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5.2.3 Image Encoding and Decoding

Overview​

The image encoding and decoding functionality is similar to the ROS image_transport package. RDK uses hardware units to accelerate conversion between MJPEG/H264/H265 and BGR8/RGB8/NV12 formats, which can significantly reduce CPU usage while improving format conversion efficiency. The X86 platform only supports conversion between MJPEG and BGR8/RGB8/NV12 formats.

Code repository: (https://github.com/D-Robotics/hobot_codec)

Supported Platforms​

PlatformRuntime EnvironmentExample Function
RDK X3, RDK X3 ModuleUbuntu 20.04 (Foxy), Ubuntu 22.04 (Humble)Start MIPI camera to capture images, encode them, and display via Web
RDK X5, RDK X5 Module, RDK S100Ubuntu 22.04 (Humble)Start MIPI camera to capture images, encode them, and display via Web
RDK S600Ubuntu 24.04 (Jazzy)Start MIPI camera to capture images, encode them, and display via Web
X86Ubuntu 20.04 (Foxy)Use the image publisher tool to publish YUV images, encode them, and display via Web

Prerequisites​

RDK Platform​

  1. RDK has been flashed with the Ubuntu system image.

  2. TogetheROS.Bot has been successfully installed on RDK.

  3. RDK is connected to an F37 or other MIPI camera.

X86 Platform​

  1. The X86 environment is configured with Ubuntu 20.04 system image.

  2. The X86 version of tros.b has been installed.

Usage​

The following uses JPEG encoding as an example to describe obtaining NV12 format image data from a camera or image publisher tool, compressing and encoding it as JPEG, and previewing the image on a PC web browser.

RDK Platform​

  1. Obtain YUV data and start JPEG encoding:

    Log in to RDK via SSH, use mipi_cam as the data source, configure hobot_codec input as NV12 format and output as JPEG format. You can change mipi_cam to the actual sensor model in use.

    a. Start mipi_cam

    # Configure tros.b environment
    source /opt/tros/setup.bash
    ros2 launch mipi_cam mipi_cam.launch.py mipi_video_device:=F37

    b. Start hobot_codec encoding

    # Configure tros.b environment
    source /opt/tros/setup.bash
    ros2 launch hobot_codec hobot_codec_encode.launch.py codec_in_mode:=shared_mem codec_in_format:=nv12 codec_out_mode:=ros codec_out_format:=jpeg codec_sub_topic:=/hbmem_img codec_pub_topic:=/image_jpeg

  2. View JPEG encoded images on the web. Open another terminal:

    # Configure tros.b environment
    source /opt/tros/setup.bash
    ros2 launch websocket websocket.launch.py websocket_image_topic:=/image_jpeg websocket_only_show_image:=true

  3. Open a browser on the PC (Chrome/Firefox/Edge) and enter http://IP:8000, where IP is the RDK/X86 device IP address. Click Web Display in the upper left to view the real-time JPEG encoded feed.

    web-f37-codec

X86 Platform​

  1. Obtain YUV data and start JPEG encoding:

    a. Start the image publisher node

    # Configure tros.b environment
    source /opt/tros/setup.bash
    // Copy the image files required for the example from the tros.b installation path
    cp -r /opt/tros/${TROS_DISTRO}/lib/hobot_image_publisher/config/ .

    // Start the image publisher node

    ros2 launch hobot_image_publisher hobot_image_publisher.launch.py publish_output_image_w:=960 publish_output_image_h:=544 publish_message_topic_name:=/hbmem_img publish_fps:=20

    b. Start JPEG image encoding and publishing pkg

    # Configure tros.b environment
    source /opt/tros/setup.bash
    ros2 launch hobot_codec hobot_codec.launch.py codec_in_mode:=shared_mem codec_in_format:=nv12 codec_out_mode:=ros codec_out_format:=jpeg codec_sub_topic:=/hbmem_img codec_pub_topic:=/image_jpeg

  2. View JPEG encoded images on the web. Open another terminal:

    # Configure tros.b environment
    source /opt/tros/setup.bash
    ros2 launch websocket websocket.launch.py websocket_image_topic:=/image_jpeg websocket_only_show_image:=true

  3. Open a browser on the PC (Chrome/Firefox/Edge) and enter http://IP:8000, where IP is the RDK/X86 device IP address. Click Web Display in the upper left to view the real-time JPEG encoded feed.

Notes​

If the Hobot codec node fails to start, troubleshoot using the following steps:

  1. Check whether the tros.b environment is configured
  2. Verify parameters are correct. For details, refer to the Hobot_codec README.md
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