1 README for Linux device driver for the IBM "C-It" USB video camera
5 This driver does not use all features known to exist in
6 the IBM camera. However most of needed features work well.
8 This driver was developed using logs of observed USB traffic
9 which was produced by standard Windows driver (c-it98.sys).
10 I did not have data sheets from Xirlink.
18 Frame rate: 3 - 30 frames per second (FPS)
19 External interface: USB
20 Internal interface: Video For Linux (V4L)
22 - by V4L: Contrast, Brightness, Color, Hue
23 - by driver options: frame rate, lighting conditions, video format,
24 default picture settings, sharpness.
28 Xirlink "C-It" camera, also known as "IBM PC Camera".
29 The device uses proprietary ASIC (and compression method);
30 it is manufactured by Xirlink. See http://www.xirlink.com/
31 http://www.ibmpccamera.com or http://www.c-itnow.com/ for
34 This very chipset ("X Chip", as marked at the factory)
35 is used in several other cameras, and they are supported
41 The Linux driver was developed with camera with following
42 model number (or FCC ID): KSX-XVP510. This camera has three
43 interfaces, each with one endpoint (control, iso, iso). This
44 type of cameras is referred to as "model 1". These cameras are
45 no longer manufactured.
47 Xirlink now manufactures new cameras which are somewhat different.
48 In particular, following models [FCC ID] belong to that category:
54 (see http://www.xirlink.com/ibmpccamera/ for updates, they refer
55 to these new cameras by Windows driver dated 12-27-99, v3005 BETA)
56 These cameras have two interfaces, one endpoint in each (iso, bulk).
57 Such type of cameras is referred to as "model 2". They are supported
58 (with exception of 352x288 native mode).
60 Some IBM NetCameras (Model 4) are made to generate only compressed
61 video streams. This is great for performance, but unfortunately
62 nobody knows how to decompress the stream :-( Therefore, these
63 cameras are *unsupported* and if you try to use one of those, all
64 you get is random colored horizontal streaks, not the image!
65 If you have one of those cameras, you probably should return it
66 to the store and get something that is supported.
68 Tell me more about all that "model" business
69 --------------------------------------------
71 I just invented model numbers to uniquely identify flavors of the
72 hardware/firmware that were sold. It was very confusing to use
73 brand names or some other internal numbering schemes. So I found
74 by experimentation that all Xirlink chipsets fall into four big
75 classes, and I called them "models". Each model is programmed in
76 its own way, and each model sends back the video in its own way.
78 Quirks of Model 2 cameras:
79 -------------------------
81 Model 2 does not have hardware contrast control. Corresponding V4L
82 control is implemented in software, which is not very nice to your
83 CPU, but at least it works.
85 This driver provides 352x288 mode by switching the camera into
86 quasi-352x288 RGB mode (800 Kbits per frame) essentially limiting
87 this mode to 10 frames per second or less, in ideal conditions on
88 the bus (USB is shared, after all). The frame rate
89 has to be programmed very conservatively. Additional concern is that
90 frame rate depends on brightness setting; therefore the picture can
91 be good at one brightness and broken at another! I did not want to fix
92 the frame rate at slowest setting, but I had to move it pretty much down
93 the scale (so that framerate option barely matters). I also noticed that
94 camera after first powering up produces frames slightly faster than during
95 consecutive uses. All this means that if you use 352x288 (which is
96 default), be warned - you may encounter broken picture on first connect;
97 try to adjust brightness - brighter image is slower, so USB will be able
98 to send all data. However if you regularly use Model 2 cameras you may
99 prefer 176x144 which makes perfectly good I420, with no scaling and
100 lesser demands on USB (300 Kbits per second, or 26 frames per second).
102 Another strange effect of 352x288 mode is the fine vertical grid visible
103 on some colored surfaces. I am sure it is caused by me not understanding
104 what the camera is trying to say. Blame trade secrets for that.
106 The camera that I had also has a hardware quirk: if disconnected,
107 it needs few minutes to "relax" before it can be plugged in again
108 (poorly designed USB processor reset circuit?)
110 [Veo Stingray with Product ID 0x800C is also Model 2, but I haven't
111 observed this particular flaw in it.]
