ROS video streaming

Video streaming ROS package based on Video4Linux API (ver. 2) which is originally developed for the Servosila Engineer mobile robot.

It is written in C++17 and provides clear API.

Prerequisites

• Ubuntu 16.04 (Xenial)
• ROS Kinetic
• OpenCV 3 (comes with ROS)
• GNU GCC (with C++17 support)
• Video4Linux2 API

Installation

Video4Linux2

Install v4l-utils apt package:

sudo apt-get install v4l-utils

ROS Kinetic

Manually or using ansible playbook.

Getting Started

To download the latest available release, clone the repository into your catkin workspace (e.g. ~/catkin_ws):

cd ~/catkin_ws/src && git clone https://github.com/ramsafin/ros-video-streaming.git

Build ROS package:

cd ~/catkin_ws && catkin_make --pkg ros_video_streaming

Run tests (Note! Change parameters in launch file):

rostest ros_video_streaming cameraHz.test

Example (launch file)

The following ROS launch file will start ROS master node along with video_streamer node.

<launch>
  
  <!-- start video streaming node -->
  <include file="$(find ros_video_streaming)/launch/camera.launch">
    
    <!-- ROS node name -->
    <arg name="camera_name" value="camera"/>
    
    <arg name="frame_id" value="$(arg camera_name)"/>

    <!-- video device -->
    <arg name="device_name" value="/dev/video0"/>
    
    <!-- frame resolution -->
    <arg name="width" value="640"/>
    <arg name="height" value="480"/>

    <!-- frame rate -->
    <arg name="fps" value="30"/>
    
    <!-- ROS image format (as defined in sensor_msgs/image_encodings.h -->
    <arg name="image_format" value="yuv422"/>

    <!-- camera info -->
    <arg name="camera_info_url" value="file:///$(find ros_video_streaming)/calibration/camera.yaml"/>

    <!-- whether to start image_view node (visualization) -->
    <arg name="image_view_enabled" value="false"/>
    
    <!-- image_view topic, e.g. 'rosrun image_view image_view image:=/camera/image_raw' -->
    <arg name="image_view_topic" value="image_raw"/>

    <!-- image_proc node -->
    <arg name="image_proc_enabled" default="false"/>
  
  </include>
  
</launch>

Limitations and Issues

• YUV422 image format in ROS Kinetic represents UYVY (other formats does not supported, e.g. YUYV). In this case frames are converted into grayscale format, as it is computationally less demanded compared to the conversion into an RGB.

• No synchronization between multiple cameras (e.g. in case of stereo systems).

• Published frames timestamp is represented by ROS Time (not native driver's timestamp).

• Captured frames are not queued and potentially can be lost during streaming.

Paper

R. Safin, and R. Lavrenov "Implementation of ROS Package for Simultaneous Video Streaming from Several Different Cameras"

The 2018 International Conference on Artificial Life and Robotics (ICAROB 2018)At: B-Con Plaza, Beppu, Oita, Japan.