Joe Clark: Media access

Updated 2003.05.27

Toronto Usability Summit presentation, 2003.05.23

Thanks to TUS and the audiencemembers interested in my presentation. I’ve never had quite so many AV devices actually work all at once.

The topic of the presentation was “Accessibility and usability of onscreen menu systems for home video.” The presentation explored accessibility and usability of the kind of menu interfaces you find in VCRs, DVD players, and electronic set-top boxes (as for digital cable TV or satellite TV). Issues covered included:

Contents (skip)


How many Canadians with disabilities are there?

Statscan figures

Statistics Canada’s figures, published in 1994, estimate the number of people with two disabilities as surveyed in the 1991 census. The numbers are old and won’t be updated until late this year or next year. StatsCan’s definition of mobility impairment is unrelated to onscreen menu usage, so those figures are not cited here.

Canada Ontario
Visual impairments 510,755 202,705
“Legally blind” 36,910 13,360
Hearing impairments 1,076,555 409,020

Viewing and equipment ownership

Meanwhile, what are the viewing habits and TV/VCR ownership patterns of people with disabilities?

In detail:

The Who’s Watching? study by the American Foundation for the Blind found the following:

Issue Blind audience in survey “General population”
Percent who own television 99% 99%
Percent who own VCR 83% 85%
Percent who have cable 68% 64%
Percent who rent, borrow, or buy videos (of those who own a VCR) 81% 79%
Percent who rent, borrow, or buy videos one or more times per week (of those who own a VCR) 26% 31%
Percent who watch television at least 2 or 3 times per week 97% 95%
Mean number of hours of television watched per week 24 29

A survey by the Canadian Hard of Hearing Association found:


Too often, designers and usability experts work on esoteric, fancy, or expensive products, services, or environments. Everyday devices, to take one example, are seen as much too boring to be worth designing well or making especially usable.

This, of course, is an arse-backward way of doing things. Some precepts we can use here:

How does accessibility relate to usability?

The accessibility issue

What is the basic issue in considering accessibility and usability of onscreen menu devices?

Programming vs. interface

We’ve got two issues: Making the programming accessible and making the interface to that programming accessible

Visual menu system, or, in some cases, single-button access
  • Delivered on second audio program (SAP) on TV
    • SAP is a feature of stereo television audio. It’s a monaural audio track available in addition to the regular stereo audio
  • Must use visual menu system to turn it on in most cases
  • Some TVs have single-button SAP
  • But there is no SAP on digital TV, including direct-to-home satellite

Degrees of accessibility

We can consider two degrees or levels of accessibility.

Can engage basic functions and any function related to a disability
Can do everything a nondisabled person can

In detail:

  • You can do obvious things like turn power on and off, change volume and channels (including via keypad, which blind people can use even if mobility-impaired cannot)
  • Typical disability-related functions are captioning and audio description
  • Captioning viewers are typically not disabled in any other way that is relevant to using a menu system, so they can generally wade through those menu systems
    • Still, single-button access is better
  • Does not have to be direct access; can be sequential, as cycling through audio tracks until DX comes up
  • The problem lies in interactive interfaces that ask you to respond to visual prompts, then asks you do respond differently to further visual prompts
  • Through better programming and adaptive technology, it is now realistic to imagine full accessibility
  • Will cost money
  • The mobility-impaired user could:
    • Adapt existing hardware, as by attaching a hardware remote to a board
    • Use a software or voice interface, including through optical or FireWire ports on digital STBs
    • Send commands over IP or a computer
      • In the lingo, these are called environmental-control systems, but they’re more complex because of the software interface
  • Visually-impaired
    • Large print
      • Not as easy as it sounds
        • Screenfonts are terrible
        • Backgrounds and colours must be knowledgeably chosen
  • Blind
    • Speech output
    • Can be synthesized by the STB or downloaded on demand, or downloaded in advance and saved
    • In those cases, you can use synthesized or recorded human speech. Synthesized is cheaper and scales well to large volumes of text, human is better but scales worse

TV accessibility issues

On analogue TV, you can watch programming with audio descriptions by turning your TV, VCR, or other device to the SAP channel. The issue, of course, is that few devices give you one-button access to SAP. (And even if they do, the button is never in the same place on different remotes and will probably not be visually or tactually discernible from other buttons. Remember, we’re talking about people with diminished or nonexistent vision here.)

In the majority of cases, you have to activate an onscreen menu system that you cannot actually see. Hence the problem.

Now, why not just set it and forget it? Why not just figure out how to turn SAP on (perhaps your friend or family member can do that for you) and leave your TV on SAP?

  1. When no described programming is running, you’d need the TV station to place regular audio on the SAP channel. While that is much more likely to happen now, there are still times when all you hear on SAP is silence or a recording telling you how to turn SAP off
  2. SAP audio is scratchy, low-quality mono. Wouldn’t you prefer to listen to full stereo on undescribed shows? If you don’t have full access to the programming, shouldn’t you at least be compensated by pristine stereo sound?
  3. On some stations, SAP is used for reading services (as on WKBW in Buffalo) or even alternate-language programming (as on CPAC). CBC in Toronto runs CBC Radio on SAP; Newsworld runs VoicePrint
  4. Very occasionally, on an undescribed show the SAP channel will be filled with music-and-sound-effects audio rather than the full mix of dialogue, music, and sound effects (due to a mistake made in selecting a studio videotape’s numerous audio tracks for transmission)

Satellite and digital-TV issues

What about satellite TV? There simply is no SAP on such signals, nor is there SAP on digital specialty channels or the digital tier of a digital cable system. Needless to say, this is complicated.

The entire problem of described audio on satellite or digital services is eminently solvable and will, I predict, actually be solved.

DVD accessibility issues

Most of the time, you have to select described audio through an onscreen menu system, which of course you cannot see if you are visually-impaired. The complex and unstandardized cursor movements needed to run these menus are a barrier, albeit a smaller one, to mobility-impaired users.

Have a look at a PDF (it’s even the tagged accessible kind) of a few menu screens from DVDs with audio description. As you will find, the discs don’t even use the same term for audio description in each case, and every one of them requires different keystrokes.


Current projects underway to solve the problem of accessibility to onscreen menus:

Improvements needed

  1. More research and awareness; Cf. WGBH recommendations
  2. Use of existing data structures, as coding of DVD audio streams for description
  3. Standards-compliant development of universal methods for onscreen menu accessibility
  4. More hardware remotes with one-button access to captions and SAP
  5. Better software APIs for set-top boxes to permit use by adaptive technology


You might find my glossary of accessibility terms useful.

You were here: joeclark.orgMedia accessTUS presentation