SMPTE RP 2052-10-2013 Conversion from CEA-608 Data to SMPTE-TT.pdf

1、 SMPTE RP 2052-10:2013 Revision of SMPTE RP 2052-10:2012 SMPTE RECOMMENDED PRACTICE Conversion from CEA-608 Data to SMPTE-TT Page 1 of 25 pages Table of Contents Page Foreword . 2 Intellectual Property 2 1 Scope . 3 2 Conformance Notation . 3 3 Normative References . 3 4 Definitions and Acronyms 4 4

2、.1 Definitions . 4 4.2 Acronyms 4 5 CEA-608 Data Mapping to SMPTE-TT 4 5.1 Conversion Constraints . 5 5.2 SMPTE Namespaces for CEA-608 5 5.3 Translating Metadata Information . 5 5.4 Channel Conversion . 8 5.5 Preserved and Enhanced Modes 8 5.6 Header Information . 8 5.7 Region Mapping 8 5.8 Cursor P

3、ositioning . 10 5.9 Style Mapping . 12 5.10 Tunneling CEA-608 Data . 18 Annex A Bibliography (Informative) . 19 Annex B Example Encoding (Informative) . 20 Annex C Example Translation (Informative) 24 Copyright 2013 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Pla

4、ins, NY 10601 (914) 761-1100 Approved June 5, 2013 Page 2 of 25 pages SMPTE RP 2052-10:2013 Foreword SMPTE (the Society of Motion Picture and Television Engineers) is an internationally-recognized standards developing organization. Headquartered and incorporated in the United States of America, SMPT

5、E has members in over 80 countries on six continents. SMPTEs Engineering Documents, including Standards, Recommended Practices, and Engineering Guidelines, are prepared by SMPTEs Technology Committees. Participation in these Committees is open to all with a bona fide interest in their work. SMPTE co

6、operates closely with other standards-developing organizations, including ISO, IEC and ITU. SMPTE Engineering Documents are drafted in accordance with the rules given in Part XIII of its Administrative Practices. SMPTE RP 2052-10 was prepared by Technology Committee 24TB. Intellectual Property At th

7、e time of publication no notice had been received by SMPTE claiming patent rights essential to the implementation of this Engineering Document. However, attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. SMPTE shall not be held respo

8、nsible for identifying any or all such patent rights. SMPTE RP 2052-10:2013 Page 3 of 25 pages pages 1 Scope This recommended practice document defines the preferred method of converting from CEA-608 data streams to SMPTE-TT (as defined in SMPTE ST 2052-1). This document details how such a conversio

9、n can be made, and defines some constraints on the translation process so that the resulting SMPTE-TT file is interoperable between SMPTE-TT implementations. 2 Conformance Notation Normative text is text that describes elements of the design that are indispensable or contains the conformance languag

10、e keywords: “shall“, “should“, or “may“. Informative text is text that is potentially helpful to the user, but not indispensable, and can be removed, changed, or added editorially without affecting interoperability. Informative text does not contain any conformance keywords. All text in this documen

11、t is, by default, normative, except: the Introduction, any section explicitly labeled as “Informative“ or individual paragraphs that start with “Note: The keywords “shall“ and “shall not“ indicate requirements strictly to be followed in order to conform to the document and from which no deviation is

12、 permitted. The keywords, “should“ and “should not“ indicate that, among several possibilities, one is recommended as particularly suitable, without mentioning or excluding others; or that a certain course of action is preferred but not necessarily required; or that (in the negative form) a certain

13、possibility or course of action is deprecated but not prohibited. The keywords “may“ and “need not“ indicate courses of action permissible within the limits of the document. The keyword reserved indicates a provision that is not defined at this time, shall not be used, and may be defined in the futu

14、re. The keyword forbidden indicates reserved and in addition indicates that the provision will never be defined in the future. A conformant implementation according to this document is one that includes all mandatory provisions (“shall“) and, if implemented, all recommended provisions (“should“) as

15、described. A conformant implementation need not implement optional provisions (“may“) and need not implement them as described. Unless otherwise specified, the order of precedence of the types of normative information in this document shall be as follows: Normative prose shall be the authoritative d

16、efinition; Tables shall be next; followed by formal languages; then figures; and then any other language forms. 3 Normative References The following standards contain provisions which, through reference in this text, constitute provisions of this recommended practice. At the time of publication, the

17、 editions indicated were valid. All standards are subject to revision, and parties to agreements based on this recommended practice are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. SMPTE ST 2052-1:2013, Timed Text Format (SMPTE-TT) C

