[Gphoto-user] A new Mars camera about which I need more information

[<ki...@ba...>]

This is a report on a new Mars camera and a request for help from anyone 
who
has one of these, or a similar one. I have some incomplete information
(described below) based upon correspondence with an owner of such a 
camera.
Unfortunately, the correspondence stopped just at the point that I was
actually almost getting enough information to be able to support the 
camera, as
will be clear below. It will also be clear why the camera will not make it
into the upcoming next public release of libgphoto2: there are problems
which are minor (major problems such as proprietary compression mode take 
a
bit longer!) and could be solved with a little bit of follow-through on 
the
part of the camera owner.

The account follows, beginning with a quote from my reply to the first
letter from the owner.


--------------------------------------------
> hello, my camera inst working on gphoto -P and it says that it is
> supported.
>
> here is a debug of what he says, like he can read the number of images
> on the cam, but not download them.
>

then, after I looked at some debug output, I replied:

0090  18 00 04 00 0c b0 04 dc-98 02 9a 00 0c b0 04 f4
00a0  18 04 30 01 0c b0 04 0d-98 06 c6 01 0c b0 04 25 00b0  18 08 5c 02 0c
b0 04 3e

My analysis follows now.

1. The camera is using an unknown code for the first byte of data given in
the configuration data block, for each photo. Currently known codes are
listed in the source-code file libgphoto2(version)/camlibs/mars/mars.c, in
the function "mars_get_comp_ratio" and then again, but organized 
differently
now, in "mars_get_picture_width". The bytes which appear in your log file 
in
these locations are not previously known.

----------------------------

Since the data appeared uncompressed, I suggested simply to add the new ID
bytes in the appropriate functions, which was done (below) according to 
the
next letter I received, and is reported to work:

(owner reports back)

i did these changes in mars.c:

in mars_get_comp_ratio
i added:
         case 0x18: return 1;
         case 0x98: return 1;

and in mars_get_picture_width
i added:
         case 0x18: return 640;
         case 0x98: return 640;

and the pictures are being downloaded!!!
the only problem is that they are very dark ill attach a photo of my
face for you to see!

-------------------------------------------

I then wondered what the code for the uncompressed photos is. Here is the
last response I got from the camera owner, included in my reply to it. My
reply contains an educated guess on my part, concerning the code for a
320x240 photo, but I can't post new code involving mere guesswork, and I
can't add support for this camera until I actually know what is happening:

------------------------------------------------------
Date: Sat, 5 Mar 2005 01:38:27 -0600 (CST)
From: ki...@ba...
To: (deleted)
Subject: Re: new things!



On Sat, 5 Mar 2005, (deleted) wrote:

> hello sir, just to tell you that i found out how to download 320x240
> pictures off the cam, later ill send you a diff with all the changes,
> cause now im going out.
>
> thanks again for all your help!
>

I think I get it now, having looked at your photo. The new codes 0x18 and
0x98 instead of 0x08 and 0x88 are for photos taken _with_ _flash_! If my
reaoning is correct, then I suspect the following, too:

1. If you take photos without flash, then the codes are not new, neither 
for
640x480 nor for 320x240. The way to test this would be to take some 
outdoor,
daylight photos, if necessary with the flasher turned off. I suspect that
for daylight photos at 320x240 the codes are 0x02 and 0x82 (already 
listed).

2. Extrapolating, I suspect that the new codes for 320x240 with flash are
0x12 for the first photo listed on a line of config data, and 0x92 for the
second photo listed on a line of config data. Could I possibly be right
about that?

Furthermore, I am curious about the existence or nonexistence of 
compression
mode. Nothing on the website seemed to mention that. Is there any mention 
of
it in your docs, or anything resembling it among the possible settings
listed on the LED of the camera? Not that the knowledge would do much 
good.
I have no idea how to handle the compression if it is there so I will be
glad if it is not.

Theodore Kilgore

------------------------------------------------------

Additional comments (as of today, March 24):

During the previously-described correspondence, I also learned which 
camera
this is:

------------------------------------------------------
Hello, my camera is this one
http://www.ebigchina.com/ebcps/4/pd/408515.html

the manual calls it "DIGITAL CAMERA CD302N"

in the manual says in the specifications:
"
Product Type: Digital Camera
Electronic Coupling Element: CMOS Sensor 300k Pixels
Image Resolution: 640x480 Pixels (VGA) 320x240 Pixels (QVGA)
Memory Devices: Built-in 4*16Mb(SDRAM)
Memory Capacity: 26 Pieces (VGA) 104 Pieces (QVGA)
Viewfinder: Built-in
Auto shoot: 10s
Shutter Speed: 1/6-1/15000 seconds
Shoot Mode: Single/Continuous Photograph/PC camera
Automatic Energy Saving: Automatically enter the energy saving mode in
60s.
AVI video: 60s(QVGA)
Image Process: Automatic Exposure/Automatic White Balance
Working voltage: AAA 1.5V*3/USB 5V
Transmission Interface: USB Interface
Working Temperature: 0-40:C
Operation System: Windows98 SE/2000/ME/XP"

------------------------------------------------------------

The decisive thing, I believe, which causes the new code(s) is that the
camera uses a flashbulb or LED, and the code indicates the use of said
flash. I don't own a Mars camera with this feature, so do not know about 
it
until I get a full report.

I also got the photo which is mentioned above. Indeed, the background is
very dark. The default treatment of photos will get a photo out of the
camera, but in order to get a nicer photo I am sure that it will need some
kind of different treatment. This would need some work and tweaking, and
again I say that I don't have one of these cameras to test!

It should be fairly easy to solve the indicated problems and get the 
camera
added, but I need the help of an owner who is willing to do a bit of 
testing
and tweaking (involving some experimentation with source code changes for 
te
camera library, of course). Volunteers are welcome.

Final note to anyone who has a new compressed-mode-only Mars camera and 
has
read this hoping for some exciting news:

Sorry. I have been spending a lot of time lately working on the compressed
mode for the sq905 cameras, about which I knew a bit more to start with. I
hope to get done with that. It may be foolish optimism, but I think it is
almost licked.


Theodore Kilgore