Video Conferencing System - Architecture
High-Level Architecture
Video Conferencing — WebRTC Architecture with SFU Media Server
Core Components
1. Signaling Service
Purpose: WebRTC signaling, session management, and call orchestration
Responsibilities:
- WebRTC offer/answer exchange
- ICE candidate negotiation
- Session state management
- Participant join/leave coordination
- Meeting room management
Technology Stack:
- Node.js with Socket.IO for WebSocket connections
- Redis for session state storage
- PostgreSQL for persistent meeting data
- Load balancing with sticky sessions
2. Media Servers (SFU Architecture)
Purpose: Selective Forwarding Unit for efficient media routing
SFU Benefits:
- Lower server CPU usage vs MCU
- Better quality preservation
- Scalable to large meetings
- Client-side mixing flexibility
Media Processing:
SFU Media Processing — Fan-in/Fan-out Architecture
Features:
- Adaptive bitrate streaming
- Simulcast support (multiple quality streams)
- Bandwidth optimization
- Packet loss recovery (NACK, FEC)
3. Recording Service
Purpose: Meeting recording and playback functionality
Recording Pipeline:
Recording Pipeline — Media Stream to Playback
Components:
- Media Compositor: Combines audio/video streams
- Encoder: H.264/VP8 video, Opus audio encoding
- Storage: Distributed file system (S3/GCS)
- Transcoding: Multiple format generation
- Metadata: Recording index and search
4. Chat Service
Purpose: Real-time messaging during meetings
Architecture:
- WebSocket connections for real-time delivery
- Message persistence in Cassandra
- Redis pub/sub for message routing
- Rich media support (files, images, reactions)
5. User Service
Purpose: Authentication, authorization, and user management
Features:
- OAuth 2.0 / SAML integration
- JWT token management
- User profile and preferences
- Meeting permissions and roles
- Calendar integration
Media Architecture
WebRTC Media Flow
WebRTC Media Flow — Signaling and P2P Media Paths
SFU Media Routing
SFU Media Routing — Client Upload to Selective Download
Adaptive Bitrate Streaming
Adaptive Bitrate Streaming — Dynamic Quality Selection
Scaling Architecture
Horizontal Scaling
Horizontal Scaling — Multi-Region with Auto-Scaling Media Servers
Auto-Scaling Strategy
- CPU-based: Scale when CPU > 70%
- Connection-based: Scale when connections > 1000 per server
- Latency-based: Scale when P95 latency > 100ms
- Predictive: Scale before peak hours
- Geographic: Scale based on regional demand
Security Architecture
End-to-End Encryption
End-to-End Encryption — Encrypted Media with Key Exchange
Security Layers
- Transport Security: TLS 1.3 for all connections
- Media Encryption: SRTP with AES-256
- Signaling Encryption: WSS (WebSocket Secure)
- Authentication: OAuth 2.0 / JWT tokens
- Authorization: Role-based access control
Monitoring and Observability
Metrics Collection
Metrics Collection — Application to Dashboard Pipeline
Key Metrics
- Connection Success Rate: % of successful meeting joins
- Audio/Video Quality: Packet loss, jitter, latency
- Server Performance: CPU, memory, network utilization
- User Experience: Join time, call duration, drop rate
- Business Metrics: Active users, meeting minutes, revenue
Alerting System
- Critical: Service outages, high error rates
- Warning: Performance degradation, capacity limits
- Info: Deployment notifications, maintenance windows
- Escalation: PagerDuty integration for 24/7 support
Disaster Recovery
Multi-Region Deployment
- Active-Active: Multiple regions serving traffic
- Failover: Automatic traffic routing during outages
- Data Replication: Cross-region database replication
- Backup: Regular backups with point-in-time recovery
- Testing: Regular disaster recovery drills
Recovery Time Objectives
- RTO: 5 minutes for service restoration
- RPO: 1 minute for data loss tolerance
- Availability: 99.99% uptime SLA
- Monitoring: Real-time health checks and alerts