What is the definition error 2.3b: PCR_discontinuity_error?

What is the definition error 2.3b: PCR_discontinuity_error?

The formal definition of this error is given in the TR 101 290: Measurement guidelines for DVB systems document that is published by ETSI. A brief summary of this error is given below. For more information about this error or the test that generates it, please consult ETSI TR 101 290.

MPEG transport streams must periodically contain PCR (program clock register) values which are a snapshot of the encoders' program clock at the time that PCR value was generated. These values are then used on the decoder end to reconstruct the 27MHz system clock and ensure that the stream is kept in sync.

A PCR_discontinuity_error (2.3b) occurs when two sequential PCR values differ from each other by more than 100 milliseconds without the discontinuity_indicator flag being set in the stream. A difference of more than 100ms is allowed, but only if the discontinuity_indicator flag is set, otherwise this error will be reported.