Video Conferencing System - Architecture
High-Level Architecture
┌─────────────────────────────────────────────────────────────────┐
│ Client Applications │
├─────────────┬─────────────┬─────────────┬─────────────────────┤
│ Web Browser │ Desktop App │ Mobile App │ Room System │
│ (WebRTC) │ (Native) │ (Native) │ (Hardware) │
└─────────────┴─────────────┴─────────────┴─────────────────────┘
│
┌─────────┴─────────┐
│ Load Balancer │
│ (Global CDN) │
└─────────┬─────────┘
│
┌─────────────────────────────┼─────────────────────────────┐
│ Edge Layer │
├─────────────────────────────┼─────────────────────────────┤
│ ┌─────────────┐ ┌─────────┴─────────┐ ┌─────────────┐ │
│ │ STUN/TURN │ │ Media Gateway │ │ Edge Cache │ │
│ │ Servers │ │ (WebRTC Proxy) │ │ (Static) │ │
│ └─────────────┘ └─────────┬─────────┘ └─────────────┘ │
└─────────────────────────────┼─────────────────────────────┘
│
┌─────────────────────────────┼─────────────────────────────┐
│ Core Services Layer │
├─────────────────────────────┼─────────────────────────────┤
│ ┌─────────────┐ ┌─────────┴─────────┐ ┌─────────────┐ │
│ │ Signaling │ │ Media Servers │ │ Recording │ │
│ │ Service │ │ (SFU/MCU) │ │ Service │ │
│ │ │ │ │ │ │ │
│ └─────────────┘ └─────────┬─────────┘ └─────────────┘ │
│ │ │
│ ┌─────────────┐ ┌─────────┴─────────┐ ┌─────────────┐ │
│ │ Meeting │ │ Chat Service │ │ User │ │
│ │ Service │ │ │ │ Service │ │
│ └─────────────┘ └───────────────────┘ └─────────────┘ │
└─────────────────────────────────────────────────────────┘
│
┌─────────────────────────────┼─────────────────────────────┐
│ Data Layer │
├─────────────────────────────┼─────────────────────────────┤
│ ┌─────────────┐ ┌─────────┴─────────┐ ┌─────────────┐ │
│ │ PostgreSQL │ │ Redis │ │ Cassandra │ │
│ │ (Metadata) │ │ (Sessions) │ │ (Analytics) │ │
│ └─────────────┘ └───────────────────┘ └─────────────┘ │
│ │
│ ┌─────────────┐ ┌───────────────────┐ ┌─────────────┐ │
│ │ Object │ │ Elasticsearch │ │ Time Series │ │
│ │ Storage │ │ (Search/Logs) │ │ DB (Metrics)│ │
│ │ (S3) │ │ │ │ (InfluxDB) │ │
│ └─────────────┘ └───────────────────┘ └─────────────┘ │
└─────────────────────────────────────────────────────────┘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:
Participant A ──┐
├──► SFU ──┐──► Participant B
Participant C ──┘ ├──► Participant D
└──► Participant EFeatures:
- 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:
Media Streams → Compositor → Encoder → Storage → Playback APIComponents:
- 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
┌─────────────┐ Signaling ┌─────────────┐
│ Client A │◄────────────────►│ Client B │
└─────────────┘ └─────────────┘
│ │
│ Media (P2P or via SFU) │
└────────────────────────────────┘SFU Media Routing
┌─────────────┐ ┌─────────────┐
│ Client A │ │ Client B │
│ │ │ │
│ ┌─────────┐ │ Upload │ ┌─────────┐ │
│ │ Camera │ ├──────────┐ │ │ Display │ │
│ └─────────┘ │ │ │ └─────────┘ │
│ ┌─────────┐ │ ▼ │ ┌─────────┐ │
│ │ Mic │ │ ┌─────────┐ │ │ Speaker │ │
│ └─────────┘ │ │ SFU │ │ └─────────┘ │
└─────────────┘ │ Server │ └─────────────┘
└─────────┘
│
Download
▼
┌─────────────┐
│ Client C │
│ │
│ ┌─────────┐ │
│ │ Display │ │
│ └─────────┘ │
│ ┌─────────┐ │
│ │ Speaker │ │
│ └─────────┘ │
└─────────────┘Adaptive Bitrate Streaming
Client Bandwidth Assessment
│
▼
┌─────────────────────┐
│ Quality Selection │
│ - 4K (8 Mbps) │
│ - 1080p (4 Mbps) │
│ - 720p (2 Mbps) │
│ - 480p (1 Mbps) │
│ - 240p (500 kbps) │
└─────────────────────┘
│
▼
Stream DeliveryScaling Architecture
Horizontal Scaling
┌─────────────────────────────────────────────────────────┐
│ Load Balancer │
└─────────────────────┬───────────────────────────────────┘
│
┌─────────────┼─────────────┐
│ │ │
▼ ▼ ▼
┌─────────────┐ ┌─────────────┐ ┌─────────────┐
│ Region │ │ Region │ │ Region │
│ US-East │ │ EU-West │ │ Asia-Pac │
└─────────────┘ └─────────────┘ └─────────────┘
│ │ │
▼ ▼ ▼
┌─────────────┐ ┌─────────────┐ ┌─────────────┐
│ Media │ │ Media │ │ Media │
│ Servers │ │ Servers │ │ Servers │
│ (Auto-scale)│ │ (Auto-scale)│ │ (Auto-scale)│
└─────────────┘ └─────────────┘ └─────────────┘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
┌─────────────┐ Encrypted ┌─────────────┐
│ Client A │ Media Stream │ Client B │
│ │◄────────────────►│ │
│ Private Key │ │ Private Key │
└─────────────┘ └─────────────┘
│ │
└────── Key Exchange ────────────┘
(via Signaling Server)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 ┌─────────────┐
│ Application │──────────────►│ Prometheus │
│ Services │ │ Server │
└─────────────┘ └─────────────┘
│
┌─────────────┐
│ Grafana │
│ Dashboard │
└─────────────┘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