Timestamp synchronization of D455 Realsense camera and other cameras
Hi,
I am using the D455 camera with other cameras and I need to do the time synchronization between these cameras, but I would like to know what causes these timestamp differences.
As far as I know, the camera will get a timestamp from the computer clock source and calculate the time offset to the camera clock source, and use it as an offset to apply to the time reported by the camera, if so, there should not have a time difference. But I have noticed up to 40 seconds timestamp difference between D455 and other kinds of cameras.
I guess that these cameras will reset the timestamp when they are connected to a computer, and then there would be an enabling process where different cameras may take different time, which may cause this synchronization issue. But this is only my guess and cannot explain why the difference can be up to 40 seconds.
Any help and explanation are highly appreciated!
Best,
Shifan
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Hi Shifanzhu Each camera that is attached to the same computer will be capturing independently by default and not synchronizing their timestamps with each other. You may therefore achieve closer timestamps if the Global Time feature is enabled, as described at the link below.
https://github.com/IntelRealSense/librealsense/pull/3909
Alternatively, you could set up a hardware sync system where all but one of the cameras follow the timestamp timing of a 'master' RealSense camera that transmits a sync trigger pulse to the other cameras, or all cameras instead sync to a trigger pulse sent by a signal generator device.
The simplest form of hardware sync, which syncs depth streams only, is detailed in the Intel white-paper guide at the link below.
https://dev.intelrealsense.com/docs/multiple-depth-cameras-configuration
More advanced control over sync timing and support for RGB in addition to depth is provided by the External Synchronization (Genlock) version of the hardware sync system in the white paper below:
https://dev.intelrealsense.com/docs/external-synchronization-of-intel-realsense-depth-cameras
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