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Video Description in More than one Language. Overview Need Capability Approaches Conclusion. Disclaimer: This presentation does not contain any recommendations, assessments or positions from or by NAB. Video Description.
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Video Description inMore than one Language • Overview • Need • Capability • Approaches • Conclusion Disclaimer: This presentation does not contain any recommendations, assessments or positions from or by NAB
Video Description The term ‘video description’ means the insertion of audio narrated descriptions of a television program’s key visual elements into natural pauses between the program’s dialogue. (S. 3304) AKA: Descriptive Video, Visually Impaired (VI)
Video Description Insertion Voice under? “no dialog” “no dialog” “no dialog” Primary Audio Dialog Descriptive insertions Audio with Video Description (Complete Mix)
Pause to reflect • Receiver makers refused to support the original Dolby design to save bits by enabling supplemental audio tracks • So service providers must consume bits to send everything for any audio service • Wonder if that lack of innovation is in Gary’s book… moving on…
Initial Mandates • Initial video description rules will go into effect October 2011. • Four Networks (ABC, CBS, Fox, and NBC) and top 5 national non-broadcast networks will have to provide 50 hrs./quarter with video description1 • Broadcast stations and MVPDs with technical capability to do so generally must pass through audio containing video descriptions. 1. For the top 25 DMAs and 50k+ subscriber systems respectively
More to Come from the FCC • Reports • Rule makings • Not later than this or sooner than that • Soonest for all DMAs : 2037 • Not tomorrow … but it is coming • English is assumed, but the Spanish speaking population is growing … • So what can we do?
Dolby E 8 ch. PCM Stream, compressed3 Mb/s total, twisted pair or coax Digital Audio Interfaces Studio/Master Control Video Subsystem Video Video Source Coding Router/MC Switcher Work File Audio Subsystem Audio Audio Source Coding Ancillary Data Control Data
Eight is enough For one additional service (with 5.1) -- need to replicate the path to get more than one language or type of service
Uncompressed Audio Interconnects AES-3: 2 ch / PCM stream, uncompressed 1.92 Mb/s, Twisted Pair or Coax (may also carry 8-channel Dolby E) then in HANC: 16 channels total Digital Audio Interface Studio/Master Control Video Subsystem Video Video Source Coding & Compression MC SW Work File Audio Subsystem Audio Audio Source Coding & Compression Ancillary Data Control Data
Sixteen is enough • For a pair of 5.1 channel services, each with an associated stereo audio descriptive video mix. • For a 5.1 service and 5 stereo services • So audio in several languages with VI and HI could be supported – but only one could be 5.1
RemoteProduction& PostVenues DTV Contribution Distribution LocalStation NetworkCenter HD or SD ATSCDigital For MPEG links, Audio channels can be carried as program elements with PMT-based signaling
Transmission • Digital Transmission • A large number of audio services for a single video (MPEG-2 Transport) can be signaled and sent (depending on the number of descriptors associated with each audio) • Analog Transmission • Second audio or video description <choose>
Transport Component Organization ATSC Transport Virtual Channel 1 MDTV Audio Audio Video Audio Audio PSI(P) Virtual Channel 2
Multi-Program Multiplex PES Streams Video+PCR Audio1: CM eng Audio2: VI eng Audio 3: CM spa Audio 4: VI spa Program 1 OK Mux Multi- Program Transport Stream Program 2 Program 3 Mux SI Tables (PMT) 4 each AC-3 and ISO-639 descriptors PSIP Tables Each event different descriptors
Electra 8000 – Hardware overview Dual ASI Output Management Port PSIP input Optional Audio Card 5.1 + 2.0 or 3 x 2.0 Optional Audio Card 5.1 + 2.0 or 3 x 2.0 Optional Audio Card 5.1 + 2.0 or 3 x 2.0 Optional Audio Card 5.1 + 2.0 or 3 x 2.0 CPC Control Card ASI Output Card 2 ASI StatMux Engine Midplane Encoder Encoder Encoder Encoder Encoder Video Encoding Video Encoding Video Encoding Video Encoding Audio Encoding 3 X 2.0 Audio Encoding 3 x 2.0 Audio Encoding 3 x 2.0 Audio Encoding 3 x 2.0 SDI / HDSDI (embedded audio)
Encoder Outputs Optional Audio Cards Each can encode or transcode from Dolby E one 5.1 + one 2.0 Dolby Digital Video Inputs One configuration would be to provide one 5.1 in English with the Descriptive Video on a Dolby E path, and the Spanish 5.1 with Descriptive Video in Spanish on another Dolby E path. Note this configuration supports more than my example case. The maximum audio + video shown is Four video programs (HD, SD or mixed) Four 5.1 surround channels Sixteen 2.0 stereo channels Based on slide from
Announcement Paradigms • This Program has English, Spanish, with Video Description in both Languages • Separate virtual channels • English • English Description for the Blind • English for the Hearing Impaired • Spanish • Spanish Description for the Blind • Spanish for the Hearing Impaired But Cable may have to do something like this if delivery to NTSC sets is required
Terrestrial Emission Overview(signaling and announcement) Event 1 Event 2 Events & tracks CM (5.1, eng) CM (5.1, eng) + VI (2, eng) CM ( 5.1, spa + VI (2, spa) EIT 0 (partial) EIT 0 (partial) Event 1 – AC-3 descriptor with one audio service Event 2 – AC-3 descriptor with four audio services PMT – one ISO-639 descriptor Event 2 – AC-3 descriptor with four audio services PMT – four ISO-639 descriptors (one per program element) ATSC Transport PSIP & PSI
DTV Receiver Audio Audio Decoding RF Tuner & VSB De- Modulator Transport De- Multiplex Video Decoding Display Processor Video RF Channel Select PSIP Data Audio Select Program Guide Database Program select from user
CEA-CEB-21 Recommended Practice for Selection and Presentation of DTV Audio In progress since July 2008, but almost done
Key Issues • User set up and control • Explicit Language selection • Explicit VI and HI selection • Differences between stream construction (Off-air and Cable)
Key Recommendations • Receivers should gather user preferences and allow them to be changed later • Receivers should read the tables and descriptors and use the contents • Receivers should automatically select best fit to preferences when more than one stream is present
Key Recommendations • Should consider the following items when providing for user selection of their preferred audio stream: • Stream type (CM, VI, or HI,) as signaled by the bsmod field in the AC-3_audio_stream_descriptor(). • The language field encoded in the AC-3_audio_stream_descriptor(). • The component_name_descriptor() to provide supplemental audio stream information to users, if needed.
Conclusion • Multiple language, multiple community service audio tracks are part of your future (unless English is declared to be the <ONE> Official Language for the United States of America) • Force fitting to the 2-audio mold is problematic • When breaking the mold, plan ahead
Credits ATSC CEA Mike Dolan Graham Jones