clock correlation can be achieved , for example , utilizing the rtp stream between a sender and receiver by determining a baseline at the start of , for example , a communication . this baseline is derived as a point in time from an arriving packet and represents a point from which subsequent packets deviate . using this baseline , an early packet or a late packet can be detected . an early packet pushes the baseline down to that earlier point , while late arriving packets , if they are arriving late for a continuous period of time , represents a shift in the opposite direction from the baseline , resulting in a baseline moving to the “ earliest ” packet out of the sequence of the late arriving packets .