.TH DV4LSTART 1

.SH NAME
dv4lstart \- redirect V4L API to access a camcorder from a V4L program

.SH SYNOPSIS
.BI "dvlstart [" options "] " command " [" argument " ...]"
.sp

.SH DESCRIPTION
.B dv4lstart
enables
.I command
to access a dv1394
(Firewire) camcorder by using the video4linux (V4L) API.
.B dv4lstart
uses the LD_PRELOAD facility 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 
.I command,
use /dev/video0.
Any existing, real V4L device named /dev/video0 can not be accessed
from an application started with
.B dv4lstart
(applications started normally can access the real /dev/video0)

.SH OPTIONS
.TP
.BI "\-c, \-\-color\-correction"
Set this option if red objects look blue.
.TP
.BI "\-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.
.TP
.BI "\-r, \-\-rgb\-only
Set this option to prevent V4L applications from choosing
YUV palettes. Try this option if you get low frame rates.
.TP
.BI "\-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.
.TP
.B "\-h, \-\-help"
displays a help message

.SH EXAMPLES
The command

\ \ $ dv4lstart v4l-info

outputs some information about the simulated V4L device.

\ \ $ dv4lstart -c gqcam -v /dev/video0 

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

.SH 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.
.B dv4lstart
will not work there.

If
.B dv4lstart
does not work, try 
.I dv4l
instead.

.SH SEE ALSO
dv4l(1)