Braille printers drivers

[Bruno Mascret]

Hi all,

We are planning to make braille printers drivers for cups as a part of
the natbraille's project.
We wonder if such work already exists.

Do you have some ideas about existing project?

Best regards,
Bruno


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[Samuel Thibault]

Bruno Mascret, le Thu 29 May 2008 10:38:24 +0200, a écrit :
> We are planning to make braille printers drivers for cups as a part of
> the natbraille's project.
> We wonder if such work already exists.
>
> Do you have some ideas about existing project?

The idea has been around for some time.  IIRC liblouis has something
like cups filters.

Samuel


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[Kenny Hitt]

Hi.  I'm not sure of the need.  The last printer I set up was easy with cups.
I just chose the lline printer driver and it worked.  Normally, the difference with Braille printers is the format of the file.  The text will need to be converted to brf first.  This user uses turbobraille to translate the file before printing.  nfbtrans will also work to translate to and from brf file format.
I do admit my experience with Braille printers is limited, so hopefully others will respond.

          Kenny

On Thu, May 29, 2008 at 10:38:24AM +0200, Bruno Mascret wrote:

> Hi all,
>
> We are planning to make braille printers drivers for cups as a part of  
> the natbraille's project.
> We wonder if such work already exists.
>
> Do you have some ideas about existing project?
>
> Best regards,
> Bruno
>
>
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[Samuel Thibault]

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.

> 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?

lp foo.txt

looks faster to me than

nfbtrans foo.txt foo.brf
lp foo.brf
rm -f foo.brf

Just like

lp foo.pdf

is faster than

pdf2ps foo.pdf foo.ps
lp foo.ps
rm -f foo.ps

(modulo the syntax of nfbtrans which I don't know)

Alternatively, nfbtrans could send the output to the printer directly,
but just running lp foo.txt should be the right way to go...

Samuel


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[Kenny Hitt]

Hi.  Nfbtrans can be used in a pipe.  It's free, but not GPL.  I don't know the license for turbobraille, but it might already be GPL.
i don't know if it can use pipes.  I'll check with the turbobraille author and find out.  I believe he uses either Debian or ubuntu, but don't think he's on this list.

          kenny

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.
>
> > 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?
>
> lp foo.txt
>
> looks faster to me than
>
> nfbtrans foo.txt foo.brf
> lp foo.brf
> rm -f foo.brf
>
> Just like
>
> lp foo.pdf
>
> is faster than
>
> pdf2ps foo.pdf foo.ps
> lp foo.ps
> rm -f foo.ps
>
> (modulo the syntax of nfbtrans which I don't know)
>
> Alternatively, nfbtrans could send the output to the printer directly,
> but just running lp foo.txt should be the right way to go...
>
> Samuel
>
>
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[Samuel Thibault]

Kenny Hitt, le Thu 29 May 2008 05:33:54 -0500, a écrit :
> Nfbtrans can be used in a pipe.

Ok, but still

lp foo.txt

is easier than

nfbtrans foo.txt - | lp

And also, think about software that print themselves, like mutt:
pressing 'p' from mutt to just print your mail and have nfbtrans
automaticaly run by cups would be just fine.

Samuel


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[Jason White-14]

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.

Correct.
>
> > 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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[Kenny Hitt]

Hi.  I agree.  That's why I pointed out the 2 solutions that i know exist.  Since I'm a user and not a developer, all i can do is provide info.
I can contact the authors of both programs, but a developer will need to create Debian packages once licensing issues are clarifyed.
.
          Kenny

On Thu, May 29, 2008 at 11:41:33AM +0100, Samuel Thibault wrote:

> Kenny Hitt, le Thu 29 May 2008 05:33:54 -0500, a écrit :
> > Nfbtrans can be used in a pipe.
>
> Ok, but still
>
> lp foo.txt
>
> is easier than
>
> nfbtrans foo.txt - | lp
>
> And also, think about software that print themselves, like mutt:
> pressing 'p' from mutt to just print your mail and have nfbtrans
> automaticaly run by cups would be just fine.
>
> Samuel
>
>
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[Samuel Thibault]

Hello,

Jason White, le Thu 29 May 2008 20:49:50 +1000, a écrit :

> 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.
>
> Correct.
> >
> > > 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

Ok, then my example was bad, think about printers that need a rasterized
bitmap instead of a .ps. Then the conversion that happens involves
context-dependent rules, like the wanted dpi, B&W, grey or colors, etc.
I don't see how the particularities of braille couldn't fit within what
CUPS can express: printer filters can already add their own options,
which are sometimes numerous.

