I must say sorry for my poor english.
but i am very happy to share my finding
rtsp://aaa.bbb.ccc.ddd:554/user=xxxxx&password=xxxxx&channel=1&stream=.sdp?real_stream--rtp-caching=100
How to find it ? There is a website to view the cam, and I trace the website source code , and find the rstp keyword at the javascript.
Wrong Thinking:
There is a mobile apps (android) to view the cam, I try to decompile it and recompile it with a message box (toast), but the mobile using protocol with port 34567.
Thank you for your share.