frame metadata backend_timestamp = 0?

[amm385]

Required Info
Camera Model	D435
Firmware Version	don't have it on me :(
Operating System & Version	Ubuntu 18
Kernel Version (Linux Only)	4.9.140-tegra
Platform	NVIDIA Jetson
SDK Version	2.36.0
Language	python
Segment	Robot

Issue Description

I'm getting a value of 0 for my frame's backend_timestamp value:
frame.get_frame_metadata(rs.frame_metadata_value.backend_timestamp)
frame.get_frame_metadata(rs.frame_metadata_value.time_of_arrival) and frame.get_timestamp() are both working correctly. What does this mean? From what I've read on this forum, sensor_timestamp and frame_timestamp require a kernel patch, but time_of_arrival should be supported universally.

[MartyG-RealSense]

Hi @amm385 I extensively researched your issue with backend_timestamp being zero. My understanding is that backend_timestamp is a system time timestamp that is dependent on the OS, and not a firmware-generated timestamp. So there was no clear reason why the timestamp would be 0.

My research did find a case though where a couple of RealSense users encountered this zero result on Raspberry Pi 4, which like Jetson uses an Arm processor. There was also a case of a zero result for this timestamp on an Android device, which typically use Arm processors. So I wonder whether the zero result is Arm-related.

IntelRealSense/realsense-ros#1324

There was not a clear solution on the above case. One of the Pi 4 users used a laptop instead.

[amm385]

Thanks for the response, I too was suspecting it might be related to the ARM architecture, or the kernel build specific to that architecture.

Interestingly, I have a separate arm computer that is working fine, so it must be something very specific to the instance i'm having issues with. (The computer I have that's functioning is a Jetson TX2, the one that's returning 0 is an industrialized TX2)

Either way, good to know this is not just a simple user error on my end, will continue to look into it

[MartyG-RealSense]

Thanks very much @amm385 for the update. Good luck with your investigations!

[MartyG-RealSense]

Hi @amm385 Do you require further assistance with this case, please? Thanks!

[amm385]

tbh I've put this problem on the backburner for now. If I revisit and figure something out, I'll be sure to update, but no assistance needed for now

[MartyG-RealSense]

Okay, I will close the case for now. Please feel free to create a new case if you return to the problem and require assistance. Good luck, and thanks for the update!