a first frame buffer for storing a reference picture, wherein {HEAD ~ the reference picture} comprises {TAIL ~ a mid point picture} in an EP to EP stream during one time period, and a clean reference picture during another time period 
comprises
a first frame buffer for storing a reference picture , wherein { HEAD ~ the reference picture } comprises { TAIL ~ a mid point picture } in an EP to EP stream during one time period , and a clean reference picture during another time period
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH