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289 lines
11 KiB
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289 lines
11 KiB
Plaintext
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Readme for Linux device driver for the OmniVision OV511 USB to camera bridge IC
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Author: Mark McClelland
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Homepage: http://alpha.dyndns.org/ov511
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INTRODUCTION:
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This is a driver for the OV511, a USB-only chip used in many "webcam" devices.
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Any camera using the OV511/OV511+ and the OV6620/OV7610/20/20AE should work.
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Video capture devices that use the Philips SAA7111A decoder also work. It
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supports streaming and capture of color or monochrome video via the Video4Linux
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API. Most V4L apps are compatible with it. Most resolutions with a width and
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height that are a multiple of 8 are supported.
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If you need more information, please visit the OV511 homepage at the above URL.
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WHAT YOU NEED:
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- If you want to help with the development, get the chip's specification docs at
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http://www.ovt.com/omniusbp.html
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- A Video4Linux compatible frame grabber program (I recommend vidcat and xawtv)
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vidcat is part of the w3cam package: http://mpx.freeshell.net/
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xawtv is available at: http://linux.bytesex.org/xawtv/
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HOW TO USE IT:
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Note: These are simplified instructions. For complete instructions see:
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http://alpha.dyndns.org/ov511/install.html
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You must have first compiled USB support, support for your specific USB host
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controller (UHCI or OHCI), and Video4Linux support for your kernel (I recommend
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making them modules.) Make sure "Enforce bandwidth allocation" is NOT enabled.
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Next, (as root):
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modprobe usbcore
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modprobe usb-uhci <OR> modprobe usb-ohci
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modprobe videodev
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modprobe ov511
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If it is not already there (it usually is), create the video device:
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mknod /dev/video0 c 81 0
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Optionally, symlink /dev/video to /dev/video0
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You will have to set permissions on this device to allow you to read/write
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from it:
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chmod 666 /dev/video
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chmod 666 /dev/video0 (if necessary)
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Now you are ready to run a video app! Both vidcat and xawtv work well for me
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at 640x480.
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[Using vidcat:]
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vidcat -s 640x480 -p c > test.jpg
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xview test.jpg
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[Using xawtv:]
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From the main xawtv directory:
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make clean
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./configure
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make
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make install
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Now you should be able to run xawtv. Right click for the options dialog.
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MODULE PARAMETERS:
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You can set these with: insmod ov511 NAME=VALUE
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There is currently no way to set these on a per-camera basis.
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NAME: autobright
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TYPE: integer (Boolean)
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DEFAULT: 1
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DESC: Brightness is normally under automatic control and can't be set
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manually by the video app. Set to 0 for manual control.
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NAME: autogain
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TYPE: integer (Boolean)
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DEFAULT: 1
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DESC: Auto Gain Control enable. This feature is not yet implemented.
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NAME: autoexp
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TYPE: integer (Boolean)
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DEFAULT: 1
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DESC: Auto Exposure Control enable. This feature is not yet implemented.
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NAME: debug
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TYPE: integer (0-6)
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DEFAULT: 3
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DESC: Sets the threshold for printing debug messages. The higher the value,
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the more is printed. The levels are cumulative, and are as follows:
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0=no debug messages
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1=init/detection/unload and other significant messages
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2=some warning messages
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3=config/control function calls
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4=most function calls and data parsing messages
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5=highly repetitive mesgs
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NAME: snapshot
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TYPE: integer (Boolean)
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DEFAULT: 0
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DESC: Set to 1 to enable snapshot mode. read()/VIDIOCSYNC will block until
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the snapshot button is pressed. Note: enabling this mode disables
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/proc/video/ov511/<minor#>/button
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NAME: cams
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TYPE: integer (1-4 for OV511, 1-31 for OV511+)
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DEFAULT: 1
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DESC: Number of cameras allowed to stream simultaneously on a single bus.
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Values higher than 1 reduce the data rate of each camera, allowing two
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or more to be used at once. If you have a complicated setup involving
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both OV511 and OV511+ cameras, trial-and-error may be necessary for
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finding the optimum setting.
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NAME: compress
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TYPE: integer (Boolean)
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DEFAULT: 0
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DESC: Set this to 1 to turn on the camera's compression engine. This can
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potentially increase the frame rate at the expense of quality, if you
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have a fast CPU. You must load the proper compression module for your
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camera before starting your application (ov511_decomp or ov518_decomp).
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NAME: testpat
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TYPE: integer (Boolean)
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DEFAULT: 0
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DESC: This configures the camera's sensor to transmit a colored test-pattern
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instead of an image. This does not work correctly yet.
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NAME: dumppix
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TYPE: integer (0-2)
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DEFAULT: 0
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DESC: Dumps raw pixel data and skips post-processing and format conversion.
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It is for debugging purposes only. Options are:
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0: Disable (default)
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1: Dump raw data from camera, excluding headers and trailers
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2: Dumps data exactly as received from camera
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NAME: led
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TYPE: integer (0-2)
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DEFAULT: 1 (Always on)
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DESC: Controls whether the LED (the little light) on the front of the camera
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is always off (0), always on (1), or only on when driver is open (2).
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This is not supported with the OV511, and might only work with certain
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cameras (ones that actually have the LED wired to the control pin, and
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not just hard-wired to be on all the time).
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NAME: dump_bridge
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TYPE: integer (Boolean)
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DEFAULT: 0
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DESC: Dumps the bridge (OV511[+] or OV518[+]) register values to the system
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log. Only useful for serious debugging/development purposes.
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NAME: dump_sensor
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TYPE: integer (Boolean)
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DEFAULT: 0
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DESC: Dumps the sensor register values to the system log. Only useful for
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serious debugging/development purposes.