18、EA-608-E (ANSI) (2008), Line 21 Data Services Page 4 of 25 pages SMPTE RP 2052-10:2013 4 Definitions and Acronyms 4.1 Definitions CEA-608: the term is used in this document to refer to the CEA-608 standard or to a data stream complying to that standard, depending on context. CEA 608 closed captions

19、are composed of a byte sequence which is carried embedded in a video signal, and which when played on a suitably equipped video device creates text captions on the display. Chunk: A segment of a media timeline that forms part of a larger contiguous sequence of timeline segments where each segment ha

20、s a 1 to 1 mapping with a SMPTE-TT document. Namespace: mechanism for scoping the definitions of names in an XML document. Presentation processor: Hardware or software that creates a visible rendition of a document as defined in W3C TML. SMPTE-TT document: an encoding of some XML content conforming

21、to the SMPTE-TT document type. 4.2 Acronyms TTML: (W3C) Timed Text Markup Language CEA: Consumer Electronics Association SMPTE-TT: SMPTE Profile of W3C Timed Text TTML: (W3C) Timed Text Markup Language W3C: World Wide Web Consortium XML: eXtensible Markup Language XDS: eXtended Data System 5 CEA-608

22、 Data Mapping to SMPTE-TT This document defines conversion from CEA-608 data streams to a SMPTE-TT document (or series of document chunks) that will, when presented using a conforming SMPTE-TT Presentation Engine, give a functionally equivalent display. In most cases there will be no single correct

23、translation, but multiple possible interpretations that will generate a similar outcome when rendered. The constraints given in this document are intended to promote consistency amongst implementations of SMPTE-TT processors and to improve interoperability of SMPTE-TT files when displayed on those d

24、ifferent implementations. CEA-608 data can be obtained from various sources, including extraction from the NTSC line 21 waveform, data carried in line 21 of serial digital interface video or other methods such as directly from caption authoring file formats. Many formats may be acceptable so long as

25、 they enable the output waveform recreated by a presentation processor from tunneled data to conform to the CEA-608 standard. The reference model for CEA-608 captioning contains two 32 x 15 character memories, one of which corresponds to the currently displayed captions, and another which is an off-

26、screen composition area. The text which is mapped to SMPTE-TT corresponds to the text placed in the current display memory. SMPTE RP 2052-10:2013 Page 5 of 25 pages pages 5.1 Conversion Constraints SMPTE-TT documents converted from CEA-608 data streams shall have the constraints defined in Section 5

27、 of this specification. The process of translation from a specific CEA-608 data stream may lead to a number of possible SMPTE-TT documents; no unique conversion is defined by this document. 5.2 SMPTE Namespaces for CEA-608 TTML allows for metadata to be added in private namespaces. SMPTE-TT document

28、s need not use the prefixes below, although such prefixes are used in examples throughout this specification. It is assumed that if a full namespace declaration is not given in an example XML fragment then the definitions in Table 1 Namespaces are set in an outer context in the surrounding XML. Tabl

29、e 1 Namespaces Name Prefix Value 608 metadata m608: http:/www.smpte-ra.org/schemas/2052-1/2013/smpte-tt#cea608 5.3 Translating Metadata Information The URI used for the origin attribute shall be: http:/www.smpte-ra.org/schemas/2052-1/2013/smpte- tt#cea608. An informative XML schema is published as R

30、P 2052-10b and posted online here: http:/www.smpte-ra.org/schemas/2052-1/2013/smpte-tt-608.xsd The following metadata attributes may be added to the smpte:information item. 5.3.1 m608:channel The channel(s) from which the translation was made. This applies to the content of the translated content of

31、 the document only, not the tunneled data. Values: (CC1 | CC2 | CC3 | CC4) Initial: CC1 Applies to: smpte:information Inherited: no Percentages: N/A Animatable: none 5.3.2 m608:fieldStart Determines the field association with the first two bytes of tunneled data (see Section 5.10). This does not app

32、ly to the translated content of the document. When tunneled data is present, this attribute shall be present. Values: 1 | 2 Initial: 1 Applies to: smpte:information Inherited: no Percentages: N/A Animatable: none Page 6 of 25 pages SMPTE RP 2052-10:2013 5.3.3 XDS Data attribute: Program Name (m608:p

33、rogramName) Values: | none Initial: none Applies to: smpte:information Inherited: no Percentages: N/A Animatable: none The values of this attribute, when used, shall be set to the string of ASCII characters in the XDS packet as defined in CEA-608, Section 9.5.1.3. Program name may be carried in comp

34、osite XDS Data, or in its own packet in the CEA-608 data. Either form may be used to set this attribute, however if program name is specified in both forms, then that specified in its own packet shall take precedence for setting this attribute. 5.3.4 XDS Data attribute: Program Type (m608:programTyp

