PowerPoint 프레젠테이션

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1 Topic 2 Digital TV Source Multiplexing

2 Contents of the 2 nd week lecture Digital Terrestrial TV Overview MPEG-2 Transport Stream Electronic Program Guide 2

3 Digital Terrestrial TV Overview

4 디지털지상파 TV 시스템모델 4

5 Digital Broadcasting Systems 5

6 DTV 세계전개현황 6

7 MPEG-2 Transport Stream 4.2 Organization of the MPEG-2 multiplex: program and transport streams

8 Introduction to MPEG System MPEG System MPEG 비디오, MPEG 오디오, 데이터를동기를맞추면서다중화 시스템 MPEG-1 MPEG-2 기능 - 임의의수의비디오, 오디오등의개별적부호화비트스트림을다중화해서하나의프로그램으로서비트스트림구성 - 1.5Mbps 정도의전송속도를갖는저장미디어에사용 - Program stream : MPEG-1 과같이하나의프로그램구성 - Transport stream : 복수의프로그램구성 - 확장기능및부가기능제공 8

9 Introduction to MPEG-2 System MPEG-2 System ; ISO/IEC defines the organization of the multiplex, foresees two different ways of multiplexing these PESs in order to form two different kinds of bitstreams depending on the application. schemes for the multiplexing process Program Stream Transport Stream 9

10 MPEG-2 Bit Streams Elementary Stream (ES) the most basic type of MPEG-2 signals and are generated by the encoder separate data streams for video, audio, and data signals Packetized Elementary Stream (PES) Program Stream Transport Stream 10

11 MPEG-2 System Synchronization Clock Reference Information System layer includes DTS and PTS Program clock reference (PCR) adaptation field can have PCR (similar to SCR in MPEG-1 system) 11

12 MPEG-2 System 12

13 Packetized Elementary Stream (PES) Result of the packetization process The payload is the data bytes taken sequentially from the original elementary stream No specific format for forming the PES packet Entire video frame in one PES packet (but need variable size frames) Fixed size packets PES headers distinguish PES packets of various streams and also contain time stamp information 13

14 MPEG-2 PES 헤더 (1) 14

15 MPEG-2 PES Structure 15

16 MPEG-2 PES 헤더 (2) 16

17 MPEG-2 Program Stream Primarily intended for storage and retrieval from storage media Grouping of video, audio, and data elementary streams that have a common time base Each program stream consists of only one program Similar to MPEG-1 System stream Useful in error free environments(quasi error-free -10 (QEF) medium ; BER < 10 ) Large packet size (ex Bytes) Packets size may be variable (hard for decoder to predict start and end of packets) DVD standard uses the MPEG-2 Program Stream 17

18 MPEG-2 PS 상위계층의데이터구조 18

19 MPEG-2 PS 하위계층의데이터구조 19

20 MPEG-1 스트림 ID 스트림 ID 스트림종류 Reservation Private stream Padding stream Private stream 2 110x xxxx MPEG Audio stream 1110 xxxx MPEG Video stream Reservation for MPEG 20

21 MPEG-2 스트림추가 스트림 ID 스트림종류 Program Stream map 허락제어메세지 허락관리메세지 DSM 메시지제어명령 xx ITU-T 용예약 ITU-T 용예약 Transport stream 에서의 program stream 전송용 Program stream directory 21

22 MPEG-2 PS PSI PSI(Program Specification Information) Program Stream map packet - 프로그램의부가정보나개별비트스트림마다의부가정보기술패켓 Program stream directory packet - 저장미디어에서사용되는랜덤액세스를위한정보 - 개별비트스트림마다랜덤액세스를위한진입점을비트스트림선두로부터의바이트수로표현 22

24 24

25 MPEG-2 Transport Stream (1) Combines multiple programs into a single stream The programs may or may not have common time base Fixed length packet size Intended for non error free environments(error -4 prone media; BER > 10 Easier to detect start and end of frames Easy to recover from packet loss/corruption More difficult to produce and demultiplex than program stream 25

26 Transport Stream (2) Multiplexes various PES into one stream along with information for synchronizing between them Short, fixed length packets 188 bytes (4 byte header + adaptation field or payload or both) Constraints for forming transport packets: First byte of PES packet must be first byte of transport packet payload Each transport packet must contain data from only one PES packet 26

27 MPEG-2 TS Multiplexer Video Source MPEG-2 Elementary Encoder ES Packetizer Uncompressed stream MPEG encoded stream PES Systems Layer MUX Transport Stream Audio Source MPEG-2 Elementary Encoder ES Packetizer Data Source Packetizer 27

28 28

29 Arrangement of the PESs 29

30 Composition of Transport packet 30

31 Transport Packet Structure 31

32 TS packet header (1) 32

33 TS packet header (2) 33

35 MPEG-2 tables (1) PSI(Program Specific Information) transport packets - used by decoder to learn about the transport stream Program Allocation/Association Table (PAT) TS 를구성하는서비스리스트포함 이리스트에는 Program Number (0~65535) 와 PMT PID 값으로구성되어있어, PMT PID 값을통해특정서비스의 PMT 에접근가능 The presence of this table is mandatory, and it is carried by the packets of PID equal to zero (PID = ) 35

