Motion - Bug Report 2006x 05x 23x 092100

BUG: White Screen with auto brightness feature

I've also observed that autobrightness blinks. But when autobrightness is off and I change bright, saturation or hue, screen goes white too. Then, if I change contrast, all work again.

For example:

  1. - Initial conditions: bright=225, contrast=2 -> ok
  2. - Change: bright=224, contrast = 2 -> BLINKS!!
  3. - Change: bright=224, contrast = 1 -> ok
  4. - Change: brgiht=224, contrast = 1 -> OK

As you can see, settings for step 2 and step 4 are the same, but in the first one, screen is painted white.

Sorry for my poor English and Tkanks for your great work!!

Environment

Motion version: 3.2.6
ffmpeg version:  
Shared libraries: ffmpeg, mysql, postgresql
Server OS:  

-- GramSmi - 23 May 2006

Cameras are very different from each other and it is nearly impossible to make an autobrightness that works with all camera. In 99% of the cases it is best to leave it all up to the camera and not use auto-brightness.

Several people have wanted to code a better feature. Some started. I have not yet seen any code that actually worked with any camera.

One problem is that many cameras have very few actual steps of brightness settings and contrast. Especially at low light conditions. And that makes it impossible to make a regulation loop that works.

In video.c you will find this code.

/* Constants used by auto brightness feature
 * Defined as constant to make it easier for people to tweak code for a
 * difficult camera.
 * The experience gained from people could help improving the feature without
 * adding too many new options.
 * AUTOBRIGHT_HYSTERESIS sets the minimum the light intensity must change before
 * we adjust brigtness.
 * AUTOBRIGHTS_DAMPER damps the speed with which we adjust the brightness
 * When the brightness changes a lot we step in large steps and as we approach the
 * target value we slow down to avoid overshoot and oscillations. If the camera
 * adjusts too slowly decrease the DAMPER value. If the camera oscillates try
 * increasing the DAMPER value. DAMPER must be minimum 1.
 * MAX and MIN are the max and min values of brightness setting we will send to
 * the camera device.
 */
#define AUTOBRIGHT_HYSTERESIS 10
#define AUTOBRIGHT_DAMPER 5
#define AUTOBRIGHT_MAX 255
#define AUTOBRIGHT_MIN 0

Try and play with these 4 values and see if that can make your camera run better.

-- KennethLavrsen - 23 May 2006

Duplicate of BugReport2006x02x07x212816 so I close this one.

-- KennethLavrsen - 24 May 2006
Topic revision: r3 - 24 May 2006, KennethLavrsen
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