Today’s distribution platforms offer a higher quality display of subtitling and more flexible positioning options than traditional analogue television. File- and IP-based production facilities demand clearly specified ways to carry subtitles during production, exchange, archiving and distribution to their customers, including the use of online services. To handle these new contexts, broadcasters need a low-complexity, but thoroughly specified subtitling format.
To meet these requirements, the EBU Group 'Subtitles in XML' has created EBU-TT, which stands for EBU Timed Text. EBU-TT is the follow-up to the widely used EBU STL format (EBU Tech 3264). The EBU-TT family consists of the following specifications:
1. Archive & Exchange
2. STL mapping
3. Live contribution
EBU-TT Part 3 (EBU Tech 3370) was published in December 2015 as draft v0.9 for prototype implementation. It provides a System Model and Content Profile for authoring and contribution of live subtitling. It also introduces the concept of processing 'nodes' that can help improve subtitling quality in production. Part 3 feedback is welcome via: firstname.lastname@example.org.
EBU-TT part 'D' (EBU Tech 3380) is the format for the distribution of subtitles over IP. There also is a document for the use of EBU-TT-D in ISO BMFF / MPEG-DASH (EBU Tech 3381). Other specs reference EBU-TT-D, such as HbbTV 2.0, and Freeview Play.
The EBU has also developed a recommendation on the transport of subtitles inside and outside of MXF files (EBU R 133).
EBU Member BBC has published BBC Subtitles Guidelines. These are intended to serve as the basis for all subtitle work across the BBC (prepared and live, online and broadcast, internal and supplied)
Also check out this list of existing open source subtitling software and samples.
EBU Project Group on Subtitles in XML
Technical aspects of subtitling are being addressed by the EBU Group 'Subtitles in XML', which is part of the EBU's Strategic Programme on Media Information Management.
- Helps Members to use subtitles in new file-based facilities and for new distribution platforms.
- Develops broadcast specifications based on the W3C Timed Text Markup Language (TTML).
- Provides mappings and example files to help you use the format for subtitling.
Toolkit for Live Subtitling
The EBU has set up an open source software project to develop an Interoperability Toolkit for live subtitles. This toolkit will both validate the specification and help developers to verify that their implementations meet the specification and are interoperable. If you would like to participate in this project, please feel welcome! There is no requirement to be a member of the EBU or the Subtitles in XML Group.
If you are interested in Subtitles in XML, join our group on this topic and participate in the discussions.
EBU Technology & Innovation Workplan
Every two years, the EBU develops a roadmap for technology and innovation activities based on the requirements and inputs given by EBU Members. The result of this roadmap is our bi-annual EBU Technology & Innovation Workplan. Strategic programmes and project groups are set up to focus on specific areas of interest. To access the latest Workplan, click here.
Ericsson (NASDAQ: ERIC) today announced it is to support the creation of live subtiling using the new EBU-TT Live standard (EBU Tech 3370). Find out more......
EBU tech-i magazine, issue 27 includes articles on Virtual Reality, Cross-Media Production, UHD, Loudness, and much more...
This document is Part 3 of the EBU-TT series. It specifies how to use EBU-TT for the production and contribution of live subtitles. Currently in draft v. 0.9, intended for prototype implementation.
EBU Timed Text (EBU-TT) is the successor of the EBU STL subtitling format. It supports the production and archiving of subtitles, legacy STL file transcoding and tunnelling, online distribution and live subtitling.
This is the specification of an XML based archiving and interchange format for EBU-TT subtitles. This version 1.1 provides alignment with EBU-TT-D and adds metadata to support usage requirements expressed by the UK's Digital Production Partnership.
EBU tech-i magazine, Issue 25 tells you all about personalisation, why broadcasters should go IP, and how subtitles go live. And that's not all...
EBU tech-i magazine, Issue 23 tells you how you can produce smarter, introduces future broadcasting architectures, dives into the use of the 700 MHz band, explains how hackers have become 'smart', and more...
This specifies an XML based format for the distribution of subtitles over IP-based networks. It is based on W3C TTML1 and is informed by EBU-TT Part 1, specified in EBU Tech 3350. Version 1 of the specification dated March 2015 corrects two errors in the Jan. 2014 document.
This is version 1.0 of the document, dated October 2014. The aim of the document is to specify how the EBU-TT-D subtitling distribution format specified in EBU Tech 3380 can be stored using the storage format defined in ISO/IEC 14496-12.
Issue 17 of tech-i looks at UHDTV, with SVT's Per Björkman on the UHD equation, Hans Hoffmann on UHD technology parameters, David Wood on high frame rates, and a report on the recent shoot of the Eurovision Young Dancers. Besides that there are QC criteria, software engineering for media, a profile of Algerian broadcasting, a feature on access services, regulation of media convergence, a report on the EBU binaural workshop and an introduction to the semantic web.
NPO, the Netherlands public broadcasting organization, has implemented an Optical Character Recognition (OCR) solution for real time conversion of in-vision subtitles to spoken subtitling audio.
The means of transporting subtitles & captions using MXF (the de-facto standard for A/V essence) in IT-based television production environments is specified. The entire lifecycle of subtitles, from generation to playout and archive, is considered.
This article explores some of the whats and hows of Access Services – what do prepared subtitling, live subtitling, audio description, spoken subtitling and visual signing entail ... what kinds of issues emerge when offering access services ... and how can these production and delivery issues be addressed by broadcasters.
Teletext is about 25 years old and is currently being brought into the digital broadcasting environment by the DVB project. This article looks at some of the key issues involved in offering teletext and subtitling to DVB viewers.
Subtitling has become one of the "growth areas" of European broadcasting, as television services take in increasing numbers of programmes from outside their own countries. The EBU has taken the initiative of establishing a standard for the exchange of subtitle lists.
This document specifies a format for the exchange of subtitling data. The EBU standardised this data file format to enable the exchange of in- vision and teletext subtitles. The format was designed for use by broadcasters at both national and international levels.
Informative XML sample and XML Schema files can be found via:
A toolkit that provides a set of components for generating, testing and distributing subtitle documents in EBU-TT Part 3 format is in active development.
Have a look at and/or join this project: EBU-TT Live Interoperability Toolkit
More software projects
The EBU collects links to media-related open source software projects: media-related open source software