Hi all,
I'm trying to play around with the manual exposure settings of my
Creative Live! Cam Optia (the non-AF version), in order to address the
everexposure issues I described in another post
(https://lists.berlios.de/pipermail/linux-uvc-devel/2008-June/003658.html).
Unfortunately, there seems to be problems with manual exposure on this
camera: I am experiencing the exact same problem described here:
http://www.mail-archive.com/linux-uvc-devel@lists.berlios.de/msg02799.html,
that is, manual exposure can be set, but every value results in an
overexposed image no matter what value I use (lower ones or higher ones
do not matter).
I'm working on a debian 4.0 machine (debian kernel 2.6.18-6-686) with
the latest (as far as I know) version of the uvcvideo module:
[EMAIL PROTECTED]:~$ /sbin/modinfo uvcvideo
filename: /lib/modules/2.6.18-6-686/usb/media/uvcvideo.ko
version: SVN r228
I'm also using the latest svn version of uvcdynctrl
[EMAIL PROTECTED]:~$ uvcdynctrl --version
uvcdynctrl 0.2
This is the output of uvcdynctrl -c -v:
----------
Listing available controls for device video0:
Exposure, Auto Priority
ID : 0x00000010,
Type : Boolean,
Flags : { CAN_READ, CAN_WRITE },
Values : [ 20 .. 5000, step size: 1 ],
Default : 79
Exposure (Absolute)
ID : 0x00000011,
Type : Dword,
Flags : { CAN_READ, CAN_WRITE },
Values : [ 20 .. 5000, step size: 1 ],
Default : 79
Exposure, Auto
ID : 0x0000000f,
Type : Choice,
Flags : { CAN_READ, CAN_WRITE },
Values : { 'Manual Mode'[0], 'Auto Mode'[1], 'Shutter Priority
Mode'[2], 'Aperture Priority Mode'[3] },
Default : 1
Sharpness
ID : 0x00000007,
Type : Dword,
Flags : { CAN_READ, CAN_WRITE },
Values : [ 0 .. 96, step size: 1 ],
Default : 40
Power Line Frequency
ID : 0x0000000d,
Type : Choice,
Flags : { CAN_READ, CAN_WRITE },
Values : { 'Disabled'[0], '50 Hz'[1], '60 Hz'[2] },
Default : 0
Gamma
ID : 0x00000006,
Type : Dword,
Flags : { CAN_READ, CAN_WRITE },
Values : [ 0 .. 7, step size: 1 ],
Default : 3
Hue
ID : 0x00000005,
Type : Dword,
Flags : { CAN_READ, CAN_WRITE },
Values : [ -4 .. 4, step size: 1 ],
Default : 0
Saturation
ID : 0x00000004,
Type : Dword,
Flags : { CAN_READ, CAN_WRITE },
Values : [ 0 .. 8, step size: 1 ],
Default : 3
Contrast
ID : 0x00000002,
Type : Dword,
Flags : { CAN_READ, CAN_WRITE },
Values : [ 0 .. 6, step size: 1 ],
Default : 2
Brightness
ID : 0x00000001,
Type : Dword,
Flags : { CAN_READ, CAN_WRITE },
Values : [ 0 .. 100, step size: 1 ],
Default : 30
----------
There is something I don't understand: the Exposure (Auto Priority) control:
Exposure, Auto Priority
ID : 0x00000010,
Type : Boolean,
Flags : { CAN_READ, CAN_WRITE },
Values : [ 20 .. 5000, step size: 1 ],
Default : 79
is reported of being of type Boolean, but the allowable values are
described as integers; nevertheless, I'm unable to change its value in
any way, and also getting its current value returns an error:
[EMAIL PROTECTED]:~$ uvcdynctrl -g "Exposure, Auto Priority"
ERROR: Unable to retrieve control value: A Video4Linux2 API call
returned an unexpected error 5. (Code: 12)
dmesg says:
uvcvideo: Failed to query (129) UVC control 3 (unit 1) : -32 (exp. 1).
However, this is likely a problem with uvcdynctrl rather than with the
uvcvideo module.
Now, as far as manual exposure is concerned, I'm doing this:
[EMAIL PROTECTED]:~$ uvcdynctrl -s "Exposure, Auto" 0
[EMAIL PROTECTED]:~$ uvcdynctrl -g "Exposure, Auto"
0
[EMAIL PROTECTED]:~$ uvcdynctrl -s "Exposure (Absolute)" 20
[EMAIL PROTECTED]:~$ uvcdynctrl -g "Exposure (Absolute)"
20
After that, the image shown by luvcview is completely overexposed; the
same happens if I set the Exposure (Absolute) control with a high value:
[EMAIL PROTECTED]:~$ uvcdynctrl -s "Exposure (Absolute)" 4000
[EMAIL PROTECTED]:~$ uvcdynctrl -g "Exposure (Absolute)"
4000
I also tried to play around with the "Shutter Priority" and "Aperture
Priority" values for the "Exposure, Auto" control, but without any
apparent effect.
If I set "Exposure, Auto" to 1 (Auto mode) and run luvcview, I can see
that setting any value to the "Exposure (Absolute)" control results in
the image becoming immediately overexposed, and then quickly coming back
to normal as the camera automatically adjusts the exposure.
Has any body been able to manually set the exposure on the Creative
Live! Cam Optia (non-AF)?
Thanks in advance,
Moreno.
--
Moreno Marzolla
EMail: [EMAIL PROTECTED]
WWW : http://www.dsi.unive.it/~marzolla
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