Documentation/media/v4l-drivers/philips.rst

   1 Philips webcams (pwc driver)
   2 ============================
   3
   4 This file contains some additional information for the Philips and OEM webcams.
   5 E-mail: webcam@smcc.demon.nl                        Last updated: 2004-01-19
   6 Site: http://www.smcc.demon.nl/webcam/
   7
   8 As of this moment, the following cameras are supported:
   9
  10  * Philips PCA645
  11  * Philips PCA646
  12  * Philips PCVC675
  13  * Philips PCVC680
  14  * Philips PCVC690
  15  * Philips PCVC720/40
  16  * Philips PCVC730
  17  * Philips PCVC740
  18  * Philips PCVC750
  19  * Askey VC010
  20  * Creative Labs Webcam 5
  21  * Creative Labs Webcam Pro Ex
  22  * Logitech QuickCam 3000 Pro
  23  * Logitech QuickCam 4000 Pro
  24  * Logitech QuickCam Notebook Pro
  25  * Logitech QuickCam Zoom
  26  * Logitech QuickCam Orbit
  27  * Logitech QuickCam Sphere
  28  * Samsung MPC-C10
  29  * Samsung MPC-C30
  30  * Sotec Afina Eye
  31  * AME CU-001
  32  * Visionite VCS-UM100
  33  * Visionite VCS-UC300
  34
  35 The main webpage for the Philips driver is at the address above. It contains
  36 a lot of extra information, a FAQ, and the binary plugin 'PWCX'. This plugin
  37 contains decompression routines that allow you to use higher image sizes and
  38 framerates; in addition the webcam uses less bandwidth on the USB bus (handy
  39 if you want to run more than 1 camera simultaneously). These routines fall
  40 under a NDA, and may therefore not be distributed as source; however, its use
  41 is completely optional.
  42
  43 You can build this code either into your kernel, or as a module. I recommend
  44 the latter, since it makes troubleshooting a lot easier. The built-in
  45 microphone is supported through the USB Audio class.
  46
  47 When you load the module you can set some default settings for the
  48 camera; some programs depend on a particular image-size or -format and
  49 don't know how to set it properly in the driver. The options are:
  50
  51 size
  52    Can be one of 'sqcif', 'qsif', 'qcif', 'sif', 'cif' or
  53    'vga', for an image size of resp. 128x96, 160x120, 176x144,
  54    320x240, 352x288 and 640x480 (of course, only for those cameras that
  55    support these resolutions).
  56
  57 fps
  58    Specifies the desired framerate. Is an integer in the range of 4-30.
  59
  60 fbufs
  61    This parameter specifies the number of internal buffers to use for storing
  62    frames from the cam. This will help if the process that reads images from
  63    the cam is a bit slow or momentarily busy. However, on slow machines it
  64    only introduces lag, so choose carefully. The default is 3, which is
  65    reasonable. You can set it between 2 and 5.
  66
  67 mbufs
  68    This is an integer between 1 and 10. It will tell the module the number of
  69    buffers to reserve for mmap(), VIDIOCCGMBUF, VIDIOCMCAPTURE and friends.
  70    The default is 2, which is adequate for most applications (double
  71    buffering).
  72
  73    Should you experience a lot of 'Dumping frame...' messages during
  74    grabbing with a tool that uses mmap(), you might want to increase if.
  75    However, it doesn't really buffer images, it just gives you a bit more
  76    slack when your program is behind. But you need a multi-threaded or
  77    forked program to really take advantage of these buffers.
  78
  79    The absolute maximum is 10, but don't set it too high!  Every buffer takes
  80    up 460 KB of RAM, so unless you have a lot of memory setting this to
  81    something more than 4 is an absolute waste.  This memory is only
  82    allocated during open(), so nothing is wasted when the camera is not in
  83    use.
  84
  85 power_save
  86    When power_save is enabled (set to 1), the module will try to shut down
  87    the cam on close() and re-activate on open(). This will save power and
  88    turn off the LED. Not all cameras support this though (the 645 and 646
  89    don't have power saving at all), and some models don't work either (they
  90    will shut down, but never wake up). Consider this experimental. By
  91    default this option is disabled.
  92
  93 compression (only useful with the plugin)
  94    With this option you can control the compression factor that the camera
  95    uses to squeeze the image through the USB bus. You can set the
  96    parameter between 0 and 3::
  97
  98      0 = prefer uncompressed images; if the requested mode is not available
  99          in an uncompressed format, the driver will silently switch to low
 100          compression.
 101      1 = low compression.
 102      2 = medium compression.
 103      3 = high compression.
 104
 105    High compression takes less bandwidth of course, but it could also
 106    introduce some unwanted artefacts. The default is 2, medium compression.
 107    See the FAQ on the website for an overview of which modes require
 108    compression.
 109
 110    The compression parameter does not apply to the 645 and 646 cameras
 111    and OEM models derived from those (only a few). Most cams honour this
 112    parameter.
 113
 114 leds
 115    This settings takes 2 integers, that define the on/off time for the LED
 116    (in milliseconds). One of the interesting things that you can do with
 117    this is let the LED blink while the camera is in use. This::
 118
 119      leds=500,500
 120
 121    will blink the LED once every second. But with::
 122
 123      leds=0,0
 124
 125    the LED never goes on, making it suitable for silent surveillance.
