Measurements on the MPEG-2 Transport Stream - Digital Video and Audio Broadcasting Technology - page 182

The conditions of synchronization (acquisition of lock, loss of lock) can
be adjusted in test decoders.

PMT
PID=(...PAT)
Table ID =2
Program
Map
Table

PMT
PID=(...PAT)
Table ID =2
Program
Map
Table

PID

PAT
PID=0
Table ID =0
Program
Association
Table

PAT
PID=0
Table ID =0
Program
Association
Table

PID

Video ES

PMT
PID=(...PAT)
Table ID =2
Program
Map
Table

PMT
PID=(...PAT)
Table ID =2
Program
Map
Table

PID

Audio ES

PID

Fig. 11.2. PAT and PMT errors

11.2 Errored Sync Bytes (sync_byte_error)

As explained in the previous chapter, the state of synchronism with the
transport stream is considered to be the reception of at least 5 correct sync
bytes. Loss of synchronism occurs after the loss of 3 correctly received
sync bytes. However, incorrect sync bytes may occur occasionally here
and there in the transport stream due to problems in the transmission link.
This state, caused in most cases by too many bit errors, is called
“sync_byte_error” (Fig. 11.2.).
A “sync_byte_error” occurs when

• the content of a sync byte in the transport stream header is not

equal to 0x47.

11.3 Missing or Errored Program Association Table (PAT)
(PAT_error)

The program structure, i.e. the composition of the MPEG-2 transport
stream is variable or, in other words, open. For this reason, lists for de-