--- /dev/null
- in /proc/bus/usb/devices). A hint consists of a string with the following
- format::
+Philips webcams (pwc driver)
+============================
+
+This file contains some additional information for the Philips and OEM webcams.
+E-mail: webcam@smcc.demon.nl Last updated: 2004-01-19
+Site: http://www.smcc.demon.nl/webcam/
+
+As of this moment, the following cameras are supported:
+
+ * Philips PCA645
+ * Philips PCA646
+ * Philips PCVC675
+ * Philips PCVC680
+ * Philips PCVC690
+ * Philips PCVC720/40
+ * Philips PCVC730
+ * Philips PCVC740
+ * Philips PCVC750
+ * Askey VC010
+ * Creative Labs Webcam 5
+ * Creative Labs Webcam Pro Ex
+ * Logitech QuickCam 3000 Pro
+ * Logitech QuickCam 4000 Pro
+ * Logitech QuickCam Notebook Pro
+ * Logitech QuickCam Zoom
+ * Logitech QuickCam Orbit
+ * Logitech QuickCam Sphere
+ * Samsung MPC-C10
+ * Samsung MPC-C30
+ * Sotec Afina Eye
+ * AME CU-001
+ * Visionite VCS-UM100
+ * Visionite VCS-UC300
+
+The main webpage for the Philips driver is at the address above. It contains
+a lot of extra information, a FAQ, and the binary plugin 'PWCX'. This plugin
+contains decompression routines that allow you to use higher image sizes and
+framerates; in addition the webcam uses less bandwidth on the USB bus (handy
+if you want to run more than 1 camera simultaneously). These routines fall
+under a NDA, and may therefore not be distributed as source; however, its use
+is completely optional.
+
+You can build this code either into your kernel, or as a module. I recommend
+the latter, since it makes troubleshooting a lot easier. The built-in
+microphone is supported through the USB Audio class.
+
+When you load the module you can set some default settings for the
+camera; some programs depend on a particular image-size or -format and
+don't know how to set it properly in the driver. The options are:
+
+size
+ Can be one of 'sqcif', 'qsif', 'qcif', 'sif', 'cif' or
+ 'vga', for an image size of resp. 128x96, 160x120, 176x144,
+ 320x240, 352x288 and 640x480 (of course, only for those cameras that
+ support these resolutions).
+
+fps
+ Specifies the desired framerate. Is an integer in the range of 4-30.
+
+fbufs
+ This parameter specifies the number of internal buffers to use for storing
+ frames from the cam. This will help if the process that reads images from
+ the cam is a bit slow or momentarily busy. However, on slow machines it
+ only introduces lag, so choose carefully. The default is 3, which is
+ reasonable. You can set it between 2 and 5.
+
+mbufs
+ This is an integer between 1 and 10. It will tell the module the number of
+ buffers to reserve for mmap(), VIDIOCCGMBUF, VIDIOCMCAPTURE and friends.
+ The default is 2, which is adequate for most applications (double
+ buffering).
+
+ Should you experience a lot of 'Dumping frame...' messages during
+ grabbing with a tool that uses mmap(), you might want to increase if.
+ However, it doesn't really buffer images, it just gives you a bit more
+ slack when your program is behind. But you need a multi-threaded or
+ forked program to really take advantage of these buffers.
+
+ The absolute maximum is 10, but don't set it too high! Every buffer takes
+ up 460 KB of RAM, so unless you have a lot of memory setting this to
+ something more than 4 is an absolute waste. This memory is only
+ allocated during open(), so nothing is wasted when the camera is not in
+ use.
+
+power_save
+ When power_save is enabled (set to 1), the module will try to shut down
+ the cam on close() and re-activate on open(). This will save power and
+ turn off the LED. Not all cameras support this though (the 645 and 646
+ don't have power saving at all), and some models don't work either (they
+ will shut down, but never wake up). Consider this experimental. By
+ default this option is disabled.
+
+compression (only useful with the plugin)
+ With this option you can control the compression factor that the camera
+ uses to squeeze the image through the USB bus. You can set the
+ parameter between 0 and 3::
+
+ 0 = prefer uncompressed images; if the requested mode is not available
+ in an uncompressed format, the driver will silently switch to low
+ compression.
+ 1 = low compression.
+ 2 = medium compression.
+ 3 = high compression.
+
+ High compression takes less bandwidth of course, but it could also
+ introduce some unwanted artefacts. The default is 2, medium compression.
+ See the FAQ on the website for an overview of which modes require
+ compression.
+
+ The compression parameter does not apply to the 645 and 646 cameras
+ and OEM models derived from those (only a few). Most cams honour this
+ parameter.
