Viz Engine Administrator Guide

Version 5.0 | Published December 20, 2022 ©

Working with Synchronous Output

Information: This is supported on the Classic Render Pipeline only!

With a dual channel setup it is easy to create two fill/key pairs for the left and right eye/camera during a stereo production. A special version of the Video Wall Distributor synchronously distributes one command to the two instances of the Viz Engine. It includes a built-in locking mechanism that makes sure both Viz Engines stay in sync, even if one of them drops a frame. This feature can be set On or Off by a simple command sent through the distributor.

This section contains information on the following topics:

Hardware Requirements

  • Certified Vizrt workstation.

  • Two NVIDIA Quadro (GPUs must be identical).

  • Matrox video in- and output card.

Software Requirements

  • Viz Artist/Viz Engine version 3.3 or later.

Synchronous Output Configuration

The Viz Engine installer includes an option for dual channel support. Choosing this option generates desktop icons to start the configuration and the Viz Engine for channel 1 as well as for channel 2.

Note: Viz Artist is only available for channel 1 as it always runs on the first GPU.

The configurations use one video input per channel and embedded audio on the channel. The table below shows the main differences in the configurations:

Viz Engine 1

Viz Engine 2

Stereo Mode



Video In A



Video In B


Video 1

Video In C+D



Clip A

Clip 1

Clip 1

Clip B

Clip 2

Clip 2

Video Out A



Video Out B



Video Out C



Video Out D



Communication Port



Since this configuration puts an extra load on the Matrox card, it is important to use the available resources with care:

  • In the video section of the scene, switch off all unused layers.

  • Let the GPU do the color conversion.

The Matrox card itself is synced through the first instance of Viz Engine.

It is important that only one display is active in the NVIDIA control panel. If you span the desktop across multiple GPUs, the affinity mask has no effect and both Viz Engines render on GPU.

To Configure a Machine with Two Graphics Cards

  1. Install Viz Engine and create shortcuts for two channels using the -u1 and -u2 parameter.

  2. Create two copies of the selected Viz Config file and place them in your Viz directory and rename one to VIZENGINE-0.cfg and the other VIZENGINE-1.cfg.

  3. Load the correct output format using the configuration profiles and apply dualchannel-0.cfg for instance 1 and dualchannel-1.cfg for instance 2.

  4. Start Viz Config for both instances (channel 1 and channel 2) and enter settings for the Viz Graphics Hub (see Database) and enable Auto Log-in.

    • Auto log-in is needed as dual channel Engines start without a UI.

  5. Start Viz Engine for channel 1 and then Viz Engine for channel 2.

    • Channel 1 signals are available on Matrox OutA (fill) and OutC (key).

    • Channel 2 signals are available on Matrox OutB (fill) and Out D (key).

See Also