This descriptor carries information about the system clock used to generate the timestamps in the transport stream. The external_clock_reference may be set to '1' if an external clock was used to generate the timestamps./p>
If the accuracy of the system clock is more accurate than the required 30 parts per million, the accuracy of the clock can be communicated by encoding the accuracy in the clock accuracy fields.
The accuracy of the system clock is expressed as:
clock_accuracy_integer x 10 10-clock_accuracy_exponent ppm
(MPEG-2 equation 2-26)
See: Descriptors Generally