code: public void muteVideo(boolean mute) {
          if (!audioOnly && (null != localStream) && (isActive())) {
              for (MediaStreamTrack eachTrack : localStream.videoTracks) {
                  eachTrack.setEnabled(!mute);
              }
          }
      }
docs: Mute or unmute the local video
  
  @param mute If true, mute the video. If false, unmute the video