Dvb Serviceinformation

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Dvb Serviceinformation

  1. 1. DVB-SI introduction Presentation on DVB-SI Srikanth Eswaran
  2. 2. PSI & SI – what are they <ul><li>Program Specific Information (PSI) </li></ul><ul><ul><li>Defined in the MPEG-2 systems specifications </li></ul></ul><ul><ul><li>Provide information required to decrypt and display chosen event </li></ul></ul><ul><ul><li>PAT, PMT and CAT are three main tables in PSI </li></ul></ul><ul><li>Service Information (SI) </li></ul><ul><ul><li>Information on available services </li></ul></ul><ul><ul><li>Frequencies which carry these services </li></ul></ul><ul><ul><li>Common interest categories/groups for these services </li></ul></ul><ul><ul><li>Events in a service </li></ul></ul><ul><ul><li>Network details of service help manage revenue flow to service providers </li></ul></ul>
  3. 3. Impacts of errors <ul><li>Errors in Audio – Video </li></ul><ul><ul><li>Cause annoyance to people watching the TV </li></ul></ul><ul><ul><li>Some glitches that users might put up with </li></ul></ul><ul><ul><li>No major revenue loss </li></ul></ul><ul><li>Errors in Service Information </li></ul><ul><ul><li>Improper data display (EPG, etc) could make it difficult for users to make purchasing decisions </li></ul></ul><ul><ul><li>Immediate loss of revenue for service provider </li></ul></ul>
  4. 4. DVB Service delivery model Refers to radio frequencies within the RF spectrum 3Hz to 300 Ghz An automatic device that receives, amplifies, and retransmits a signal on a different frequency A sequence of programmes under the control of a broadcaster which can be broadcast as part of a chedule
  5. 5. Why is PSI/SI required? <ul><li>Automatic Tuning of receiver upon selection </li></ul><ul><ul><li>TSID and channel number are required to tune </li></ul></ul><ul><li>Program location </li></ul><ul><ul><li>Program in BROADCASTING: set of elements having common start and stop times </li></ul></ul><ul><ul><li>Program in MPEG: collection of elementary streams with same PCR_PID and program number </li></ul></ul><ul><li>EPG (Electronic Program Guide) </li></ul><ul><li>API (Application Programming Interface) </li></ul><ul><li>CA (Conditional Access) </li></ul>
  6. 6. Table Structure – PSI & SI (MPEG-2 & DVB) PAT SDT OTHER TS NIT OTHER Delivery Sys. RST ST STUFFING TABLE . RUNNING STATUS . PROGRAMME CLOCK REF. PID=Ox0011 PID=0x0010 PID=Ox0011 TIME AND DATE. CAT PCR TSDT TOT TIME OFFSET . BAT SERVICE DESCRIPTION . NETWORK INFORMATION. EVENT INFORMATION. BOUQUET INFORMATION. NIT ACTUAL Delivery Sys. EIT ACTUAL TS SDT ACTUAL TS TDT PID=Ox0011 PID=0x0010 PID=0X0012 PID=0X0012 PMT EIT OTHER TS EIT ACTUAL TS
  7. 7. Table Structure – PSI & SI (MPEG-2 & DVB)
  8. 8. Example table associations - DVB
  9. 9. PAT & PMT <ul><li>PAT Program Association Table </li></ul><ul><li>This table lists all the services found in this Transport Stream. Each service is identified by a PMT. The PAT is always on PID 0. </li></ul><ul><li>Program Map Table </li></ul><ul><li>This table identifies all the Elementary Streams within a service. There is one PMT per service, but there may be more that one PMT on the same PID. </li></ul>
  10. 10. Structure of PAT and PMT tables
  11. 11. SI Tables <ul><li>NIT Network Information Table </li></ul><ul><ul><li>groups a number of Transport Streams together </li></ul></ul><ul><ul><li>provides tuning information for an IRD (Integrated Receiver Decoder). </li></ul></ul><ul><ul><li>For each different delivery mechanism (e.g. terrestrial and satellite) there is a different Network ID for same service </li></ul></ul><ul><li>BAT Bouquet Association Table </li></ul><ul><ul><li>Provides group of services which are presented to the user as though they were on the same Transport Stream. </li></ul></ul><ul><ul><li>The user may select different services within the bouquet, but be unaware that the IRD is in fact retuning its input to pick up a new transport stream within the network. </li></ul></ul>
  12. 12. SI Tables <ul><li>SDT Service Description Table </li></ul><ul><ul><li>provides a name, language codes, running status and country availability. </li></ul></ul><ul><li>EIT Event Information Table </li></ul><ul><ul><li>Present/Following information allows events on a service such as classifications like “running”, “not running”, “paused”, “starts in a few seconds”. </li></ul></ul><ul><ul><li>Schedule information is arranged by table, sub-table, segment and section into 3 hours blocks within which the program guide information can be transmitted. </li></ul></ul><ul><ul><li>In general, the EIT information may be scrambled, although different countries may provide regulations which restrict this practise. </li></ul></ul>
