Frequency drop while running driver with pcap

[Muhammed Yavuz Köseoğlu]

• OS and Version: [e.g. Ubuntu 20.04]
• ROS Version: [e.g. Noetic]
• Built from Source or Downloaded from Official Repository:
• Version: [#510]

While getting ros message from pcap file frequency is fluctuating around between 7.5hz and 9hz. In my case even if frequency dropped but it stayed stable it can be tolerated.

To reproduce the behavior i am sharing my VLP16_points.launch:

<!-- -*- mode: XML -*- -->
<!-- run velodyne_pointcloud/TransformNodelet in a nodelet manager for a VLP-16 -->

<launch>

  <!-- declare arguments with default values -->
  <arg name="calibration" default="$(find velodyne_pointcloud)/params/VLP16db.yaml"/>
  <arg name="device_ip" default="" />
  <arg name="frame_id" default="velodyne" />
  <arg name="manager" default="$(arg frame_id)_nodelet_manager" />
  <arg name="max_range" default="130.0" />
  <arg name="min_range" default="0.4" />
  <arg name="pcap" default="/home/yavz-20-vm/ExtremeSSD/yavz/ytu_map_2_08_04_23.pcap" />
  <arg name="port" default="2368" />
  <arg name="read_fast" default="false" />
  <arg name="read_once" default="true" />
  <arg name="repeat_delay" default="0.0" />
  <arg name="rpm" default="600.0" />
  <arg name="gps_time" default="false" />
  <arg name="pcap_time" default="true" />
  <arg name="cut_angle" default="-0.01" />
  <arg name="timestamp_first_packet" default="false" />
  <arg name="laserscan_ring" default="-1" />
  <arg name="laserscan_resolution" default="0.007" />
  <arg name="organize_cloud" default="false" />

  <!-- start nodelet manager and driver nodelets -->
  <include file="$(find velodyne_driver)/launch/nodelet_manager.launch">
    <arg name="device_ip" value="$(arg device_ip)"/>
    <arg name="frame_id" value="$(arg frame_id)"/>
    <arg name="manager" value="$(arg manager)" />
    <arg name="model" value="VLP16"/>
    <arg name="pcap" value="$(arg pcap)"/>
    <arg name="port" value="$(arg port)"/>
    <arg name="read_fast" value="$(arg read_fast)"/>
    <arg name="read_once" value="$(arg read_once)"/>
    <arg name="repeat_delay" value="$(arg repeat_delay)"/>
    <arg name="rpm" value="$(arg rpm)"/>
    <arg name="gps_time" value="$(arg gps_time)"/>
    <arg name="pcap_time" value="$(arg pcap_time)"/>
    <arg name="cut_angle" value="$(arg cut_angle)"/>
    <arg name="timestamp_first_packet" value="$(arg timestamp_first_packet)"/>
  </include>

  <!-- start transform nodelet -->
  <include file="$(find velodyne_pointcloud)/launch/transform_nodelet.launch">
    <arg name="model" value="VLP16"/>
    <arg name="calibration" value="$(arg calibration)"/>
    <arg name="manager" value="$(arg manager)" />
    <arg name="fixed_frame" value="" />
    <arg name="target_frame" value="" />
    <arg name="max_range" value="$(arg max_range)"/>
    <arg name="min_range" value="$(arg min_range)"/>
    <arg name="organize_cloud" value="$(arg organize_cloud)"/>
  </include>

  <!-- start laserscan nodelet -->
  <include file="$(find velodyne_pointcloud)/launch/laserscan_nodelet.launch">
    <arg name="manager" value="$(arg manager)" />
    <arg name="ring" value="$(arg laserscan_ring)"/>
    <arg name="resolution" value="$(arg laserscan_resolution)"/>
  </include>

</launch>

It is expected to hz of /velodyne_points topic to be 10hz and stable.

[Joshua Whitley]

There are many issues on a system that can cause this including disk utilization and CPU utilization. Can you please make sure you are running this with no other nodes running and possibly provide the bag file?

[Muhammed Yavuz Köseoğlu]

Sorry for my late response, i had gotten over the problem with playing pcap on udpreplay.