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To keep Raspberry Pi video-wall displays in sync, align the system clocks on every Pi and use playback software that coordinates when each device starts or where it is in the video. Clock synchronization alone is not enough: test the complete setup on the actual hardware and content, because the available project documentation does not establish a universal frame-accuracy guarantee.
How do I sync multiple Raspberry Pis for a video wall?
Think of synchronization as two separate jobs: keeping the Pis’ clocks aligned, then coordinating playback. A shared clock helps devices act on a common time, but it does not tell them what to play or control their playback positions. The player or controller must handle that second job.
Raspberry Pi Ltd’s camera software documentation says clocks on separate devices should be synchronized with NTP, normally enabled by default in Raspberry Pi OS, or with a protocol such as PTP if NTP is not precise enough. The guidance concerns camera timing; it explains why clock alignment matters, but it is not a performance guarantee for every video-wall player.
1. Align the clocks
Check that each Pi has the correct system time and that its NTP synchronization is working. If your measured timing requirements exceed what your NTP setup can provide, investigate PTP. Do not assume that installing a more precise clock protocol will, by itself, synchronize the media players.
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2. Choose playback software that coordinates playback
Use a system that explicitly controls playback across devices, rather than relying on each Pi to launch a video independently. For example, the OMXPlayer-Sync project describes a networked master/slave setup, while Pi Video Machine describes a control machine sending control messages to Raspberry Pi players. Both are project-specific implementations; check their compatibility with your current Pi models, operating system, and player before relying on them.
3. Verify the result on the wall
Test with the actual screens, network, content, frame rate, display modes, and Pi models you plan to deploy. Record how far apart visible events appear on the displays and check again over the length of playback. The cited documentation provides no directly comparable current accuracy benchmark, so do not label a system frame-accurate based only on a successful clock check or a project’s description.
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Which playback approach should I use?
The right choice depends on whether your priority is coordinated playback, centralized management, or a tiled-wall layout. The sources describe different capabilities and assumptions, but do not provide a head-to-head timing test.
| Approach | What the documentation describes | Important checks |
|---|---|---|
| OMXPlayer-Sync | Networked local playback in a master/slave arrangement. | The repository’s setup instructions are legacy and include a customized OMXPlayer package from 2017. Verify compatibility with your OS, Pi, and player; follow its specific filename, cable, and video-duration requirements. |
| Pi Video Machine | A player script on each Pi, with control ports and a control interface on another machine. | The documented workflow uses OMXPlayer and has dependencies that may not fit current systems. Check compatibility and clock behavior, particularly for high-frame-rate video. |
| rein zor/videowall | A synchronized mirrored or tiled-wall architecture. | The repository describes an older Raspberry Pi 3 or Zero setup using Raspbian Stretch Lite, a Pi client, Ethernet adapter, and microSD card. Treat it as an architectural example, not evidence of current OS or hardware support. |
| PiSignage groups | Group-level display settings, including resolution and orientation, as well as player options by product version. | Group management and player selection do not establish frame-accurate synchronization across a wall. Check the version-specific player behavior and measure your own installation. |
For additional context, the project documentation is available from OMXPlayer-Sync, Pi Video Machine, and reinzor/videowall. PiSignage documents its group settings and player options here.
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What to know about OMXPlayer-Sync’s setup
If you choose OMXPlayer-Sync, the repository lists several operational assumptions that can prevent the documented setup from working as expected:
- Use the same filename for the media on the master and slave players.
- Connect the RJ45 cable before starting the master.
- Use videos at least 60 seconds long, as the project recommends.
- Check the repository’s installation and player requirements against your current OS and hardware; its customized OMXPlayer package dates to 2017.
These are instructions for that project, not universal requirements for every multi-Pi playback system.
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Why are my video-wall screens out of sync?
Work through the chain from clocks to playback to display output. Changing several components at once makes it harder to identify the source of drift.
- Check system time on every Pi. Confirm NTP is operating on each device. If clock differences remain significant for your use case, investigate the synchronization method and network configuration before changing players.
- Confirm that playback is actually coordinated. Make sure the selected software controls starts or playback positions across devices. A shared clock alone is not a playback controller.
- Check the project’s own operating requirements. For OMXPlayer-Sync, verify matching filenames, the RJ45 connection before master startup, and the recommended minimum video duration.
- Check player and display settings. Confirm that every Pi uses a compatible player and that resolution and orientation settings match the intended wall layout.
- Test the exact media and installation. Check encoding, frame rate, Pi model, OS image, network, and display mode using the content you intend to show. Record observed alignment over time instead of inferring accuracy from clock synchronization.
How should I plan the network?
Wired Ethernet may be appropriate for a multi-player installation, but the available ports and connectivity on your particular Pi hardware determine what you need. If there are not enough ports for the wired clients, a network switch can add ports; choose its port count and speed for the actual installation. The cited project documentation does not prescribe a switch model or specification. Some hardware may need an Ethernet adapter, but that is not a universal requirement.
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How do PiSignage player versions affect a video wall?
PiSignage’s documentation lists different player defaults by product version: OMXPlayer for versions earlier than 4 and Chromium for version 4 and later. It lists MPV for avoiding gaps between videos in certain situations, and VLC/EXO for 4K support on Raspberry Pi in version 4 and later. Those are player and playback-option details, not a claim that any of these choices keeps multiple screens frame-accurately synchronized. Confirm the behavior for the version and hardware you intend to use, then test the wall.
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