iStream API can tunnel the vMix API functions for you

First you need to address the iStream API (with user and password):


http://[ipaddress]/?user=[user]&password=[password]


then you add


&action=vmix


and continue with regular vMix expressions e.g.


&function=setmastervolume&value=50


(this will set the master volume to 50%)





The following site is very helpful in finding API examples: https://vmixapi.com/?function=SetMasterVolume