Setup Synchronized Playback Displays for Multiple Screens

This article provides the instructions to configure synchronized multimedia playback across multiple screens.

Appspace applies the master-slave clock synchronization when scheduling content to ensure the unified synchronization of content across multiple distributed screens.

Clock synchronization nominates a master device as the timekeeper, while slave devices adjust their time to synchronize with the master device’s time, synchronizing content playback between screens and speakers, preventing latency drift.

If you are looking to configure video walls instead, please refer to Setup Video Wall Displays with Appspace.


  • The devices must meet the manufacturer’s minimum hardware and technical specifications. Please refer to Supported Devices & Operating Systems.

    Two or more Appspace App supported devices, installed and configured with the Appspace App within the same environment. However, we only support the following:

    Devices Clock Sync Mode Playlist Channels Advanced Channels Cards
    Chrome OS with i3 processor and above Master and Slave Video and images Media Zone and Text Widget Announcement Card and Data Visualization Card
    BrightSign OS 8
    LG webOS

    • Image and video resolution will depend on the individual device’s resolution.
    • Channel scheduling and dayparting are supported in playlist channels.
    • Only single channel is supported.
  • An active Appspace account, with sufficient User IDs for user mode, or Device IDs for device mode.
  • An active Internet connection.
  • It is recommended that the device clock is set to automatically retrieve time from a Network Time Protocol (NTP) server, with the correct time zone, in order for it to sync correctly with the Appspace server.

    • Appspace cloud servers by default retrieve time from a NTP server. If an Appspace on-premises server is used, ensure the server time is automatically retrieved by a NTP server.
    • Appspace has updated the timezone configurations, which now includes timezones other than GMT. This enables users with daylight savings to adjust the time accordingly.

      For more information, please refer to the Appspace 7.1-ac.8 Release Notes.

  • Please ensure your network is configured to allow Appspace whitelist URLs and the relevant network ports.
  • On your proxy server, whitelist the hostnames listed in the ‘How to set up networks with SSL content filters’ section in the following article:

Configure Synchronized Playback

The table below provides a quick description of all device properties required for configuring synchronized playback for mirrored displays.

Configuration Property Name Property Value Applicability Description
Synchronized Playback player.scheduling.mode synchronized Master and Slave devices Enables the synchronized playback at the layout level.
player.clocksync.mode master Master device Designates each device as a master or slave. Select only one device to act as the master clock.
slave Slave devices
player.clocksync.masterip < IP address > Slave devices only The master device’s IP address is used by the slave device to synchronize the clock.
remote.enable true Master device only Grants permission to slave devices to connect to the master device via WebSocket.
player.content.preloadtime < Number > Master and Slave devices Defines a pre-load time in seconds for content on the device. This helps adjust content playback on devices that take a longer time to load or play (such as low power devices); playing all content in a synchronized manner.
Recommended preload time:
- LG WebOS - 3.5 seconds
- Chrome - 1.5 seconds
- UWP - 3 seconds
- BrightSign - 3 seconds
Debugging player.clocksync.debug true Optional for Master and Slave devices Enable or disable an overlay on the screen that shows debug information.
  • Content will sync every 30 seconds to ensure smoother experience during mid playback.
  • Layout transitioning and video transitioning will be disabled by default. Image transitioning will still be available.

Follow the instructions below to configure synchronized playback on multiple screens for the Appspace App devices.

  1. Register your master and slave devices individually. Follow the instructions in the Register a device article. (Skip this step if devices have already been registered.)
  2. Once all devices have been registered, navigate to Devices from the Appspace menu.
  3. Select the designated master device, and add in the following device properties:
    Device Property Value
    player.scheduling.mode synchronized
    player.clocksync.mode master
    player.clocksync.masterip < master IP address >
    player.content.preloadtime < seconds >
  4. Select the slave device, and add in the following device properties:
    Device Property Value
    player.scheduling.mode synchronized
    player.clocksync.mode slave
    player.clocksync.masterip < master IP address >
    player.content.preloadtime < seconds >
  5. Repeat Step 4 for all slave devices.
  6. You may now assign the desired channel to the devices

Debug Synchronized Playback

To debug synchronized playback on mirrored displays, add the following device property to both the master and slave devices:

Device Property Value
player.clocksync.debug true
Once in debug mode, the debug layer appears on all devices, and switches between four colors (purple, blue, green, black) if all devices are in sync.
The debug layer also displays the following information:
  • Device time.
  • Identify if the device is a master or slave.
  • The Delta (differential) sync between the master, and slave devices.
  • The round-trip between the master, and slave devices.
  • The last updated Delta sync, and round-trip between the master, and slave devices. If the round-trip between devices is larger than 0.5 seconds, the device will show as offline.
  • The master device, will display the number of slave devices connected to it.
  • The slave device, will display the master IP address connected to.

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