this is not the official repo of ros2_v4l2_camera, please goto the gitlab
in this repo, the camera node can publish shm_msgs::msg::Imagexm
based on ros2_shm_msgs
With shm_msgs msg types, zero copy(during the IPC communication period) can be achieved, and transport latency and cpu usage can be reduced.
You must select the msg type according the size of data, for example, shm_msgs::msg::Image1m
for the 640X480 RBG8
image transport.
This is because in most of ddses, the constraints of zero-copy transport is the bounded size of data.
the dds config files canbe checked in ros2_shm_msgs
for rmw_cyclonedds
export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp
export CYCLONEDDS_URI=file:https:///$HOME/shm_cyclonedds.xml
# t0
iox-roudi
for rmw_fastrtps_cpp
export RMW_IMPLEMENTATION=rmw_fastrtps_cpp
export FASTRTPS_DEFAULT_PROFILES_FILE=$HOME/shm_fastdds.xml
export RMW_FASTRTPS_USE_QOS_FROM_XML=1
cd src
git clone https://github.com/ZhenshengLee/ros2_shm_msgs.git
# the added work of zero-copy support is hosted in the `outdoor/rolling` branch.
git clone -b outdoor/rolling https://github.com/ZhenshengLee/ros2_v4l2_camera.git
colcon build
driver(after a camera pluged in, in my case that's a logitech525 usbcam)
ros2 run v4l2_camera v4l2_camera_shm1m_node --ros-args --log-level info
# ros2 run v4l2_camera v4l2_camera_shm1m_node --ros-args --log-level debug
image1m_subscriber
cd install/v4l2_camera/lib/v4l2_camera
./v4l2_camera_image1m_subscriber
[INFO] [1654154565.559710174] [shm_image1m_subscriber]: Received...
[INFO] [1654154565.559730953] [shm_image1m_subscriber]: get-image1m-transport-time: 0.253
image1m_rviz_bridge
# config topic remapping
ros2 launch v4l2_camera shm_image1m_bridge.launch.py
rviz2
rviz2
# add topic of image
run normal(basically shm) image tranport
# t1
ros2 run v4l2_camera v4l2_camera_node --ros-args --log-level info
# ros2 run v4l2_camera v4l2_camera_node --ros-args --log-level debug
# t2
cd install/v4l2_camera/lib/v4l2_camera
./v4l2_camera_image_subscriber
in my pc of dell 3630, the zero-copy transport of a shm_msgs::msg::Image1m can save about 80% of transport time, from 1.4ms to 0.3ms
A ROS 2 camera driver using Video4Linux2 (V4L2).
- Lists and exposes all user-settable controls of your camera as ROS 2 parameters.
- Uses
cv_bridge
to convert raw frames to ROS 2 messages, so supports a wide range of encoding conversions. - Supports
image_transport
to enable compression. - Supports composing the camera node and using ROS 2 intra-process commmunication with zero-copy messaging.
This article details how to build and run this package. It focuses on Raspberry Pi OS with the Raspberry Pi Camera Module V2 but should generalise for most systems.
This package is available from the ROS package repositories and can therefore be installed with the following command and your ROS version name:
sudo apt-get install ros-${ROS_DISTRO}-v4l2-camera
If you need to modify the code or ensure that you have the latest updates you will need to clone this repository, and then build the package.
git clone --branch ${ROS_DISTRO} https://gitlab.com/boldhearts/ros2_v4l2_camera.git src/v4l2_camera
rosdep install --from-paths src/v4l2_camera --ignore-src -r -y
colcon build
Most users will also want to set up compressed transport using the dependencies below.
Run the camera node to publish camera images, using the default parameters:
ros2 run v4l2_camera v4l2_camera_node
You can use rqt-image-view
to preview the images (open another terminal):
sudo apt-get install ros-${ROS_DISTRO}-rqt-image-view
ros2 run rqt_image_view rqt_image_view
See further below for information about enabling compression.
The v4l2_camera_node
interfaces with standard V4L2 devices and
publishes images as sensor_msgs/Image
messages.
-
/image_raw
-sensor_msgs/Image
The image.
-
video_device
-string
, default:"/dev/video0"
The device the camera is on.
-
pixel_format
-string
, default:"YUYV"
The pixel format to request from the camera. Must be a valid four character 'FOURCC' code supported by V4L2 and by your camera. The node outputs the available formats supported by your camera when started. Currently supported:
"YUYV"
or"GREY"
-
output_encoding
-string
, default:"rgb8"
The encoding to use for the output image. Can be any supported by
cv_bridge
given the input pixel format. Currently these are for"YUYV"
:" yuv422_yuy2"
(no conversion), or"mono8"
,"rgb8"
,"bgr8"
,"rgba8"
and"bgra8"
, plus their 16 bit variants, and for"GREY"
these are"mono8"
(no conversion),"rgb8"
,"bgr8"
,"rgba8"
and"bgra8"
, plus their 16 bit variants. -
image_size
-integer_array
, default:[640, 480]
Width and height of the image.
-
Camera Control Parameters
Camera controls, such as brightness, contrast, white balance, etc, are automatically made available as parameters. The driver node enumerates all controls, and creates a parameter for each, with the corresponding value type. The parameter name is derived from the control name reported by the camera driver, made lower case, commas removed, and spaces replaced by underscores. So
Brightness
becomesbrightness
, andWhite Balance, Automatic
becomeswhite_balance_automatic
.
This package uses image_transport
to publish images and make
compression possible. However, by default it only supports raw
transfer, plugins are required to enable compression. These need to be
installed separately:
sudo apt-get install ros-${ROS_DISTRO}-image-transport-plugins
Once installed, they will be automatically used by the driver and
additional topics will be available, including
/image_raw/compressed
.