buffertime not working?

hi all,

i'm going to develop a remote desktop project like VNC or RDP. The desktop is captured and encoded as H.264.

The code of flex client is very simple:

< mx:VideoDisplay x="276" y="114" width="240" height="320" bufferTime="0" autoPlay="true" live="true" source="rtmp://.../livestream"/>

But there seems to be above 10 frames buffering at the client side. That means the first I frame does not show until succedent P frames are received.

i also test FME+FMS, the framerate was set as 1fps, the live stream also delayed several secondes.