36 PAT Fields 36

37 MPEG-2 tables(2) Conditional access table (CAT) 유료채널에대한접근정보를제공하는테이블이다. CAT 는 EMM 패켓의 PID 을알려주며, EMM 을통해수신자격정보와사용자정보등을알수있게된다. - EMM ; Entitlement Management Message 37

38 CAT Fields 38

39 MPEG-2 tables (3) Program map table (PMT) one PMT for each program present in the multiplex 프로그램을구성하고있는 Elementary Stream 들의 PID 정보포함 스크램블될프로그램관련사적정보포함 ( 예 ; the ECM, which is one of the two pieces of information necessary for unscrambling programs with conditional access, the other being the EMM carried by the CAT) * ECM; Entitlement Control Message 39

40 PMT Fields 40

41 41

42 MPEG-2 tables (4) Transport stream description table (TSDT) describes the contents of the multiplex transported by packets of PID =

43 Private tables These tables carry private data, which are either in free format (see Table 4.10) or in a format similar to the CAT, except for the section length, which can be as much as 4096 bytes, compared with 1024 for the other tables. 43

44 Service Information(SI) Transport streams 가운데시청자가원하는스트림을찾아내어수신기가수신하게되고각서비스에서제공하는여러가지개개의프로그램에대한내용와프로그램의종류에대한정보를제공하기위해서는 MPEG-2 에서정의하고있는스트림외의별도의정보가수록된정보가전송되어야함 이러한별도의정보를 SI 또는프로그램안내정보라함 SI 규격에는 DVB 와 ATSC 규격이있다. 44

45 DVB SI Within the DVB specifications there is found another level of service information (SI), which adds to the MPEG PSI by providing data to aid in the automatic tuning of IRD(Integrated Receiver Decoder)s, and other data intended for display to the consumer DVB has specified seven additional SI tables, of which three are mandatory and four are optional NIT(Network Information Table) - 지싱파, 위성, 케이블등과같은전송시스템의물리적정보전달 SDT(Service Descriptor Table) EIT(Event Information Table) BAT(Bouquet Association Table) RST(Running Status Table) TDT(Time and Data Table) TOT(Time Offset Table) ST(Stuffing Table) 45

46 Service Information 46

47 Mandatory tables of DVB-SI Network Information Table(NIT) NIT 는하나트랜스포트스트림으로구성된전송망의파라미터정보를전달하는테이블로서, DVB 방식을사용하는시스템에서 TS 스트림의유일한식별을하기위해사용된다. 하나의 TS 는 NIT 의 transport_stream_id 와 original_network_id 의조합으로다른 TS 와구별이가능하다. 47

48 Mandatory tables of DVB-SI Service Description Table (SDT) 방송서비스에대한정보를제공하게되는데, 서비스제공자나서비스의이름등에관한내용을전달하게된다. 각각의 TS 마다개별 SDT 가존재하게되고, 해당 TS 내의모든서비스에대한리스트를갖게된다. Time and date table (TDT) 셋톱박스내부실시간클록업데이트에사용 48

49 Mandatory tables of DVB-SI Event information table (EIT) 방송프로그램과관련되어, 프로그램의이름, 시작시간, 방영시간등을전달하는실질적인가이드역할을수행하게된다. EIT 는각서비스내에 이벤트 라고부르는개별방송프로그램에대한정보를시간순으로제공하게되는데, 크게 Present/Following event 와 Schedule event 로구분된다. Present/Following event 정보는현재와다음프로그램의정보를시간적순서에따라계속해서정보를전달 Schedule event 는현재 / 다음이벤트이후에발생하게되는이벤트의목록및스케쥴정보를제공 Schedule event 는선택사항이고, 모든이벤트정보는시간적순서로전달되어야한다. 49

50 ATSC PSIP PSIP(Program and System Information Protocol) STT(System Time Table) RRT(Rating Region Table) MGT(Master Guide Table) VCT(Virtual Channel Table) EIT(Event Information Table) DVB-SI 보다는간단한구조 50

51 Electronic Program Guide

52 EPG(Electronic Program Guide) EPG(Electronic Program Guide) 텔레비전방송프로그램의편성표를텔레비전화면상에표시하는것으로, 텔레비전을시청하는사람은이편성표를통해원하는프로그램을선택하거나시간, 제목, 채널, 장르등의기준을통해원하는프로그램을검색할수있는서비스 52

53 EPG 서비스 DTV MPEG-2 TS 기반의 PSI 및 DVB SI 정보를이용하는테이블전송방법사용 TV anytime 메타데이터표준규격을근간으로하는 DVB-H ESG 에서는 XML 을활용한메타데이터 EPG 규격사용 Analog TV using vertical blanking interval 53

(JBE Vol. 22, No. 6, November 2017) (Special Paper) 22 6, (JBE Vol. 22, No. 6, November 2017) ISSN 2

(Special Paper) 22 6, 2017 11 (JBE Vol. 22, No. 6, November 2017) https://doi.org/10.5909/jbe.2017.22.6.744 ISSN 2287-9137 (Online) ISSN 1226-7953 (Print) UHD AV a),b), a),b) Transport Overhead Analysis