Video Viewer

This provides a simple alternative to visualize videos on the ROS2 network, since the QoS settings and the compression settings are important and seemingly cant be set in the native tools like rqt_image_view.

Installation

You need access to the following libraries:

  image-transport
  compressed-image-transport
  theora-image-transport      [OPTIONAL]
  OpenCV

Note, the image_transport libraries must also be installed on the computer publishing the images. OpenCV is not requried on the publisher side.

Eg.

sudo apt-get update && sudo apt-get install \
  ros-${ROS_DISTRO}-image-transport \
  ros-${ROS_DISTRO}-compressed-image-transport \
  ros-${ROS_DISTRO}-theora-image-transport

Clone this repo to your colcon_ws and just build it:

colcon build

Usage

ros2 run video_view video_viewer_node  --ros-args -p image_topic:=/camera/color/image_raw

Don't forget to set the image_topic and source your workspace!

A GUI will pop up and it will show you the video stream. To exit, press ESC or q.

You can also run it as a composable node, using the component video_view::VideoViewer

Parameters:

• image_topic: base name of the image topic to subscribe to
  • Default: image
  • Example -p image_topic:=/camera/color/image_raw
• qos: Quality of service
  • Choose from SYSTEM_DEFAULT, DEFAULT, PARAMETER_EVENTS, SERVICES_DEFAULT, PARAMETERS, SENSOR_DATA
  • Default: SENSOR_DATA
  • Example: -p qos:=SENSOR_DATA
• rotate: rotate the image
  • Choose from rotate_0, rotate_90, rotate_180, rotate_270
  • Default: rotate_0
  • Example: -p rotate:=rotate_180
• image_transport: method for the image transport
  • Choose from raw, compressed, theora
  • Default: compressed
  • Example: -p image_transport:=theora
  • Theora reduces the images the most, and is best for video streams.

Troubleshooting

If you see the error message

[WARN] [1689224185.637869370] [TheoraSubscriber]: [theora] Packet was not a Theora header

it is because the image transport was started before this node was launched. You need to restart the source image stream. If using a realsense camera, it is as simple as running

ros2 param set camera/camera enable_color False
ros2 param set camera/camera enable_color True

I've noticed that this needs to be run on the local device that has the realsense node running.