ETSI EN 300 743 V1.5.1 (2014-01)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Digitalna videoradiodifuzija (DVB) - Sistemi za podnasloveDigital Video Broadcasting (DVB) - Subtitling systems33.170Televizijska in radijska difuzijaTelevision and radio broadcastingICS:Ta slovenski standard je istoveten z:EN 300 743 Version 1.5.1SIST EN 300 743 V1.5.1:2014en01-marec-2014SIST EN 300 743 V1.5.1:2014SLOVENSKI

ETSI EN 300 743 V1.5.1 (2014-01) Digital Video Broadcasting (DVB); Subtitling systems

Reference REN/JTC-DVB-327 Keywords broadcasting, digital, DVB, TV, video ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE

Siret N° 348 623 562 00017 - NAF 742 C Association à but non lucratif enregistrée à la Sous-Préfecture de Grasse (06) N° 7803/88

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© European Telecommunications Standards Institute 2014. © European Broadcasting Union 2014. All rights reserved.

DECTTM, PLUGTESTSTM, UMTSTM and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE™ are Trade Marks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association. SIST EN 300 743 V1.5.1:2014

ETSI ETSI EN 300 743 V1.5.1 (2014-01) 3 Contents Intellectual Property Rights ................................................................................................................................ 5 Foreword ............................................................................................................................................................. 5 1 Scope ........................................................................................................................................................ 6 2 References ................................................................................................................................................ 6 2.1 Normative references ......................................................................................................................................... 6 2.2 Informative references ........................................................................................................................................ 6 3 Definitions and abbreviations ................................................................................................................... 7 3.1 Definitions .......................................................................................................................................................... 7 3.2 Abbreviations ..................................................................................................................................................... 8 4 Introduction to DVB subtitling system .................................................................................................... 9 4.1 Overview ............................................................................................................................................................ 9 4.2 Data hierarchy and terminology ....................................................................................................................... 12 4.3 Temporal hierarchy and terminology ............................................................................................................... 14 5 Subtitle decoder model ........................................................................................................................... 14 5.1 Decoder temporal model .................................................................................................................................. 15 5.1.1 Service acquisition ...................................................................................................................................... 15 5.1.2 Presentation Time Stamps (PTS) ................................................................................................................ 16 5.1.3 Display definition ....................................................................................................................................... 16 5.1.4 Page composition ........................................................................................................................................ 16 5.1.5 Region composition .................................................................................................................................... 16 5.1.6 Points to note .............................................................................................................................................. 17 5.2 Buffer memory model ...................................................................................................................................... 17 5.2.1 Pixel buffer memory ................................................................................................................................... 18 5.2.2 Region memory .......................................................................................................................................... 18 5.2.3 Composition buffer memory ....................................................................................................................... 18 5.3 Cumulative display construction ...................................................................................................................... 18 5.4 Decoder rendering bandwidth model ............................................................................................................... 18 5.4.1 Page erasure ................................................................................................................................................ 19 5.4.2 Region move or change in visibility ........................................................................................................... 19 5.4.3 Region fill ................................................................................................................................................... 19 5.4.4 CLUT modification..................................................................................................................................... 19 5.4.5 Graphic object decoding ............................................................................................................................. 19 5.4.6 Character object decoding .......................................................................................................................... 20 6 PES packet format .................................................................................................................................. 20 7 The PES packet data for subtitling ......................................................................................................... 20 7.1 Syntax and semantics of the PES data field for subtitling ................................................................................ 20 7.2 Syntax and semantics of the subtitling segment ............................................................................................... 21 7.2.1 Display definition segment ......................................................................................................................... 21 7.2.2 Page composition segment .......................................................................................................................... 23 7.2.3 Region composition segment ...................................................................................................................... 24 7.2.4 CLUT definition segment ........................................................................................................................... 27 7.2.5 Object data segment .................................................................................................................................... 28 7.2.5.1 Pixel-data sub-block .............................................................................................................................. 30 7.2.5.2 Syntax and semantics of the pixel code strings ..................................................................................... 31 7.2.6 End of display set segment ......................................................................................................................... 33 7.2.7 Disparity Signalling Segment ..................................................................................................................... 34 8 Requirements for the subtitling data ...................................................................................................... 39 8.1 Scope of Identifiers .......................................................................................................................................... 39 8.2 Scope of dependencies ..................................................................................................................................... 39 8.2.1 Composition page ....................................................................................................................................... 39 8.2.2 Ancillary page ............................................................................................................................................. 39 SIST EN 300 743 V1.5.1:2014

