Video Chat Application : Problem downstream on ios device

Hi

     I made real time video chat application between mobile (ios and android device with flash builder 4.7 on flex 4.6.0 and adobe air 15) and flash desktop website (flash builder 4.6, on flex 4.6.0 air 4.0).   It's almost done, but there is a problem only ios device subscribe stream is very lag for the first time that video streaming start.   Sometime it is stop for several time before it can be play that stream. I find the cause of it such as network, flash desktop build version, buffer (it's very smooth but there is problem when you press home button while using video chat, It's stream is gone T^T)

I have the example of downstream :

// ------------ sample code that using netstream ------------

if(subscribeNetStream == null)

  subscribeNetStream = new NetStream(subscribeNetConnection);

  trace("Initial for playing agent video")

  subscribeNetStream.client = {onMetaData:function(obj:Object):void{}};

  // display metadata

  var clientMetaData:Object = new Object();

  clientMetaData.onMetaData = function(info:Object):void{

  trace("onMetaData");

  // print debug information about the metaData

  for (var propName:String in info){

  trace("  "+propName + " = " + info[propName]);

  }

  };

  subscribeNetStream.client = clientMetaData;

  // trace the NetStream status information

  subscribeNetStream.addEventListener(NetStatusEvent.NET_STATUS, subscribeNetStatusHandler);

  // set the buffer time to zero since it is chat

  subscribeNetStream.bufferTime = 0;

  // subscribe to the named stream

  subscribeNetStream.play("Stream_name");

  // attach to the stream

  if(!videoSubscriber){

  videoSubscriber = new Video(uicAgent.width, uicAgent.height);

  }

  videoSubscriber.attachNetStream(subscribeNetStream);

  uicAgent.addChild(videoSubscriber);

------------------- netstream/netconnection handle method ----------------------------

privatefunction subscribeNetStatusHandler(event:NetStatusEvent):void{

  trace(event.currentTarget+" : "+event.info.clientid+" : Subscribe netStatus = "+event.info.code+"\n "+event.info.description);

  switch(event.info.code) {

  case"NetConnection.Connect.Success":

  {

  trace("Success to play");

  playStream();

  break;

  }

  case"NetStream.Buffer.Empty" :

  {

  if(holdingNetStream)

  holdingNetStream.seek(0);

  }

  default:

  {

  break;

  }

  }

  }

// --------- End of sample code ------------------

I have no idea for solving this problem please suggest me

Thank you

Pornphop Sudpan