Access Services for UHDTV: an Initial Investigation of W3C TTML2 Subtitles (Closed-Captions)

Ultra High Definition Television and High Dynamic Range has been a focus of research for the past few years, however only now is work starting on the provision of access services for such content. These services are used by a large minority of the audience (up to 25%) and legislation mandates their inclusion in many territories. — The authors present work undertaken to verify the transform for use with HLG high dynamic range video in Appendix P of the W3C Timed Text Markup Language version 2 working draft specification which is likely to be used for subtitling in traditional and IP-based video services. Further they present test results investigating whether there is a perceived brightness variability for subtitles using the TTML conversions when displayed over different HDR video content.

Published

2017-10

Content type

Original Research

Keywords

HDR, High Dynamic Range, HLG, Hybrid Log-Gamma, Video, ITU-R BT.2100, Subtitles, Closed-captions, W3C TTML2, EBU-TT-D

DOI

10.5594/M001777

ISBN

978-1-61482-959-1