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diff --git a/Documentation/usb/ibmcam.txt b/Documentation/usb/ibmcam.txt new file mode 100644 index 0000000..ce2f21a --- /dev/null +++ b/Documentation/usb/ibmcam.txt @@ -0,0 +1,324 @@ +README for Linux device driver for the IBM "C-It" USB video camera + +INTRODUCTION: + +This driver does not use all features known to exist in +the IBM camera. However most of needed features work well. + +This driver was developed using logs of observed USB traffic +which was produced by standard Windows driver (c-it98.sys). +I did not have data sheets from Xirlink. + +Video formats: + 128x96 [model 1] + 176x144 + 320x240 [model 2] + 352x240 [model 2] + 352x288 +Frame rate: 3 - 30 frames per second (FPS) +External interface: USB +Internal interface: Video For Linux (V4L) +Supported controls: +- by V4L: Contrast, Brightness, Color, Hue +- by driver options: frame rate, lighting conditions, video format, + default picture settings, sharpness. + +SUPPORTED CAMERAS: + +Xirlink "C-It" camera, also known as "IBM PC Camera". +The device uses proprietary ASIC (and compression method); +it is manufactured by Xirlink. See http://www.xirlink.com/ +http://www.ibmpccamera.com or http://www.c-itnow.com/ for +details and pictures. + +This very chipset ("X Chip", as marked at the factory) +is used in several other cameras, and they are supported +as well: + +- IBM NetCamera +- Veo Stingray + +The Linux driver was developed with camera with following +model number (or FCC ID): KSX-XVP510. This camera has three +interfaces, each with one endpoint (control, iso, iso). This +type of cameras is referred to as "model 1". These cameras are +no longer manufactured. + +Xirlink now manufactures new cameras which are somewhat different. +In particular, following models [FCC ID] belong to that category: + +XVP300 [KSX-X9903] +XVP600 [KSX-X9902] +XVP610 [KSX-X9902] + +(see http://www.xirlink.com/ibmpccamera/ for updates, they refer +to these new cameras by Windows driver dated 12-27-99, v3005 BETA) +These cameras have two interfaces, one endpoint in each (iso, bulk). +Such type of cameras is referred to as "model 2". They are supported +(with exception of 352x288 native mode). + +Some IBM NetCameras (Model 4) are made to generate only compressed +video streams. This is great for performance, but unfortunately +nobody knows how to decompress the stream :-( Therefore, these +cameras are *unsupported* and if you try to use one of those, all +you get is random colored horizontal streaks, not the image! +If you have one of those cameras, you probably should return it +to the store and get something that is supported. + +Tell me more about all that "model" business +-------------------------------------------- + +I just invented model numbers to uniquely identify flavors of the +hardware/firmware that were sold. It was very confusing to use +brand names or some other internal numbering schemes. So I found +by experimentation that all Xirlink chipsets fall into four big +classes, and I called them "models". Each model is programmed in +its own way, and each model sends back the video in its own way. + +Quirks of Model 2 cameras: +------------------------- + +Model 2 does not have hardware contrast control. Corresponding V4L +control is implemented in software, which is not very nice to your +CPU, but at least it works. + +This driver provides 352x288 mode by switching the camera into +quasi-352x288 RGB mode (800 Kbits per frame) essentially limiting +this mode to 10 frames per second or less, in ideal conditions on +the bus (USB is shared, after all). The frame rate +has to be programmed very conservatively. Additional concern is that +frame rate depends on brightness setting; therefore the picture can +be good at one brightness and broken at another! I did not want to fix +the frame rate at slowest setting, but I had to move it pretty much down +the scale (so that framerate option barely matters). I also noticed that +camera after first powering up produces frames slightly faster than during +consecutive uses. All this means that if you use 352x288 (which is +default), be warned - you may encounter broken picture on first connect; +try to adjust brightness - brighter image is slower, so USB will be able +to send all data. However if you regularly use Model 2 cameras you may +prefer 176x144 which makes perfectly good I420, with no scaling and +lesser demands on USB (300 Kbits per second, or 26 frames per second). + +Another strange effect of 352x288 mode is the fine vertical grid visible +on