h.264 - AS3.0 Loopback H264 Flv by appendBytes is not smooth -

i use data generation mode loopback h264 flv real-time vide,the video data collected webrtc , pushed immediatly flash player. set buffer time=0, , sure there no "buffer empty" during time,but freeze while when camera move fast. if set buffer time=3, play smoothly.

any 1 can me, thank you.