Re: My Microdia (SN9C201) webcam succumbs to glare in Linux

[Jean-Francois Moine <moinejf@free.fr>]

On Fri, 16 Mar 2012 08:53:51 +1100
Xavion <xavion.0@gmail.com> wrote:

> As you can probably gather from the attached screenshots, I'm
> attempting to use my SN9C201 webcam for home security.  The problem is
> that it succumbs to external glare during the middle hours of sunny
> days when used in Linux.
> 
> The same problem doesn't occur in Windows, probably since the software
> automatically adjusts to the current lighting conditions.  These
> screenshots were taken only five minutes apart and the sunlight
> intensity didn't change much in-between.
> 
> No amount of adjusting the webcam's settings (via V4L2-UCP) seemed to
> make any significant difference.  For this reason, I'm guessing that
> there's at least one other adjustable setting that the GSPCA driver
> isn't tapping into yet.
	[snip]

Hi Xavion,

It seems that the exposure is not set correctly. May you try the patch
below? (to be applied to the gspca test version 2.15.7 - the exposure
may be too low at init time, set it to 800)

--- build/sn9c20x.c~
+++ build/sn9c20x.c
@@ -1650,10 +1650,9 @@
 	case SENSOR_OV7670:
 	case SENSOR_OV9655:
 	case SENSOR_OV9650:
-		exp[0] |= (3 << 4);
-		exp[2] = 0x2d;
-		exp[3] = expo;
-		exp[4] = expo >> 8;
+		exp[0] |= (2 << 4);
+		exp[2] = 0x10;			/* AECH */
+		exp[3] = expo * 255 / 0x1780;
 		break;
 	case SENSOR_MT9M001:
 	case SENSOR_MT9V112:

-- 
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Jef		|		http://moinejf.free.fr/