1 Data Broadcasting Ken McCann

2 Application Example - Internet via satellite Delivery of web pages at up to 38 Mbit/s

3 DVB Return Channel Return channel used for interactive services depends on the physical network, e.g.: Telecom modem via PSTN & ISDN for terrestrial or satellite TVTelecom modem via PSTN & ISDN for terrestrial or satellite TV DVB/DAVIC modem for cable TVDVB/DAVIC modem for cable TV

4 DVB Data Broadcasting DVB Data Broadcasting standard, EN , provides a set of network-independent protocols optimised to different applications: data pipingdata piping data streamingdata streaming multiprotocol encapsulationmultiprotocol encapsulation data carouseldata carousel object carouselobject carousel

5 DVB Data Piping DVB Data Piping uses MPEG Transport Stream (TS) packets without any intermediate layer provides non-synchronised end-to-end delivery of data through DVB networksprovides non-synchronised end-to-end delivery of data through DVB networks 188 byte packets with 184 byte payload188 byte packets with 184 byte payload DVB descriptor to identify data pipeDVB descriptor to identify data pipe Any other mechanism relies on the applicationAny other mechanism relies on the application

6 DVB Data Streaming Based on the MPEG Packetised Elementary Stream (PES) construct that is used for video and audio: Asynchronous data streams carry no timing information (e.g. RS232)Asynchronous data streams carry no timing information (e.g. RS232) Synchronous data streams allow clock and data to be regenerated (e.g. E1, T1)Synchronous data streams allow clock and data to be regenerated (e.g. E1, T1) Synchronised data streams allow playback in sync. with video and audioSynchronised data streams allow playback in sync. with video and audio Data Audio Video

7 Multiprotocol Encapsulation Based on the MPEG section construct that is used for MPEG PSI and DVB SI: optimised for Internet Protocol (IP) but can be used for any other network protocoloptimised for Internet Protocol (IP) but can be used for any other network protocol “datagrams” can be fragmented into multiple sections if they exceed maximum payload of a single section (4080 bytes)“datagrams” can be fragmented into multiple sections if they exceed maximum payload of a single section (4080 bytes)

8 Data Carousel Based on the MPEG Digital Storage Media Command and Control (DSMCC) data carousel supports cyclic transmission of data modules to receiverssupports cyclic transmission of data modules to receivers analogous to traditional Teletextanalogous to traditional Teletext data is structured into Modules, Groups and SuperGroupsdata is structured into Modules, Groups and SuperGroups could be used for software download to receiverscould be used for software download to receivers

9 Object Carousel Based on the MPEG DSMCC object carousel supports cyclic transmission of structured groups of objects from broadcast server to client (receiver)supports cyclic transmission of structured groups of objects from broadcast server to client (receiver) can download application, data files, data streams and trigger eventscan download application, data files, data streams and trigger events typically used to provide interactive servicestypically used to provide interactive services

10 Conclusions DVB data broadcasting specification provides a comprehensive set of network-independent protocolsDVB data broadcasting specification provides a comprehensive set of network-independent protocols capacity for data broadcasting can be traded against capacity for video and audio in a totally flexible mannercapacity for data broadcasting can be traded against capacity for video and audio in a totally flexible manner