For some days I've been working on google's IMA (or DFP).
Now I need to know how to mute them even when it is loaded. I searched for that. Can't find a proper solution.
Note:
I didn't use any video player. Because I am adding it before a game loads.
You should use setVolume right after you started your adsmanager instance (see here for details) :
adsmanager.start();
//0 to mute, 1 to unmute
adsManager.setVolume(0);