  13. 13. SI Tables <ul><li>TDT Time and Date Table </li></ul><ul><ul><li>Provides UTC (Universal Time) coded as MJD (Modified Julian Date) </li></ul></ul><ul><li>TOT Time Offset Table </li></ul><ul><ul><li>Is used to provide time offsets to give local time. </li></ul></ul><ul><li>RST Running Status Table </li></ul><ul><ul><li>These are sent out only once to update the status of an event. The RST updates this information and allows timely automatic switching to events </li></ul></ul><ul><li>ST Stuffing Table </li></ul><ul><ul><li>Used to replace or invalidate tables. </li></ul></ul>
  14. 14. SI Tables for partial bitstreams <ul><li>Partial bitstreams </li></ul><ul><ul><li>Are those that have only partial SI information corresponding to that bitstream (for eg., recorded bitstreams) </li></ul></ul><ul><li>DIT Discontinuity Information Table </li></ul><ul><ul><li>Used to inform a downstream device that transport stream information has been removed and the stream may be a partial stream missing some SI tables. </li></ul></ul><ul><li>SIT Selection Informative </li></ul><ul><ul><li>Table Used to inform a downstream device that Transport Stream information has been removed and the streammay be a partial stream missing some SI tables. </li></ul></ul>
  15. 15. Conditional Access Table <ul><li>This table controls the scrambling of a service. It associates one or more CA systems with their EMM (Entitlement Management Message) stream and any other extra data that may be required. </li></ul><ul><li>CAT contents </li></ul>This gives info that customer is authorized to decramble channels using ECMs that appear later
  16. 16. PMT with CAT information This has the control word that is sent to CA module on receiver side to descramble the channel
  17. 17. How are the tables packed into transport streams? <ul><li>Concept of Sections </li></ul><ul><li>Syntatic structure used to map MPEG-2 & SI tables into TS packets </li></ul><ul><li>Sections within each table limited to 1024 bytes, except EIT (4096b) </li></ul><ul><li>Elements of a section </li></ul><ul><ul><li>Table ID – which table is being referred to </li></ul></ul><ul><ul><li>Table ID extension – which subtable is being referred to </li></ul></ul><ul><ul><li>Section number – applies only to sub tables </li></ul></ul><ul><ul><li>Version number – indicates newer versions of table sent earlier </li></ul></ul><ul><ul><li>Current next indicator – ‘now’ or ‘next’ – either table to be used for current event transmissions or for future! </li></ul></ul><ul><li>Mapping of these tables into TS packets (ordering, stuffing, etc) </li></ul>
  18. 18. PID values for SI table sections
  19. 19. Values for table_ids
  20. 20. NIT section syntax example
  21. 21. EIT section syntax example
  22. 22. Descriptors in tables <ul><li>Boquet name example in BAT </li></ul><ul><li>CA identifer descriptor </li></ul>
  23. 23. Descriptor tags
  24. 24. Service information acquisition and storage <ul><li>Mode of transmissions and receptions </li></ul><ul><ul><li>Data and object carousel way of transmitting schedules </li></ul></ul><ul><ul><li>SI parser on receiver end, which extracts PAT, PMT, SDT, EIT table information to retrieve mainly the list of services and events </li></ul></ul><ul><li>Storage considerations </li></ul><ul><ul><li>Embedded database to store information from these tables particularly the EIT and SDT to reproduce on EPG screen when requested by user </li></ul></ul><ul><ul><li>Customized databases, or choice of DBs like SQ-Lite (self-contained, serverless, zero-configuration, transactional SQL database engine) </li></ul></ul><ul><ul><li>Compression – any technique or using libraries such as zlib </li></ul></ul><ul><ul><li>Persistency of the DB cache into flash in file format </li></ul></ul>
  25. 25. References <ul><li>Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems </li></ul><ul><li>ETSI EN 300 468 V1.3.1 (1998-02) - http://tinyurl.com/5ylbvb </li></ul><ul><li>Interactive TV Web - http://www.interactivetvweb.org/ </li></ul><ul><li>Neil Pickford - Communications Lab - http://happy.emu.id.au/lab/ </li></ul><ul><li>DVB SI Basics - Snell and Wilcox - http://www.snellwilcox.com </li></ul><ul><li>Digital Video Broadcasting - Instituto de Telecomunicações - Pólo de Aveiro - http://www.av.it.pt/ </li></ul><ul><li>ATSC - http://www.atsc.org </li></ul><ul><li>SQLite - http://www.sqlite.org </li></ul>
  26. 26. <ul><li>Thank you ! </li></ul><ul><li>Questions? </li></ul>

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