Atsc working Draft Template
Table D4 Receiver Behavior with Hidden and Hide Guide Attributes hidden
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- D.4.3 The Event Information Tables (EITs)
Table D4 Receiver Behavior with Hidden and Hide Guide Attributes
hidden hide_guide Receiver Behavior Description Surf Guide ‘0’ x Normal channel ‘1’ ‘1’ Special access only ‘1’ ‘0’ Inactive channel D.4.3 The Event Information Tables (EITs) The purpose of an EIT is to list all events for those channels that appear in the VCT for a given time window. As mentioned before, EIT-0 describes the events for the first 3 hours, EIT-1 for the next 3 hours, and so on. EIT-i and EIT-j have different PIDs as defined in the MGT. In PSIP, tables can have a multitude of instances. The different instances of a table share the same table_id value and PID but use different table_id_extension values. In PSIP, an instance of EIT-k contains the list of events for a single virtual channel with a unique source_id . For this reason, the table_id_extension has been renamed as source_id in the EIT syntax. Figure D5 shows, for example, the NBZ-S instance for EIT-0. Following similar 21 The 16-bit “Transmission Signal ID” for the NTSC VBI is specified in CEA-608 [5]. 115 ATSC A/65:2013 Program and System Information Protocol, Annex D 7 August 2013 procedures, the NBZD, NBZ-M, and NBZ-H instances of EIT-0 can be constructed. The process can be extended and repeated to obtain all of the instances for the other tables in the time sequence: EIT-1, EIT-2, etc. The three events programmed for the 3-hour period for NBZ-S are listed in Figure D5. The field event_id is a number used to identify each event. If an event time period extends over more than one EIT, the same event_id has to be used. The event_id is used to link events with their messages defined in the ETT, and therefore it has to be unique only within a virtual channel and a 3-hour interval defined by EITs. The event_id is followed by the start_time and then the length_in_seconds . Notice that events can have start times before the activation time (14:00 EDT in this example) of the table. The ETM_location specifies the existence and the location of an Extended Text Message (ETM) for this event. ETMs are simply long textual descriptions. The collection of ETMs constitutes an Extended Text Table (ETT). num_events_in_section = 3 EIT-0 source_id = 22 (NBZ-S instance) event ID local start time Length (seconds) ETM location title descriptors 51 12:30 7200 ‘01’ Soccer Live content_advisory 52 14:30 3600 ‘00’ Golf Report closed_caption 53 15:30 9000 ‘01’ Car Racing content_advisory Download 4.82 Kb. Do'stlaringiz bilan baham: |
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