ETSI ETSI EN 300 743 V1.5.1 (2014-01) 4 8.3 Order of delivery .............................................................................................................................................. 39 8.3.1 PTS field ..................................................................................................................................................... 39 8.4 Positioning of regions and objects .................................................................................................................... 39 8.4.1 Regions ....................................................................................................................................................... 39 8.4.2 Objects sharing a PTS ................................................................................................................................. 39 8.4.3 Objects added to a region ............................................................................................................................ 40 9 Translation to colour components .......................................................................................................... 40 9.1 4- to 2-bit reduction .......................................................................................................................................... 41 9.2 8- to 2-bit reduction .......................................................................................................................................... 41 9.3 8- to 4-bit reduction .......................................................................................................................................... 41 10 Default CLUTs and map-tables contents ............................................................................................... 41 10.1 256-entry CLUT default contents ..................................................................................................................... 41 10.2 16-entry CLUT default contents ....................................................................................................................... 42 10.3 4-entry CLUT default contents ......................................................................................................................... 43 10.4 2_to_4-bit_map-table default contents ............................................................................................................. 43 10.5 2_to_8-bit_map-table default contents ............................................................................................................. 44 10.6 4_to_8-bit_map-table default contents ............................................................................................................. 44 11 Structure of the pixel code strings (informative) .................................................................................... 44 Annex A (informative): How the DVB subtitling system works ......................................................... 46 A.1 Data hierarchy and terminology ............................................................................................................. 46 A.2 Temporal hierarchy and terminology ..................................................................................................... 46 A.3 Decoder temporal model ........................................................................................................................ 46 A.4 Decoder display technology model ........................................................................................................ 46 A.4.1 Region based with indexed colours .................................................................................................................. 46 A.4.2 Colour quantization .......................................................................................................................................... 47 A.5 Examples of the subtitling system in operation ...................................................................................... 47 A.5.1 Double buffering .............................................................................................................................................. 47 A.5.1.1 Instant graphics ........................................................................................................................................... 47 A.5.1.2 Stenographic subtitles ................................................................................................................................. 50 Annex B (informative): Use of the DDS for HDTV services ............................................................... 53 Annex C (informative): Illustration of the application of the disparity_shift_update_sequence mechanism for 3D content ............................................................................ 54 Annex D (informative): Guidelines on the use of EN 300 743 for 3D content ................................... 58 Annex E (informative): Bibliography ................................................................................................... 62 History .............................................................................................................................................................. 63

ETSI ETSI EN 300 743 V1.5.1 (2014-01) 5 Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http://ipr.etsi.org). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This European Standard (EN) has been produced by Joint Technical Committee (JTC) Broadcast of the European Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique (CENELEC) and the European Telecommunications Standards Institute (ETSI). NOTE: The EBU/ETSI JTC Broadcast was established in 1990 to co-ordinate the drafting of standards in the specific field of broadcasting and related fields. Since 1995 the JTC Broadcast became a tripartite body by including in the Memorandum of Understanding also CENELEC, which is responsible for the standardization of radio and television receivers. The EBU is a professional association of broadcasting organizations whose work includes the co-ordination of its members' activities in the technical, legal, programme-making and programme-exchange domains. The EBU has active members in about 60 countries in the European broadcasting area; its headquarters is in Geneva. European Broadcasting Union CH-1218 GRAND SACONNEX (Geneva) Switzerland Tel: +41 22 717 21 11 Fax: +41 22 717 24 81

The Digital Video Broadcasting Project (DVB) is an industry-led consortium of broadcasters, manufacturers, network operators, software developers, regulatory bodies, content owners and others committed to designing global standards for the delivery of digital television and data services. DVB fosters market driven solutions that meet the needs and economic circumstances of broadcast industry stakeholders and consumers. DVB standards cover all aspects of digital television from transmission through interfacing, conditional access and interactivity for digital video, audio and data. The consortium came together in 1993 to provide global standardisation, interoperability and future proof specifications.