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NAME: printph
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TYPE: integer (Boolean)
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DEFAULT: 0
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DESC: Setting this to 1 will dump the first 12 bytes of each isoc frame. This
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is only useful if you are trying to debug problems with the isoc data
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stream (i.e.: camera initializes, but vidcat hangs until Ctrl-C). Be
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warned that this dumps a large number of messages to your kernel log.
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NAME: phy, phuv, pvy, pvuv, qhy, qhuv, qvy, qvuv
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TYPE: integer (0-63 for phy and phuv, 0-255 for rest)
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DEFAULT: OV511 default values
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DESC: These are registers 70h - 77h of the OV511, which control the
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prediction ranges and quantization thresholds of the compressor, for
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the Y and UV channels in the horizontal and vertical directions. See
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the OV511 or OV511+ data sheet for more detailed descriptions. These
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normally do not need to be changed.
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NAME: lightfreq
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TYPE: integer (0, 50, or 60)
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DEFAULT: 0 (use sensor default)
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DESC: Sets the sensor to match your lighting frequency. This can reduce the
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appearance of "banding", i.e. horizontal lines or waves of light and
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dark that are often caused by artificial lighting. Valid values are:
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0 - Use default (depends on sensor, most likely 60 Hz)
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50 - For European and Asian 50 Hz power
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60 - For American 60 Hz power
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NAME: bandingfilter
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TYPE: integer (Boolean)
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DEFAULT: 0 (off)
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DESC: Enables the sensor´s banding filter exposure algorithm. This reduces
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or stabilizes the "banding" caused by some artificial light sources
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(especially fluorescent). You might have to set lightfreq correctly for
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this to work right. As an added bonus, this sometimes makes it
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possible to capture your monitor´s output.
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NAME: fastset
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TYPE: integer (Boolean)
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DEFAULT: 0 (off)
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DESC: Allows picture settings (brightness, contrast, color, and hue) to take
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effect immediately, even in the middle of a frame. This reduces the
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time to change settings, but can ruin frames during the change. Only
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affects OmniVision sensors.
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NAME: force_palette
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TYPE: integer (Boolean)
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DEFAULT: 0 (off)
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DESC: Forces the palette (color format) to a specific value. If an
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application requests a different palette, it will be rejected, thereby
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forcing it to try others until it succeeds. This is useful for forcing
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greyscale mode with a color camera, for example. Supported modes are:
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0 (Allows all the following formats)
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1 VIDEO_PALETTE_GREY (Linear greyscale)
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10 VIDEO_PALETTE_YUV420 (YUV 4:2:0 Planar)
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15 VIDEO_PALETTE_YUV420P (YUV 4:2:0 Planar, same as 10)
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NAME: backlight
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TYPE: integer (Boolean)
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DEFAULT: 0 (off)
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DESC: Setting this flag changes the exposure algorithm for OmniVision sensors
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such that objects in the camera's view (i.e. your head) can be clearly
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seen when they are illuminated from behind. It reduces or eliminates
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the sensor's auto-exposure function, so it should only be used when
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needed. Additionally, it is only supported with the OV6620 and OV7620.
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NAME: unit_video
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TYPE: Up to 16 comma-separated integers
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DEFAULT: 0,0,0... (automatically assign the next available minor(s))
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DESC: You can specify up to 16 minor numbers to be assigned to ov511 devices.
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For example, "unit_video=1,3" will make the driver use /dev/video1 and
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/dev/video3 for the first two devices it detects. Additional devices
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will be assigned automatically starting at the first available device
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node (/dev/video0 in this case). Note that you cannot specify 0 as a
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minor number. This feature requires kernel version 2.4.5 or higher.
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NAME: remove_zeros
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TYPE: integer (Boolean)
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DEFAULT: 0 (do not skip any incoming data)
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DESC: Setting this to 1 will remove zero-padding from incoming data. This
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will compensate for the blocks of corruption that can appear when the
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camera cannot keep up with the speed of the USB bus (eg. at low frame
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resolutions). This feature is always enabled when compression is on.
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NAME: mirror
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TYPE: integer (Boolean)
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DEFAULT: 0 (off)
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DESC: Setting this to 1 will reverse ("mirror") the image horizontally. This
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might be necessary if your camera has a custom lens assembly. This has
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no effect with video capture devices.
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NAME: ov518_color
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TYPE: integer (Boolean)
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DEFAULT: 0 (off)
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DESC: Enable OV518 color support. This is off by default since it doesn't
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work most of the time. If you want to try it, you must also load
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ov518_decomp with the "nouv=0" parameter. If you get improper colors or
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diagonal lines through the image, restart your video app and try again.
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Repeat as necessary.
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WORKING FEATURES:
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o Color streaming/capture at most widths and heights that are multiples of 8.
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o Monochrome (use force_palette=1 to enable)
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o Setting/getting of saturation, contrast, brightness, and hue (only some of
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them work the OV7620 and OV7620AE)
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o /proc status reporting
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o SAA7111A video capture support at 320x240 and 640x480
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o Compression support
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o SMP compatibility
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HOW TO CONTACT ME:
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You can email me at mark@alpha.dyndns.org . Please prefix the subject line
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with "OV511: " so that I am certain to notice your message.
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CREDITS:
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The code is based in no small part on the CPiA driver by Johannes Erdfelt,
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Randy Dunlap, and others. Big thanks to them for their pioneering work on that
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and the USB stack. Thanks to Bret Wallach for getting camera reg IO, ISOC, and
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image capture working. Thanks to Orion Sky Lawlor, Kevin Moore, and Claudio
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Matsuoka for their work as well.
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