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This page describes the accessibility stack of Debian and provides configuration hints for users. For development details, please look at accessibility-devel.

TODO: magnification tools.

Debian installer accessibility

The Debian installer has braille, speech, and contrast accessibility features which are documented in the installation manual .

Software speech is not yet supported in the standard installer, but an experimental image can be downloaded from http://people.debian.org/~sthibault/espeakup/

Braille support

Braille device support is handled by brltty, which is started as a background daemon. It also provides screen reading support for the Linux text console. Screen reading support for the gnome desktop is provided by Orca . It does not drive braille devices itself, it "connects" to brltty via BrlAPI to do so. If Orca does not manage to output braille, make sure that

Some braille devices have an integrated braille keyboard. Brltty supports simulating keypresses on the text console. For proper simulation on Xorg (handle non-qwerty layouts, in particular), the brltty-x11 package should be installed. It provides xbrlapi, which should be started at Xorg session startup, before starting orca.

The PC keyboard can also be used as a braille keyboard. In /etc/brltty.conf, uncomment key-table keypad, and restart brltty. One can then switch to braille by pressing insert+asterisk on the numpad, and switch back to normal by pressing insert+slash on the numpad. The default is to use the asdfjkl, keys as braille keys, but /etc/brltty/kbd-braille.kti can be modified to use other keys.

Brltty also has very basic graphical screen reading support, which is limited to text fields, e.g. edit's main widget, or gnome-terminal's terminal. This is shipped in the brltty-x11 package, and can be started by running

brltty -b ba -x as

at Xorg session startup. -b ba tells it to connect via BrlAPI to the already-running brltty that drives the actuall braille device. -x as selects the At-Spi driver, which performs graphical screen reading.

Speech support

Debian provides a lot of speech syntheses, a list can be found in the speechsynthesis blend task. Screen readers can often directly use some of the speech syntheses, or use generic interfaces, such as gnomespeech, or speech-dispatcher. Gnome-speech is mostly just a thin common layer. speech-dispatcher is more evolved: it runs as a daemon, which screen readers can connect to in order to emit speech. speech-dispatcher then has several modules to support various speech syntheses.

Console fonts

The Linux text console font can be tuned to get better accessibility: in /etc/default/console-setup, one can set FONTFACE to Terminus, in order to be able to select bigger fonts such as even FONTSIZE=32x16. That will of course reduce the amount of text displayed on the screen too. To fine-tune the exact amount of text displayed on the screen, SCREEN_WIDTH and SCREEN_HEIGHT can be set.

Graphical User Interface

Currently, you can access the GNOME desktop with Orca. Please see the article Orca for more details.

Color Themes for accessibility

The GNOME magnifier supports inverting colors. However, some people prefer other colors for the graphical environment or prefer to have only high contrast without all colors inverted. For this there is a package called gnome-accessibility-themes, where different themes are included. You can install it with

aptitude install gnome-accessibility-themes

These can then be selected in the preferences menu of GNOME.

gdm accessibility

The gdm graphical greeter supports accessibility, orca just needs to be enabled.

Troubleshooting

Xorg issues

Xorg may not want to start if no actual physical screen is attached to the video board. One can however use the dummy driver, which will not make use of any graphical card, and still let the gnome desktop start etc. Install the xserver-xorg-video-dummy package, and add the following lines to /etc/X11/xorg.conf (create one if you don't have any):

Section "Device"
    Identifier "noscreendevice"
    Driver     "dummy"
EndSection

speech-dispatcher issues

Some users use the ibmtts or viavoice speech-synthetiser with orca, and they think that it is not convinient. According to them, the speech synthetiser is slow, its reactivity is slow, and it often crashes. The problem is that no alternative seems to exist, as gnome-speech is no longer supported by ibmtts' vendors.

However, the package who connects ibmtts to gnome-speech is under the LGPL. So, it was packaged and its name in Debian is gnome-speech-ibmtts.

How can you install it? Firstly, install ibmtts or viavoice speech synthetiser. Then, run (as root user):

apt-get install gnome-speech-ibmtts

NOTE: if you install ibmtts after the Debian package, you have to do:

dpkg-reconfigure gnome-speech-ibmtts

otherwise, the viavoice config file will not be generated and orca will not see viavoice at the starting of the preferences menu.

NOTE: you likely will need to do, before the first reboot of orca, a backup of your ~/.local/share/orca, then delete the contents of its contents. Do this with:

cp -Rp ~/.local/share/orca ~/.local/share/orcabackup
rm -r ~/.local/share/orca/*

You will need to recreate all your preferences (shortcuts, etc.).

This process allows users who do not want to use speech-dispatcher immediately to find a solution. Anyway, this solution is not ideal for the long-time future, as gnome-speech, or at-spi, will be deprecated with Gnome-3. It can however be a good transition. But it does not work for amd64 architectures. Only i386 is supported.

Note that you do not experience this issue if you migrate from lenny (5.0) to squeeze (6.0), as the migration maintains the necessary configuration so that ibmtts can be accessed via gnome-speech.

Tips and tricks

Orca can be enabled to start automatically in the user session by hand by running

gconftool-2 --type bool --set /desktop/gnome/interface/accessibility true
gconftool-2 --type bool --set /desktop/gnome/applications/at/visual/startup true

It can also be useful to run

gconftool-2 --type bool --set /desktop/gnome/sound/event_sounds true

to enable desktop sound effects.

More tips are available on http://brl.thefreecat.org/wiki/