TTML TTML NIGEL MEGITT, IRT SUBTECH1 SYMPOSIUM 24 MAY 2018
TTML 2 WHAT IS TTML? TTML stands for Timed Text Markup Language. Think of it as a big toolbox from which the right tools can be extracted and used for speci fi c applications, like subtitles and captions, or In general terms, it speci fi es a model for text audio description scripts. that changes over time and has presentation requirements like position, font, size, colour etc. For example, it supports clock time, media time and SMPTE timecode. Not all applications needs all of those. Formally, it is an information set that can be concretely represented in XML. It blends timing semantics from SMIL with presentation semantics from XSL-FO and CSS
TTML 3 WHAT DOES IT LOOK LIKE? (1) It’s a bit like an HTML document in structure…
TTML 4 WHAT DOES IT LOOK LIKE? (2) … but with times on some elements, And styles that are de fi ned in the head and then referenced, or are speci fi ed directly.
TTML 5 HISTORY OF TTML IN W3C TIMED TEXT WORKING GROUP (TTWG) 2013 • Simple Delivery Profile SDP • TTML1 Second Edition 2018 2003 2016 • IMSC 1.0.1 Profile • W3C begins • IMSC 1 Profile • TTML1 Third Edition CR work on TTML • TTML2 CR 2010 • TTML1 published (“DFXP” profile)
TTML 6 ADOPTION AND USAGE TTML or pro fi les or TTML are referenced by a lot of TTML has many open source and commercial other standards: authoring, validation and presentation tools on and o ff the web. • SMPTE-TT (FCC “safe harbor” format) TTML is currently mainly used in pro fi le form for • EBU-TT and EBU-TT-D subtitles and captions, for example by: • DVB TTML spec EN 303 560 • BBC • ATSC 3.0 • Net fl ix • ARIB-TT • Britbox • HbbTV 2 and Freeview Play • (I actually don’t know all the users!) • MPEG CMAF • MPEG DASH Web browsers generally do not natively play back • DVB DASH TTML, with some exceptions. Usually implementers • and probably more! write custom code to play back TTML subtitles where native playback is not supported.
7 FUTURE OF TTML TTML 2 is a Candidate Recommendation. It TTWG is likely to be re-chartered for a 2 year adds many features including: period in the near future. • Support for global scripts • Audio “styling” Beyond the standards home for TTML, real world usage seems to be on the increase, but is • Embedded or referenced fonts, images, data hard to measure. • Conditional formatting (e.g. for responsive presentation) • Improved pro fi le semantics • HDR and 3D rendering support IMSC 1.1 is a Candidate Recommendation pro fi le that adopts some of those additional features.
+ + D E THANK YOU! NIGEL MEGITT nigel.megitt@bbc.co.uk
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