如何在WebRTC视频通话中控制带宽？

I am trying to develop a Video Calling/Conferencing application using WebRTC and node.js. Right now there is no facility to control bandwidth during during video call. Is there any way to control/reduce bandwidth. (like I want make whole my web application to work on 150 kbps while video conferencing).I am trying to develop a Video Calling/Conferen