mjpeg_cam

Overview

This package captures MJPEG video stream from usb cameras. Unlike the usb_cam package, this driver copies the JPEG data to the CompressedImage message directly. There is no extra overhead from decoding and re-encoding the image. So, only compressed images are published. This driver is suitable for applications where the images are captured by a low power device (e.g. the Raspberry Pi) and sent to a remote node for further processing.

Installation

Building from Source

Dependencies

• Robot Operating System (ROS) (middleware for robotics),
• libv4l-dev (for accessing the usb camera)

  sudo apt-get install libv4l-dev

• v4l-utils (for changing camera settings)

  sudo apt-get install v4l-utils

  Building

To build from source, clone the latest version from this repository into your catkin workspace and compile the package using catkin_make.

Usage

Run the main node with

roslaunch mjpeg_cam mjpeg_cam_run.launch

Nodes

mjpeg_cam

Captures video stream from a usb camera and publishes the images.

Published Topics

• image/compressed (sensor_msgs/CompressedImage, default: "/mjpeg_cam/image/compressed')

Parameters

• device_name (string, default: "/dev/video0")

  The name of the usb camera device.

• width (int, default: 640)

  The width of the image.

• height (int, default: 480)

  The height of the image.

• framerate (int, default: 30)

  The framerate of the video.

• exposure (int, default: 128)

  The exposure of the camera.

• brightness (int, default: 128)

  The brightness of the image.

• autoexposure (bool, default: true)

  Turns auto exposure on/off.

The exposure, brightness, and autoexposure settings are dynamically reconfigurable. Simply run rosrun rqt_reconfigure rqt_reconfigure and select the node name (default: "mjpeg_cam") to access these settings.