Saya mau tau PCR dari Transport stream. Jelaskan dalam bahasa sunda

To assist the decoder in presenting programs on time, at the right speed, and with synchronization, programs usually periodically provide a Program Clock Reference, or PCR, on one of the PIDs in the program.  This is also known as the master clock.  Timing in MPEG2 references this clock, for example the presentation time stamp (PTS) is relative to the PCR.  The first 33 bits is based on a 90 kHz clock, incremented for éach Hertz or cycle.  The 9 bit extension is based on a 27 MHz clock.