Slide 1: Implementing Closed Captioning for DTV
Implementing Closed Captioning for DTV Graham Jones NAB Broadcast Engineering Conference April, 2004 1
Slide 2: Agenda
Agenda • Terminology • FCC rules • Standards • Carriage of DTV closed captions • PSIP and the caption service descriptor NAB Broadcast Engineering Conference 2004 2
Slide 3: Terminology
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 NAB Broadcast Engineering Conference 2004 3
Slide 4: Terminology
Terminology • Native 708 – DTVCC encoded and transmitted in the 708 format in which they were authored • Translated or Derived 708 – 708 DTVCC translated from line 608 line 21 legacy captions – Sometimes misleadingly referred to as “upconverted” – Sometimes misleadingly referred to as “transcoded” •
Slide 5: So, what’s the difference?
So, what’s the difference? 608 line 21 NAB Broadcast Engineering Conference 2004 5
Slide 6: Native 708
Native 708 NAB Broadcast Engineering Conference 2004 6
Slide 7: Native 708
Native 708 NAB Broadcast Engineering Conference 2004 7
Slide 8: Translated 708 DTVCC – as encoded
Translated 708 DTVCC – as encoded NAB Broadcast Engineering Conference 2004 8
Slide 9: DTV caption menu
DTV caption menu NAB Broadcast Engineering Conference 2004 9
Slide 10: Translated 708 DTVCC – user format
Translated 708 DTVCC – user format NAB Broadcast Engineering Conference 2004 10
Slide 11: Translated 708 DTVCC – user format
Translated 708 DTVCC – user format NAB Broadcast Engineering Conference 2004 11
Slide 12: Translated 708 DTVCC – user format
Translated 708 DTVCC – user format NAB Broadcast Engineering Conference 2004 12
Slide 13: Translated 708 DTVCC – user format
Translated 708 DTVCC – user format NAB Broadcast Engineering Conference 2004 13
Slide 14: FCC rules for DTVCC
FCC rules for DTVCC Report and Order 00-259 July 21, 2000 Amended Part 15 and Part 79 of the FCC Rules NAB Broadcast Engineering Conference 2004 14
Slide 15: Part 15.122 Decoders for DTV receivers
Part 15.122 Decoders for DTV receivers Effective July 2002 Part 79.1 Closed captions for DTV programming Phased schedule NAB Broadcast Engineering Conference 2004 15
Slide 16: FCC Rules Summary
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 ca
Slide 17: FCC Rules Summary
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 C
Slide 18: FCC Rules – New Programming
FCC Rules – New Programming 1/1/02 – 12/31/03 900 hours/quarter 1/1/04 – 12/31/05 1350 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 languag
Slide 19: Exemptions
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 NAB Broadcast Engineering Conference 2004 19
Slide 20: FCC Rules – Pre-rule Programming
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
Slide 21: CEA Standards
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 se
Slide 22: SCTE Standards
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, the
Slide 23: SMPTE Standards
SMPTE Standards • SMPTE 333M – DTV Closed-Caption Server to Encoder Interface • SMPTE 334M – Vertical Ancillary Data Mapping for Bit-Serial Interface NAB Broadcast Engineering Conference 2004 23
Slide 24: ATSC Standards
ATSC Standards • ATSC A/53B Digital Television Standard – Carriage of DTVCC in the ATSC transport • ATSC A/65B PSIP Standard – Caption Service Descriptor (CSD) NAB Broadcast Engineering Conference 2004 24
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Slide 28: Recommended Implementation
Recommended Implementation 9 708 DTV caption data 9 608 compatibility bytes 9 Caption service descriptor in EIT (and PMT for cable) ¾ All these elements should be carried in the ATSC bitstream ¾ For distribution upstream of the ATSC encoder they can be carried in a caption distribution packet (CPD)
Slide 29: Caption Encoding and Distribution
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 NAB Broadcast Engineering Conference 2004 29
Slide 30: Carriage of 708 Captions
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) –
Slide 31: Carriage of 708 Captions
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) –
Slide 32: NAB Broadcast Engineering Conference 2004
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Slide 33: Currently used only for 292M HD signals
Currently used only for 292M HD signals Encoder embeds CDPs in VANC as per SMPTE 334M NAB Broadcast Engineering Conference 2004 33
Slide 34: Recording, Processing, Distribution
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 NAB Broadcast Engineering Co
Slide 35: Compression Distribution Systems
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 fo
Slide 36: Local Station Arrangements
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 a
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Slide 38: Caption Input to the ATSC Encoder
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 NAB Broa
Slide 39: Serial link for 708 data into the 708 encoder
PSIP EIT must contain Serial link for the caption service 708 data into descriptor to announce the 708 encoder and describe the services present NAB Broadcast Engineering Conference 2004 39
Slide 40: PSIP and Caption Service Descriptor
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 ca
Slide 41: Monitoring
Monitoring • The written paper discusses various requirements for 708 caption monitoring – Presence – Display/functionality – Synchronization – Regulatory compliance NAB Broadcast Engineering Conference 2004 41
Slide 42: 708 Equipment
708 Equipment • Four known vendors for 708 encoders NAB Broadcast Engineering Conference 2004 42
Slide 43: 708 Authoring Software
708 Authoring Software • Coming soon… NAB Broadcast Engineering Conference 2004 43
Slide 44: Conclusions
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
Slide 45: Sources of Information
Sources of Information • Caption Central – www.captioncentral.com • Closed Captioning Handbook by Gary Robson, Focal Press • NCAM – DTV Access Project – www.dtvaccess.org NAB Broadcast Engineering Conference 2004 45
Slide 46: DTV Draft House
DTV Draft House • Demonstration of 708 closed captioning by NCAM NAB Broadcast Engineering Conference 2004 46
Slide 47: SMPTE EG 43 Trial publication on web site
SMPTE EG 43 Trial publication on web site www.smpte.org and for sale on CD-ROM NAB Broadcast Engineering Conference 2004 47
Slide 48: Acknowledgements
Acknowledgements • SMPTE • Gerry Field, NCAM • John Demshock, WFTV • Rudy Pruitt, PBS • Members of the ATSC Closed Captioning Working Group Thank you gjones@nab.org NAB Broadcast Engineering Conference 2004 48