Dark picture on Genius E-Messenger 112 webcam with yesterday's v4l-dvb code.

Dark picture on Genius E-Messenger 112 webcam with yesterday's v4l-dvb code.

[Victor]

Hello.

I'm using Genius E-Messenger 112 webcam on Slackware 12.2 with 2.6.27.7 kernel 
(custom-built) and yesterday's v4l-dvb sources checked out via "mercurial" 
("hg log" returns "11445:dba0b6fae413" as latest commit). the camera uses 
gspca_main and gspca_pac207 kernel modules.`

Camera works (with LD_PRELOAD=v4l2convert.so) in mplayer (mplayer tv://) and 
skype, but picture is way too dark. It looks like "contrast" is permanently 
set at maximum, and doesn't change (although it looks like camera tries to 
adjust brightness automatically).

How can this be fixed?

Few articles in the web talk about "/sys/module/gspca/parameters/gamma", etc, 
but it looks like such advice is outdated. I assume this device is not 
completely supported (people on the web recommend to avoid using this camera 
on linux), so perhaps I could provide additional data to make it work in the 
future. Or, perhaps, someone could tell me where (in gspca source) I could 
start trying to fix that problem.

-- 
With best regards, Victor

Re: Dark picture on Genius E-Messenger 112 webcam with yesterday's v4l-dvb code.

[Jean-Francois Moine]

On Sat, 11 Apr 2009 18:16:14 +0400
Victor <ErV2005@rambler.ru> wrote:

> Hello.

Hello Victor,

> I'm using Genius E-Messenger 112 webcam on Slackware 12.2 with
> 2.6.27.7 kernel (custom-built) and yesterday's v4l-dvb sources
> checked out via "mercurial" ("hg log" returns "11445:dba0b6fae413" as
> latest commit). the camera uses gspca_main and gspca_pac207 kernel
> modules.`
> 
> Camera works (with LD_PRELOAD=v4l2convert.so) in mplayer (mplayer
> tv://) and skype, but picture is way too dark. It looks like
> "contrast" is permanently set at maximum, and doesn't change
> (although it looks like camera tries to adjust brightness
> automatically).
> 
> How can this be fixed?

Did you try to change the webcam controls? (there are brightness,
exposure, autogain and gain - they may be changed by programs as
v4l2ucp or vlc)

> Few articles in the web talk about
> "/sys/module/gspca/parameters/gamma", etc, but it looks like such
> advice is outdated. I assume this device is not completely supported
> (people on the web recommend to avoid using this camera on linux), so
> perhaps I could provide additional data to make it work in the
> future. Or, perhaps, someone could tell me where (in gspca source) I
> could start trying to fix that problem.

You may ask to Hans de Goede who is the maintainer of the pac207
driver.

Cheers.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

Re: Dark picture on Genius E-Messenger 112 webcam with yesterday's v4l-dvb code.

[Victor]

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Hello,

On Sunday 12 April 2009 21:08:31 you wrote:
> On Sat, 11 Apr 2009 18:16:14 +0400
>
> Victor <ErV2005@rambler.ru> wrote:
> > Hello.
>
> Hello Victor,
>
> > I'm using Genius E-Messenger 112 webcam on Slackware 12.2 with
> > 2.6.27.7 kernel (custom-built) and yesterday's v4l-dvb sources
> > checked out via "mercurial" ("hg log" returns "11445:dba0b6fae413" as
> > latest commit). the camera uses gspca_main and gspca_pac207 kernel
> > modules.`
> >
> > Camera works (with LD_PRELOAD=v4l2convert.so) in mplayer (mplayer
> > tv://) and skype, but picture is way too dark. It looks like
> > "contrast" is permanently set at maximum, and doesn't change
> > (although it looks like camera tries to adjust brightness
> > automatically).
> >
> > How can this be fixed?
>
> Did you try to change the webcam controls? (there are brightness,
> exposure, autogain and gain - they may be changed by programs as
> v4l2ucp or vlc)
I can modify brightness, exposure, gain/autogain from vlc.
It looks like the problem is related to automatic gain function. Automatic 
gain is enabled by default. When it is enabled, it slowly sets "gain" to the 
maximum, "brightness" to minimum, and "exposure" according to the situation 
(somewhere in the middle).
"Normal" results are produced when gain is near zero.
That's why picture looks bad. 
I could run vlc each time I'm going to use webcam, of course, but I'd like to 
keep automatic brightness/contrast/gain feature and fix it.

As I understand it, automatic exposure is handled by 
"gspca_auto_gain_n_exposure" routine which is located at line 2048 in gspca.c, 
but "gspca_auto_gain_n_exposure" is actually called 
from "pac207_do_auto_gain", line 338 of pac207.c, and at least some data that 
could produce wrong result (avg_lum) seems to be read from the frame data of 
the webcam (line 385 of pac207.c). 

So I'm not quite sure - given this info,
> You may ask to Hans de Goede who is the maintainer of the pac207
> driver.
>
> Cheers.
should I continue discussion here or contact maintainer of pac207 instead?

-- 
Best regards, Victor

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Re: Dark picture on Genius E-Messenger 112 webcam with yesterday's v4l-dvb code.

[Victor]

On Sunday 12 April 2009 21:08:31 you wrote:
> You may ask to Hans de Goede who is the maintainer of the pac207
> driver.
>
> Cheers.
After some thinking, I decided to contact maintainer of pac207, because 
problem most likely belong to that module. Thanks for the help.


-- 
Best regards, Victor