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

Ultrahigh-definition television and high dynamic range (HDR) have 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 hybrid log-gamma HDR video in Appendix P of the World Wide Web Consortium Timed Text Markup Language (W3C TTML) version 2 working draft specification, which is likely to be used for subtitling in traditional and Internet Protocol (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.

The authors present work undertaken to verify the transform for use with hybrid log-gamma HDR video in Appendix P of the World Wide Web Consortium Timed Text Markup Language (TTML) version 2 working draft specification.