National transposition dates Date of adoption of this EN: 9 January 2014 Date of latest announcement of this EN (doa): 30 April 2014 Date of latest publication of new National Standard or endorsement of this EN (dop/e):

31 October 2014 Date of withdrawal of any conflicting National Standard (dow): 31 October 2014

ETSI ETSI EN 300 743 V1.5.1 (2014-01) 6 1 Scope The present document specifies the method by which subtitles, logos and other graphical elements may be coded and carried in DVB bitstreams. The system applies Colour Look-Up Tables (CLUTs) to define the colours of the graphical elements. The transport of the coded graphical elements is based on the MPEG-2 system described in ISO/IEC 13818-1 [1]. 2 References References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the reference document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. 2.1 Normative references The following referenced documents are necessary for the application of the present document. [1] ISO/IEC 13818-1: "Information technology - Generic coding of moving pictures and associated audio information: Systems". [2] ETSI EN 300 468: "Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems". [3] Recommendation ITU-R BT.601: "Studio encoding parameters of digital television for standard 4:3 and wide-screen 16:9 aspect ratios". [4] Recommendation ITU-R BT.656-4: "Interfaces for digital component video signals in 525-line and 625-line television systems operating at the 4:2:2 level of Recommendation ITU-R BT.601 (Part A)". [5] ETSI EN 300 743 (V1.2.1): "Digital Video Broadcasting (DVB); Subtitling systems". [6] ETSI EN 300 743 (V1.3.1): "Digital Video Broadcasting (DVB); Subtitling systems". 2.2 Informative references The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. Not applicable. SIST EN 300 743 V1.5.1:2014

ETSI ETSI EN 300 743 V1.5.1 (2014-01) 7 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: ancillary page: means of conveying subtitle elements that may be shared by multiple subtitle services within a subtitle stream NOTE: For example, an ancillary page can be used to carry logos or character glyphs. Colour Look-Up Table (CLUT): look-up table applied in each region for translating the objects' pseudo-colours into the correct colours to be displayed CLUT-family: family of CLUTs which may consist of: • one CLUT with 4 entries; • one CLUT with 16 entries; • one CLUT with 256 entries. A CLUT-family is used in a region to define colours for decoders with different rendering capabilities.

NOTE: Three CLUTs are defined to allow flexibility in the decoder design. Not all decoders may support a CLUT with 256 entries, some may provide sixteen or even only four entries. A palette of four colours might be enough for graphics that are basically monochrome, like very simple subtitles, while a palette of sixteen colours allows for cartoon-like coloured objects or coloured subtitles with antialiassed edges. composition page: means of conveying subtitle elements for one specific subtitle service display definition: definition of the video image display size for which a subtitle stream has been prepared display set: set of subtitle segments of a specific subtitle service to which the same PTS value is associated epoch: period of time for which the decoder maintains an invariant memory layout NOTE: This layout may be altered by resets to the decoder state caused by receiving page composition segments with page state = "mode change". The end of an epoch therefore signals the "death" of a page. The epoch may, if so desired, be considered to be the highest level data structure in DVB subtitling. object: graphical unit that can be positioned within a region; examples of an object include a character glyph, a logo, a map, etc. NOTE: Each object has its own object_id. Packet IDentifier (PID): Transport packet identifier NOTE: See ISO/IEC 13818-1 [1].

page: set of subtitles for a subtitle service during a certain period NOTE: A page consists of one or more page instances. Each page update or refresh will result in a new page instance. A page contains a number of regions, and in each region there may be a number of objects. page composition: composition (use and positioning) of regions that may be displayed within the page NOTE: At any new page instance the page composition may change; for example, some regions may not yet or no longer be displayed. At any one time, only one page composition can be active for displaying.

page instance: period of time during which that page does not change i.e. there is no change to the page composition, to any region composition, to any object within a region or any applicable CLUT NOTE: Typically, a new page instance is defined by the PTS of a display set. SIST EN 300 743 V1.5.1:2014

ETSI ETSI EN 300 743 V1.5.1 (2014-01) 8 PES packet: See ISO/IEC 13818-1 [1]. pixel-data: string of data bytes that contains, in coded form, the representation of a graphical object Presentation Time Stamp (PTS): See ISO/IEC 13818-1 [1]. region: rectangular area on the page in which objects can be positioned NOTE: Regions may be shared by multiple subtitling services within the same subtitle stream. Objects that share one or more horizontal scan lines on the screen are included in the same region.

