Implementing Closed Captioning for DTV

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1 Implementing Closed Captioning for DTV Graham Jones NAB Broadcast Engineering Conference April,

2 Agenda Terminology FCC rules Standards Carriage of DTV closed captions PSIP and the caption service descriptor 2

3 Terminology DTV ATSC broadcast, also cable and DBS DTVCC closed captions for DTV CEA-608-B standard for analog NTSC captioning CEA-708-B standard for DTV captioning 3

4 Terminology Native 708 DTVCC encoded and transmitted in the 708 format in which they were authored Translated or Derived DTVCC translated from line 608 line 21 legacy captions Sometimes misleadingly referred to as upconverted Sometimes misleadingly referred to as transcoded Transcoded line 21 data may be transcoded to fill required 608 compatibility bytes in the 708 caption distribution 4

misleadingly referred to as upconverted Sometimes misleadingly referred to as transcoded Transcoded

5 So, what s the difference? 608 line 21 5

6 Native 708 6

7 Native 708 7

8 Translated 708 DTVCC as encoded 8

9 DTV caption menu 9

10 Translated 708 DTVCC user format 10

11 Translated 708 DTVCC user format 11

12 Translated 708 DTVCC user format 12

13 Translated 708 DTVCC user format 13

14 FCC rules for DTVCC Report and Order July 21, 2000 Amended Part 15 and Part 79 of the FCC Rules 14

15 Part Decoders for DTV receivers Effective July 2002 Part 79.1 Closed captions for DTV programming Phased schedule 15

16 FCC Rules Summary Since July 2002, DTV receivers with >7.8 screen height, and STBs, must have caption decoders complying with section 9 of CEA-708-B, with some optional features defined as mandatory CEA-708-B is incorporated by reference into the rules STBs with NTSC output must output 608 captions in line 21 16

of CEA-708-B, with some optional features defined as mandatory CEA-708-B is

17 FCC Rules Summary Part 79 now says transmitted closed captions must reflect the changes in Part 15, i.e. DTV programs must include CEA-708-B captions During the transition 708 captions may be translated from existing 608 caption data Multi-channel program distributors receiving programs with CEA-708-B captions must deliver to the home with that captioning intact No distinction between DTVCC for high definition and standard definition 17

18 FCC Rules New Programming 1/1/02 12/31/ hours/quarter 1/1/04 12/31/ hours/quarter After 1/1/06 100% (some exceptions) New digital programming is prepared or formatted for display on digital televisions, that was first published or exhibited after July 1, 2002 Spanish language schedule leads to 100% by

prepared or formatted for display on digital televisions, that was first

19 Exemptions Programs shown 2 a.m.- 6 a.m. Commercials no longer than five minutes Programs not in English or Spanish Local non-news programming Some local PBS instructional programming Several other program types 19

or Spanish Local non-news programming Some local PBS

20 FCC Rules Pre-rule Programming 1/1/03 12/31/07 30% of programming (1/1/05 for Spanish) After 1/1/08 75% of programming (1/1/12 for Spanish) Pre-rule programming is that first published or exhibited before July 1, 2002 So DTV services now have the same hourly captioning requirements as NTSC services 20

programming is that first published or exhibited before July 1, 2002 So DTV

21 CEA Standards CEA-608-B closed captioning and data for line 21 of NTSC signals CEA-708-B DTV closed captions only for ATSC bitstreams Defines format of 708 DTV captions, decoders, and encoding of 708 data and 608 compatibility bytes in the DTV bitstream Other information, e.g. caption service descriptor, parental guidance, and other program information previously carried in VBI, is carried in PSIP 21

22 SCTE Standards SCTE 43 Digital Video Systems Characteristics for Cable TV Requires DTV captions to be encoded in accordance with CEA-708-B and transported in accordance with A/53B SCTE 54 Digital Video Service Multiplex and Transport for Cable TV When captions are delivered in A/53B, then the caption service descriptor shall be present in the PMT and in the EIT, if present 22

23 SMPTE 333M SMPTE Standards DTV Closed-Caption Server to Encoder Interface SMPTE 334M Vertical Ancillary Data Mapping for Bit-Serial Interface 23

