External Device Sync Guide: OptiHub

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This page provides general instructions on how to use the OptiHub for integrating external devices with Flex series mocap systems. The OptiHub not only provides power for the USB cameras, but it also includes external sync in/out ports for integration of external devices. With proper configurations, you can have another device (master) control the mocap system or have the mocap system control another external device (slave), or both. Setup instructions for both slave and master devices will be covered. Note that the sync setup may vary depending on the type of integrated devices as well as the morphology of the communicated sync signals. Use this guide for understanding the general idea of how external devices are implemented, and apply it for your own needs.

External Device Synchronization

On the OptiHub, there are one External SYNC In and one External SYNC Out ports for connecting external devices. In general, master devices connect to the input port for controlling the mocap system, and slave devices connect to the output port to be triggered by the mocap system. Once the devices are connected, input and output source needs to be specified under the Custom Synchronization pane in Motive.


Important Note

Please note that the OptiHub is not designed for precise synchronization with external devices. It is used to provide only a rough synchronization to a trigger event on the input/output signal. Using an OptiHub, there will be some amount of time delay between the trigger events and the desired actions, and for this reason, the OptiHub is not suitable for the precisely synchronizing to an external device. To accomplish such synchronization, it is recommended to use the eSync instead along with an Ethernet camera system.

Additional Notes:

  • Unlike the eSync, the OptiHub cannot generate an output signal at a higher frequency than the camera capture rate.
  • When using multiple OptiHubs, input and output ports of only the master OptiHub can be used. The master OptiHub is the first OptiHub within the daisy-chained RCA sync chain.

  • The OptiHub 2.
  • The OptiHub 2.
  • TrackingBars2.png

    Duo/Trio Tracking Bars: For Tracking Bars, use the Sync In/Out ports on the I/O-X USB hub.

    Synchronization Setup

    Setting Up a Master Device

    Step 1. [Hardware] Connect a master device into the External SYNC In port of the master OptiHub.

    Step 2. [Motive] Launch Motive. Open the Synchronization pane under the Tools tab.

    Step 3. [Motive:Synchronization pane] From the drop-down menu, change the sync mode to Custom Synchronization. This mode allows users to configure custom sync settings for integrating, or outputting, sync signals.

    Step 4. [Motive:Synchronization pane:Custom Synchronization:Sync Input] Configure the Sync Input source and the corresponding source settings. If you are using an external device connected to the External SYNC In port as the sync source, set the input source to Sync In. See more under the Input Source section of this page.

    Step 5. [Motive:Synchronization pane:Custom Synchronization] Once everything is configured, press Apply.

    Setting Up a Slave Device

    Step 1. [Hardware] Connect a slave device into the External SYNC Out port of the master OptiHub.

    Step 2. [Motive] Launch Motive. Synchronization pane under the Tools tab.

    Step 3. [Motive:Synchronization pane] From the drop-down menu, change the sync mode to Custom Synchronization. This mode allows users to configure custom sync settings for integrating, or outputting, sync signals.

    Step 4. [Motive:Synchronization pane:Custom Synchronization:External Sync Output] For setting up a slave device, configure the Sync Output source under the External Sync Output settings. Select desired output signal characteristic (type and polarity) that the slave device will receive. See the Output Source section of this page for details.

    Step 5. [Motive:Synchronization pane:Custom Synchronization] Once configured, press Apply to configure the settings.

    Input Source

    The Sync Input configuration determines how the camera system is synchronized. Depending on which input source is configured under the custom sync settings, the cameras will shutter at the corresponding frequency. To configure the sync input signals, first define an input Source and then configure the respective trigger settings. The following input sources can be configured with the OptiHub:

    Internal Sync

    (The camera system will be the master)

    The Internal Sync sets the OptiHub as the sync source. This is the default sync configuration which uses either the OptiSync or the WiredSync protocol for synchronizing the cameras. If the OptiSync is used, the Master OptiHub will generate an internal sync signal which will be propagated to other (slave) OptiHub(s) via the Hub Sync Out Jack and Hub Sync In Jack. If the WiredSync is used, the internal sync signal will still be generated but it will be routed directly to the cameras via the RCA cables connecting the camera sync chain.

