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Caption streams are transmitted with many packet wrappers around them. These are the picture user data, which contains the caption data, which contains the cc_data, which contains the
Caption Channel packets, which contains the Service Block, which contains the caption streams.
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This structure was designed for any digital audio or metadata that is to be synchronized with a video frame. SDI transports every eight bits in a 10-bit aligned packet and the ancillary flag bytes are replaced by 128 bit header.
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CTA-708 supports eight font tags: undefined, monospaced serif, proportional serif, monospaced sans serif, proportional sans serif, casual, cursive, and small capitals. Below are some font examples, for more see the
Knowledge
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caption descriptor which indicates the language of each caption and if formatted for "easy reader" (3rd-grade level for language learners) in the PSIP EIT on a per-event basis and optionally in the
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regulation in all 13-inch (33 cm) diagonal or larger digital televisions. Further, some broadcasters are required by FCC regulations to caption a percentage of their broadcasts.
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channel that has 960 bit/s typically allocated for backward compatible "encapsulated" Line 21 captions, and 1.08 kB/s allocated for CTA-708 captions, for a total of 1.2 kB/s. The
678:(2015) "The majority of premium content produced for the United States today still contains 608 captions embedded in the 608 over 708 digital formats."
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A cdp_timecode is used when cdp data stream is discontinuous (i.e., not padded) and the cdp_service_info is used to add extra details to the
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captions, and downloadable fonts. CTA-708 caption streams can also encapsulate EIA-608 byte pairs internally, a fairly common usage.
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active video frame or video packet. Common video packets are a picture header, a picture parameter set, and a
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and must be pre-rendered by the receiver. With the digital video frames, they also include more of the
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https://www.adobe.com/content/dam/acom/en/devnet/video/pdfs/introduction_to_closed_captions.pdf
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subtitles. Unlike EIA-608 byte pairs, CTA-708 captions are not able to be modulated on an
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and DVD subtitles, CTA-708 captions are low bandwidth and textual like traditional
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broadcast metadata such as language code, easy reader, and widescreen usage.
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contains the encoding specifics. The main form of signalling is via a
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Standard for closed captioning for ATSC digital television
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CTA-708 caption decoders are required in the U.S. by
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may be too technical for most readers to understand
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699:Table A7 Picture User Data Syntax6 for 5F485C53d01
344:PMT only if the video always sends caption data.
313:character set, and include stubs to support full
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401:Breaking up individual commands and characters
390:Issuing commands and appending text to windows
434:cc_data Packets extracted from video frames
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688:https://ecfsapi.fcc.gov/file/6008646915.pdf
423:DTVCC Packet assembly from cc_data Packets
64:Learn how and when to remove these messages
483:link format demodulated from transmission
234:Learn how and when to remove this message
216:Learn how and when to remove this message
200:, without removing the technical details.
161:Learn how and when to remove this message
514:MPEG-4 Video user data structure prefix
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741:: CS1 maint: archived copy as title (
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767:ANSI/CTA-708 R-2018
619:Proportional Serif
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288:Run-length encoding
783:Digital television
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334:ATSC A/53 Standard
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93:Please help
88:verification
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47:Please help
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553:ASCII bslbf
542:0x000001B2
373:OSI Layers
305:receiver's
777:Categories
663:References
584:free form
496:SMPTE 259M
454:SMPTE 259M
431:Injection
428:Transport
252:(formerly
121:newspapers
50:improve it
611:article.
502:essence.
471:Physical
379:Comments
330:bandwidth
110:"CTA-708"
56:talk page
737:cite web
575:X*8 bits
506:ISO/IEC
439:Network
409:Service
406:Session
299:Teletext
206:May 2016
727:May 25,
547:32 bits
533:32 bits
512:14496-2
442:unused
420:Packet
398:Coding
311:Latin-1
295:EIA-608
286:Unlike
258:CEA-708
254:EIA-708
192:Please
135:scholar
18:CEA-708
581:binary
567:uimsbf
561:8 bits
528:Value
519:Length
510:H.262/
322:MPEG-2
315:UTF-32
277:Canada
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721:(PDF)
714:(PDF)
609:Fonts
602:Fonts
556:GA94
508:13818
458:H.222
450:Link
342:H.222
142:JSTOR
128:books
765:the
743:link
729:2012
596:PSIP
525:Type
522:Name
479:8VSB
338:PSIP
303:ATSC
275:and
266:ATSC
264:for
256:and
250:-708
114:news
477:or
475:SDI
462:MXF
460:or
456:or
417:--
349:FCC
291:DVB
248:CTA
196:to
97:by
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