1 README for Linux device driver for the IBM "C-It" USB video camera
2
3 INTRODUCTION:
4
5 This driver does not use all features known to exist in
6 the IBM camera. However most of needed features work well.
7
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.
11
12 Video formats:
13 128x96 [model 1]
14 176x144
15 320x240 [model 2]
16 352x240 [model 2]
17 352x288
18 Frame rate: 3 - 30 frames per second (FPS)
19 External interface: USB
20 Internal interface: Video For Linux (V4L)
21 Supported controls:
22 - by V4L: Contrast, Brightness, Color, Hue
23 - by driver options: frame rate, lighting conditions, video format,
24 default picture settings, sharpness.
25
26 SUPPORTED CAMERAS:
27
28 IBM "C-It" camera, also known as "Xirlink 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
32 details and pictures.
33
34 The Linux driver was developed with camera with following
35 model number (or FCC ID): KSX-XVP510. This camera has three
36 interfaces, each with one endpoint (control, iso, iso). This
37 type of cameras is referred to as "model 1". These cameras are
38 no longer manufactured.
39
40 Xirlink now manufactures new cameras which are somewhat different.
41 In particular, following models [FCC ID] belong to that category:
42
43 XVP300 [KSX-X9903]
44 XVP600 [KSX-X9902]
45 XVP610 [KSX-X9902]
46
47 (see http://www.xirlink.com/ibmpccamera/ for updates, they refer
48 to these new cameras by Windows driver dated 12-27-99, v3005 BETA)
49 These cameras have two interfaces, one endpoint in each (iso, bulk).
50 Such type of cameras is referred to as "model 2". They are supported
51 (with exception of 352x288 native mode).
52
53 Quirks of Model 2 cameras:
54 -------------------------
55
56 Model 2 does not have hardware contrast control. Corresponding V4L
57 control is not used at the moment. It may be possible to implement
58 contrast control in software, at cost of extra processor cycles.
59
60 This driver provides 352x288 mode by switching the camera into
61 quasi-352x288 RGB mode (800 Kbits per frame) essentially limiting
62 this mode to 10 frames per second or less, in ideal conditions on
63 the bus (USB is shared, after all). The frame rate
64 has to be programmed very conservatively. Additional concern is that
65 frame rate depends on brightness setting; therefore the picture can
66 be good at one brightness and broken at another! I did not want to fix
67 the frame rate at slowest setting, but I had to move it pretty much down
68 the scale (so that framerate option barely matters). I also noticed that
69 camera after first powering up produces frames slightly faster than during
70 consecutive uses. All this means that if you use videosize=2 (which is
71 default), be warned - you may encounter broken picture on first connect;
72 try to adjust brightness - brighter image is slower, so USB will be able
73 to send all data. However if you regularly use Model 2 cameras you may
74 prefer videosize=1 which makes perfectly good I420, with no scaling and
75 lesser demands on USB (300 Kbits per second, or 26 frames per second).
76
77 The camera that I had also has a hardware quirk: if disconnected,
78 it needs few minutes to "relax" before it can be plugged in again
79 (poorly designed USB processor reset circuit?)
80
81 Model 2 camera can be programmed for very high sensitivity (even starlight
82 may be enough), this makes it convenient for tinkering with. The driver
83 code has enough comments to help a programmer to tweak the camera
84 as s/he feels necessary.
85
86 WHAT YOU NEED:
87
88 - A supported IBM PC (C-it) camera (model 1 or 2)
89
90 - A Linux box with USB support (2.3/2.4; 2.2 w/backport may work)
91
92 - A Video4Linux compatible frame grabber program such as xawtv.
93
94 HOW TO COMPILE THE DRIVER:
95
96 You need to compile the driver only if you are a developer
97 or if you want to make changes to the code. Most distributions
98 precompile all modules, so you can go directly to the next
99 section "HOW TO USE THE DRIVER".
100
101 The driver consists of two files in usb/ directory:
102 ibmcam.c and ibmcam.h These files are included into the
103 Linux kernel build process if you configure the kernel
104 for CONFIG_USB_IBMCAM. Run "make xconfig" and in USB section
105 you will find the IBM camera driver. Select it, save the
106 configuration and recompile.
