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Re: Braille printers drivers

On Thu, May 29, 2008 at 11:17:51AM +0100, Samuel Thibault wrote:
> Kenny Hitt, le Thu 29 May 2008 05:06:21 -0500, a écrit :
> > Normally, the difference with Braille printers is the format of the file.
> Just like any other printer.

> > The text will need to be converted to brf first.
> Just like .pdf usually need to be converted to .ps first.

It's a highly natural-language-dependent process, involving context-dependent
rules as well as conversion of the input file format to appropriate page
layout and formatting instructions for braille. Think of it as analogous to
converting a TeX or XML file to PS or PDF, with a BRF file as equivalent to a
PS or PDF file.

> > This user uses turbobraille to translate the file before printing.  nfbtrans will also work to translate to and from brf file format.
> Then why not including them to cups?

For the same reasons that Troff, TeX/LaTeX, etc., are not included.

However, if Cups is given a text file, or an XML file, etc., destined for a
braille device, it would be useful if the filter could run the user's chosen
braille software during processing, even though that software would be a
separate package from Cups.

If Cups is presented with a BRF file (i.e., already prepared for braille
output), it should just send it unmodified to the braille device. Options for
selecting which pages to print would be useful, however.

A BRF file is just an ASCII file, formatted with spaces and line-end
characters, with form feeds separating the pages. I don't know whether all
braille devices will accept Unix-style line endings, or whether some would
require CR/LF line terminators, or indeed to what extent this is configurable.

Other braille devices would need special drivers, as they don't accept BRF
files directly but operate in a kind of graphic mode in which the dots have to
be specified individually, together with the spacing and other details - a
kind of rasterized format.

Although the North American ASCII-braille correspondence is commonly
implemented in braille devices, different schemes are used in Europe, and
it may be necessary for the driver to be able to convert between them.

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