> 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.

I would still be happy to be able to use lp foo.tex instead of having to
run TeX myself.

> > > 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.

I'm not surprised about TeX/LaTeX because people usually prefer to check
what it looks like before printing.  I'm surprised about troff.  I
remember printing some troff files quite directly, and I see no reason
why not including it.

> 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.

That's precisely what is being suggested here :)
Note also that CUPS doesn't do the PDF->PS conversion itself, it just
calls gs...

> 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.

That fits the CUPS model.

> 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.

And then it makes even more sense to put that into a CUPS filter (which
would still use an external program to do the txt->brf translation).

> 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.

Just a CUPS option.

Samuel


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[Jason White-14]

On Thu, May 29, 2008 at 12:08:03PM +0100, Samuel Thibault wrote:
 
> That's precisely what is being suggested here :)
> Note also that CUPS doesn't do the PDF->PS conversion itself, it just
> calls gs...
Or pdftops from xpdf-utils.

The proposal is moving in the right direction. The user would need to be able
to specify, in configuration options, what braille software to use, and which
file formats it can accept as input.

The user may want to check the output with a braille display first, but that
case is already covered by the proposed handling of BRF files.

There is also the scenario in which the user has written a BRF file on a
braille device and wants it reverse translated, formatted and printed. In this
situation, the output device is a printer, and the input is a BRF file. Do we
need a proposal for that as well?

Finally, there's the problem that BRF files would be hard to distinguish
automatically from other types of ASCII input in a way that is reliable.
Perhaps the following test can be taken as sufficient:

Find the first non-whitespace text at the start of the file, then read the
file until the next form feed is encountered. If the page length and the
longest line length are within the dimensions of the output braille device,
then it's a BRF file.

BRF files also use entirely uppercase or entirely lowercase letters, which
could serve as an additional check.

Admittedly this is heuristic, but is it good enough?



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[Samuel Thibault]

Jason White, le Thu 29 May 2008 21:24:34 +1000, a écrit :
> There is also the scenario in which the user has written a BRF file on a
> braille device and wants it reverse translated, formatted and printed. In this
> situation, the output device is a printer, and the input is a BRF file. Do we
> need a proposal for that as well?

I don't think.

> Finally, there's the problem that BRF files would be hard to distinguish
> automatically from other types of ASCII input in a way that is reliable.

Can't we just rely on the extension?

> Find the first non-whitespace text at the start of the file, then read the
> file until the next form feed is encountered. If the page length and the
> longest line length are within the dimensions of the output braille device,
> then it's a BRF file.

Since text files are usually 80 wide, that could work indeed.

> BRF files also use entirely uppercase or entirely lowercase letters, which
> could serve as an additional check.

Why not.

Samuel


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[Kenny Hitt]

hi.  i just talked to the author of nfbtrans.  it's in the public domain.  He has no problems if Debian wants to distribute it under the GPL.
Where do you want me to send the zip of the source code.  It is only ever been distributed in source for.

          kenny


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[Mario Lang-2]

Jason White <jason@...> writes:

> 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.
>
> Correct.
>>
>> > 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.

True.  But I'd expect from a braille printer driver to at least
correctly handle UTF-8 braille.

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[Jason White-14]

On Thu, May 29, 2008 at 12:32:16PM +0100, Samuel Thibault wrote:
> Can't we just rely on the extension?

No, the BRF content could originate from a pipe under scenarios that we would
wish to support.

Also, I'm not sure whether the original file name is available to a Cups
filter once the job has entered the queue.


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