Build your own in-car entertainment system — individual touch displays for each passenger, streaming multimedia over a local network with no internet required. Using off-the-shelf hardware and open-source software, each screen costs around $180–$200.
Last updated: February 7, 2026
What's New (Feb 2026)
- Pre-built SD card image — Download, flash, and boot. No manual installation needed. Download here (~1.2GB)
- Rock-solid sync — Integrated kodisync for frame-accurate synchronization. Now achieves sub-10ms sync spread (vs. multiple attempts needed before)
- Auto-negotiation — No more manual master/slave configuration. Each Pi generates a unique hostname from its MAC address and devices auto-discover each other
- One image for all — Flash the same image to all SD cards. No per-device configuration required
Complete wiring diagram: PoE switch powers each Raspberry Pi + touch screen over a single Ethernet cable.
How it works
The system uses a distributed architecture — no central multi-head controller needed. Each passenger screen is an independent Raspberry Pi 4 running Kodi, powered and networked through a single Ethernet cable via Power over Ethernet (PoE). A pocket router acts as the DLNA/DHCP server, serving media files from a USB drive to all screens on the local network.
What you need
| Component | Role |
| PoE switch | Powers and networks all Raspberry Pi screens over single Ethernet cables |
| GL-MT300N-V2 pocket router | DLNA media server + DHCP server (see pocket router DLNA guide) |
| Raspberry Pi 4 + PoE HAT | Media player endpoint (one per passenger screen) |
| Full HD touch display | Passenger-facing screen (one per seat) |
| USB media drive | Stores multimedia files, plugged into the pocket router |
Why this architecture
- Single-cable per screen — PoE eliminates separate power cables, simplifying in-car wiring
- Distributed decoding — each Raspberry Pi handles its own multimedia decoding and rendering, so there is no central bottleneck
- Easily scalable — add more screens by swapping in a PoE switch with more ports
- Fully offline — works in areas with no mobile coverage; all content is served locally
- Individual or shared playback — each passenger can browse and play their own content, or all screens can be synchronized
Cost per screen
Each passenger display costs approximately $180–$200, including the Raspberry Pi 4, PoE HAT, and a full HD touch screen. The PoE switch and pocket router are shared across all screens.
Software stack
- Kodi — open-source media player running on each Raspberry Pi, with DLNA client support built in
- OpenWrt + minidlna — runs on the pocket router, serving media files over DLNA
- Raspberry Pi OS — base operating system for the Pi endpoints
- media-mux — synchronization software that coordinates playback across all screens
For the DLNA server setup on the pocket router, see the companion post: Transforming Your GL-MT300N-V2 Pocket Router into a DLNA Multimedia Server.
Installation
Option 1: Pre-built Image (Recommended)
The easiest way to get started — download and flash the same image to all SD cards:
- Download the pre-built image (~1.2GB)
- Flash to each SD card using balenaEtcher or Rufus
- Insert SD cards into your Raspberry Pi 4's and boot
That's it! Each Pi automatically generates a unique hostname and discovers other devices on the network.
Option 2: Manual Installation
For custom setups, you can install on an existing Raspberry Pi OS. See the manual installation guide for step-by-step instructions.
How sync works
Connect a 3-key USB keyboard to any Raspberry Pi — this becomes the sync trigger device. Press KEY_1 to synchronize all screens:
- The sync script reads the currently playing media and position from the trigger device
- Discovers all media-mux devices on the network via Avahi/mDNS
- Opens the same media file on all devices
- Uses kodisync to pause all players at the exact same frame
- Seeks all players to the same position and resumes playback simultaneously
Sync accuracy: The system achieves sub-200ms synchronization, typically with less than 10ms spread between devices. This is a significant improvement over the earlier version shown in the video, which required multiple sync attempts.
SOURCE CODE
github.com/hackboxguy/media-mux — sync software + pre-built SD card image
github.com/hackboxguy/multiscreen-media — hardware build guide and bill of materials
Version 2 now available: A self-hosting version that eliminates the pocket router. One Pi becomes the master automatically, providing DHCP, DNS, NTP, and DLNA. See Self-Hosting PoE Raspberry Pi 4 Infotainment System.
