Matflix
Hardware architecture for a bus-powered local media distribution device. A ruggedized single-board computer creates a Wi-Fi hotspot serving movies, series, and music to passengers from local NVMe storage without an internet connection.
RK3588 / Raspberry Pi CM4 · Linux (DietPi / Ubuntu Server) · Nginx · Wi-Fi 6 (802.11ax) · Wi-Fi Direct · BLE · NVMe · ESP32
01 Product overview
What the product does
Matflix is a ruggedized device designed for public minibuses. It creates a local Wi-Fi hotspot that serves movies, series, music, and podcasts from onboard NVMe storage. Nearby vehicles can exchange new content through Wi-Fi Direct without a central internet connection.
02 Problem and context
What it needed to solve
Mobile data can be expensive or inconsistent along public transport routes. The system needed to distribute a media library without depending on a continuous internet connection while fitting the power, heat, dust, and vibration constraints of a vehicle.
03 My contribution
What I worked on
- Designed the full hardware stack including SBC selection, storage architecture, dual-radio Wi-Fi configuration, and power subsystem
- Designed the P2P synchronization protocol using Wi-Fi Direct and BLE beacons for inter-bus content propagation
- Specified the mechanical enclosure, thermal management, vibration isolation, and automotive electrical integration
- Developed the bill of materials and cost model targeting sub-$150 per unit at volume
- Authored the complete system architecture documentation covering compute, storage, networking, power, and enclosure
05 Engineering and outcomes
Implementation details
System
- Rockchip RK3588-based SBC (or Raspberry Pi CM4) as compute core with hardware H.264/H.265 decode
- 1TB NVMe M.2 SSD for content library with EXT4 filesystem, capable of 30+ concurrent 720p streams
- Dual Wi-Fi radio: MediaTek MT7921/MT7922 (Wi-Fi 6, passenger-facing) plus dedicated 5GHz adapter (bus-to-bus P2P sync)
- BLE beacon via ESP32 module for low-power bus discovery and content manifest diffing before full Wi-Fi sync
- 12V/24V automotive DC-DC buck converter with TVS diode, automotive fuse, and LiPo UPS for graceful shutdown
- IP54-rated aluminum passive-cooling enclosure with vibration-dampened mounting bracket
- Ad injection middleware serving mandatory 15-minute interstitials as the primary revenue mechanism
Verified results
- 30+ Concurrent StreamsHardware-decoded video on RK3588 with NVMe sequential read handles 30 simultaneous 720p streams well within thermal and bandwidth limits.
- Zero-Internet DistributionP2P Wi-Fi Direct sync lets nearby buses exchange new content without a central connection.
- Sub-$150 Unit CostBill of materials designed for cost targets compatible with individual matatu owner-operator economics across the Kenyan market.
Lessons
- For this hardware, durability and power mattered more than peak throughput. Voltage spikes, heat, dust, and vibration shaped the design.
- Peer-to-peer synchronization architectures are underexplored for content distribution. The matatu fleet becomes the CDN. Each bus acts as both a consumer and a propagation node. This model scales without any central infrastructure cost.
- Ad injection at the network layer is simpler and more reliable than application-level ad insertion, and it prevents users from bypassing ads by switching media apps.