+
+leds
+ This settings takes 2 integers, that define the on/off time for the LED
+ (in milliseconds). One of the interesting things that you can do with
+ this is let the LED blink while the camera is in use. This::
+
+ leds=500,500
+
+ will blink the LED once every second. But with::
+
+ leds=0,0
+
+ the LED never goes on, making it suitable for silent surveillance.
+
+ By default the camera's LED is on solid while in use, and turned off
+ when the camera is not used anymore.
+
+ This parameter works only with the ToUCam range of cameras (720, 730, 740,
+ 750) and OEMs. For other cameras this command is silently ignored, and
+ the LED cannot be controlled.
+
+ Finally: this parameters does not take effect UNTIL the first time you
+ open the camera device. Until then, the LED remains on.
+
+dev_hint
+ A long standing problem with USB devices is their dynamic nature: you
+ never know what device a camera gets assigned; it depends on module load
+ order, the hub configuration, the order in which devices are plugged in,
+ and the phase of the moon (i.e. it can be random). With this option you
+ can give the driver a hint as to what video device node (/dev/videoX) it
+ should use with a specific camera. This is also handy if you have two
+ cameras of the same model.
+
+ A camera is specified by its type (the number from the camera model,
+ like PCA645, PCVC750VC, etc) and optionally the serial number (visible
++ in /sys/kernel/debug/usb/devices). A hint consists of a string with the
++ following format::
+
+ [type[.serialnumber]:]node
+
+ The square brackets mean that both the type and the serialnumber are
+ optional, but a serialnumber cannot be specified without a type (which
+ would be rather pointless). The serialnumber is separated from the type
+ by a '.'; the node number by a ':'.
+
+ This somewhat cryptic syntax is best explained by a few examples::
+
+ dev_hint=3,5 The first detected cam gets assigned
+ /dev/video3, the second /dev/video5. Any
+ other cameras will get the first free
+ available slot (see below).
+
+ dev_hint=645:1,680:2 The PCA645 camera will get /dev/video1,
+ and a PCVC680 /dev/video2.
+
+ dev_hint=645.0123:3,645.4567:0 The PCA645 camera with serialnumber
+ 0123 goes to /dev/video3, the same
+ camera model with the 4567 serial
+ gets /dev/video0.
+
+ dev_hint=750:1,4,5,6 The PCVC750 camera will get /dev/video1, the
+ next 3 Philips cams will use /dev/video4
+ through /dev/video6.
+
+ Some points worth knowing:
+
+ - Serialnumbers are case sensitive and must be written full, including
+ leading zeroes (it's treated as a string).
+ - If a device node is already occupied, registration will fail and
+ the webcam is not available.
+ - You can have up to 64 video devices; be sure to make enough device
+ nodes in /dev if you want to spread the numbers.
+ After /dev/video9 comes /dev/video10 (not /dev/videoA).
+ - If a camera does not match any dev_hint, it will simply get assigned
+ the first available device node, just as it used to be.
+
+trace
+ In order to better detect problems, it is now possible to turn on a
+ 'trace' of some of the calls the module makes; it logs all items in your
+ kernel log at debug level.
+
+ The trace variable is a bitmask; each bit represents a certain feature.
+ If you want to trace something, look up the bit value(s) in the table
+ below, add the values together and supply that to the trace variable.
+
+ ====== ======= ================================================ =======
+ Value Value Description Default
+ (dec) (hex)
+ ====== ======= ================================================ =======
+ 1 0x1 Module initialization; this will log messages On
+ while loading and unloading the module
+
+ 2 0x2 probe() and disconnect() traces On
+
+ 4 0x4 Trace open() and close() calls Off
+
+ 8 0x8 read(), mmap() and associated ioctl() calls Off
+
+ 16 0x10 Memory allocation of buffers, etc. Off
+
+ 32 0x20 Showing underflow, overflow and Dumping frame On
+ messages
+
+ 64 0x40 Show viewport and image sizes Off
+
+ 128 0x80 PWCX debugging Off
+ ====== ======= ================================================ =======
+
+ For example, to trace the open() & read() functions, sum 8 + 4 = 12,
+ so you would supply trace=12 during insmod or modprobe. If
+ you want to turn the initialization and probing tracing off, set trace=0.
+ The default value for trace is 35 (0x23).
+
+
+
+Example::
+
+ # modprobe pwc size=cif fps=15 power_save=1
+
+The fbufs, mbufs and trace parameters are global and apply to all connected
+cameras. Each camera has its own set of buffers.
+
+size and fps only specify defaults when you open() the device; this is to
+accommodate some tools that don't set the size. You can change these
+settings after open() with the Video4Linux ioctl() calls. The default of
+defaults is QCIF size at 10 fps.
+
+The compression parameter is semiglobal; it sets the initial compression
+preference for all camera's, but this parameter can be set per camera with
+the VIDIOCPWCSCQUAL ioctl() call.
+
+All parameters are optional.
+
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