[Access to system timestamps]

Actually for collecting the eye data I do still use an almost unaltered eye data callback function like described in https://forum.vive.com/topic/9341-vive-eye-tracking-at-120hz/ . I do still use the timestamp which comes with it as I suppose that it is an altered system timestamp.

Using Windows & Unity:

                private void Update()
                {  

                  long timestamp = 0;

                  SRanipal_Eye_API.SRanipal_GetSystemTime(ref long timestamp)

                  Vector3 headPose = Camera.main.transform.rotation.eulerAngles;

                  timestamp = SRanipalSystemToEyeTrackerTimeStamp(long timeStamp)

                }

I am proposing that the timestamp above can now be compared with eyeData.timestamp which you get through the eye data callback function for synchronizing purposes. Cheers. 😃

 

[Access to system timestamps]

I assume that SRanipal_Eye_API.SRanipal_GetSystemTime(ref long timestamp) gives you the you the tick count since system start.

To get it along the EyeData.timeStamp you could use this:

int SRanipalSystemToEyeTrackerTimeStamp(long timeStamp)
                {
                    // Value is generated by observation
                    long maxEyeDataTimestampValue = uint.MaxValue;
                    timeStamp %= maxEyeDataTimestampValue;
                    // Magic trick to round the integer at the fourth last digit
                    timeStamp += 500;
                    // Cutting of the last three digits
                    timeStamp /= 1000;
                    return (int) timeStamp;
                }

[Access to system timestamps]

I guess SRanipal_Eye_API.SRanipal_UpdateTimeSync(); should do the trick.