35、e) Values: | none Initial: none Applies to: smpte:information Inherited: no Percentages: N/A Animatable: none The values of this attribute, when used, shall be set to the list of 2-character hex codes listed in CEA-608, Section 9.5.1.4. 5.3.5 XDS Data attribute: Content Advisory (m608:contentAdvisor

36、y) Values: | none Initial: none Applies to: smpte:information Inherited: no Percentages: N/A Animatable: none The values of this attribute, when used, shall be set to the 4-character hex representation of the 2-byte payload according to CEA-608, Section 9.5.1.5: 5.3.6 XDS Data attribute: Caption Ser

37、vices (m608:captionService) Values: Initial: none Applies to: smpte:information Inherited: no Percentages: N/A Animatable: none Note: The values of this attribute are drawn from CEA-608, Section 9.5.1.7 The original data for this attribute is in binary format. The value of this string is constructed

38、 by the concatenation of the field value strings in Table 2 separated by whitespace, from 1 up to 7 field values. xml:lang shall be set to the language codes in Table 3. SMPTE RP 2052-10:2013 Page 7 of 25 pages pages Table 2 Field and Channel mapping 608 Binary value Meaning Field Value 0 0 0 field

39、one, channel C1, captioning F1C1CC 0 0 1 field one, channel C1, Text F1C1TX 0 1 0 field one, channel C2, captioning F1C2CC 0 1 1 field one, channel C2, Text F1C2TX 1 0 0 field two, channel C1, captioning F2C1CC 1 0 1 field two, channel C1, Text F2C1TX 1 1 0 field two, channel C2, captioning F2C2CC 1

40、 1 1 field two, channel C2, Text F2C2TX 5.3.7 XDS Data attribute: Copy and Redistribution Control Packet (m608:copyAndRedistributionControl) Values: Initial: None Applies to: smpte:information Inherited: No Percentages: N/A Animatable: None The values of this attribute, when used, shall be set to th

41、e 4-character hex representation of the 2-byte payload according to CEA-608, Section 9.5.1.8 5.3.8 XDS Data attribute: Audio Services (xml:lang) If XDS caption services packet is not present, then xml:lang shall be set according to this paragraph. If the SMPTE-TT document is encoding the Primary Syn

42、chronous Caption Service (CC1) then the content is primary language captioning data in the same language; thus the language code used on the root xml:lang attribute shall be the ISO language code defined by the Main audio language bits of the XDS Audio Service (see CEA-608, Section 9.5.1.6) from Tab

43、le 3 Language codes: Table 3 Language codes L2 L1 L0 Language xml:lang code 0 0 0 Unknown 0 0 1 English en 0 1 0 Spanish es 0 1 1 French fr 1 0 0 German de 1 0 1 Italian it 1 1 0 Other 1 1 1 None If the SMPTE-TT document is encoding the Secondary Synchronous Caption Service (CC2 or CC3), then the co

44、ntent is secondary language captioning data in the same language; thus the language code used on the root xml:lang attribute shall be the ISO language code defined by the SAP audio language bits of the XDS Audio Service (see CEA-608, Section 9.5.1.6). Page 8 of 25 pages SMPTE RP 2052-10:2013 If the

45、XDS Audio Service packet and the XDS Captions Services packet are both not present; or the SMPTE-TT document is encoding from one of the Special Non-synchronous channels (CC2, CC4), then the xml:lang attribute should be set to the null string. Additionally, if the converted document contains only tu

46、nnel information and no presentation elements, xml:lang should be set to the empty string. 5.3.9 Additional XDS data Translation of other XDS data, such as V-chip rating, time data, and text streams, are not defined by this specification but, if required, may be translated in a similar manner into a

47、 private namespace. 5.3.10 XDS Data example The following example illustrates the use of CEA-608 XDS Data items to define a conversion from the captions of an English language news program: 5.4 Channel Conversion A separate logical sequence of SMPTE-TT chunks shall be created for each of CC1, CC2, C

48、C3 and CC4 channels where present. 5.5 Preserved and Enhanced Modes When translating from existing CEA-608 information, unless it is known that the exact replication of the visual appearance is required, Enhanced mode will give greater latitude to create a more conformant SMPTE-TT document. If exact

49、 replication is required, then Preserved mode will be needed. The Preserved mode of translation for CEA-608 shall preserve the color, background spacing and timing of captions, including individual character timings in rollup and paint on mode. The Enhanced mode of translation for CEA-608 shall retain equivalence classes of caption style, but may map to alternative specific styles (e.g., all text that is red in the original sequence shall be mapped to the same st