107
108 HOW TO USE THE DRIVER:
109
110 I recommend to compile driver as a module. This gives you an
111 easier access to its configuration. The camera has many more
112 settings than V4L can operate, so some settings are done using
113 module options.
114
115 Typically module is installed with command 'modprobe', like this:
116
117 # modprobe ibmcam framerate=1
118
119 Alternatively you can use 'insmod' in similar fashion:
120
121 # insmod /lib/modules/2.x.y/usb/ibmcam.o framerate=1
122
123 Module can be inserted with camera connected or disconnected.
124
125 The driver can have options, though some defaults are provided.
126
127 Driver options: (* indicates that option is model-dependent)
128
129 Name Type Range [default] Example
130 -------------- -------------- -------------- ------------------
131 debug Integer 0-9 [0] debug=1
132 flags Integer 0-0xFF [0] flags=0x0d
133 framerate Integer 0-6 [2] framerate=1
134 hue_correction Integer 0-255 [128] hue_correction=115
135 init_brightness Integer 0-255 [128] init_brightness=100
136 init_contrast Integer 0-255 [192] init_contrast=200
137 init_color Integer 0-255 [128] init_color=130
138 init_hue Integer 0-255 [128] init_hue=115
139 lighting Integer 0-2* [1] lighting=2
140 sharpness Integer 0-6* [4] sharpness=3
141 videosize Integer 0-2* [2] videosize=1
142
143 Options for Model 2 only:
144
145 Name Type Range [default] Example
146 -------------- -------------- -------------- ------------------
147 init_model2_rg Integer 0..255 [0x70] init_model2_rg=128
148 init_model2_rg2 Integer 0..255 [0x2f] init_model2_rg2=50
149 init_model2_sat Integer 0..255 [0x34] init_model2_sat=65
150 init_model2_yb Integer 0..255 [0xa0] init_model2_yb=200
151
152 debug You don't need this option unless you are a developer.
153 If you are a developer then you will see in the code
154 what values do what. 0=off.
155
156 flags This is a bit mask, and you can combine any number of
157 bits to produce what you want. Usually you don't want
158 any of extra features this option provides:
159
160 FLAGS_RETRY_VIDIOCSYNC 1 This bit allows to retry failed
161 VIDIOCSYNC ioctls without failing.
162 Will work with xawtv, will not
163 with xrealproducer. Default is
164 not set.
165 FLAGS_MONOCHROME 2 Activates monochrome (b/w) mode.
166 FLAGS_DISPLAY_HINTS 4 Shows colored pixels which have
167 magic meaning to developers.
168 FLAGS_OVERLAY_STATS 8 Shows tiny numbers on screen,
169 useful only for debugging.
170 FLAGS_FORCE_TESTPATTERN 16 Shows blue screen with numbers.
171 FLAGS_SEPARATE_FRAMES 32 Shows each frame separately, as
172 it was received from the camera.
173 Default (not set) is to mix the
174 preceding frame in to compensate
175 for occasional loss of Isoc data
176 on high frame rates.
177 FLAGS_CLEAN_FRAMES 64 Forces "cleanup" of each frame
178 prior to use; relevant only if
179 FLAGS_SEPARATE_FRAMES is set.
180 Default is not to clean frames,
181 this is a little faster but may
182 produce flicker if frame rate is
183 too high and Isoc data gets lost.
184
185 framerate This setting controls frame rate of the camera. This is
186 an approximate setting (in terms of "worst" ... "best")
187 because camera changes frame rate depending on amount
188 of light available. Setting 0 is slowest, 6 is fastest.
189 Beware - fast settings are very demanding and may not
190 work well with all video sizes. Be conservative.
191
192 hue_correction This highly optional setting allows to adjust the
193 hue of the image in a way slightly different from
194 what usual "hue" control does. Both controls affect
195 YUV colorspace: regular "hue" control adjusts only
196 U component, and this "hue_correction" option similarly
197 adjusts only V component. However usually it is enough
198 to tweak only U or V to compensate for colored light or
199 color temperature; this option simply allows more
200 complicated correction when and if it is necessary.
