let mediaDst = {
   audio: {}
   video: {parameters: {resolution: {}}}
};

//input => output copy
mediaDst.video.parameters.resolution = {width: 0, height: 0};

//max width = 500 height = auto by aspect ratio
mediaDst.video.parameters.resolution = {width: 500, height: 0};1

//max height = 500 width = auto by aspect ratio
mediaDst.video.parameters.resolution = {width: 0, height: 500};

//width & height as specified by the user
mediaDst.video.parameters.resolution = {width: 500, height: 500};

startStreamingOut(roomId, "rtmp", url, {}, mediaDst)