rosbag_timing_inspector

A GUI tool to visualize and analyze message timing from ROS 2 bags (.mcap or .db3).

Built with Dear ImGui + ImPlot. No message deserialization is performed – only timestamps and topic names are read, so it opens even bags with custom or unavailable message types.

Features

• Timeline tab: zoomable 2D scatter plot – X = time, Y = topic lane. Each dot is one message. Pan/zoom with mouse. Toggle per-topic visibility and color. Measure mode: click twice to place two vertical markers and read the delta-T.
• Histograms / Stats tab: per-topic inter-message interval histogram and a statistics table (count, mean, std, min, max in ms).

Dependencies

System packages (Ubuntu / ROS 2 Jazzy):

sudo apt install libglfw3-dev

ROS 2 packages resolved automatically by rosdep:

• rosbag2_cpp
• rosbag2_storage
• rosbag2_storage_mcap
• rosbag2_storage_sqlite3

Third-party libraries (imgui, implot, tinyfiledialogs) are fetched automatically by CMake via FetchContent at build time – no manual installation needed.

Build

cd ~/ros2_ws

# Install ROS 2 dependencies
rosdep install --from-paths src/rosbag_timing_inspector --ignore-src -r -y

# Build (release build recommended for large bags)
colcon build --packages-select rosbag_timing_inspector \
             --cmake-args -DCMAKE_BUILD_TYPE=Release

Launch

source ~/ros2_ws/install/setup.bash

# Pass a bag path directly:
rosbag_timing_inspector /path/to/recording.mcap
rosbag_timing_inspector /path/to/recording.db3

# Or open without arguments and use File > Open bag...:
rosbag_timing_inspector

Usage tips

License

MIT – Copyright (C) 2026 Jose Luis Blanco Claraco