 126
 127    By default the camera's LED is on solid while in use, and turned off
 128    when the camera is not used anymore.
 129
 130    This parameter works only with the ToUCam range of cameras (720, 730, 740,
 131    750) and OEMs. For other cameras this command is silently ignored, and
 132    the LED cannot be controlled.
 133
 134    Finally: this parameters does not take effect UNTIL the first time you
 135    open the camera device. Until then, the LED remains on.
 136
 137 dev_hint
 138    A long standing problem with USB devices is their dynamic nature: you
 139    never know what device a camera gets assigned; it depends on module load
 140    order, the hub configuration, the order in which devices are plugged in,
 141    and the phase of the moon (i.e. it can be random). With this option you
 142    can give the driver a hint as to what video device node (/dev/videoX) it
 143    should use with a specific camera. This is also handy if you have two
 144    cameras of the same model.
 145
 146    A camera is specified by its type (the number from the camera model,
 147    like PCA645, PCVC750VC, etc) and optionally the serial number (visible
 148    in /proc/bus/usb/devices). A hint consists of a string with the following
 149    format::
 150
 151       [type[.serialnumber]:]node
 152
 153    The square brackets mean that both the type and the serialnumber are
 154    optional, but a serialnumber cannot be specified without a type (which
 155    would be rather pointless). The serialnumber is separated from the type
 156    by a '.'; the node number by a ':'.
 157
 158    This somewhat cryptic syntax is best explained by a few examples::
 159
 160      dev_hint=3,5              The first detected cam gets assigned
 161                                /dev/video3, the second /dev/video5. Any
 162                                other cameras will get the first free
 163                                available slot (see below).
 164
 165      dev_hint=645:1,680:2      The PCA645 camera will get /dev/video1,
 166                                and a PCVC680 /dev/video2.
 167
 168      dev_hint=645.0123:3,645.4567:0     The PCA645 camera with serialnumber
 169                                         0123 goes to /dev/video3, the same
 170                                         camera model with the 4567 serial
 171                                         gets /dev/video0.
 172
 173      dev_hint=750:1,4,5,6       The PCVC750 camera will get /dev/video1, the
 174                                 next 3 Philips cams will use /dev/video4
 175                                 through /dev/video6.
 176
 177    Some points worth knowing:
 178
 179    - Serialnumbers are case sensitive and must be written full, including
 180      leading zeroes (it's treated as a string).
 181    - If a device node is already occupied, registration will fail and
 182      the webcam is not available.
 183    - You can have up to 64 video devices; be sure to make enough device
 184      nodes in /dev if you want to spread the numbers.
 185      After /dev/video9 comes /dev/video10 (not /dev/videoA).
 186    - If a camera does not match any dev_hint, it will simply get assigned
 187      the first available device node, just as it used to be.
 188
 189 trace
 190    In order to better detect problems, it is now possible to turn on a
 191    'trace' of some of the calls the module makes; it logs all items in your
 192    kernel log at debug level.
 193
 194    The trace variable is a bitmask; each bit represents a certain feature.
 195    If you want to trace something, look up the bit value(s) in the table
 196    below, add the values together and supply that to the trace variable.
 197
 198    ====== ======= ================================================ =======
 199    Value  Value   Description                                      Default
 200    (dec)  (hex)
 201    ====== ======= ================================================ =======
 202        1    0x1   Module initialization; this will log messages       On
 203                   while loading and unloading the module
 204
 205        2    0x2   probe() and disconnect() traces                     On
 206
 207        4    0x4   Trace open() and close() calls                      Off
 208
 209        8    0x8   read(), mmap() and associated ioctl() calls         Off
 210
 211       16   0x10   Memory allocation of buffers, etc.                  Off
 212
 213       32   0x20   Showing underflow, overflow and Dumping frame       On
 214                   messages
 215
 216       64   0x40   Show viewport and image sizes                       Off
 217
 218      128   0x80   PWCX debugging                                      Off
 219    ====== ======= ================================================ =======
 220
 221    For example, to trace the open() & read() functions, sum 8 + 4 = 12,
 222    so you would supply trace=12 during insmod or modprobe. If
 223    you want to turn the initialization and probing tracing off, set trace=0.
 224    The default value for trace is 35 (0x23).
 225
 226
 227
 228 Example::
 229
 230      # modprobe pwc size=cif fps=15 power_save=1
 231
 232 The fbufs, mbufs and trace parameters are global and apply to all connected
 233 cameras. Each camera has its own set of buffers.
 234
 235 size and fps only specify defaults when you open() the device; this is to
 236 accommodate some tools that don't set the size. You can change these
 237 settings after open() with the Video4Linux ioctl() calls. The default of
 238 defaults is QCIF size at 10 fps.
 239
 240 The compression parameter is semiglobal; it sets the initial compression
 241 preference for all camera's, but this parameter can be set per camera with
 242 the VIDIOCPWCSCQUAL ioctl() call.
 243
 244 All parameters are optional.
 245