some colored surfaces. I am sure it is caused by me not understanding +what the camera is trying to say. Blame trade secrets for that. + +The camera that I had also has a hardware quirk: if disconnected, +it needs few minutes to "relax" before it can be plugged in again +(poorly designed USB processor reset circuit?) + +[Veo Stingray with Product ID 0x800C is also Model 2, but I haven't +observed this particular flaw in it.] + +Model 2 camera can be programmed for very high sensitivity (even starlight +may be enough), this makes it convenient for tinkering with. The driver +code has enough comments to help a programmer to tweak the camera +as s/he feels necessary. + +WHAT YOU NEED: + +- A supported IBM PC (C-it) camera (model 1 or 2) + +- A Linux box with USB support (2.3/2.4; 2.2 w/backport may work) + +- A Video4Linux compatible frame grabber program such as xawtv. + +HOW TO COMPILE THE DRIVER: + +You need to compile the driver only if you are a developer +or if you want to make changes to the code. Most distributions +precompile all modules, so you can go directly to the next +section "HOW TO USE THE DRIVER". + +The ibmcam driver uses usbvideo helper library (module), +so if you are studying the ibmcam code you will be led there. + +The driver itself consists of only one file in usb/ directory: +ibmcam.c. This file is included into the Linux kernel build +process if you configure the kernel for CONFIG_USB_IBMCAM. +Run "make xconfig" and in USB section you will find the IBM +camera driver. Select it, save the configuration and recompile. + +HOW TO USE THE DRIVER: + +I recommend to compile driver as a module. This gives you an +easier access to its configuration. The camera has many more +settings than V4L can operate, so some settings are done using +module options. + +To begin with, on most modern Linux distributions the driver +will be automatically loaded whenever you plug the supported +camera in. Therefore, you don't need to do anything. However +if you want to experiment with some module parameters then +you can load and unload the driver manually, with camera +plugged in or unplugged. + +Typically module is installed with command 'modprobe', like this: + +# modprobe ibmcam framerate=1 + +Alternatively you can use 'insmod' in similar fashion: + +# insmod /lib/modules/2.x.y/usb/ibmcam.o framerate=1 + +Module can be inserted with camera connected or disconnected. + +The driver can have options, though some defaults are provided. + +Driver options: (* indicates that option is model-dependent) + +Name Type Range [default] Example +-------------- -------------- -------------- ------------------ +debug Integer 0-9 [0] debug=1 +flags Integer 0-0xFF [0] flags=0x0d +framerate Integer 0-6 [2] framerate=1 +hue_correction Integer 0-255 [128] hue_correction=115 +init_brightness Integer 0-255 [128] init_brightness=100 +init_contrast Integer 0-255 [192] init_contrast=200 +init_color Integer 0-255 [128] init_color=130 +init_hue Integer 0-255 [128] init_hue=115 +lighting Integer 0-2* [1] lighting=2 +sharpness Integer 0-6* [4] sharpness=3 +size Integer 0-2* [2] size=1 + +Options for Model 2 only: + +Name Type Range [default] Example +-------------- -------------- -------------- ------------------ +init_model2_rg Integer 0..255 [0x70] init_model2_rg=128 +init_model2_rg2 Integer 0..255 [0x2f] init_model2_rg2=50 +init_model2_sat Integer 0..255 [0x34] init_model2_sat=65 +init_model2_yb Integer 0..255 [0xa0] init_model2_yb=200 + +debug You don't need this option unless you are a developer. + If you are a developer then you will see in the code + what values do what. 0=off. + +flags This is a bit mask, and you can combine any number of + bits to produce what you want. Usually you don't want + any of extra features this option provides: + + FLAGS_RETRY_VIDIOCSYNC 1 This bit allows to retry failed + VIDIOCSYNC ioctls without failing. + Will work with xawtv, will not + with xrealproducer. Default is + not set. + FLAGS_MONOCHROME 2 Activates monochrome (b/w) mode. + FLAGS_DISPLAY_HINTS 4 Shows colored pixels which have + magic meaning to developers. + FLAGS_OVERLAY_STATS 8 Shows tiny numbers on screen, + useful only for debugging. + FLAGS_FORCE_TESTPATTERN 16 Shows blue screen with numbers. + FLAGS_SEPARATE_FRAMES 32 Shows each frame separately, as + it was received from the camera. + Default (not set) is to mix the + preceding frame in to compensate + for occasional loss of Isoc data + on high frame rates. + FLAGS_CLEAN_FRAMES 64 Forces "cleanup" of each frame + prior to use; relevant only if + FLAGS_SEPARATE_FRAMES