libonvif
Library implementing client ONVIF for Windows and Linux
LIBONVIF Connects Your Program to IP Camera
libonvif is an open source project that implements client ONVIF for communicating with compatible IP Camera. Compile easily from source on Windows and Linux.
libonvif comes with an example program that implements discovery on the local network to find compatible cameras and return the RTSP string for streaming.
Tested on Hikvision, Dahua, Axis, Foscam, Trendnet, Amcrest, Reolink, Vivotek, Speco and others. Should work for any Onvif...