Motion - Support Question 2011x 06x 30x 111729

Logitech C200 auto exposure control

Question

Auto exposure doesn't work well. It seems like exposure is calibrated for light inside room, where it works good. But if i direct camera outside (through a window), image is overexposed. Almost 80 % of pixels are just white. This problem exists only on Linux, on Windows it works normally.

With uvcdynctrl command i can only set "Exposure, Auto" to Manual Mode [1] and Aperture Priority Mode [3]. If I understand correctly that is camera's own auto exposure control. Can I somehow set motion to override this, so that it can calculate average brightnes of the image and then sets absolute exposure accordingly ?

uvcdynctrl -c -v output:
 Exposure, Auto Priority
    ID      : 0x00000010,
    Type    : Boolean,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : [ 0 .. 1, step size: 1 ],
    Default : 0
  Exposure (Absolute)
    ID      : 0x00000011,
    Type    : Dword,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : [ 1 .. 10000, step size: 1 ],
    Default : 166
  Exposure, Auto
    ID      : 0x0000000f,
    Type    : Choice,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : { 'Auto Mode'[0], 'Manual Mode'[1], 'Shutter Priority Mode'[2], 'Aperture Priority Mode'[3] },
    Default : 3
  Backlight Compensation
    ID      : 0x0000000c,
    Type    : Dword,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : [ 0 .. 1, step size: 1 ],
    Default : 1
  Sharpness
    ID      : 0x00000007,
    Type    : Dword,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : [ 0 .. 255, step size: 1 ],
    Default : 20
  White Balance Temperature
    ID      : 0x00000008,
    Type    : Dword,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : [ 0 .. 10000, step size: 10 ],
    Default : 4000
  Power Line Frequency
    ID      : 0x0000000d,
    Type    : Choice,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : { 'Disabled'[0], '50 Hz'[1], '60 Hz'[2] },
    Default : 2
  Gain
    ID      : 0x00000003,
    Type    : Dword,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : [ 0 .. 255, step size: 1 ],
    Default : 0
  White Balance Temperature, Auto
    ID      : 0x00000009,
    Type    : Boolean,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : [ 0 .. 1, step size: 1 ],
    Default : 1
  Saturation
    ID      : 0x00000004,
    Type    : Dword,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : [ 0 .. 255, step size: 1 ],
    Default : 38
  Contrast
    ID      : 0x00000002,
    Type    : Dword,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : [ 0 .. 255, step size: 1 ],
    Default : 32
  Brightness
    ID      : 0x00000001,
    Type    : Dword,
    Flags   : { CAN_READ, CAN_WRITE },
    Values  : [ 0 .. 255, step size: 1 ],
    Default : 128

motion -n :
[0] Processing thread 0 - config file /etc/motion/motion.conf
[0] Motion 3.2.12 Started
[0] ffmpeg LIBAVCODEC_BUILD 3412993 LIBAVFORMAT_BUILD 3415808
[0] Thread 1 is from /etc/motion/motion.conf
[0] motion-httpd/3.2.12 running, accepting connections
[0] motion-httpd: waiting for data on port TCP 8080
[1] Thread 1 started
[1] cap.driver: "uvcvideo"
[1] cap.card: "UVC Camera (046d:0802)"
[1] cap.bus_info: "usb-0000:00:07.2-2"
[1] cap.capabilities=0x04000001
[1] - VIDEO_CAPTURE
[1] - STREAMING
[1] Test palette MJPG (640x480)
[1] Using palette MJPG (640x480) bytesperlines 0 sizeimage 31466 colorspace 00000008
[1] found control 0x00980900, "Brightness", range 0,255
[1]     "Brightness", default 128, current 128
[1] found control 0x00980901, "Contrast", range 0,255
[1]     "Contrast", default 32, current 32
[1] found control 0x00980902, "Saturation", range 0,255
[1]     "Saturation", default 38, current 38
[1] found control 0x00980913, "Gain", range 0,255
[1]     "Gain", default 0, current 0
[1] mmap information:
[1] frames=4
[1] 0 length=31466
[1] 1 length=31466
[1] 2 length=31466
[1] 3 length=31466
[1] Using V4L2
[1] Resizing pre_capture buffer to 1 items
[1] Started stream webcam server in port 8081

Environment

Motion version: 3.2.12
ffmpeg version:  
Libraries: ffmpeg, mysql, postgresql
Server OS: Debian Squeeze, kernel 2.6.32-5
-- UrosS - 30 Jun 2011

Answer

Topic revision: r1 - 30 Jun 2011, UrosS
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