From mboxrd@z Thu Jan 1 00:00:00 1970 References: <513682.96359.qm@web23108.mail.ird.yahoo.com> From: Olaf Meeuwissen Date: Wed, 22 Apr 2009 09:25:06 +0900 In-Reply-To: <513682.96359.qm@web23108.mail.ird.yahoo.com> (Hin-Tak Leung's message of "Tue\, 21 Apr 2009 17\:05\:14 +0000 \(GMT\)") Message-ID: <87r5zla61p.fsf@avasys.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Printing-architecture] [Printing-summit] Another Common Dialog List-Id: Printing architecture under linux List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Hin-Tak Leung Cc: "printing-architecture@lists.linux-foundation.org" , Johannes Meixner , DavidSuffield , "printing-summit@lists.linux-foundation.org" Hin-Tak Leung writes: > --- On Tue, 21/4/09, Suffield, David wrote: > >> > From: Johannes Meixner [mailto:jsmeix@suse.de]=20 >> >=20 >> > How does the scanner unit enumerate nowadays? >>=20 >> There is no change with scanner USB enumeration. As far as >> I know there is no well defined "scanner" interface like the >> "mass storage" interface.=C2=A0=20 > > [snip] ... just want to say that the USB specification has an imaging > device class (I don't remember the precise name), besides printer and > mass storage. The imaging device class is where many usb-capable > digital camera/camcorder appears as. I think the class is called ptp > but can't remember the name... There was a scanner device class in a draft of the USB spec (ID =3D 6) but that never made the cut for the final standard :-( As a result the bulk of the USB scanners now use the vendor specific class (ID =3D 255). There may be some that use something else but there is NO reliable way you can identify a scanner device short of consulting a database (which needs to be updated continuously to account for new devices hitting the shelves). FWIW, SCSI devices are a little bit better off but even there all is not well. Although the bulk identify themselves as a SCANNER, there are a number of (Epson and HP) devices that think they are a PROCESSOR. There has been some discussion regarding SCSI scanner on the sane-devel mailing list in the threads below: http://lists.alioth.debian.org/pipermail/sane-devel/2009-January/023456.h= tml http://lists.alioth.debian.org/pipermail/sane-devel/2009-January/023507.h= tml http://lists.alioth.debian.org/pipermail/sane-devel/2009-January/023528.h= tml Hope this helps, --=20 Olaf Meeuwissen, LPIC-2 FLOSS Engineer -- AVASYS Corporation FSF Associate Member #1962 Help support software freedom http://www.fsf.org/jf?referrer=3D1962