Clock synchronization between R200 and PC

[hhelf]

HI,

I am developing application using R200 and librealsense where I need to know each frame time stamp to synchronize it with another data coming from another sensor. The function get_frame_timestamp() returns the time since the R200 was up.

How is it possible to synchronize the time stamp of R200 with the PC timestamp?

Thanks!

[MartyG]

One of the leaders of Librealsense recommended using a "fuzzy-matching timestamp based model", since the R200 lacks some of the hardware sync features that the SR300 has.

[hhelf]

Thanks for the reply. However, my concern is not how to match the time stamps but rather how to match the time since the R200 was up to the time the PC was up.

I mean the PC is up since X mSec. The time stamp that came from R200 means that the frame has been captured Y mSec since the R200 was up. X and Y lays in totally different time spaces.

How to bring them into the same time space in order to apply some time matching algorithm?

Thanks again for your time!

[MartyG]

I wonder if rs_timestamp_domain might help.

https://software.intel.com/sites/products/realsense/camera/rs_8h.html# abdab21f07d0c6ac32acf6d1ac6436945 Intel® RealSense™ Cross Platform API (librealsense): /Users/mcurfman/ws/Linux_SDK/realsense_documentation/librealsense/s…

The easiest way to sync the camera timestamp with an external sensor may be to use GPIO though. The R200's successor the ZR300 has these hardware connection pins (two), as does the new 400 Series cameras (four).

Taken from the documentation page link above:

"When you have an external device (such as a compass, magnetometer, light sensor, or other) and wish to synchronize it precisely with image and motion streams, you can connect that sensor to a GPIO that is available on some devices. Every time the sensor signals, you get a timestamp callback with a frame number, source ID, and a timestamp".