Hi @pcw0915, please refer to this example here. I hope that it can help you at this moment. Recently, NTPClient Library is added into the Arduino SDK and will be released in our next release, 4.0.6 (https://github.com/ambiot/ambpro2_arduino/tree/dev/Arduino_package/hardware/libraries/NTPClient). I have tried to overlay the time on the video stream using StreamRTSP->VideoOnly example. Hope it helps! 
VideoOnly.zip (1.3 KB)