1、 Copyright 2013 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 Approved August 14, 2013 1 Document Roadmap SMPTE ST 2052-1, Timed Text Format (SMPTE-TT), specifies a core standard and defines the Timed Text format. SMPTE-TT can be use
2、d in an end-to-end broadband infrastructure as a native format including authoring and rendering. However, existing (legacy) captioning formats exist worldwide that have a large body of captions authored in and/or distributed in their individual syntax. To properly translate those existing caption s
3、yntax formats, individual “Format Translation” documents are created as SMPTE Recommended Practices. SMPTE RP 2052-10, Conversion of CEA-608 Data to SMPTE-TT, describes how the legacy CEA-608 syntax (including analog video waveform) can be mapped into the SMPTE-TT format and SMPTE RP 2052-11, Conver
4、sion of CEA-708 Data to SMPTE-TT, describes how the CEA-708 syntax can be mapped into the SMPTE-TT format. Additional translation documents are envisioned for inclusion in the 2052 “family” of specifications. 2 Scope This document provides context to the 2052 “family” of the core standard and the re
5、lated, optional, format conversion document(s). This document is introductory and does not contain any normative requirements. 2.1 Scope SMPTE ST 2052-1:2013 This Standard defines the SMPTE profile of W3C Timed Text Markup Language (TTML), designated SMPTE-TT, which may represent Captions or Subtitl
6、es. It identifies the features from TTML required for interoperability between display systems for the format. In order to preserve certain semantic features of the input formats, SMPTE-TT also defines some standard metadata terms to be used, and some extension features not found in TTML. 2.2 Scope
7、SMPTE RP 2052-10:2013 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 conversion can be made, and defines some constraints on the translation process so that the resu
8、lting SMPTE-TT file is interoperable between SMPTE-TT implementations. Page 1 of 5 pages SMPTE 2052-0:2013 Revision of SMPTE 2052-0:2010 SMPTE ROADMAP SMPTE-TT and Format Translation Roadmap for the 2052 Document Suite SMPTE 2052-0:2013 Page 2 of 5 pages 2.3 Scope SMPTE RP 2052-11:2013 This recommen
9、ded practice document defines the preferred method of converting from CEA-708 data streams to SMPTE-TT (as defined in SMPTE ST 2052-1). This document details how such a conversion can be made, and defines some constraints on the translation process so that the resulting SMPTE-TT file is interoperabl
10、e between SMPTE-TT implementations. 2.4 Other Related Documents SMPTE has also published informative documents related to the use of the 2052 “family”. SMPTE Technical Report - TTML Features for IMF Data Essence https:/www.smpte.org/sites/default/files/24TB-Captions-Report-IMF-TTML-Features-20121001
11、.pdf and 24TB Technical Report - Internet Caption Technical Requirements for SMPTE Timed Text https:/www.smpte.org/sites/default/files/24TB-FCC-Technical-Requirements-20120908.pdf Tutorials and background information about SMPTE-TT are also available: SMPTE PDA Now: SMPTE Timed Text http:/sas- https
12、:/ SMPTE Webcast: Internet Captioning Implications of the Multi-Platform, Multi-Display Ecosystem http:/youtu.be/QxagWb2dqPE https:/www.smpte.org/sites/default/files/2013-07-26-Captions-Livingston-V3-Handout.pdf 3 Contextual Overview of 2052 SMPTE-TT Figure 1 depicts a simplified pictorial of the ov
13、erall ecosystem of how captioning flows from authoring to end-device. In general, the introduction of broadband content distribution (more of a “PC-type” distribution means) into the existing “Broadcast / Cable-type” distribution means created a potential “gap” and the investigation that resulted in
14、 SMPTE-TT and related translation RP(s). SMPTE 2052-0:2013 Page 3 of 5 pages Figure 1 SMPTE 2052-0:2013 Page 4 of 5 pages Figure 2 depicts how the SMPTE-TT specification, in a specific example for CEA-608, receives content from the format translator (in this example SMPTE RP 2052-10). Also of note,
15、the “tunnel” feature of SMPTE-TT whereby the “waveform” of CEA-608 is translated into SMPTE-TT, but can be recreated at the analog video output of the end-device. Ov e r vi e w E x amp l e : L e g acy CE A - 608S o ur c eS t an d ar d : C E A - 608L e g a c y a n d C u r r e n t C o n ten tC E A - 6
16、 0 8 “ Wav efo rm ”S ta n d a r d : S M P TE - TT & C o m p a n i o n RP s“ CE A - 6 0 8 S y n t a x ”Au th o r i n g Fo r m a t( s ). c ap fi l esEtc,T r a n s l a t i o n M a pW a v e f o r m - c o m p a t i b l e “ T u n n el ”SM P T E - TTS t an d ar d : W3 C T T M LT r a ns po r tO t h er E sse
17、nc eC o n t ai n erFigure 2 SMPTE 2052-0:2013 Page 5 of 5 pages Figure 3 depicts the SMPTE-TT embodiment in a client (end-device) and how TTML is both rendered and how the “tunnel” provides the source for the analog waveform in the CEA-608 example. D e l i v e r yS t an d ar d : C E A - 608T T M L -
18、 C o m p l i a n t P a r s i n g , Ren d e r i n g , e tc .S ta n d a r d : S M P TE - TT & C o m p a n i o n RP sW avef o r m C r eat io n ( e.g . C o m po s it e A na lo g )T T M L S y n t a xW a v e f o r m - c o m p a t i b l e “ T u n n el ”Vi d eo E ssenc e D efi n ed E l sew h ereS t an d ar d : W3 C T T M LT r a ns po r tC E A - 608 “ Wav efo rm ”C o n t ai n erOv e r vi e w E x amp l e : L e g acy CE A - 608SM P T E - TTFigure 3
