ROS2 – Recording formats

Available Formats

MCAP (Modern Capture Format)

• Newer format designed to be a high-performance alternative to rosbag2.
• More efficient in terms of storage and playback speed.
• Cross-platform & language support (C++, Python, Rust, Go, etc.).
• Better compression support (Zstandard, LZ4, and others).
• Designed for large datasets and works well with sensors like LiDAR, cameras, and IMUs.
• Faster indexing and seeking, improving playback efficiency.

ROSBAG (ROS 1 & ROS 2)

• Originally designed for ROS 1 and adapted for ROS 2.
• Uses SQLite or other storage backends in ROS 2.
• Slower when handling large datasets compared to MCAP.
• Compression support, but not as efficient as MCAP.
• Limited indexing & metadata support, which can slow down seeking.

Which One Should You Use?

• If you are using ROS 2, MCAP is the preferred format because of its speed, efficiency, and better compression.
• If you are working with older ROS 1 systems, you might still need to use rosbag.

How to use MCAP in ROS2?

ROS 2 supports MCAP as a storage backend for ros2 bag. To record using MCAP:

ros2 bag record -a --storage mcap

To play it back:

ros2 bag play