How: Automated XGA resolution JPG USB image capture at rate 1 FPS (webcam?)
John Faughnan
a digital camera as a "webcam", especially for videoconferencing. It
also turns up lots of replies that tell the user to do a usenet search
(I've done it). Nothing so far answers my question.
I am currently using a Logitech webcam and ConquerCam [1] (excellent
$10 webcam software) to capture 15 FPS 640x480 (approximately) output
of which 1 FPS is sent to a web server for sharing. Each JPG is about
110K so the bandwidth is fine.
This works fairly well enough for my purposes (sharing a whiteboard
remotely). The resolution needs to be better however. I'm interested
in capture of a higher resolution STILL image at about 1 FPS (or
slower) for meetings lasting 1-3 hours.
I think, with decent optics, a 2 megapixel image would suffice.
Shutter speed is NOT critical since these are STILL images and the
camera would be mounted (so 1/15 sec exposure is more than enough).
Focus and a reasonably high f stop are important. I probably need to
be able to manually adjust shutter speed and f stop, or at least set
shutter speed.
Has anyone had experience using a commercial lower end digital camera
in this way? Fuji seems to promote this somewhat with their line of
cameras. I'd like to spend less than $250 on a USB connected device.
I'm aware of the heat problem with many digital cameras (prolonged use
increases device temperature -- need a cooling fan!).
Another solution, of course, would be a higher resolution webcam with
better optics -- but there is no market for this (too much bandwidth
for most uses). A very high end Digital Video camera would work but
that's too much money.
--
john
jfau...@spamcop.net
www.faughnan.com
[meta: jfaughnan, jgfaughnan, 030219, digital image capture,
conferencing, remote collaboration, imaging, webcam, cheap,
inexpensive, low cost]
John Faughnan
to and search on jfaughnan webcam to find the rest.
Since my posting, with the help of some correspondents and some
testing, I've learned more. I'll share it here.
1. The best bet is to wait for Logitech to put out a device with
better optics. The resolution isn't the problem: 640x480 will suffice
for sharing a whiteboard though 1024x768 is truly optimal. A 640x480
whiteboard image taken with a Canon G2 (excellent optics) is very
readable. The problem is the Logitech Pro webcam optics and the crude
focusing mechanism.
2. Digital cameras aren't designed for this type of use and are an
awkward fit.
I tried my Canon G2 with the Canon Remote Capture (USB) software. The
maximal automated acquistion rate with the Windows version is 1 image
q 5 seconds. (0.2 FPS). There is very limited ability to control the
camera. Documentation is also limited, the readme.txt file in the
downloadable version has the most information. Some Canon cameras work
better with this software than others. (The S200/230 may work best.)
Heat is a problem. The cameras are not designed to be constantly
processing images and sending them out the USB cable (remote viewing
of image). They get hot. I would worry about shortening camera life.
Web searches suggest Fuji has the most interest in this domain with
their "PC Cam" support, however it appears to be flaky and
inconsitently implemented across their model line. See the Fuji
FinePix F401 with "PC-Cam" at 1280 x 960
(http://www.dpreview.com/news/0205/02053001finepixf401z.asp). There is
very little documentation; I don't have confidence in this solution.
3. If one wants to try a digital camera, the best approach would be to
write a small batch file to sweep the upload directory on the main
server, and copy the latest file to a web server. (Use sleep or doze
or wait or other utility to insert a 1 second pause and just loop
through a copy and delete command). The digital cameras by design save
every image with a new name, hence the need to sweep and copy/rename.
I think a manual trigger would also be more practical than an
automated acquisition.
4. The software drivers and interface in this domain are flaky.
Something about installing the Logitech device and/or ConquerCam broke
my Canon USB driver setup with Windows 2000. In particular, the
ConquerCam view goes black every few minutes. I belived the fault is
in the Logitech drivers, in particular I think the very latest version
is flaky. I have not been able to fix this new problem so far.
5. A very high end digital video camera might work. See
http://www.oreillynet.com/pub/a/wireless/2001/11/02/wireless_webcam_pt1.html.
This was out of our price range.
Overall, the Logitech Pro is the best bet. Focus is critical. I got
focus working at a fixed distance and I use a string measure to always
set the camera the same distance. The camera plane has to be
perpendicular to the whiteboard. We need Logitech to boost resolution,
improve optics, and incorporate a tripod mount. It is unlikely that
digital camera vendors will make their cameras work this way, but the
SONY CLIE incorporated camera would be something to look at if one
wanted to investigate further.
john (older posting follows)
jfau...@spamcop.net (John Faughnan) wrote in message news:<5c0dbfb4.03021...@posting.google.com>...
> A quick google usenet search turns up hundreds of postings about using
> a digital camera as a "webcam", especially for videoconferencing. It
> also turns up lots of replies that tell the user to do a usenet search
> (I've done it). Nothing so far answers my question.
>
> I am currently using a Logitech webcam and ConquerCam [1] (excellent
> $10 webcam software) to capture 15 FPS 640x480 (approximately) output
> of which 1 FPS is sent to a web server for sharing. Each JPG is about
> 110K so the bandwidth is fine.
>
> This works fairly well enough for my purposes (sharing a whiteboard
> remotely). The resolution needs to be better however. I'm interested
> in capture of a higher resolution STILL image at about 1 FPS (or
> slower) for meetings lasting 1-3 hours.
>
> I think, with decent optics, a 2 megapixel image would suffice.
> Shutter speed is NOT critical since these are STILL images and the
> camera would be mounted (so 1/15 sec exposure is more than enough).
> Focus and a reasonably high f stop are important. I probably need to
> be able to manually adjust shutter speed and f stop, or at least set
> shutter speed.