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Version: 2.0 (Legacy)

The OpenHD Ecosystem

Understanding the OpenHD system architecture and component relationships.

System Overview​

OpenHD consists of multiple interconnected components:

  • Air Unit: Onboard aircraft systems
  • Ground Unit: Ground station hardware
  • Ground Software: Control and display applications
  • Communication Protocol: Data exchange standards

Core Components​

OpenHD Core​

  • Video Pipeline: H.264/H.265 encoding and streaming
  • Telemetry System: MAVLink integration and forwarding
  • RF Management: Radio frequency control and optimization
  • Configuration System: Parameter management and storage

WFB-ng (WiFi Broadcast Next Generation)​

  • Packet Injection: Raw packet transmission
  • FEC (Forward Error Correction): Error recovery mechanisms
  • Diversity Reception: Multiple antenna support
  • Link Adaptation: Dynamic parameter adjustment

Architecture Layers​

Hardware Layer​

  • Single Board Computers: Raspberry Pi, Radxa, etc.
  • Radio Hardware: WiFi cards and antennas
  • Camera Interfaces: CSI, USB, IP cameras
  • Sensors: GPS, IMU, environmental sensors

System Layer​

  • Linux Distribution: Custom OpenHD Linux images
  • Kernel Modifications: RF drivers and optimizations
  • System Services: Background processes and daemons
  • Hardware Abstraction: Device-specific adaptations

Application Layer​

  • OpenHD Service: Main system control service
  • Camera Service: Video capture and encoding
  • Telemetry Service: MAVLink processing
  • Web Interface: Configuration web UI

User Interface Layer​

  • QOpenHD: Primary ground station software
  • Mobile Apps: Android and iOS applications
  • Web Interface: Browser-based configuration
  • OSD System: On-screen display overlay

Data Flow​

Video Pipeline​

Camera → Encoder → Packetizer → RF Transmitter
                                      ↓
RF Receiver → Depacketizer → Decoder → Display

Telemetry Flow​

Flight Controller → OpenHD Air → RF Link → OpenHD Ground → Ground Software

Control Flow​

Ground Software → OpenHD Ground → RF Link → OpenHD Air → Flight Controller

Communication Protocols​

Internal Protocols​

  • OpenHD Protocol: Internal system communication
  • MAVLink: Flight controller integration
  • REST API: Web interface communication
  • UDP Streams: Video and telemetry distribution

RF Protocols​

  • WFB-ng: Video and telemetry transmission
  • WiFi 802.11: Standard WiFi for configuration
  • Custom Frames: Optimized data structures
  • Frequency Management: Channel selection and hopping

Development Environment​

Build System​

  • CMake: Cross-platform build system
  • Cross-compilation: ARM target compilation
  • Package Management: Debian package creation
  • Continuous Integration: Automated testing and builds

Dependencies​

  • GStreamer: Video processing pipeline
  • FFmpeg: Video encoding and decoding
  • OpenCV: Computer vision operations
  • Qt: User interface framework

Development Tools​

  • Git: Version control system
  • GitHub: Repository hosting and collaboration
  • Docker: Containerized build environments
  • QEMU: ARM emulation for testing

Component Interaction​

Service Communication​

  • D-Bus: Inter-process communication
  • Shared Memory: High-performance data sharing
  • Unix Sockets: Local communication channels
  • Network Sockets: Remote communication

Configuration Management​

  • JSON Configuration: Human-readable settings
  • Parameter Validation: Input validation and bounds checking
  • Default Values: Fallback configuration values
  • Runtime Updates: Dynamic parameter changes

Extension Points​

Plugin Architecture​

  • Video Plugins: Custom video processing
  • Telemetry Plugins: Custom telemetry handling
  • OSD Plugins: Custom display elements
  • Protocol Plugins: Additional communication protocols

API Interfaces​

  • REST API: HTTP-based configuration interface
  • WebSocket API: Real-time data streaming
  • UDP API: Low-latency data access
  • Callback API: Event-driven programming

Quality Assurance​

Testing Framework​

  • Unit Tests: Component-level testing
  • Integration Tests: System-level testing
  • Hardware Tests: Real hardware validation
  • Performance Tests: Latency and throughput measurement

Code Quality​

  • Static Analysis: Code quality checking
  • Code Reviews: Peer review process
  • Documentation: Comprehensive code documentation
  • Coding Standards: Consistent coding practices

Deployment​

Image Building​

  • Custom Linux Images: Tailored system images
  • Package Installation: Automated package deployment
  • Configuration Templates: Default system configurations
  • Hardware Variants: Device-specific optimizations

Update Mechanism​

  • OTA Updates: Over-the-air system updates
  • Package Updates: Individual component updates
  • Configuration Migration: Settings preservation
  • Rollback Capability: Revert to previous versions

Performance Considerations​

Latency Optimization​

  • Pipeline Optimization: Minimize processing delays
  • Kernel Bypassing: Direct hardware access
  • Priority Scheduling: Real-time process scheduling
  • Buffer Management: Minimize buffering delays

Resource Management​

  • CPU Allocation: Process priority management
  • Memory Management: Efficient memory usage
  • Power Management: Battery life optimization
  • Thermal Management: Heat dissipation strategies

Future Development​

Planned Features​

  • AI Integration: Computer vision and autonomous features
  • Cloud Integration: Remote monitoring and control
  • Mesh Networking: Multi-node communication
  • Protocol Evolution: Enhanced communication protocols

Technology Roadmap​

  • Hardware Support: New platform support
  • Protocol Enhancements: Improved communication
  • User Interface: Enhanced user experience
  • Performance: Continued optimization

:::info Developer Resources Additional developer documentation, APIs, and tools are available in the OpenHD GitHub repositories. :::

:::warning System Complexity The OpenHD ecosystem is complex. Start with simple modifications and gradually work on more complex features. :::

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