Canoscan 8400f

[Brian J Densmore]

I'm back at considering working on a driver for the Canoscan 8400f. I have
been requested by another developer to help do this. I have the Mac
driver. Mac, if I remember it is *nix based now. What is the take on
driver writing in regards to RE drivers to implement drivers? Has anyone
ever decompiled OSX drivers? What would be a recommended decompiler? I do
not have any MAcs so could never install the driver and run it, but the
Canoscan 8400f is a fairly complex and high end scanner. I'd like to make
a Linux driver that supports 100% of the features. Is it a taboo to
decompile drivers for making Linux drivers? Or for getting over stumbling
blocks? Is doing blackbox RE the only acceptable method of RE for Linux
drivers? Would Sane accept my code if I decompiled the driver? Copyright
issues? There shouldn't be any, since I'll not be seeing actual original
source code.

Thanks,
Brian


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[m. allan noah-3]

On Fri, Oct 2, 2009 at 11:53 AM,  <brian@...> wrote:
> I'm back at considering working on a driver for the Canoscan 8400f. I have
> been requested by another developer to help do this. I have the Mac
> driver. Mac, if I remember it is *nix based now. What is the take on
> driver writing in regards to RE drivers to implement drivers? Has anyone
> ever decompiled OSX drivers? What would be a recommended decompiler? I do
> not have any MAcs so could never install the driver and run it,

IMHO, decompiling has never been worth it. You spend more time trying
to figure out their code than figuring out the communication protocol,
which is what you really need.

> but the
> Canoscan 8400f is a fairly complex and high end scanner.

It costs ~$150 new? it is neither complex nor high end. It is cheap
consumer-grade junk, which appears to use a third-party chip from
genesys logic. This is a good thing, because we already have a working
backend for the older GL chips, and the newer ones are somewhat
compatible.

> I'd like to make
> a Linux driver that supports 100% of the features. Is it a taboo to
> decompile drivers for making Linux drivers? Or for getting over stumbling
> blocks? Is doing blackbox RE the only acceptable method of RE for Linux
> drivers? Would Sane accept my code if I decompiled the driver? Copyright
> issues? There shouldn't be any, since I'll not be seeing actual original
> source code.

You dont need to decompile. Search mailing list archives for genesys,
and google for datasheets. You will find plenty. then get some usb
sniffer logs, and use Pierre's tools as a base for interpreting them.

might also help to open the scanner and get the names off the chips,
particularly the GL chip and the AFE.

allan
--
"The truth is an offense, but not a sin"

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[Brian J Densmore]

On Fri, October 2, 2009 11:43 am, m. allan noah wrote:

> On Fri, Oct 2, 2009 at 11:53 AM,  <brian@...> wrote:
>> I'm back at considering working on a driver for the Canoscan 8400f. I
>> have
>> been requested by another developer to help do this. I have the Mac
>> driver. Mac, if I remember it is *nix based now. What is the take on
>> driver writing in regards to RE drivers to implement drivers? Has anyone
>> ever decompiled OSX drivers? What would be a recommended decompiler? I
>> do
>> not have any MAcs so could never install the driver and run it,
>
> IMHO, decompiling has never been worth it. You spend more time trying
> to figure out their code than figuring out the communication protocol,
> which is what you really need.
>
>> but the
>> Canoscan 8400f is a fairly complex and high end scanner.
>
> It costs ~$150 new? it is neither complex nor high end. It is cheap
> consumer-grade junk, which appears to use a third-party chip from
> genesys logic. This is a good thing, because we already have a working
> backend for the older GL chips, and the newer ones are somewhat
> compatible.

It was considerably more than a $150 scanner when it came out and supports
medium format negatives and can scan at a physical 18MP resolution
(3200x6400) at 48 bit color. I don't know many scanners capable of that.
Even today. It may not be quite as high end as some dedicated photo
scanners of today. There wasn't anything anywhere near it's capabilities
when it came out, outside of professional equipment. So it may be old news
now, but it's still a very impressive scanner. I just wish HP had done it.

> You dont need to decompile. Search mailing list archives for genesys,
> and google for datasheets. You will find plenty. then get some usb
Yes, the genesys driver is the one to use. I believe, I provided or found
most of those datasheets. But some aren't disclosed, or weren't the last
time I looked. IIRC the 8400 used three chips for the scan process, plus
support chips.

> might also help to open the scanner and get the names off the chips,
> particularly the GL chip and the AFE.
Been there.


I really haven't dipped into it yet. I'm looking primarily for fallback
capabilities, and want to develop a plan of attack ahead of diving in.
Like I said, I want to be able to scan those medium format negatives at
3200x6400 48 bit color. Thank you for your input and suggestions. I do
appreciate all good suggestions, especially from those who've been through
it.

Brian


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[Marcus Menzel]

Hi Brian,

> It was considerably more than a $150 scanner when it came out and supports
> medium format negatives and can scan at a physical 18MP resolution
> (3200x6400) at 48 bit color. I don't know many scanners capable of that.
> Even today. It may not be quite as high end as some dedicated photo
> scanners of today. There wasn't anything anywhere near it's capabilities
> when it came out, outside of professional equipment. So it may be old news
> now, but it's still a very impressive scanner. I just wish HP had done it.

your right about this scanner - i own a 8800F, so if you start working on a
driver, I can help out with testing. Since I'm not a programmer I can't help
you further.

regards,
Marcus

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