Guidelines for delivering Accessibility Services using HbbTV

Tech Report 065

This report offers suggestions for how HbbTV can be used to provide accessibility services for those with sensory differences.

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It is important to note that the options described in this report are not the only options available to television services for providing accessibility services (AS). They are specifically those that may be available where the viewer has a television set equipped with HbbTV (Hybrid broadcast broadband TV) and a working broadband internet connection, and where the HbbTV services are available. All these suggested solutions are based on the technologies currently available in European consumer equipment.
There can be other options for AS not involving HbbTV. For example, the delivery of a composite image that includes both the programme image and the signer can also be achieved by delivering a second broadcast channel - though this might be seen as inefficient use of broadcast spectrum.

It is a remarkable fact that on average, 10% of people per country have sensorial disabilities or differences. In Europe this equates to approximately 40 million people across the 18 countries polled. This is a large proportion of the audience that broadcasters must cater to.

The PDF of this report has been constructed with accessibility features such as alternate text describing the diagrams and figures in the report. This alternate text will be read by the many text-to-speech applications that are used by the sight-impaired communities.

Additionally, this alternate text will pop-up when a mouse pointer is hovered over the images, but this has been found to be subject to the PDF reader used to open the file. The Adobe Acrobat Reader performs this function whereas the Microsoft Acrobat Reader embedded in the Microsoft 365 (Office) suite appears not to. Other PDF readers may or may not perform the function.

Key words: HbbTV, Accessibility Service, Sensory Disability, Sensory Difference, Subtitle, Dialog+, NGA, Audio Description, Sign Language Interpretation, Accessible Audio Experiences, Clean Audio.

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22/11/2021: Typo correction (SDI changed to SLI in 'Conclusions' - no other change).