Knowledge Base

Video Slave 3 - Playback with multiple video devices

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One important feature that sets Video Slave 3 apart from other solutions on the market is its flexibility when it comes to video output destinations.

With Video Slave 3, you can play to multiple video output destinations at the same time and Video Slave will do its best to keep all video devices in proper sync. For each video device there are separate settings so you can decide what each video device should display in a very fine grained manner (details are explained in this article).

There are currently four different types of video devices available in Video Slave:

  • screen video devices (Internal Video Device and Fullscreen Video Device)
    There are currently two screen video devices in Video Slave. The first is the video player view in the main window. The other one is the fullscreen window.
  • Syphon video devices (Pro/Dub only)
    When using Video Slave as a host to supply video frames to another application using the Syphon framework, this kind of video device is used. There is always only one Syphon video device.
  • Blackmagic video devices
    Video Slave supports playout through Blackmagic DeckLink, UltraStudio and Intensity devices. When the application is started, it scans the system for the available devices. PCIe cards or external devices with multiple outputs show up as separate video devices per output. In Video Slave 3 dub, two Blackmagic devices can be used at the same time
  • AJA video devices
    As a new feature of version 3, Video Slave now also supports playout through devices from AJA's KONA, Io and T-TAP product range. As with Blackmagic devices, Video Slave scans the system for available devices when it is launched. PCIe cards or external devices with multiple outputs show up as separate video devices per output. In Video Slave 3 dub, two AJA devices can be used at the same time.


For each enabled video device, Video Slave renders video frames several times per second (depending on the settings and the type of device). Thus, it is crucial to only set the devices enabled that you really need. Each render pass uses precious computing time and using more devices than actually needed can cause hiccups during playback.

If you're using two Blackmagic or AJA devices when doing ADR for example, you should consider turning off the internal and fullscreen video devices to avoid hiccups and stutters during playback.

Video Slave and the AVID Video Engine in Pro Tools

If Video Slave is used on the same machine that also runs Pro Tools 11 or later, we recommend that you turn the AVID video engine off. You can do so by opening the Playback Engine window in Pro Tools and uncheck the checkbox labelled "Video Engine". After disabling the video engine, it is important to restart Video Slave if you're using Blackmagic or AJA cards. Pro Tools apparently blocks the video hardware if the AVID video engine is turned on. We also learned that turning off the video engine in Pro Tools positively affects Video Slave's performance.