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1、 CEA Standard Line 21 Data Services CEA-608-D May 2007 NOTICE Consumer Electronics Association (CEA) Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeabi
2、lity and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards, Bulletins and other technical publications shall not in any respect preclude any member or nonmember of CEA from manufa
3、cturing or selling products not conforming to such Standards, Bulletins or other technical publications, nor shall the existence of such Standards, Bulletins and other technical publications preclude their voluntary use by those other than CEA members, whether the standard is to be used either domes
4、tically or internationally. Standards, Bulletins and other technical publications are adopted by CEA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, CEA does not assume any liability to any patent owner, nor does it assume any obligation whatever to
5、 parties adopting the Standard, Bulletin or other technical publication. Note: The users attention is called to the possibility that compliance with this standard may require use of an invention covered by patent rights. By publication of this standard, no position is taken with respect to the valid
6、ity of this claim or of any patent rights in connection therewith. The patent holder has, however, filed a statement of willingness to grant a license under these rights on reasonable and nondiscriminatory terms and conditions to applicants desiring to obtain such a license. Details may be obtained
7、from the publisher. This CEA Standard is considered to have International Standardization implication, but the International Electrotechnical Commission activity has not progressed to the point where a valid comparison between the CEA Standard and the IEC document can be made. This Standard does not
8、 purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. (Formulat
9、ed under the cognizance of the CEA R4.3 TV Data Systems Subcommittee.) Published by CONSUMER ELECTRONICS ASSOCIATION 2007 Technology Phone 800.854.7179; Fax 303.397.2740; Internet http:/ ; Email SMPTE Standards: Society of Motion Picture Email: engsmpte.org; Internet http:/www.smpte.org ATSC Standa
10、rds: Advanced Television Systems Committee (ATSC), 1750 K Street N.W., Suite 1200, Washington, DC 20006; Phone 202.828.3130; Fax 202.828.3131; Internet http:/www.atsc.org/standards.html ECMA Standards: European Computer Manufacturers Association (ECMA), 114 Rue du Rhne, CH1204 Geneva, Switzerland; I
11、nternet http:/www.ecma-international.org/publications/index.html FCC FCC Regulations, U.S. Government Printing Office, Washington, D.C. 20401; Internet http:/www.access.gpo.gov/cgi-bin/cfrassemble.cgi?title=199847 3 CEA-608-D FIPS Standards: National Institute of Standards and Technology and Informa
12、tion Technology, U.S. Government Printing Office, Washington, D.C. 2040; http:/www.itl.nist.gov/fipspubs/ IETF Standards: Internet Engineering Task Force (IETF), c/o Corporation for National Research Initiatives, 1895 Preston White Drive, Suite 100, Reston, VA 20191-5434 USA; Phone 703-620-8990; Fax
13、 703-758- 5913; Email ietf-infoietf.org ; Internet http:/www.ietf.org/rfc/rfc0791.txt?number=791 and http:/www.ietf.org/rfc/rfc1071.txt?number=1071 IEC and ISO Standards: Global Engineering Documents, World Headquarters, 15 Inverness Way East, Englewood, CO USA 80112-5776; Phone 800-854-7179; Fax 30
14、3-397-2740; Internet http:/ ; Email ISO Central Secretariat, 1, rue de Varembe, Case postale 56, CH-1211 Geneve 20, Switzerland; Phone + 41 22 749 01 11; Fax + 41 22 733 34 30; Internet http:/www.iso.ch ; Email centraliso.ch 4 CEA-608-D 3 Definitions 3.1 Definitions With respect to definition of te
15、rms, abbreviations and units, the practice of the Institute of Electrical and Electronics Engineers (IEEE) as outlined in the Institutes published standards shall be used. Where an abbreviation is not covered by IEEE practice, or CEA-608-D practice differs from IEEE practice, then the abbreviation i
16、n question is described in Section 3.2.1 or 3.2.2. 3.2 Terms Employed 3.2.1 Acronyms1 AC Article Clear AE Article End ANE Article Name End ANS Article Name Start AOF Reserved (formerly Alarm Off) AON Reserved (formerly Alarm On) ANSI American National Standards Institute ASB Analog Source Bit ASCII
17、American Standard Code for Information Interchange APS Analog Protection System ANSI American National Standards Institute ATSC Advanced Television Systems Committee BS Backspace CEA Consumer Electronics Association CGMS Copy Generation Management System CR Carriage Return CRTC Canadian Radio-televi
18、sion and Telecommunications Commission DER Delete to End of Row DVR Digital Video Recorder ECMA European Computer Manufacturers Association EDM Erase Displayed Memory EIA Electronic Industries Alliance ENM Erase Non-Displayed Memory EOC End of Caption FCC Federal Communications Commission FIPS Feder
