Subtitling

Helping Members to use subtitles in new facilities and for new distribution platforms.

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.

EBU-TT

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

EBU-TT part 1 (EBU Tech 3350) defines an easy-to-use XML structure for the interchange and archiving of subtitles. It builds on the W3C Timed text Markup Language (TTML) 1.0.

2. STL mapping

EBU-TT Part 2 (EBU Tech 3360) is a mapping guide on how to map EBU STL files to EBU-TT. This currently is a v0.9 publication open for comments from the industry.

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: subtitling@ebu.ch.

The EBU has set up an open source software project to develop an Interoperability Toolkit for live subtitles. Learn more in this EBU-TT Live Webinar.

EBU-TT-D

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. 

Related publications

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)

Software

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.

Main activities:

  • 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.

​Join us

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.

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.

EBU tech-i magazine, Issue 24 explains why Hybrid is here to stay, how HbbTV applicatiins can be discovered over broadband, everything you need to know about Netflix, plus... what's in the sandbox. And there is more!

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...

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.

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.

XML Files

Informative XML sample and XML Schema files can be found via:

EBU-TT example files

EBU-TT-D XML Schema

Software implementation

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

Related topics