Stream Music channel and control volume

I’ve created a Test App on Mac to Load Radio- and/or TV-Channels with htmlViewer (htmlViewer.LoadURL(“http://www1.iwannahearthatstuff…”).
What i try to figure out is to change the Volume of the Stream without changing then overall Systemvolume.
Has anybody an idea how to do that?

Thanks in advance.

Chances are the HTML5 Audio player is used. So you can manipulate it in JavaScript.


Thank’s Michel, i’ll Check this out.