---
name: "dv4lstart"
section: "1"
platform: "linux"
package: "dv4l"
version: "1.0-5.2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/dv4lstart"
---

# dv4lstart(1)

redirect V4L API to access a camcorder from a V4L program

## 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 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)

## 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)](/dv4l/1.md)