19、al Information Processing Standard FON Flash On IEC International Electrotechnical Commission IEEE Institute of Electrical and Electronics Engineers IETF Internet Engineering Task Force IRE Institute of Radio Engineers ISO International Organization for Standardization NRZ Non-Return-to-Zero NTSC Na
20、tional Television Standards Committee PAC Preamble Address Code PSP Pseudo Sync Pulse RCD Redistribution Control Descriptor RCL Resume Caption Loading RDC Resume Direct Captioning RTD Resume Text Display RU2 Roll Up Captions 2 Rows RU3 Roll Up Captions 3 Rows RU4 Roll Up Captions 4 Rows SMPTE Societ
21、y of Motion Picture and Television Engineers 1 While some commands are included in Section 3.2.1, a complete list of commands may be found in 47 C.F.R. 15.119. 5 CEA-608-D TC1 TeleCaption I TC2 TeleCaption II TO1 Tab Offset 1 Column TO2 Tab Offset 2 Columns TO3 Tab Offset 3 Columns TR Text Restart T
22、SID Transmission Signal Identifier URL Uniform Resource Locator UTC Coordinated Universal Time2 XDS eXtended Data Service 3.2.2 Glossary (Informative) Base Row: The bottom row of a roll-up display. The cursor always remains on the base row. Rows of text roll upward into the contiguous rows immediate
23、ly above the base row. Box: The area surrounding the active character display. In Text Mode, the box is the entire screen area defined for display, whether or not displayable characters appear. In Caption Mode, the box is dynamically redefined by each caption and each element of displayable characte
24、rs within a caption. The box (or boxes, in the case of a multiple-element caption) includes all the cells of the displayed characters, the non- transparent spaces between them, and one cell at the beginning and end of each row within a caption element in those decoders which use a solid space to imp
25、rove legibility. Character: A single group of 7 data bits plus a parity symbol. Captioning: Textual representation of program dialogue that may include other program descriptions. Caption File: A computer file that defines the captions used by a captioning encoder. Captioning Diskette: A computer di
26、skette with a caption file written on it. This file has captioning data used by an encoder to insert captions. Captioning Sync: The timing relationship between the picture and the appearance of captions on that picture. See Section E.2. Caption Master Tape: The earliest videotape generation of a pro
27、duction on which captions have been recorded. Cell: The discrete screen area in which each displayable character or space may appear. A cell is one row high and one column wide. Channel Grazing: When a viewer changes channels frequently to search for a desired show. Channel Surfing: When a viewer ch
28、anges channels frequently to search for a desired show. Column: One of 32 vertical divisions of the screen, each of equal width, extending approximately across the full width of the Safe Caption Area (see also). Two additional columns, one at the left of the screen and one at the right, may be defin
29、ed for the appearance of a box in those decoders which use a solid space to improve legibility, but no displayable characters may appear in those additional columns. For reference, columns may be numbered 0 to 33, with columns 1 to 32 reserved for displayable characters. Control Code or Control Char
30、acter: The framing characters of an XDS packet, or the characters that control the display of text in closed captioning. Default: 1) A condition which exists when no explicit parameters are given, or 2) A specified parameter to be used when an explicit parameter is not intended to be recognized or a
31、cted upon. Examples: 2 Since unanimous agreement could not be achieved by ITU on using either the English word order CUT, or the French word order, TUC, a compromise to use neither was reached. 6 -,-,- CEA-608-D a) If no PAC is received after a Carriage Return (CR) in roll-up style captioning, the d
32、efault position for the new row is Indent 0. b) A mid-screen PAC can be preceded by a default address that is used by any decoder which does not recognize mid-screen PACs. Display Disable: To turn off the display of captions or text (and accompanying background) at the receiver, rather than through
33、codes transmitted on line 21 which unconditionally erase the display. The receiver may disable the display because the user selects an alternate mode, e.g. TV Mode, or because no valid line 21 data are present. Display Enable: To allow the display of captions or text when they are transmitted on lin
34、e 21 and received as valid data. NOTEFor display to be enabled, the user shall have selected Caption Mode or Text Mode, and valid data for the selected mode shall be present on line 21. Displayable Character: Any letter, number, or symbol which is defined for on-screen display, plus the 0x20 space.
