Hi,
Do you mean the VPIStatus or trackingStatus?
For the return status VPIStatus, VPI also uses 0 to represent SUCCESS.
https://docs.nvidia.com/vpi/Status_8h_source.html#l00080
trackingStatus is a VPI array, and it indeed uses 1 for tracking loss.
This information is mentioned in the below:
vpiSubmitOpticalFlowPyrLK()
[in,out] trackingStatus Status array for tracking status for each input in prevPts. If element is one, the corresponding keypoint isn’t being tracked, otherwise, it is. The type of the array must be [VPI_ARRAY_TYPE_U8]
Thanks.