[TTWG][ttml-imsc1.2] FPWD of IMSC 1.2

The Timed Text Working Group recently published a First Public Working Draft of IMSC 1.2:

https://www.w3.org/TR/ttml-imsc1.2/


This specification defines two profiles of [ttml2<https://www.w3.org/TR/ttml-imsc1.2/#bib-ttml2>]: a text-only profile and an image-only profile. These profiles are intended to be used across subtitle and caption delivery applications worldwide, thereby simplifying interoperability, consistent rendering and conversion to other subtitling and captioning formats.

This specification improves on [ttml-imsc1.1<https://www.w3.org/TR/ttml-imsc1.2/#bib-ttml-imsc1.1>] by supporting contemporary practices, while retaining compatibility with [ttml-imsc1.1<https://www.w3.org/TR/ttml-imsc1.2/#bib-ttml-imsc1.1>] documents. Relative to [ttml-imsc1.1<https://www.w3.org/TR/ttml-imsc1.2/#bib-ttml-imsc1.1>], any addition or deprecation of features are summarized at Appendix § L. Summary of substantive changes<https://www.w3.org/TR/ttml-imsc1.2/#substantive-changes-summary>.

New feature: external font resources

The main change in this version is the addition of support for referencing of external font resources, so that a relationship can be specified between a font resource and specified font family name, and optionally the Unicode range of code points, style and weight. Minimally, OTF and WOFF formats must be supported by conforming presentation processors. Fallback font resources can be defined using this mechanism.

Review

Please review the draft and file any comments in the GitHub repository at https://github.com/w3c/imsc/issues/ using the label imsc1.2 or send them to public-tt@w3.org<mailto:public-tt@w3.org?subject=%5Bimsc%5D> (archives<https://lists.w3.org/Archives/Public/public-tt/>) with [imsc] at the start of your email's subject.

Nigel Megitt
Co-Chair, Timed Text Working Group