update multi-Channel best practice

Author: xianing

windows/APIExample/APIExample/Advanced/MultiChannel/CAgoraMultiChannelDlg.cpp

@@ -90,9 +90,6 @@ bool CAgoraMultiChannelDlg::InitAgora()
 	//set channel profile in the engine to the CHANNEL_PROFILE_LIVE_BROADCASTING.
 	m_rtcEngine->setChannelProfile(CHANNEL_PROFILE_LIVE_BROADCASTING);
 	m_lstInfo.InsertString(m_lstInfo.GetCount(), _T("live broadcasting"));
-	//set client role in the engine to the CLIENT_ROLE_BROADCASTER.
-	m_rtcEngine->setClientRole(CLIENT_ROLE_BROADCASTER);
-	m_lstInfo.InsertString(m_lstInfo.GetCount(), _T("setClientRole broadcaster"));
 	return true;
 }
 
@@ -238,7 +235,12 @@ void CAgoraMultiChannelDlg::OnBnClickedButtonJoinchannel()
 	options.autoSubscribeVideo = true;
 	options.publishLocalAudio = m_chkPublishAudio.GetCheck();
 	options.publishLocalVideo = m_chkPublishVideo.GetCheck();
-	pChannel->setClientRole(CLIENT_ROLE_BROADCASTER);
+	if (m_chkPublishAudio.GetCheck() || m_chkPublishVideo.GetCheck()) {
+		pChannel->setClientRole(CLIENT_ROLE_BROADCASTER);
+	}
+	else {
+		pChannel->setClientRole(CLIENT_ROLE_AUDIENCE);
+	}
 	//join channel
 	if (0 == pChannel->joinChannel(APP_TOKEN, "", 0, options))
 	{