35、Element: In a pop-on or paint-on style caption, each contiguous area of cells containing displayable characters and non-transparent spaces between those characters. A single caption may have multiple elements. An element is not necessarily a perfect rectangle, but may include rows of differing width
36、s. Encoder: A device that adds the caption data signal to line 21 of an NTSC video signal. Erase Display: In Caption Mode, to clear the screen of all characters (and accompanying background) in response to codes transmitted on line 21. The caption service provider can accomplish the erasure either b
37、y sending an Erase Displayed Memory (EDM) command or by sending an Erase Non-Displayed Memory (ENM) command followed by an End of Caption (EOC) command, effectively making a blank caption “appear.“ Display can also be erased by the receiver when the caption memory erasure conditions are met, such as
38、 the user changing TV channels. In Text Mode, to clear the screen of all characters without affecting the solid background box. The text service provider can accomplish the erasure by sending a Text Restart (TR) command. Display can also be erased by the receiver under the same memory erasure condit
39、ions as captions. Field Reversal: Some video processing equipment (Time Base Correctors, Tape Machines, etc.) may place video from field 1 on field 2, and place video from field 2 on field 1. General Purpose Captioning: Captioning done for wide distribution in which the exact specifications of the d
40、ecoders to be used are unknown. Open captioning is not general purpose because the specifications of the character generator are known and controllable. Closed captioning done for a closed user group in which the decoder model used for viewing can be specified is also not general purpose. Thus, this
41、 phrase refers to closed captioning which may be accessed by general audiences who provide their own decoders and who, therefore, need captions which provide compatible displays on all decoder models. Hex Notation: Hexidecimal notation in the format 0x00, 0x01, , 0x0F. In some tables the prefix 0x m
42、ay not be included. Immediately: When receiver functions are supposed to occur “immediately,“ it is expected that they occur in the same video frame as, or no more than one video frame after, the receipt of the command which triggers the function. In the case of redundant control-byte pairs, such as
43、 Erase Displayed Memory, receipt of the command means upon receipt of the first of the redundant pairs, assuming it passes parity. Informational Character: The characters within the packet that contain the message. Informational Characters are always sent in pairs. This excludes the Start, Continue,
44、 End, Type when used, the solid background changes shape and size to conform to the caption element(s) displayed. In Text Mode, use of a solid background is required; the solid background completely fills the box area regardless of the presence or parameters of displayable characters. Solid Space: O
45、ne cell of the solid background in which no displayable character is present. Special Characters: Displayable characters (except for “transparent space“) which require a two-byte sequence of one non-printing and one printing character. The non-printing byte varies depending on the data channel. Regu
46、lar characters require a unique one-byte code which is the same in either data channel. Sub-packet: A contiguous group of two-character pairs that begins with a XDS control character and ends with a command to restore operation to the previous state. Text: When written with an upper-case “T,“ refers
47、 to Text Mode. When written with a lower-case “t,“ refers to any combination of displayable characters. Transparent Space: Transmitted as a special character, it is a one-column-wide space behind which program video is always visible. 8 CEA-608-D Type Character: The character following the Control c
48、haracter which indicates a specific XDS packet type. Window: The invisible rectangle that defines the top and bottom limits of a roll-up caption. The window can be 2 to 4 rows high. The lowest row of the window is called the base row. 3.3 Compliance Notation As used in this standard, “shall” denotes
49、 a mandatory provision of the standard. “Should” denotes a provision that is recommended but not mandatory. “May” denotes a feature, whose presence does not preclude compliance, that may or may not be present at the option of the implementer. Unless a section or subsection is explicitly labeled Informative or Regulatory, it shall be considered Normative. A section or subsection labeled Informative or Regulatory remains as such thro