DV4LSTART(1) | General Commands Manual | DV4LSTART(1) |
dv4lstart - redirect V4L API to access a camcorder from a V4L program
dvlstart [options] command [argument ...]
dv4lstart enables command to access a dv1394 (Firewire) camcorder by using the video4linux (V4L) API. 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 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)
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.
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.