Apologies for digging up an old post but I just wanted to add to this thread for anyone searching for RTSP / Dahua. RTSP is included in the firmware and works very well.
I have an DVR0804LE-AS.
rtsp://:554/cam/realmonitor?channel=1&subtype=00&authbasic=YWRtaW46YWRtaW4=
replace with your LAN DVR IP (won't work through firewalls/routers without port forwarding of TCP 554).
channel=1 (Represents the video input port number on the DVR)
subtype=00 (00 = Main Stream, 01 = Extra Stream)
Test on VLC media player.
Other ports that are open on the DVR :-
tcp 0 0 0.0.0.0:554 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:37777 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:23 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:3800 0.0.0.0:* LISTEN
udp 0 0 0.0.0.0:37778 0.0.0.0:*
udp 0 0 0.0.0.0:20000 0.0.0.0:*
udp 0 0 0.0.0.0:5050 0.0.0.0:*