113 Model 2 camera can be programmed for very high sensitivity (even starlight
114 may be enough), this makes it convenient for tinkering with. The driver
115 code has enough comments to help a programmer to tweak the camera
116 as s/he feels necessary.
120 - A supported IBM PC (C-it) camera (model 1 or 2)
122 - A Linux box with USB support (2.3/2.4; 2.2 w/backport may work)
124 - A Video4Linux compatible frame grabber program such as xawtv.
126 HOW TO COMPILE THE DRIVER:
128 You need to compile the driver only if you are a developer
129 or if you want to make changes to the code. Most distributions
130 precompile all modules, so you can go directly to the next
131 section "HOW TO USE THE DRIVER".
133 The ibmcam driver uses usbvideo helper library (module),
134 so if you are studying the ibmcam code you will be led there.
136 The driver itself consists of only one file in usb/ directory:
137 ibmcam.c. This file is included into the Linux kernel build
138 process if you configure the kernel for CONFIG_USB_IBMCAM.
139 Run "make xconfig" and in USB section you will find the IBM
140 camera driver. Select it, save the configuration and recompile.
142 HOW TO USE THE DRIVER:
144 I recommend to compile driver as a module. This gives you an
145 easier access to its configuration. The camera has many more
146 settings than V4L can operate, so some settings are done using
149 To begin with, on most modern Linux distributions the driver
150 will be automatically loaded whenever you plug the supported
151 camera in. Therefore, you don't need to do anything. However
152 if you want to experiment with some module parameters then
153 you can load and unload the driver manually, with camera
154 plugged in or unplugged.
156 Typically module is installed with command 'modprobe', like this:
158 # modprobe ibmcam framerate=1
160 Alternatively you can use 'insmod' in similar fashion:
162 # insmod /lib/modules/2.x.y/usb/ibmcam.o framerate=1
164 Module can be inserted with camera connected or disconnected.
166 The driver can have options, though some defaults are provided.
168 Driver options: (* indicates that option is model-dependent)
170 Name Type Range [default] Example
171 -------------- -------------- -------------- ------------------
172 debug Integer 0-9 [0] debug=1
173 flags Integer 0-0xFF [0] flags=0x0d
174 framerate Integer 0-6 [2] framerate=1
175 hue_correction Integer 0-255 [128] hue_correction=115
176 init_brightness Integer 0-255 [128] init_brightness=100
177 init_contrast Integer 0-255 [192] init_contrast=200
178 init_color Integer 0-255 [128] init_color=130
179 init_hue Integer 0-255 [128] init_hue=115
180 lighting Integer 0-2* [1] lighting=2
181 sharpness Integer 0-6* [4] sharpness=3
182 size Integer 0-2* [2] size=1
184 Options for Model 2 only:
186 Name Type Range [default] Example
187 -------------- -------------- -------------- ------------------
188 init_model2_rg Integer 0..255 [0x70] init_model2_rg=128
189 init_model2_rg2 Integer 0..255 [0x2f] init_model2_rg2=50
190 init_model2_sat Integer 0..255 [0x34] init_model2_sat=65
191 init_model2_yb Integer 0..255 [0xa0] init_model2_yb=200
193 debug You don't need this option unless you are a developer.
194 If you are a developer then you will see in the code
195 what values do what. 0=off.
197 flags This is a bit mask, and you can combine any number of
198 bits to produce what you want. Usually you don't want
199 any of extra features this option provides:
201 FLAGS_RETRY_VIDIOCSYNC 1 This bit allows to retry failed
202 VIDIOCSYNC ioctls without failing.
203 Will work with xawtv, will not
204 with xrealproducer. Default is
206 FLAGS_MONOCHROME 2 Activates monochrome (b/w) mode.
207 FLAGS_DISPLAY_HINTS 4 Shows colored pixels which have
208 magic meaning to developers.
209 FLAGS_OVERLAY_STATS 8 Shows tiny numbers on screen,
210 useful only for debugging.
211 FLAGS_FORCE_TESTPATTERN 16 Shows blue screen with numbers.
212 FLAGS_SEPARATE_FRAMES 32 Shows each frame separately, as
213 it was received from the camera.
