T-VIPS CP525 cMux, User Manual

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44 Functional Description
CP525 cMux User’s Manual Rev. 5.20.12 (3944) ID: um_tsmux
• CP525 search for expired segments. A segment is considered expired if the end time
of all events in that segment is located in earlier segments. The segment is then placed
in the “expired” group instead of group 0.
• Group 0 gets one segment from group 1. The similar will be done for group 1, group
2 and further on.
5.11.3 Notes about the playout sequence
As a consequence of the described approach by handling each EIT segment (up to 8 sections)
individually, the playout sequence for sections within a specific table ID will not be strictly in
sequence. The playout of section numbers
within a segment will however be in sequence.
Figure 5.13 shows how the playout sequence of tables may change during a day due to expired
events. For simplicity in the figure, it is assumed that the repetition rate for expired events is
2x the rate for active events.
0 1 2 3 4 5 6 7
EIT Segments for 24-hour period
Red = Expired
Green = Not expired
Phase 1
Phase 2
Phase 3
Playout sequence:
0,1,2,3,4,5,6,7,0,1,2,3,4,5,6,7,...
0 1 2 3 4 5 6 7
Playout sequence:
0,1,2,3,4,5,6,7,2,3,4,5,6,7,0,1,2,3,4,5,6,7,2,3,4,5,6,7...
0 1 2 3 4 5 6 7
Playout sequence:
0,1,2,3,4,5,6,7,4,5,6,7,0,1,2,3,4,5,6,7,...
Time
Figure 5.13 Event expiration and playout sequence
5.12 Programming Metadata Communication Protocol (PMCP)
Programming Metadata Communication Protocol (PMCP), specified in ATSC A/76, is a standard
for use within digital television broadcast facilities for transfer of source data used to generate
EIT and ETT tables comprising the electronic program guide (EPG) listings and other program-
related information. PMCP is a XML-based platform-independent protocol for the exchange
of data, which may then be transported between systems in a variety of forms such as files,
messages, web or e-mail services. The resulting data may then be sent to a ATSC PSIP generator
for conversion to a broadcast-ready format. A generic overview of EPG regeneration using
PMCP can be seen in figure
5.14
Support of the PMCP-standard on the CP525 requires a licence. This licence enables acquisition
of PMCP data from an HTTP-server or an FTP-server to regenerate PSIP EIT and ETT tables. This
is achieved by parsing the XML-based structure of PMCP and translating it into an internal data
structure, ready to be regenerated into PSIP tables. The regenerated tables are then multiplexed