More articles in Guides

Art-Sync, sACN Sync & Auto Sync

Art-Sync, sACN Sync & Auto Sync article image

What is Synchronous Mode?

Synchronous mode is a method by which all PixLite® devices in a lighting installation can output frames together at the same time. The central software or control device that is sending out the lighting data over Ethernet is responsible for generating the extra data required to sync all the listening devices to itself. Synchronous mode is most useful in situations where more than one PixLite® device is responding to highly dynamic data (such as video content or content that changes rapidly).

PixLite® Mk3 devices support both Art-Sync and sACN Sync, and also feature an internal Auto Sync failback in the event an external sync source is not present. PixLite® Mk2 controllers support Art-Sync only. Discover the range of PixLite Mk3 controllers here.

What Problem Does Synchronous Mode Solve?

When lighting data is sent over a network using sACN (E1.31) or Art-Net, each universe of data is sent using its own Ethernet packet. These packets get delivered to the PixLite® devices typically using one or more network switches. The time it takes for the packets to be delivered, as well as the order they are delivered in, can vary based on several factors that can’t be easily controlled. This means that on the network delivery side there is some uncertainty in when universes may be delivered to a PixLite® device and generally different PixLite® controllers will receive their data at slightly different times. On the PixLite® devices themselves, there may be different frame rates running on each one (depending on its configuration). Even if all PixLite® devices had the same refresh rate, there is no way to make sure that they all start outputting those frames at the same time as each other.

These factors can create a problem sometimes referred to as ‘tearing’. This is when pixels from different PixLite® devices are showing content from different frames at the same time. It can also theoretically happen (to a much lesser extent) within one device itself. Synchronous mode can help prevent this problem by forcing all devices to output frames together, increasing the visual quality of a lighting system.

The Basics of Synchronous Mode

The source of the lighting data sends out all universes that it normally would for a single frame. Then it waits for a small amount of time (enough for the devices to receive all these packets) and sends out a special synchronization packet to all devices which they will likely receive at the same time. This packet tells all the devices that they can now act on the received packets and display the updated frame on their outputs. After the devices do this once, they don’t change the output again until the next sync command is received. This process keeps all the devices in sync.

How To Enable Synchronization

The sending software that is used may or may not support synchronous mode, so check with the applicable vendor. If the sending software has synchronous mode enabled, the PixLite® will automatically go into synchronous mode. Both Art-Sync and sACN Sync are supported with PixLite® Mk3 devices. There is no configuration required on the PixLite® side, however the status of Sync Mode can be monitored – see below.

Note: PixLite® Mk2 devices only support Art-Sync.

Monitoring Synchronous Mode

Whilst no configuration on the PixLite® side is required to enable Sync Mode, the status of this mode, as well as various statistical information can be monitored with the Management Interface (on PixLite® Mk3 devices).

Simply navigate to the Statistics page of the Web Interface and view the relevant monitoring information in the following panes:

  • Pixel Data
  • Auxiliary Output Data
  • sACN (E1.31) Universes
  • Art-Net Universes

For more details on the available monitoring information, see the PixLite® Mk3 Management Guide.

Auto Sync Failback

When an active external source of synchronization is not available via the incoming data PixLite® Mk3 devices use internal algorithms to detect the end of a frame so that they can output data as close as possible to the source’s frame rate. If an external Sync is ever established, the PixLite® will switch to using this external source for synchronization as a priority.

This failback will be enforced automatically, without the need for any intervention or configuration. With or without an external source of synchronization, all outputs on a PixLite® Mk3 device will be synchronized. However the external synchronization source is always desirable and will result in a better display if multiple devices are deployed to the installation.

sACN Synchronization Caveats

sACN Sync allows every universe to have individual synchronization parameters set. This allows a highly scalable deployment where multiple sACN sources may be present and driving different parts of an installation, each with their own synchronization that do not interfere with each other.

The relevant synchronization parameters available on each universe are:

  1. Force Synchronization. This option means the device is not allowed to fail over when a synchronization source is not present or times out.
  2. Synchronization Address. This is a multicast address used to receive synchronization packets.

On a PixLite® Mk3 device, many universes may be used for a single pixel output. All these universes should have the same synchronization parameters set, or it is logically impossible for the device to follow the instructions in each data universe.

If making use of the Auxiliary DMX512 output on a PixLite® Mk3 device, the synchronization parameters for its data universe may be different to the pixel universes, as it can operate independently of the pixel frame output.

Synchronous mode is important when multiple PixLite® devices are responding to data that is rapidly changing, at the same time. If you have a lighting project where this is vital, you’ll need an Advatek PixLite® Mk3 controller! This, along with a host of other features, make the PixLite® Mk3 processor the best choice for your lighting application.

Recommendations to Give the Best Results

For a pixel system to look its best, proper synchronization and universe management should be followed. The PixLite Mk3 range of pixel controllers allows for this to happen. In order to achieve this, we recommend the following when working with a PixLite Mk3 pixel controller.

Whenever possible, an external source of synchronization should be used. Any Art-Net or sACN universes in use should have Art-Sync and sACN Sync activated. If this is not possible, then the next two recommendations will assist the controller in auto syncing more reliably to the data source.

  1. Avoid "optimizing frames". This setting removes universes from a frame that haven't changed since last time they were sent. With this enabled, the output jitter will increase because the controller will be waiting some time for a universe that will never arrive, before giving up and considering it dropped. This can be avoided by disabling "optimize frames" in the sending software.
  2. Use sequential universe numbers for all universes that the controller should listen for. Avoiding gaps in the universe numbers will improve the ability for the controller to recognize frames and self-synchronize to the data source. Consider using "Auto Patch" when configuring the device.