WebRTC Audio Broadcasting with WHEP

A TypeScript implementation of WebRTC audio broadcasting using GStreamer and the WHEP (WebRTC-HTTP Egress Protocol) signaling standard.

Features

✅ WHEP Protocol Support - HTTP-based WebRTC signaling
✅ Audio-only Broadcasting - Efficient Opus-encoded audio streaming
✅ GStreamer Integration - Professional-grade media pipeline
✅ TypeScript Implementation - Type-safe development
✅ Express.js Server - RESTful WHEP signaling server
✅ Auto Session Management - Automatic cleanup and monitoring

Prerequisites

Make sure you have GStreamer installed on your system:

# Ubuntu/Debian
sudo apt-get install gstreamer1.0-tools gstreamer1.0-plugins-base \
    gstreamer1.0-plugins-good gstreamer1.0-plugins-bad \
    gstreamer1.0-plugins-ugly gstreamer1.0-libav \
    libnice10 gstreamer1.0-nice gir1.2-gst-plugins-bad-1.0 \
    gir1.2-gst-plugins-base-1.0

# Ubuntu/Debian dev dependencies (needed to build this project)
sudo apt install build-essential libgirepository1.0-dev libcairo2-dev \
    gir1.2-gtk-3.0 pkg-config

# Check installation
gst-inspect-1.0 webrtcbin
gst-inspect-1.0 opusenc

Installation

# Clone and install dependencies
npm install

# Build the TypeScript code
npm run build

Quick Start

Option 1: Run Everything Together (Recommended)

# Start both WHEP server and broadcaster
npm run full-demo

Option 2: Manual Setup

Terminal 1 - Start WHEP Server:

npm run whep-server

Terminal 2 - Start Audio Broadcaster:

npm run dev-broadcaster

Usage Options

Available Scripts

Command	Description
npm run whep-server	Start WHEP signaling server
npm run dev-whep	Start WHEP server with auto-reload
npm run dev-broadcaster	Start broadcaster in development mode
npm run start-broadcaster	Build and run broadcaster
npm run full-demo	Run server and broadcaster together

Configuration

Configure the broadcaster by setting environment variables:

# Custom WHEP endpoint
WHEP_ENDPOINT=http://localhost:8080/whep npm run dev-broadcaster

# Different audio frequency (musical notes)
AUDIO_FREQ=880 npm run dev-broadcaster  # A5 note (880Hz)

Audio Configuration

The broadcaster generates a sine wave test signal. You can modify the frequency in src/index.ts:

const config: WHEPConfig = {
    whepEndpoint: 'http://localhost:8080/whep',
    audioFreq: 440, // 440 Hz = A4 musical note
    duration: 60, // Broadcast duration in seconds
    waveType: 0, // 0=sine, 1=square, 2=saw, etc.
    stunServer: 'stun://stun.l.google.com:19302',
};

API Endpoints

WHEP Server Endpoints

Method	Endpoint	Description
POST	/whep	Create new WHEP session (SDP offer)
GET	/whep/:sessionId	Get session information
DELETE	/whep/:sessionId	Delete session
PATCH	/whep/:sessionId	Send ICE candidates
GET	/health	Server health check
GET	/sessions	List all active sessions

Example Usage

# Check server health
curl http://localhost:8080/health

# List active sessions
curl http://localhost:8080/sessions

# Send SDP offer (example)
curl -X POST http://localhost:8080/whep \
  -H "Content-Type: application/sdp" \
  --data-binary @offer.sdp

Architecture

Components

1. WHEP Server (src/whep-server.js)

   • Express.js HTTP server
   • WHEP protocol implementation
   • Session management
   • SDP offer/answer exchange

2. WHEP Client (src/whep-client.ts)

   • GStreamer WebRTC pipeline
   • HTTP-based signaling
   • Automatic session cleanup

3. Main Application (src/index.ts)

   • Application entry point
   • Configuration management
   • Error handling

Pipeline Architecture

audiotestsrc → audioconvert → audioresample → queue →
opusenc → rtpopuspay → queue → webrtcbin → WHEP Server