(Optional) An object with functions like error, info, and warn (compatible with console)
appName
(Required) A string that names the application
eventCallback
(Optional) A callback function to receive events from the SDK
sdkConfig
(Optional) A configuration object provided the following options. numOfCallConfigs: The default value for the numOfCallConfigs is 1 if the numOfCallConfigs is undefined. After initSDK() called, use the getCallConfigs(index) to retrieve the corresponding callConfig object. The callConfig object can be passed to newPeerConnectionEx() and getUserMediaEx() in order to allow different audio headset used for different RTCPeerConnection object.