c-qcam - Connectix Color QuickCam video4linux kernel driver
  
  Copyright (C) 1999  Dave Forrest  <drf5n@virginia.edu>

  		    released under GNU GPL.

  
  1999-12-08 Dave Forrest, written with kernel version 2.2.12 in mind
  
  
  Table of Contents
  
  1.0 Introduction
  2.0 Compilation, Installation, and Configuration
  3.0 Troubleshooting
  4.0 Future Work / current work arounds
  9.0 Sample Program, v4lgrab
  10.0 Other Information
  
  
  1.0 Introduction

    The file ../../drivers/media/video/c-qcam.c is a device driver for
  the Logitech (nee Connectix) parallel port interface color CCD camera.

  This is a fairly inexpensive device for capturing images.  Logitech
  does not currently provide information for developers, but many people
  have engineered several solutions for non-Microsoft use of the Color
  Quickcam.
  
  1.1 Motivation
  
    I spent a number of hours trying to get my camera to work, and I
  hope this document saves you some time.  My camera will not work with
  the 2.2.13 kernel as distributed, but with a few patches to the
  module, I was able to grab some frames. See 4.0, Future Work.
  
  
  
  2.0 Compilation, Installation, and Configuration
  
    The c-qcam depends on parallel port support, video4linux, and the
  Color Quickcam.  It is also nice to have the parallel port readback
  support enabled. I enabled these as modules during the kernel
  configuration.  The appropriate flags are:
  
      CONFIG_PRINTER       M    for lp.o, parport.o parport_pc.o modules
      CONFIG_PNP_PARPORT   M for autoprobe.o IEEE1284 readback module
      CONFIG_PRINTER_READBACK M for parport_probe.o IEEE1284 readback module
      CONFIG_VIDEO_DEV     M    for videodev.o video4linux module

      CONFIG_VIDEO_CQCAM   M    for c-qcam.o  Color Quickcam module

  
    With these flags, the kernel should compile and install the modules.
  To record and monitor the compilation, I use:
  
   (make zlilo ; \
    make modules; \

    make modules_install ;

    depmod -a ) &>log &
   less log  # then a capital 'F' to watch the progress

  But that is my personal preference.
  
  2.2 Configuration

    The configuration requires module configuration and device
  configuration.  I like kmod or kerneld process with the
  /etc/modprobe.conf file so the modules can automatically load/unload as
  they are used.  The video devices could already exist, be generated
  using MAKEDEV, or need to be created.  The following sections detail
  these procedures.

  2.1 Module Configuration

  
    Using modules requires a bit of work to install and pass the
  parameters.  Understand that entries in /etc/modprobe.conf of:
  
     alias parport_lowlevel parport_pc
     options parport_pc io=0x378 irq=none
     alias char-major-81 videodev
     alias char-major-81-0 c-qcam
  
  will cause the kmod/modprobe to do certain things.  If you are
  using kmod, then a request for a 'char-major-81-0' will cause
  the 'c-qcam' module to load.  If you have other video sources with
  modules, you might want to assign the different minor numbers to
  different modules.
  
  2.2 Device Configuration
  
    At this point, we need to ensure that the device files exist.
  Video4linux used the /dev/video* files, and we want to attach the
  Quickcam to one of these.
  
     ls -lad /dev/video*  # should produce a list of the video devices
  
  If the video devices do not exist, you can create them with:
  
    su
    cd /dev
    for ii in 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ; do
      mknod video$ii c 81 $ii   # char-major-81-[0-16]
      chown root.root video$ii  # owned by root
      chmod 600 video$ii        # read/writable by root only
    done
  
    Lots of people connect video0 to video and bttv, but you might want
  your c-qcam to mean something more:
  
     ln -s video0 c-qcam  # make /dev/c-qcam a working file
     ln -s c-qcam video   # make /dev/c-qcam your default video source
  
    But these are conveniences.  The important part is to make the proper
  special character files with the right major and minor numbers.  All
  of the special device files are listed in ../devices.txt.  If you
  would like the c-qcam readable by non-root users, you will need to
  change the permissions.
  
  3.0 Troubleshooting
  
    If the sample program below, v4lgrab, gives you output then
  everything is working.
  
      v4lgrab | wc # should give you a count of characters
  
    Otherwise, you have some problem.
  
    The c-qcam is IEEE1284 compatible, so if you are using the proc file
  system (CONFIG_PROC_FS), the parallel printer support
  (CONFIG_PRINTER), the IEEE 1284 system,(CONFIG_PRINTER_READBACK), you
  should be able to read some identification from your quickcam with

  	 modprobe -v parport
  	 modprobe -v parport_probe
  	 cat /proc/parport/PORTNUMBER/autoprobe

  Returns:
    CLASS:MEDIA;
    MODEL:Color QuickCam 2.0;
    MANUFACTURER:Connectix;
  
    A good response to this indicates that your color quickcam is alive
  and well.  A common problem is that the current driver does not
  reliably detect a c-qcam, even though one is attached.  In this case,

       modprobe -v c-qcam

  or
       insmod -v c-qcam
  
    Returns a message saying "Device or resource busy"  Development is
  currently underway, but a workaround is to patch the module to skip
  the detection code and attach to a defined port.  Check the
  video4linux mailing list and archive for more current information.
  
  3.1 Checklist:
  
    Can you get an image?

  	    v4lgrab >qcam.ppm ; wc qcam.ppm ; xv qcam.ppm

    Is a working c-qcam connected to the port?
  	    grep ^ /proc/parport/?/autoprobe

    Do the /dev/video* files exist?
  	    ls -lad /dev/video

    Is the c-qcam module loaded?
  	    modprobe -v c-qcam ; lsmod

  
    Does the camera work with alternate programs? cqcam, etc?
  
  
  
  
  4.0 Future Work / current workarounds
  
    It is hoped that this section will soon become obsolete, but if it
  isn't, you might try patching the c-qcam module to add a parport=xxx
  option as in the bw-qcam module so you can specify the parallel port:

         insmod -v c-qcam parport=0

  
  And bypass the detection code, see ../../drivers/char/c-qcam.c and
  look for the 'qc_detect' code and call.
  
    Note that there is work in progress to change the video4linux API,
  this work is documented at the video4linux2 site listed below.

  9.0 --- A sample program using v4lgrabber,

  v4lgrab is a simple image grabber that will copy a frame from the

  first video device, /dev/video0 to standard output in portable pixmap

  format (.ppm)  To produce .jpg output, you can use it like this:
  'v4lgrab | convert - c-qcam.jpg'

  
  
  10.0 --- Other Information
  
  Use the ../../Maintainers file, particularly the  VIDEO FOR LINUX and PARALLEL
  PORT SUPPORT sections
  
  The video4linux page:

    http://linuxtv.org

  The V4L2 API spec:
    http://v4l2spec.bytesex.org/

  
  Some web pages about the quickcams:

     http://www.pingouin-land.com/howto/QuickCam-HOWTO.html

  
     http://www.crynwr.com/qcpc/            QuickCam Third-Party Drivers
     http://www.crynwr.com/qcpc/re.html     Some Reverse Engineering

     http://www.wirelesscouch.net/software/gqcam/   v4l client

     http://phobos.illtel.denver.co.us/pub/qcread/ doesn't use v4l
     ftp://ftp.cs.unm.edu/pub/chris/quickcam/   Has lots of drivers
     http://www.cs.duke.edu/~reynolds/quickcam/ Has lots of information