forwarding Unit)
• Recording servers (WebM/MP4)
• Media processing pipelines
• DataChannel messaging backends
• WebRTC-to-other-protocol bridges

Features

What we handle	Details
WebRTC Transport	ICE (Interactive Connectivity Establishment), DTLS (Datagram Transport Layer Security), SRTP (Secure Real-time Transport Protocol), SCTP (Stream Control Transmission Protocol), RTP/RTCP (Real-time Transport Protocol / Control Protocol)
DataChannels	Reliable/unreliable, ordered/unordered
RTP Processing	NACK (Negative Acknowledgment), PLI (Picture Loss Indication), FIR (Full Intra Request), REMB (Receiver Estimated Maximum Bitrate), TWCC (Transport Wide Congestion Control), RTX (Retransmission), Simulcast
Codec Depacketization	VP8, VP9, H.264, AV1, Opus
NAT Traversal	STUN (Session Traversal Utilities for NAT), TURN (Traversal Using Relays around NAT) (UDP/TCP), ICE-TCP, mDNS (Multicast DNS)
Recording	Save received streams to WebM/MP4
Crypto	Native OpenSSL when available, pure Dart fallback

Server-Side vs Browser WebRTC

webrtc_dart handles transport, not media capture/playback:

Feature	Browser WebRTC	webrtc_dart
Camera/mic access	Yes	No - use FFmpeg/GStreamer
Video encoding	Yes (hardware)	No - forward RTP packets
Video decoding	Yes (hardware)	No - depacketize only
<video> playback	Yes	N/A
Peer connections	Yes	Yes
DataChannels	Yes	Yes
RTP packet access	Limited	Full control

Installation

dependencies:
  webrtc_dart: ^0.25.3

Quick Start

DataChannel

import 'package:webrtc_dart/webrtc_dart.dart';

void main() async {
  final pc = RTCPeerConnection(RtcConfiguration(
    iceServers: [IceServer(urls: ['stun:stun.l.google.com:19302'])],
  ));

  final channel = pc.createDataChannel('chat');

  channel.onOpen.listen((_) => channel.sendString('Hello!'));
  channel.onMessage.listen((msg) => print('Received: $msg'));

  pc.onIceCandidate.listen((candidate) {
    // Send to remote peer via signaling
  });

  final offer = await pc.createOffer();
  await pc.setLocalDescription(offer);
}

Receiving Media (SFU Pattern)

final pc = RTCPeerConnection();

pc.onTrack.listen((transceiver) {
  // Access raw RTP packets
  transceiver.receiver.onRtp = (packet) {
    // Forward to other peers, record, or process
  };
});

Recording to WebM

// Record received media to file
final recorder = MediaRecorder(
  tracks: [videoTrack, audioTrack],
  path: 'output.webm',
);
await recorder.start();
// ... receive media ...
await recorder.stop();

API Overview

Class	Purpose
RTCPeerConnection	WebRTC connection management
RTCDataChannel	Data messaging
RTCRtpTransceiver	Media track handling
RTCRtpSender	Send RTP + DTMF (Dual-Tone Multi-Frequency)
RTCRtpReceiver	Receive RTP
RTCIceCandidate	ICE connectivity
RTCSessionDescription	SDP (Session Description Protocol) offer/answer

Browser Interop

Tested with Chrome, Firefox, and Safari via automated Playwright tests.

Examples

See example/ for the original examples ported from werift:

• datachannel/ - Data channel patterns
• mediachannel/ - SFU patterns (sendonly, recvonly, sendrecv)
• save_to_disk/ - Recording to WebM/MP4
• mediachannel/pubsub/ - Multi-peer SFU

To see additional examples comparing how to implement in either werift or webrtc_dart see WebRTC Examples

Performance

Comparison: webrtc_dart v0.25.0 vs werift v0.22.2

Binary parsing operations are faster than werift (TypeScript). With native OpenSSL, SRTP is now competitive.

Operation	webrtc_dart	werift	vs werift
RTP parse	3.6M/s	1.4M/s	2.6x faster
SDP parse	62K/s	22K/s	2.9x faster
STUN parse	1.2M/s	0.6M/s	2.0x faster
H.264 depacketize	2.9M/s	1.1M/s	2.6x faster
ICE candidate parse	3.6M/s	13M/s	3.7x slower*
SRTP encrypt (1KB)	157K/s	426K/s	2.7x slower**

*ICE parsing uses Dart regex vs werift's native string ops. **With native OpenSSL (was 30x slower with pure Dart).

Run benchmarks: ./benchmark/run_perf_tests.sh

Native Crypto Optimization

SRTP encryption/decryption automatically uses native OpenSSL when available (~16x faster), falling back to pure Dart for maximum portability.

Platform	Crypto Used
macOS/Linux with OpenSSL	Native (~16x faster)
Windows with OpenSSL	Native (~16x faster)
Flutter mobile	Native if available
Flutter web	Pure Dart (no FFI - Foreign Function Interface)
Dart VM without OpenSSL	Pure Dart

// Check what crypto is being used
print(CryptoConfig.description);  // "Native (OpenSSL: /path)" or "Dart (pure)"

// Force pure Dart (disable native)
CryptoConfig.useNative = false;

// Or via environment variable:
// WEBRTC_NATIVE_CRYPTO=0 dart run your_app.dart

No configuration needed - native crypto is used automatically when available.

Test Coverage

2661 tests passing (including 41 performance regression tests) with browser interop validation.

dart test                        # Run all tests
dart test --exclude-tags=slow    # Fast tests only (~7s)
dart test --tags=slow            # Slow/integration tests
dart test test/performance/      # Performance regression tests

Acknowledgments

Port of werift-webrtc by Yuki Shindo.

License

MIT