XR-Latency Calibration

Automatically evaluate the amount of frame delay between sending a picture to the stage and receiving it back through the camera.

1) Theory

This step calculate a frame number of delay between the content broadcast in the Screens and the reception of it in the camera. It set a Frame Delay according to the result. Indeed, there is delay between the moment Smode is broadcasting a content in the screens and the moment this pictures is actually get back as video input.
The main objective of this part is to count the number of frames that there is between these 2 moments. In order to do it, Smode will a broadcast a White Glitch in each screens and will wait to see it in the video input.
The difference in time between the moment of emission and reception is equals to the delay you will have to apply on the set extension and content broadcasted in the screens.
The example below is a simplified illustation of a XR set-up with 6 frames of delay.

2) Before Starting a Latency Calibration

Before launching the latency calibration, you must ensure that:
  1. Your Smode is fully optimised in graphical perfomances. Use the Profile feature if needed.
  2. The frame rate is stable. If not, it might be because your set-up isn't fully genlocked
  3. You are filming every impacted screens
  4. the camera does not move
  5. Alert people not to pass in front of the camera
Once you ensure the previous points, you can start a calibration.

3) UI Check-out


1) Viewport : Display the stream of the XR CalibratorVideo Input
2) Tracker informations : Display the current position orientation of the Tracker of the Physical Camera such as the deviation. A positive value of Position Deviation and Orientation Deviation means that your tracker is currently mooving.
3) Added delay : (Frame) delay applied for every screen in result of the XR-Latency Calibration
4) Delay in frames : (Frame) delay calculated by the algorithm
5) Delay Mean : (ms) Average time between the emission of a white content and its reception
6) Delay Standard Deviation : actual difference between the delay mean (which is an average) and the actual time between emission and reception

4) Calibration process

To launch this calibration part, simply press "calibrate" on the Calibrator Editor
and this is what should happen:

TroubleShoots

incoherents values
  • Your setup is not genlocked
  • Has the camera shutter been modified?
  • Check the EDIDs of each screens.
  • Smode is not optimised, use the Profile feature
Next step: XR-Geometry Calibration

See Also: