Note of Video Broadcasting

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  • Topic: MPEG transport stream, Elementary stream, Teletext
  • Pages : 34 (3824 words )
  • Download(s) : 108
  • Published : April 17, 2013
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Topics in Digital Video Broadcasting
Digital Video Broadcasting - Terrestrial

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Digital Video Broadcasting Terrestrial
MPEG-2 Transport Streams

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Extended Event Descriptor under EIT







Tag value = 0x4E
provides a detailed text
description of an event
may be used in addition to the
short event descriptor
possible to have more than one
extended event descriptor
text information can be (itemized)
structured into two columns
- item description field (item)
- the item text
 application: cast list
 e.g. Produce: Name of Producer
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Extended Event Descriptor under EIT






descriptor_number : the number
of the descriptor
- the number of first
extended_event_descriptor shall
be set to 0x00
- the number for the additional
ones shall be incremented by 1
last_descriptor_number : specifies
the number of the last
extended_event_descriptor
length_of_items: the length in
bytes of the following items
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Extended Event Descriptor under EIT










item_description_length: specifies the
length in bytes of the item
description
*item_description_char : specify
the item description
item_length: the length in bytes of the
item text
*item_char : specify the item text
text_length: specifies the length in
bytes of the non itemized extended
text
*text_char : specify the non itemized
extended text
* coding again conforms to EN
300368 Annex A
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Frequency List descriptor under NIT
0x62
may be used in the NIT
- other_frequency_flag being set
- a complete list of additional frequencies for a certain multiplex which is transmitted on multiple frequencies
coding_type: indicates how the frequency is coded and relates to the delivery system used
centre_frequency: list of frequencies








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Linkage Descriptor under NIT/BAT/SDT/EIT
Tag value = 0x4A
identifies a service that can be presented if the consumer requests for additional information related to a specific entity described by the SI system
can be under different tables:
- under NIT  point to a service providing additional information on the network
- under BAT  provide a link to a service informing about the bouquet
- etc
A CA replacement service: selected automatically by a receiver if the CA denies access to the specific entity described by the SI system
A service replacement service: replacement service may be selected automatically by a receiver when the running status of the current service is set to "not_running"










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Linkage Descriptor under NIT/BAT/SDT/EIT
A service to which a mobile receiver might: the service
may be selected automatically by a receiver when the
actual service is no longer receivable under its service_id
- the hand-over_type identifies whether the
linkage_descriptor links to the same service in a different
country, to a local variation of the service or an
associated service
Two events can be signalled as equivalent using: the event
being linked to may be a simulcast or may be time offset
- the event_simulcast flag shall only be set if the target
event is higher quality (Application: PVR)





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Linkage Descriptor under NIT/BAT/SDT/EIT










transport_stream_id: identifies the TS
containing the information service
indicated
original_network_id: gives the label
identifying the network_id of the
originating delivery system of the
information service indicated
service_id: identifies an information
service within a TS
- The service_id = the program_number
in the corresponding
program_map_section
- If the linkage_type field has the value
0x04, then the service_id field is not
relevant, and shall be set to 0x0000
(TS containing complete
Network/Bouquet SI)
linkage_type: the type of linkage
hand-over_type: the type of hand-over
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Linkage Descriptor - linkage_type

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Linkage Descriptor under NIT/BAT/SDT/EIT






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