Definition of PX2 image timestamp

Hi,

Does anyone know details about capture timestamps on PX2?

For example: is NvMediaGlobalTime measured as SOF timestamp or EOF timestamp?

Thanks!
https://docs.nvidia.com/drive/active/5.1.0.2L/nvvib_docs/DRIVE_OS_Linux_SDK_Development_Guide/baggage/group__basic__api__top.html#ga2b90446b84abfa7713025dddb1532169

Hello @cjluo,
please refer to the following documentation :
https://docs.nvidia.com/drive/active/5.0.10.3L/nvvib_docs/index.html#page/NVIDIA%20DRIVE%20Linux%20SDK%20Development%20Guide%2FMultimedia%2Fnvmedia_concept_ipp.html

also, consider reading the section “NvMediaIPPManagerSetTimeSource”.

sorry if I’m missing anything, I didn’t find information about if the NvMediaGlobalTime is measured as SOF or EOF timestamp.

Hi @cjluo,
following the documentation link on my previous comment, regarding what is the source of NvMediaGlobalTime:

NvMediaIPPManagerSetTimeSource api is used for the client application to establish a callback function to provide an absolute global time. When a frame is received by the capture component, it calls this function to get the absolute global time and stores this timestamp to the image.
If the application does not establish a callback function, NvMedia IPP uses the kernel based timestamp obtained from ktime_get_ts() function to get the clock monotonic time.

also, please consider going through these topics:



if the above does not answer your question, can you elaborate on your challenge that you want to solve?

Thanks for the additional info. When you mean “a frame is received by the capture component”, do you mean the “frame is fully received” (EOF) or the “starts to receive the first line of the frame”(SOF)?

I want to benchmark the camera latency on PX2 and would like to if the capture time means when the sensor starts to send the new frame or the sensor completed sending the new frame.

E.g. the table 17 of https://www.onsemi.com/pub/Collateral/AR0331-D.PDF shows the diagram about start of frame and end of frame

Hi @cjluo,

It’s timestamped after EOF. Thanks1