dv4lstart(1) [debian man page]

DV4LSTART(1)						      General Commands Manual						      DV4LSTART(1)

NAME

       dv4lstart - redirect V4L API to access a camcorder from a V4L program

SYNOPSIS

       dvlstart [options] command [argument ...]

DESCRIPTION

       dv4lstart enables command to access a dv1394 (Firewire) camcorder by using the video4linux (V4L) API.  dv4lstart uses the LD_PRELOAD facil-
       ity to intercept calls to the V4L API and make the camcorder's videostream available.

       Check that LD_PRELOAD works in your environment by starting

	 $ dv4lstart ls -l /dev/video0

       The resulting output should look like

       crw-rw---- 0 root video 81, 0 Jan  1  1970 /dev/video0

       Check your 1394 driver config by starting

	 $ gst-launch-0.10 dv1394src ! dvdemux ! dvdec !  xvimagesink

       from your shell. After turning on your camera, a video window should appear. If this works, dv4lstart should work as well.

       Inside command, use /dev/video0.  Any existing, real V4L device named /dev/video0 can not be accessed  from  an	application  started  with
       dv4lstart (applications started normally can access the real /dev/video0)

OPTIONS

       -c, --color-correction
	      Set this option if red objects look blue.

       -n, --new-dev
	      Tell  dv4lstart  to  simulate  a	new  video device rather than overriding /dev/video0. Set this option if your application needs to
	      access other video devices.

       -r, --rgb-only
	      Set this option to prevent V4L applications from choosing YUV palettes. Try this option if you get low frame rates.

       -v, --verbose level
	      Set the amount of debugging messages. A level of 0 means no output at all, 1 is the default, 3 enables all messages.

       -h, --help
	      displays a help message

EXAMPLES

       The command

	 $ dv4lstart v4l-info

       outputs some information about the simulated V4L device.

	 $ dv4lstart -c gqcam -v /dev/video0

       starts the gqcam webcam viewer, swapping red and blue colors.

LIMITATIONS

       Programs using exotic ways to access the V4L API will not work.

       Some environments don't allow the use of LD_PRELOAD for security reasons.  dv4lstart will not work there.

       If dv4lstart does not work, try dv4l instead.

SEE ALSO

       dv4l(1)

																      DV4LSTART(1)

sane-v4l(5)							File Formats Manual						       sane-v4l(5)

NAME

       sane-v4l - SANE interface for Video for Linux API

DESCRIPTION

       The  sane-v4l  library implements a SANE (Scanner Access Now Easy) backend that provides generic access to video cameras and similar equip-
       ment using the V4L (Video for Linux) API.

       This is ALPHA software. Really! Important features are missing and there are lots of bugs. The code is currently only tested on a Linux 2.4
       system with a Hauppauge WinTV video card.

DEVICE NAMES

       This backend expects device names of the form:

	      special

       Where  special  is  the	UNIX  path-name  for the special device that corresponds to the v4l device.  The special device name must be a v4l
       device or a symlink to such a device.  For example, such a device name could be /dev/video0 or /dev/bttv0.

CONFIGURATION

       The contents of the v4l.conf file is a list of device names that correspond to v4l devices.  Empty lines and lines  starting  with  a  hash
       mark (#) are ignored.  A sample configuration file is shown below:

	      /dev/bttv0
	      # this is a comment
	      /dev/video3

FILES

       /etc/sane.d/v4l.conf
	      The backend configuration file (see also description of SANE_CONFIG_DIR below).

       /usr/lib/sane/libsane-v4l.a
	      The static library implementing this backend.

       /usr/lib/sane/libsane-v4l.so
	      The shared library implementing this backend (present on systems that support dynamic loading).

ENVIRONMENT

       SANE_CONFIG_DIR
	      This  environment  variable  specifies the list of directories that may contain the configuration file.  Under UNIX, the directories
	      are separated by a colon (`:'), under OS/2, they are separated by a semi-colon (`;').  If this variable is not set,  the	configura-
	      tion  file is searched in two default directories: first, the current working directory (".") and then in /etc/sane.d.  If the value
	      of the environment variable ends with the directory separator character, then the default directories are searched after the explic-
	      itly  specified  directories.  For example, setting SANE_CONFIG_DIR to "/tmp/config:" would result in directories "tmp/config", ".",
	      and "/etc/sane.d" being searched (in this order).

       SANE_DEBUG_V4L
	      If the library was compiled with debug support enabled, this environment variable controls the debug level for this backend.   E.g.,
	      a value of 128 requests all debug output to be printed.  Smaller levels reduce verbosity.

AUTHOR

       Juergen G. Schimmer, Henning Meier-Geinitz

BUGS
:
       If more than one video card is present, a crash may occur. Frequency and geometry selection is missing.
       Send  bug  reports  to  the  SANE  mailing  list:  sane-devel@mostang.com.   You  must  be  subscribed  to  the	list  to  send	mail.  See
       http://www.mostang.com/sane/mail.html for details.

SEE ALSO

       sane(7), xcam(1).

								    28 Aug 2002 						       sane-v4l(5)