/* This is the README file for libgphoto2/camlibs/digigr8. This README is an
* integral part of the libgphoto2/camlibs/digigr8 library source code and is
* distributed with that source code under the LGPL license. a copy of which
* license may be seen in any of the source files in libgphoto2/camlibs/digigr8,
* or in the head directory of libgphoto2.
*/
INTRODUCTION:
The cameras supported here have a controller chip from S&Q Technologies.
They have USB Vendor:Product number 0x2770:0x905c. These cameras are cheap
and basic. Their functioning resembles that of the cameras supported by the
sq905 camera library, but is a bit different.
The first camera which I knew of with this USB ID was the Digigr8 from
RadioShack. Hence comes the name of this camera library. Several more cameras
have since been reported, including one which has the same make/model painted
on the plastic case as that of a camera which previously used an sq905 chip
and used the sq905 Vendor:Product number instead of this one. SQ Technologies
seems to have discontinued the SQ905 and this chip is apparently its successor.
For information about additional cameras with the same USB ID, I am totally
dependent on reports from users and testers. If you have another 0x2770:0x905c
camera and want it to work and it currently does not, then I will be very glad
to hear from you. Saying this a different way: further progress with your
camera will depend upon your input. If on the other hand your camera does work
and is not explicitly listed, I would still like to know about it for the sake
of completeness. I will give it an explicit line listing in library.c and I
will credit you as the finder of the camera, in the ChangeLog file.
WHAT CHIP IS ACTUALLY IN THESE CAMERAS?
I do not know. I did not take mine apart to look inside. (update) Someone has
reported to me that he did take his camera apart, and it really is an SQ905C
chip inside.
WHAT FEATURES DO THESE CAMERAS HAVE, AND WHAT DOES THIS DRIVER SUPPORT?
FEATURE LIST SUPPORTED (Y/N/Part)
-- USB connection to computer
-- High resolution 640x480, uncompressed Y
-- Low resolution 320x240, uncompressed Y
-- High resolution 640x480, compressed P
-- Low resolution 320x240, compressed P
-- Ability to "switch" resolution between pictures Y
-- Ability to download all pictures on camera Y
-- Ability to download the first k pictures, where
k is less than the number on the camera Y
-- Ability to download individual photos Y (faked, but works)
-- Internal battery, which recharges through the USB port (some models)
-------------------------------------------------------------------------
The following things can be done with button-pushes on the camera:
-------------------------------------------------------------------------
-- Frequency filter for use in artificial light. Can be set
to cancel 60hz or 50hz interference.
-- Delete all, delete last, resolution setting, compression mode setting.
-- "Clip" mode will shoot three frames. The camera "sees" these frames as
ordinary photos. Also the photo counter on the LED counts them.
-- "AVI" mode shoots until the shutter button is released, or until the
camera is full. The photo counter does NOT count the AVI frames,
but thinks all of the frames are part of one photo. Otherwise, the
camera sees the frames as ordinary photos, so gphoto2 will give the
actual count of all frames, whether photos or part of an AVI clip,
Also gphoto2 will download the AVI frames as if they were ordinary
photos. Apparently, AVI frames are always 320x240 regardless of the
resolution setting. AVI mode does honor the compression setting,
though, if it happens to be turned on. However, compressed AVI
processing is _not_ implemented at this time.
Notes:
The only known cameras supported by the camlibs/digigr8 have a 640x480
high-resolution setting and a 320x240 low-resolution setting. If your
0x2770:0x905c camera uses another resolution setting, then it might still
work. There is some similarity with the sq905 cameras, and I kept that part
of the code here. Specifically, if the camera has 352x288 and 176x144
resolution settings, these might work but are not tested. If your camera does
not work due to unknown resolution settings, then the new resolution settings
need to be listed in digigr8.c in digi_get_picture_width (). Please report any
such problem. I will ask you to run a gphoto2 command in debug mode and we can
easily find the information we need -- which information, understand, I do not
possess unless you share it with me.
The pictures obtained on the uncompressed settings can often be superior to
those obtained using the software which came with the camera, but not
always. Generally, considering that they are cheap, low resolution cameras,
these cameras give relatively good pictures.
The digigr8 cameras can also function as webcams, but that is outside the
scope of gphoto2.
HARDWARE LIMITATIONS AND CONSTRAINTS
The SQ905C chip, like the SQ905 before it, is a minimalist controller chip; if
any of its functionality at all were removed, it would probably be impossible to
use it to run a digital camera. To program around the limitations of the chip,
therefore, is a special challenge. Here are some examples.
