On 24/12/24 14:40, Ralph Little wrote:
Hi,
On Mon, Dec 23, 2024 at 9:14 PM Low Salt Popcorn
<[email protected] <mailto:[email protected]>>
wrote:
These "scanners" basically look like a webcam mounted on an arm atop an
upside-down letter "L" (or Greek capital letter gamma).
They look like the best option for scanning old books that don't
require
laser-printer quality resolution.
One such scanner is reviewed by CNX software:
https://www.cnx-software.com/2023/07/23/czur-et24-pro-book-scanner-
review-with-ubuntu-22-04-linux/ <https://www.cnx-
software.com/2023/07/23/czur-et24-pro-book-scanner-review-with-
ubuntu-22-04-linux/>
The author notes that the scanner practically identifies itself as a
webcam ("UVC"). So in theory it should "work" on any GNu/Linux
computer,
with only the Windows/Mac user software as the major difference.
I've also seen in various online platforms (e.g. AliExpress) similar,
but much cheaper no-brand models. So my question is, does anybody here
have such a device? Is it reasonable to assume that all scanners of
this
type are UVC-compatible devices?
https://en.wikipedia.org/wiki/USB_video_device_class <https://
en.wikipedia.org/wiki/USB_video_device_class>
If these devices are indeed all UVC, my idea is to have ffmpeg take
JPEG
or PNG snapshots of the material I'm scanning. Or otherwise simply take
one continuous video and later simply pause and screenshot individual
frames.
Note: I've searched the sane backends page:
http://www.sane-project.org/sane-backends.html#VIDEO <http://
www.sane-project.org/sane-backends.html#VIDEO>
I can't find any reference to UVC-device support
So, there is a video camera backend called sane-v4l but it is quite old
and doesn't support the newer v4l2 API standard.
We were just discussing this during the GTK porting effort recently of
the frontend utility xcam. For testing, it appears that none of the
current webcams actually work with it because the backend doesn't
support the colour formats that more recent colour webcams require.
Although xcam supports all backends so testing is possibly, it's not
really possible to test xcam with an actual camera.
If anyone wishes to write a new v4l2 backend or update the existing
sane-v4l one then that would be very welcome. Failing that, one of us
might get to it at some point.
Just curious, did the old sane backend do something more than, say,
"ffmpeg -i /dev/video0 scan.xxx"?
Anyway, I guess I have to take my chances and hope the el-cheapo book
scanners are standards compliant and don't use some proprietary protocol.
