216 lines
6.9 KiB
Plaintext
216 lines
6.9 KiB
Plaintext
c-qcam - Connectix Color QuickCam video4linux kernel driver
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Copyright (C) 1999 Dave Forrest <drf5n@virginia.edu>
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released under GNU GPL.
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1999-12-08 Dave Forrest, written with kernel version 2.2.12 in mind
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Table of Contents
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1.0 Introduction
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2.0 Compilation, Installation, and Configuration
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3.0 Troubleshooting
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4.0 Future Work / current work arounds
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9.0 Sample Program, v4lgrab
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10.0 Other Information
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1.0 Introduction
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The file ../../drivers/media/video/c-qcam.c is a device driver for
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the Logitech (nee Connectix) parallel port interface color CCD camera.
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This is a fairly inexpensive device for capturing images. Logitech
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does not currently provide information for developers, but many people
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have engineered several solutions for non-Microsoft use of the Color
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Quickcam.
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1.1 Motivation
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I spent a number of hours trying to get my camera to work, and I
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hope this document saves you some time. My camera will not work with
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the 2.2.13 kernel as distributed, but with a few patches to the
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module, I was able to grab some frames. See 4.0, Future Work.
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2.0 Compilation, Installation, and Configuration
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The c-qcam depends on parallel port support, video4linux, and the
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Color Quickcam. It is also nice to have the parallel port readback
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support enabled. I enabled these as modules during the kernel
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configuration. The appropriate flags are:
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CONFIG_PRINTER M for lp.o, parport.o parport_pc.o modules
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CONFIG_PNP_PARPORT M for autoprobe.o IEEE1284 readback module
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CONFIG_PRINTER_READBACK M for parport_probe.o IEEE1284 readback module
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CONFIG_VIDEO_DEV M for videodev.o video4linux module
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CONFIG_VIDEO_CQCAM M for c-qcam.o Color Quickcam module
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With these flags, the kernel should compile and install the modules.
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To record and monitor the compilation, I use:
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(make zlilo ; \
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make modules; \
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make modules_install ;
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depmod -a ) &>log &
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less log # then a capital 'F' to watch the progress
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But that is my personal preference.
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2.2 Configuration
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The configuration requires module configuration and device
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configuration. I like kmod or kerneld process with the
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/etc/modprobe.conf file so the modules can automatically load/unload as
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they are used. The video devices could already exist, be generated
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using MAKEDEV, or need to be created. The following sections detail
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these procedures.
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2.1 Module Configuration
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Using modules requires a bit of work to install and pass the
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parameters. Understand that entries in /etc/modprobe.conf of:
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alias parport_lowlevel parport_pc
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options parport_pc io=0x378 irq=none
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alias char-major-81 videodev
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alias char-major-81-0 c-qcam
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will cause the kmod/modprobe to do certain things. If you are
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using kmod, then a request for a 'char-major-81-0' will cause
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the 'c-qcam' module to load. If you have other video sources with
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modules, you might want to assign the different minor numbers to
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different modules.
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2.2 Device Configuration
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At this point, we need to ensure that the device files exist.
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Video4linux used the /dev/video* files, and we want to attach the
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Quickcam to one of these.
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ls -lad /dev/video* # should produce a list of the video devices
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If the video devices do not exist, you can create them with:
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su
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cd /dev
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for ii in 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ; do
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mknod video$ii c 81 $ii # char-major-81-[0-16]
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chown root.root video$ii # owned by root
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chmod 600 video$ii # read/writable by root only
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done
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Lots of people connect video0 to video and bttv, but you might want
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your c-qcam to mean something more:
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ln -s video0 c-qcam # make /dev/c-qcam a working file
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ln -s c-qcam video # make /dev/c-qcam your default video source
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But these are conveniences. The important part is to make the proper
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special character files with the right major and minor numbers. All
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of the special device files are listed in ../devices.txt. If you
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would like the c-qcam readable by non-root users, you will need to
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change the permissions.
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3.0 Troubleshooting
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If the sample program below, v4lgrab, gives you output then
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everything is working.
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v4lgrab | wc # should give you a count of characters
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Otherwise, you have some problem.
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The c-qcam is IEEE1284 compatible, so if you are using the proc file
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system (CONFIG_PROC_FS), the parallel printer support
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(CONFIG_PRINTER), the IEEE 1284 system,(CONFIG_PRINTER_READBACK), you
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should be able to read some identification from your quickcam with
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modprobe -v parport
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modprobe -v parport_probe
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cat /proc/parport/PORTNUMBER/autoprobe
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Returns:
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CLASS:MEDIA;
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MODEL:Color QuickCam 2.0;
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MANUFACTURER:Connectix;
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A good response to this indicates that your color quickcam is alive
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and well. A common problem is that the current driver does not
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reliably detect a c-qcam, even though one is attached. In this case,
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modprobe -v c-qcam
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or
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insmod -v c-qcam
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Returns a message saying "Device or resource busy" Development is
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currently underway, but a workaround is to patch the module to skip
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the detection code and attach to a defined port. Check the
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video4linux mailing list and archive for more current information.
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3.1 Checklist:
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Can you get an image?
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v4lgrab >qcam.ppm ; wc qcam.ppm ; xv qcam.ppm
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Is a working c-qcam connected to the port?
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grep ^ /proc/parport/?/autoprobe
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Do the /dev/video* files exist?
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ls -lad /dev/video
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Is the c-qcam module loaded?
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modprobe -v c-qcam ; lsmod
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Does the camera work with alternate programs? cqcam, etc?
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4.0 Future Work / current workarounds
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It is hoped that this section will soon become obsolete, but if it
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isn't, you might try patching the c-qcam module to add a parport=xxx
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option as in the bw-qcam module so you can specify the parallel port:
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insmod -v c-qcam parport=0
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And bypass the detection code, see ../../drivers/char/c-qcam.c and
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look for the 'qc_detect' code and call.
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Note that there is work in progress to change the video4linux API,
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this work is documented at the video4linux2 site listed below.
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9.0 --- A sample program using v4lgrabber,
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v4lgrab is a simple image grabber that will copy a frame from the
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first video device, /dev/video0 to standard output in portable pixmap
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format (.ppm) To produce .jpg output, you can use it like this:
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'v4lgrab | convert - c-qcam.jpg'
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10.0 --- Other Information
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Use the ../../Maintainers file, particularly the VIDEO FOR LINUX and PARALLEL
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PORT SUPPORT sections
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The video4linux page:
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http://linuxtv.org
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The V4L2 API spec:
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http://v4l2spec.bytesex.org/
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Some web pages about the quickcams:
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http://www.pingouin-land.com/howto/QuickCam-HOWTO.html
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http://www.crynwr.com/qcpc/ QuickCam Third-Party Drivers
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http://www.crynwr.com/qcpc/re.html Some Reverse Engineering
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http://www.wirelesscouch.net/software/gqcam/ v4l client
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http://phobos.illtel.denver.co.us/pub/qcread/ doesn't use v4l
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ftp://ftp.cs.unm.edu/pub/chris/quickcam/ Has lots of drivers
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http://www.cs.duke.edu/~reynolds/quickcam/ Has lots of information
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