1. The manufacturer's driver will do nothing but to download all photos
on the camera, and display them, keeping temporary copies in C:\TEMP, to be
deleted when the camera access program is closed. After downloading everything,
then, the OEM program allows the user to "select" and to "save" any or all of
the photos which have, in fact, already been downloaded (indeed the displayed
"thumbnails" came from the files in C:\TEMP, too). Now, gphoto2 does not
operate thus, has preconceived notions about how any respectable camera should
act, and regards such a primitive camera controller chip as an untamed beast.
Thus, many of the gphoto2 functions will not work unless, through a bit of
fakery which involves downloading data and throwing it away and on some
occasions resetting the camera, this primitive behavior is somewhat improved.
That all has to be done in the driver, with fakery invisible to the user. These
remarks apply not only to getting thumbnails, but also to many other gphoto2
options as well. See item 2.
2. The camera's data storage provides only sequential access, not
random access. In other words, it acts as though it were a tape drive
instead of a disk. Worse, it's like a tape drive with no fast forward and
no rewind controls. The constraints which this places are obvious. It means
for example that to download all the photos on the camera to display thumbnails
requires the camera to be reset afterwards, because that is the only way to do
the "rewind" required before any of the photos can be accessed again. It also
menas that "gphoto2 -p 2" would NOT download the second photo on the camera,
unless the support for it is so written as to download the first photo, then
the second photo, and to process only the second one, having consigned the
data from the first photo to /dev/null. The camera simply cannot do better.
The gphoto2 -p 2 command option does work, of course, but only because the
necessary jury-rigging has been built into the download function.
3. Considering the way the communication protocols of these cameras
seem to work, it would seem nearly impossible to copy any data to the camera
for storage and transport. The camera clearly does not have files on it,
only data addresses. And the camera does not keep time. For similar
reasons, it would also seem impossible to delete a photo from the camera by
action of software on the computer. The camera itself supports two choices for
deletion: delete the last photo taken, or delete all. Each action is
performed by an appropriate sequence of button pushes on the camera.
WHAT GUI FRONTENDS DOES THIS CAMERA LIBRARY SUOPPORT?
Gtkam seems to work well for me with this library. Some of the other various
frontends do not seem to work quite so well for me. But one of them may work
nicely for you, and you are hereby encouraged to try it. If you want to use
either gtkam or digikam, you are encouraged to read the camera's manual (in
gtkam, right-click on the name of the camera in the left panel, after starting
the program and having chosen the right camera).
NOTES
1. The program is set up to put out pictures in PPM or raw format. The OEM
program offers JPEGs, which the user can easily create on Linux with lots of
other software.
2. The gamma setting (actually seems to be one over gamma) used for
the construction of PPM image files has been obtained by trial and error. It
seems to work very well for outdoor pictures, but the setting is a
compromise between what happens with outdoor photos and what happens with
indoor photos. Conceivably, the program could support a choice between two
or more gamma settings, optimizing for different conditions.
3. A still-experimental postprocessing routine is added, to provide
some sharpening and color correction for different lighting conditions. The
routine can easily be turned off if one wishes, and because it is
experimental you may so wish. To disable it, just comment out the line in
get_file_func ( ) in library.c where the function digi_postprocess ( ) is
called. Then do "make install" to install your change.
4. The "High Compression" setting is approximately 98% resolved. There
do remain occasional problems starting at the left edge of the image, where
things seem to be a bit unstable. However, very few of my test photos have shown
any problems in this regard.
5. Please get back to me with reports about other SQ cameras (any cameras
with Vendor number 0x2770), with their specifications (what it says in the OEM
manual about resolution and number of pictures, as well as make and model, and
whether it works or not with any libgphoto2 driver or not, would be enough),
and with a log file if it seems it is supposed to work but there are problems.
WARRANTY?
Absolutely not. No warranty. Never. Not responsible for any actual
or potential damage or consequences to anyone or to the equipment of
anyone for using this program, whether the alleged damage or alleged
consequences are claimed to be real, imaginary, direct, collateral,
for pain and suffering, or are claimed to be inflicted upon any
"third party" who is not the user or installer of the program. The
program has been written for my pleasure and to broaden and deepen
my knowledge of computer hardware and software. The program has not
been written with the immediate expectation of financial gain or
profit on my part, nor has it been commissioned for pay. It is
presumed that any end-user of this program will have access to the
source code of the program and can judge for himself or herself
whether he/she wishes to use it or not, or can consult someone with
appropriate expertise to make such a judgment.
Theodore Kilgore
12/05/05
(revised 12/29/05, 03/28/07)
03d4cbbd6a