24 ATSC Standards ATSC A/53B Digital Television Standard Carriage of DTVCC in the ATSC transport ATSC A/65B PSIP Standard Caption Service Descriptor (CSD) 24

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26 26

27 27

28 Recommended Implementation 708 DTV caption data 608 compatibility bytes Caption service descriptor in EIT (and PMT for cable) All these elements should be carried in the ATSC bitstream For distribution upstream of the ATSC encoder they can be carried in a caption distribution packet (CPD) defined in CEA-708-B 28

29 Caption Encoding and Distribution Analog and DTV captions are quite different in the way they are encoded, distributed, and transmitted For NTSC, captions are usually encoded, distributed, and transmitted on line 21 of the video signal 29

30 Carriage of 708 Captions 708 captions for DTV have different methods for carriage before and after the ATSC encoder. They may be carried: in ATSC video user data bits for emission (A/53B) on serial data link from a caption encoder to the ATSC encoder (SMPTE 333M and Grand Alliance standard) embedded as CDP in serial digital video VANC for recording and distribution (SMPTE 334M) multiplexed in an AES3 data stream (SMPTE 337M) 30

31 Carriage of 708 Captions 708 captions for DTV have different methods for carriage before and after the ATSC encoder. They may be carried: in ATSC video user data bits for emission (A/53B) on serial data link from a caption encoder to the ATSC encoder (SMPTE 333M and Grand Alliance standard) embedded as CDP in serial digital video VANC for recording and distribution (SMPTE 334M) multiplexed in an AES3 data stream (SMPTE 337M) 31

32 32

33 Currently used only for 292M HD signals Encoder embeds CDPs in VANC as per SMPTE 334M 33

34 Recording, Processing, Distribution VANC captions are sticky data and follow video through most baseband routing and switching equipment Care needed with preserving VANC data through VTRs, servers and production switchers and DVEs Data bridges Issues of latency 34

35 Compression Distribution Systems HD program distribution from networks to affiliates or member stations typically use compressed video over satellite must extract captions from VANC place in private data PID, or in A/53B video user data IRDs are available that re-insert captions in VANC for distribution at the station 35

36 Local Station Arrangements The written paper shows various scenarios for handling DTV captions at the station 708 captions from the network Locally generated 708 Translated from 608 Up and down video format conversion VANC is most common distribution method, but use of a caption server at the station with local encoding is an alternative 36

37 37

38 Caption Input to the ATSC Encoder External VANC disembedder SMPTE 333M / Grand Alliance interface Caption service descriptor Increasing use of internal VANC disembedder from 292M video An alternative architecture uses a caption encoder or translator feeding the ATSC encoder direct 38

39 Serial link for 708 data into the 708 encoder PSIP EIT must contain the caption service descriptor to announce and describe the services present 39

40 PSIP and Caption Service Descriptor For EITs for future events, CSD will need to come from program schedule/listing service For current event EIT and PMT, it is preferable for CSD to come from the on-air program CDP or live caption encoder Actual captions could be different from scheduled captions 40

41 Monitoring The written paper discusses various requirements for 708 caption monitoring Presence Display/functionality Synchronization Regulatory compliance 41

42 708 Equipment Four known vendors for 708 encoders 42

43 708 Authoring Software Coming soon 43

44 Conclusions FCC rules require DTV 708 captions now Products are available from several manufacturers Make sure your bitstream contains both 708 and 608 data and the CSD in EIT and PMT Legal 708 DTV captioning is achievable using captions translated from 608 Producers need to move to native 708 caption authoring 44

45 Sources of Information Caption Central captioncentral.com Closed Captioning Handbook by Gary Robson, Focal Press NCAM DTV Access Project 45

46 Demonstration of 708 closed captioning by NCAM DTV Draft House 46

47 SMPTE EG 43 Trial publication on web site and for sale on CD-ROM 47

48 Acknowledgements SMPTE Gerry Field, NCAM John Demshock, WFTV Rudy Pruitt, PBS Members of the ATSC Closed Captioning Working Group Thank you 48

Implementing Closed Captioning for DTV

Implementing Closed Captioning for DTV GRAHAM JONES National Association of Broadcasters Washington, DC ABSTRACT The Federal Communications Commission (FCC) rules impose obligations on broadcasters for captioning of digital television (DTV)