214 Default (not set) is to mix the
215 preceding frame in to compensate
216 for occasional loss of Isoc data
218 FLAGS_CLEAN_FRAMES 64 Forces "cleanup" of each frame
219 prior to use; relevant only if
220 FLAGS_SEPARATE_FRAMES is set.
221 Default is not to clean frames,
222 this is a little faster but may
223 produce flicker if frame rate is
224 too high and Isoc data gets lost.
225 FLAGS_NO_DECODING 128 This flag turns the video stream
226 decoder off, and dumps the raw
227 Isoc data from the camera into
228 the reading process. Useful to
229 developers, but not to users.
231 framerate This setting controls frame rate of the camera. This is
232 an approximate setting (in terms of "worst" ... "best")
233 because camera changes frame rate depending on amount
234 of light available. Setting 0 is slowest, 6 is fastest.
235 Beware - fast settings are very demanding and may not
236 work well with all video sizes. Be conservative.
238 hue_correction This highly optional setting allows to adjust the
239 hue of the image in a way slightly different from
240 what usual "hue" control does. Both controls affect
241 YUV colorspace: regular "hue" control adjusts only
242 U component, and this "hue_correction" option similarly
243 adjusts only V component. However usually it is enough
244 to tweak only U or V to compensate for colored light or
245 color temperature; this option simply allows more
246 complicated correction when and if it is necessary.
248 init_brightness These settings specify _initial_ values which will be
249 init_contrast used to set up the camera. If your V4L application has
250 init_color its own controls to adjust the picture then these
251 init_hue controls will be used too. These options allow you to
252 preconfigure the camera when it gets connected, before
253 any V4L application connects to it. Good for webcams.
255 init_model2_rg These initial settings alter color balance of the
256 init_model2_rg2 camera on hardware level. All four settings may be used
257 init_model2_sat to tune the camera to specific lighting conditions. These
258 init_model2_yb settings only apply to Model 2 cameras.
260 lighting This option selects one of three hardware-defined
261 photosensitivity settings of the camera. 0=bright light,
262 1=Medium (default), 2=Low light. This setting affects
263 frame rate: the dimmer the lighting the lower the frame
264 rate (because longer exposition time is needed). The
265 Model 2 cameras allow values more than 2 for this option,
266 thus enabling extremely high sensitivity at cost of frame
267 rate, color saturation and imaging sensor noise.
269 sharpness This option controls smoothing (noise reduction)
270 made by camera. Setting 0 is most smooth, setting 6
271 is most sharp. Be aware that CMOS sensor used in the
272 camera is pretty noisy, so if you choose 6 you will
273 be greeted with "snowy" image. Default is 4. Model 2
274 cameras do not support this feature.
276 size This setting chooses one of several image sizes that are
277 supported by this driver. Cameras may support more, but
278 it's difficult to reverse-engineer all formats.
279 Following video sizes are supported:
281 size=0 128x96 (Model 1 only)
284 size=3 320x240 (Model 2 only)
285 size=4 352x240 (Model 2 only)
287 size=6 640x480 (Model 3 only)
289 The 352x288 is the native size of the Model 1 sensor
290 array, so it's the best resolution the camera can
291 yield. The best resolution of Model 2 is 176x144, and
292 larger images are produced by stretching the bitmap.
293 Model 3 has sensor with 640x480 grid, and it works too,
294 but the frame rate will be exceptionally low (1-2 FPS);
295 it may be still OK for some applications, like security.
296 Choose the image size you need. The smaller image can
297 support faster frame rate. Default is 352x288.
299 For more information and the Troubleshooting FAQ visit this URL:
301 http://www.linux-usb.org/ibmcam/
303 WHAT NEEDS TO BE DONE:
305 - The button on the camera is not used. I don't know how to get to it.
306 I know now how to read button on Model 2, but what to do with it?
308 - Camera reports its status back to the driver; however I don't know
309 what returned data means. If camera fails at some initialization
310 stage then something should be done, and I don't do that because
311 I don't even know that some command failed. This is mostly Model 1
312 concern because Model 2 uses different commands which do not return
313 status (and seem to complete successfully every time).
315 - Some flavors of Model 4 NetCameras produce only compressed video
316 streams, and I don't know how to decode them.
320 The code is based in no small part on the CPiA driver by Johannes Erdfelt,
321 Randy Dunlap, and others. Big thanks to them for their pioneering work on that
324 I also thank John Lightsey for his donation of the Veo Stingray camera.
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