......
externalVideoCapturer_ = std::make_shared<ExternalVideoCapturer>();
    rtcRoomClient_ = baidurtc::createBaiduRtcRoomClient();
    if (rtcRoomClient_) {
        rtcRoomClient_->initSdk((char*)appid, (char*)token, (char*)cerpath);
        if (isEnableExternalVideoCapturer) {
            rtcRoomClient_->registerExternalVideoCapturer(externalVideoCapturer_);
        }
        rtcRoomClient_->registerVideoFrameObserver(videoFrameListener_, 2);
        rtcRoomClient_->registerRtcMessageListener(this);
        rtcRoomClient_->setBitRate(300000);//500kbs;
    }
......
case WM_COMMAND:
        if (button_ == reinterpret_cast<HWND>(lp)) {
            if (BN_CLICKED == HIWORD(wp)) {
                //OnDefaultAction();
                char roomId[52];
                GetWindowTextA(
                    edit1_,
                    roomId,
                    52);
                if (roomId[0] == '\0') {
                    MessageBox("提示", "房间号不能为空", true);
                    return false;
                }
                //produce random user id
                int userId = random(10000, 20000);
                std::string userId_str = int2string(userId);
                if (isPublisher) {
                    rtcRoomClient_->publishStreaming(roomId, (char*)userId_str.c_str(), true);
                }
                else {
                    rtcRoomClient_->subscribeStreaming((char*)roomid, (char*)userid, (char*)feedid);
                }
            }
        }
......