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1.3 Components

speechd-el design is strictly modular. It contains several components layered each on top of other. Lower layer functions can be used independently of higher level features.

The lowest level components are access libraries to output devices, especially to SSIP (the Speech Dispatcher TCP communication protocol for speech output) and BrlAPI (interface to BRLTTY drivers for communication with Braille displays). They can be used to talk to the output devices directly from Elisp programs.

The next level implements common access to all the devices. Instead of talking to each device independently one can use this layer to output device independent messages that are processed and sent to the output devices as defined in the user configuration. This is the preferred way of communication with the output devices.

On the highest level there is the user interface frontend that makes Emacs read texts and events automatically, defines the corresponding minor modes, key bindings and most of the interactive commands.

There are some other auxiliary components, look into speechd-el source code if interested.