David Wood

Media accessibility relies on several building blocks, each one essential to the overall service. If any element in the user journey to being able to share in the experience of the media content is missing or even simply weak, it can negate the value of the service. In planning and implementing media accessibility services, all the elements must be strong.


The elements that allow users to take up the option of accessibility for a given piece of media content are shown in Figure 1, the “accessibility tower”.

The base level is the capability of the users’ equipment. This might be, for example, a particular type of TV set or software. Can the accessibility services be decoded by the equipment that those in the identified user group have available to them? The capabilities of the TV set can also influence how well the services are finally displayed or heard in upper level of the diagram.

The next layer represents the availability of accessibility services from the broadcast or broadband provider. Will or could the services be regularly made available by the content provider, given any economic or delivery constraints?

Built on this layer is the range of services that are provided. There are a range of needs for accessibility services, which can even differ from nation to nation. Will the totality of services offered match, with proportionality, the range of needs of your users?

Above this is a ‘findability’ layer. It can be easy or difficult to find services, for example using EPGs, apps, menus, or hand controls. Is it going to be easy to find and control the services? Will everyone know that? What can be done to make sure that they do?

Above that is the quality of content production of the accessibility services. Like any kind of content, this can be well done or less well done. Will the expertise and talent be available to make the best use of the technology? Will economics or lack of training constrain what can be provided?

The top layer is the presentation of the services – the so-called contact moment. Are the presentation, the placing of the accessibility elements, the style, colour, audio, and other appearance factors optimum for users? Are the on-screen elements ‘agreeable’ to users? How can they be made so? This can also be influenced by the capabilities of the base layer.


The finest individual technologies can be of less value if any element of the tower is weak. Providers of today’s services, and proposers for new services, should review the strength of all the elements in their own tower.

The development of individual tools is important. There are many ongoing studies. Today, for example, there are projects to develop realistic computer- generated sign language interpretation. Having sign language provided by an avatar would mean much more content could be signed. Yet, at the same time, the hard of hearing community has declared that the avatars so far seen would be a second-class service compared to human signers. The options must be studied.

As a second example, there could be several ways to make superposition of an avatar or human signer optional – using an HbbTV channel, a second conventional channel, or the new VVC video codec. Here too, the options must be studied.

We must not forget that users always need the means to communicate their experiences of service range/availability/ findability, etc. to the content provider. What is more, content can be delivered by different platforms in an ecosystem of partners and competitors. Steering this toward better accessibility is challenging and calls for different actors to accept and act on their responsibilities.


This article was first published in issue 51 of tech-i magazine.

Latest news