    When the Internal Sync is selected as the sync source, Internal Sync Freq (Hz) can be set under the Synchronization Control section. This setting determines how the OptiHub triggers the camera exposures or the camera framerate.

    Sync In

    (The camera system will be the slave)

    When synchronizing the camera system to an external device, set the source to Sync In, and the camera system references the external signal through the SYNC In port as the master sync. Then, the Input Trigger event must be defined in order for the camera systems to respond appropriately to the incoming signal; available triggers are Either Edge, Rising Edge, Falling Edge, High Gated, and Low Gated. Note that the suitable event will vary depending on characteristics of the received signal and how you want the system to synchronize with it.

    For syncing to input signals with a frequency higher than the supported camera frame rates, the Input Divider can be applied so that the sync source is downsampled to the supported rate range.

    USB Sync

    (The camera system will be the slave)

    This mode is for customers who use the software development kits and would like to have their software trigger the cameras instead. Using the provided API, the OptiHub will can receive the trigger signal from the PC via the OptiHib's USB uplink connection.

    Trigger and Camera Exposure

    Note that the precise moment of the camera exposure does not exactly coincide with the sync input trigger event. There is a fixed latency between these two events due to specific implementation of the sensors used in the cameras. This delay from the onset of the trigger-event to the start of exposure on the cameras can be calculated as the following:

    Flex 3 and Duo/Trio tracking bars

    • Camera exposure (measured in scanlines for Flex 3 cameras)
    • Imager Scan-Rate: Frame Rate Setting defined under the Devices pane.
    Imager Scan-Rate Camera Sync Time Trigger to Exposure Delay (seconds)
    OptiSync WiredSync
    100% +348e-6 -123e-6 10.097e-3 - (Exposure * 20.42e-6) + CameraSyncTime
    50% +228e-6 -224e-6 20.097e-3 - (Exposure * 40.84e-6) + CameraSyncTime
    25% -15e-6 -486e-6 20.097e-3 - (Exposure * 81.68e-6) + CameraSyncTime

    Flex 13

    Flex 13 cameras have a different trigger-to-exposure latency. From the moment the sync trigger event is received, it takes 480 microseconds for the cameras to synchronize and start exposing. After this delay, the Flex 13 cameras expose for the duration defined under the exposure settings in the Devices pane. The camera exposures are measured in microseconds for Flex 13 cameras.

    • Trigger to exposure delay in Flex 13 cameras.

    Output Source

    Using the BNC splitter for connecting additional slave devices.

    The External SYNC Out port of the OptiHub can be used if you want to set up the camera system to be a master of other systems. The output port sends out the sync signals which can be configured under the External Sync Ouput section of the Custom Synchronization pane. First of all, understand the characteristic of sync signal that the connected slave device is expecting and configure the output source accordingly.

    • All output signals can be inverted by setting the Output::Polarity to Inverted.
    • For connecting more than one slave devices, output signals may be split using a BNC splitter.
    • The sync hubs are capable of sending out the following signals:

    Exposure Time & Gated Exposure Time

    Exposure output signals to inform when the cameras are exposing. When the output type is set to Exposure Time, the sync hub asserts the output signals when the cameras are exposing, or shuttering, in the live mode. When the output is configured to Recording Pulse, the exposure signal is asserted only when Motive is recording.

    • Exposure Time output signal.

    Recording Gate

    The Recording Gate signal can be used to tell the slave device when Motive is recording or not. When configured to Recording Gate, the sync hub will output a constant high voltage signal when Motive is recording.

    • Recording Gate output signal.


    Gated Output Signal (OptiHub) Note:

    The gated (while-recording) output signal from the OptiHub is not frame-synchronous with the recorded frame data.
    When the recording trigger is received in the middle of a frame, mocap frames starting from the next one get recorded in the Take. The gate output signal, however, does not respect this and begins outputting the signal as soon as the recording trigger is received. For this reason, there could be a slight offset between the outputted gated signal and the recorded mocap data.


    The Pass-through type outputs the signal that is received through the SYNC In port.