201
202 init_brightness These settings specify _initial_ values which will be
203 init_contrast used to set up the camera. If your V4L application has
204 init_color its own controls to adjust the picture then these
205 init_hue controls will be used too. These options allow you to
206 preconfigure the camera when it gets connected, before
207 any V4L application connects to it. Good for webcams.
208
209 init_model2_rg These initial settings alter color balance of the
210 init_model2_rg2 camera on hardware level. All four settings may be used
211 init_model2_sat to tune the camera to specific lighting conditions. These
212 init_model2_yb settings only apply to Model 2 cameras.
213
214 lighting This option selects one of three hardware-defined
215 photosensitivity settings of the camera. 0=bright light,
216 1=Medium (default), 2=Low light. This setting affects
217 frame rate: the dimmer the lighting the lower the frame
218 rate (because longer exposition time is needed). The
219 Model 2 cameras allow values more than 2 for this option,
220 thus enabling extremely high sensitivity at cost of frame
221 rate, color saturation and imaging sensor noise.
222
223 sharpness This option controls smoothing (noise reduction)
224 made by camera. Setting 0 is most smooth, setting 6
225 is most sharp. Be aware that CMOS sensor used in the
226 camera is pretty noisy, so if you choose 6 you will
227 be greeted with "snowy" image. Default is 4. Model 2
228 cameras do not support this feature.
229
230 videosize This setting chooses one if three image sizes that are
231 supported by this driver. Camera supports more, but
232 it's difficult to reverse-engineer all formats.
233 Following video sizes are supported:
234
235 videosize=0 128x96 (Model 1 only)
236 videosize=1 176x144
237 videosize=2 352x288
238 videosize=3 320x240 (Model 2 only)
239 videosize=4 352x240 (Model 2 only)
240
241 The last one (352x288) is the native size of the sensor
242 array, so it's the best resolution camera (Model 1) can
243 yield. The best resolution of Model 2 is 176x144, and
244 larger images are produced by stretching the bitmap.
245 Choose the image size you need. The smaller image can
246 support faster frame rate. Default is 352x288.
247
248 WHAT NEEDS TO BE DONE:
249
250 - The box freezes if camera is unplugged after being used (OHCI).
251 Workaround: remove usb-ohci module first.
252 - On occasion camera (model 1) does not start properly (xawtv reports
253 errors), or camera produces negative image (funny colors.)
254 Workaround: reload the driver module. Reason: [1].
255 - The button on the camera is not used. I don't know how to get to it.
256 I know now how to read button on Model 2, but what to do with it?
257
258 [1]
259 - Camera reports its status back to the driver; however I don't know
260 what returned data means. If camera fails at some initialization
261 stage then something should be done, and I don't do that because
262 I don't even know that some command failed. This is mostly Model 1
263 concern because Model 2 uses different commands which do not return
264 status (and seem to complete successfully every time).
265
266 VIDEO SIZE AND IMAGE SIZE
267
268 Camera produces picture X by Y pixels. This is camera-specific and can be
269 altered by programming the camera accordingly. This image is placed onto
270 larger (or equal) area W by H, this is V4L image. At this time the driver
271 uses V4L image size (W by H) 352x288 pixels because many programs (such
272 as xawtv) expect quite specific sizes and don't want to deal with arbitrary,
273 camera-specific sizes. However this approach "hides" real image size, and
274 application always sees the camera as producing only 352x288 image. It is
275 possible to change the V4L image size to 128x96, and then if camera is
276 switched to 128x96 mode then xawtv will correctly accept this image size. But
277 many other popular sizes (such as 176x144) will not be welcomed. This is the
278 reason why all camera images are at this time placed onto 352x288 "canvas",
279 and size of that canvas (V4L) is reported to applications. It will be easy
280 to add options to control the canvas size, but it will be application-
281 specific because not all applications are ready to work with variety of
282 camera-specific sizes.
283
284 CREDITS:
285
286 The code is based in no small part on the CPiA driver by Johannes Erdfelt,
287 Randy Dunlap, and others. Big thanks to them for their pioneering work on that
288 and the USB stack.
This page was automatically generated by the
LXR engine.
Visit the LXR main site for more
information.