is set. + Default is not to clean frames, + this is a little faster but may + produce flicker if frame rate is + too high and Isoc data gets lost. + FLAGS_NO_DECODING 128 This flag turns the video stream + decoder off, and dumps the raw + Isoc data from the camera into + the reading process. Useful to + developers, but not to users. + +framerate This setting controls frame rate of the camera. This is + an approximate setting (in terms of "worst" ... "best") + because camera changes frame rate depending on amount + of light available. Setting 0 is slowest, 6 is fastest. + Beware - fast settings are very demanding and may not + work well with all video sizes. Be conservative. + +hue_correction This highly optional setting allows to adjust the + hue of the image in a way slightly different from + what usual "hue" control does. Both controls affect + YUV colorspace: regular "hue" control adjusts only + U component, and this "hue_correction" option similarly + adjusts only V component. However usually it is enough + to tweak only U or V to compensate for colored light or + color temperature; this option simply allows more + complicated correction when and if it is necessary. + +init_brightness These settings specify _initial_ values which will be +init_contrast used to set up the camera. If your V4L application has +init_color its own controls to adjust the picture then these +init_hue controls will be used too. These options allow you to + preconfigure the camera when it gets connected, before + any V4L application connects to it. Good for webcams. + +init_model2_rg These initial settings alter color balance of the +init_model2_rg2 camera on hardware level. All four settings may be used +init_model2_sat to tune the camera to specific lighting conditions. These +init_model2_yb settings only apply to Model 2 cameras. + +lighting This option selects one of three hardware-defined + photosensitivity settings of the camera. 0=bright light, + 1=Medium (default), 2=Low light. This setting affects + frame rate: the dimmer the lighting the lower the frame + rate (because longer exposition time is needed). The + Model 2 cameras allow values more than 2 for this option, + thus enabling extremely high sensitivity at cost of frame + rate, color saturation and imaging sensor noise. + +sharpness This option controls smoothing (noise reduction) + made by camera. Setting 0 is most smooth, setting 6 + is most sharp. Be aware that CMOS sensor used in the + camera is pretty noisy, so if you choose 6 you will + be greeted with "snowy" image. Default is 4. Model 2 + cameras do not support this feature. + +size This setting chooses one of several image sizes that are + supported by this driver. Cameras may support more, but + it's difficult to reverse-engineer all formats. + Following video sizes are supported: + + size=0 128x96 (Model 1 only) + size=1 160x120 + size=2 176x144 + size=3 320x240 (Model 2 only) + size=4 352x240 (Model 2 only) + size=5 352x288 + size=6 640x480 (Model 3 only) + + The 352x288 is the native size of the Model 1 sensor + array, so it's the best resolution the camera can + yield. The best resolution of Model 2 is 176x144, and + larger images are produced by stretching the bitmap. + Model 3 has sensor with 640x480 grid, and it works too, + but the frame rate will be exceptionally low (1-2 FPS); + it may be still OK for some applications, like security. + Choose the image size you need. The smaller image can + support faster frame rate. Default is 352x288. + +For more information and the Troubleshooting FAQ visit this URL: + + http://www.linux-usb.org/ibmcam/ + +WHAT NEEDS TO BE DONE: + +- The button on the camera is not used. I don't know how to get to it. + I know now how to read button on Model 2, but what to do with it? + +- Camera reports its status back to the driver; however I don't know + what returned data means. If camera fails at some initialization + stage then something should be done, and I don't do that because + I don't even know that some command failed. This is mostly Model 1 + concern because Model 2 uses different commands which do not return + status (and seem to complete successfully every time). + +- Some flavors of Model 4 NetCameras produce only compressed video + streams, and I don't know how to decode them. + +CREDITS: + +The code is based in no small part on the CPiA driver by Johannes Erdfelt, +Randy Dunlap, and others. Big thanks to them for their pioneering work on that +and the USB stack. + +I also thank John Lightsey for his donation of the Veo Stingray camera. |