region composition: composition (use and positioning) of objects within a region subtitle element: subtitle data used within a page composition and contained within a subtitle segment NOTE: Regions, region compositions, CLUTs and object data are examples of subtitle elements. subtitle segment: basic syntactical element of a subtitle stream subtitle service: service that provides subtitling for a program for a certain purpose, such as subtitles in a specific language or for the hard of hearing NOTE 1: A subtitle service is displayed as a series of one or more pages. NOTE 2: Typically, a subtitle service meets a single communication requirement (e.g. the graphics to provide subtitles in one language for one program). subtitle stream: stream of subtitling segments carried in transport packets identified by the same PID NOTE: A subtitle stream contains one or more subtitle services. transport packet: See ISO/IEC 13818-1 [1]. transport stream: stream of transport packets carrying one or more MPEG programs NOTE: See ISO/IEC 13818-1 [1]. 3.2 Abbreviations For the purposes of the present document, the following abbreviations apply: B Blue value of colour representation in default CLUT bslbf bit string, left bit first Cb Chrominance value representing B-Y colour difference signal NOTE: As defined in Recommendation ITU-R BT.601 [3], clause 7.2.3. CLUT Colour Look-Up Table Cr Chrominance value representing R-Y colour difference signal NOTE: As defined in Recommendation ITU-R BT.601 [3], clause 7.2.3. DDS Display Definition Segment DSS Disparity Signalling Segment DTV Digital TeleVision DVB Digital Video Broadcasting EDS End of Display Set Segment EIT Event Information Table G Green value of colour representation in default CLUT GOP Group of Pictures HDTV High Definition TeleVision IRD Integrated Receiver Decoder MPEG Moving Pictures Experts Group

ETSI ETSI EN 300 743 V1.5.1 (2014-01) 9 PCR Programme Clock Reference PCS Page Composition Segment PES Packetized Elementary Stream NOTE: As defined in ISO/IEC 13818-1 [1]. PID transport Packet IDentifier NOTE: As defined in ISO/IEC 13818-1 [1]. PMT Program Map Table NOTE: As defined in ISO/IEC 13818-1 [1]. PTS Presentation Time Stamp NOTE: As defined in ISO/IEC 13818-1 [1]. R Red value of colour representation in default CLUT RCS Region Composition Segment ROM Read-Only Memory SDT Service Description Table STC System Time Clock T Transparency value TS Transport Stream NOTE: As defined in ISO/IEC 13818-1 [1]. uimsbf unsigned integer, most significant bit first tcimsbf two's complement integer, msb (sign) bit first Y luminance value NOTE: As defined in Recommendation ITU-R BT.601 [3], clause 7.2.3. 4 Introduction to DVB subtitling system The present document specifies the DVB subtitling system for the transport and coding of subtitles. 4.1 Overview The DVB subtitling system defined in the present document provides a syntax for decoding subtitle streams. A subtitle stream conveys one or more subtitle services; each service containing the textual and/or graphical information needed to provide subtitles or glyphs for a particular purpose. Separate subtitle services may be used, for example, to convey subtitles in several languages.

Each subtitle service displays its information in a sequence of so-called pages that are intended to be overlayed on the associated video image. A subtitle page contains one or more regions, each region being a rectangular area with a specified set of attributes. These attributes include a region identifier, the horizontal and vertical size, pixel depth and background colour. A region is used as the background structure into which graphical objects are placed. An object may represent a character, a word, a line of text or an entire sentence; it might also define a logo or icon.

The use and positioning of objects within a region is defined by the region composition segment.

The use and positioning of regions within a page is defined by the page composition segment, in which a list of displayed regions is provided, each with their own spatial position. A page composition need not change when objects are added to or removed from a region. Furthermore regions may be declared but not used. By way of example one region can be used to display multiple subtitle fragments, as depicted in figure 1. First the text "Shall we?" is displayed in the region; subsequently this text is removed and the new text "Said the fly on the mirror" is displayed. It is possible to use more than one region at the same time; for example one region could be used to display subtitles on the bottom of the screen, while another one might be used to display a logo somewhere else on the screen.

Figure 1: Two regions overlayed on top of video; one with a logo and another one with subtitles A DVB subtitle stream is carried in PES packets and the timing of their presentation is defined by the PTS in the PES header. Upon reception and decoding of the subtitle data for a page (such as the page composition, the region composition, the objects to be used and any other associated data) the page