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MCAP is a modular container format and logging library for pub/sub messages with arbitrary message serialization. It is primarily intended for use in robotics applications, and works well under various workloads, resource constraints, and durability requirements.

• File format specification
  • Kaitai Struct definition
• Motivation
• Support Matrix

MCAP libraries are provided in the following languages. For guidance on each language, see its corresponding README:

Language	Readme	API docs	Package name	Version
C++	readme	API docs	mcap
Go	readme	API docs		seereleases
Python	readme	API docs	mcap
JavaScript/TypeScript	readme	API docs	@mcap/core
Swift	readme	API docs		seereleases
Rust	readme	API docs	mcap

To run the conformance tests, you will need to useGit LFS,which is used to store the test logs undertests/conformance/data.

Inspect, merge, and split MCAP files from the command line using the MCAP CLI.

Install withbrew install mcap or download the latest version directly from thereleases page.

MIT License.

Release numbering follows a major.minor.patch format, abbreviated as "X.Y.Z" below.

CI will build the appropriate packages once tags are pushed, as described below.

1. Update theVersion in go/mcap/version.go
2. Tag a release matching the version numbergo/mcap/vX.Y.Z.

Tag a release matchingreleases/mcap-cli/vX.Y.Z.

The version number is set at build time based on the tag.

1. Update the version in all relevant files
   • cpp/bench/conanfile.py
   • cpp/build-docs.sh
   • cpp/build.sh
   • cpp/docs/conanfile.py
   • cpp/examples/conanfile.py
   • cpp/mcap/include/mcap/types.hpp (MCAP_LIBRARY_VERSION)
   • cpp/mcap/include/conanfile.py
   • cpp/test/conanfile.py
2. Tag a release matching the version numberreleases/cpp/vX.Y.Z

There are several python packages; updating any follows a similar process.

1. Update the version in the appropriate__init.py__ file
2. Tag a release
   • For the core mcap library, match the patternreleases/python/vX.Y.Z
   • For other packages, usereleases/python/PACKAGE/vX.Y.Z
     • For example,releases/python/mcap/v1.2.3

There are several TS packages; updating any follows a similar process.

1. Update the version in the appropriatepackage.json
2. Tag a release matchingreleases/typescript/PACKAGE/vX.Y.Z
   • For example,releases/typescript/core/v1.2.3

Tag a release matching the version numberreleases/swift/vX.Y.Z

1. Update the version in rust/Cargo.toml
2. Tag a release matching the version numberreleases/rust/vX.Y.Z

If you use MCAP in your research, please cite it in your work. Our suggestedcitation format is:

@software{MCAP,  title = {MCAP: serialization-agnostic log container file format},  author = {{Foxglove Developers}},  url = {https://mcap.dev},  version = {your version},  date = {your date of access},  year = {2024},  publisher = {{Foxglove Technologies}},  note = {Available from https://github.com/foxglove/mcap}}

Please replace the version and date fields with the version of the software youused, and the date you obtained it. Citing MCAP will help spread awareness ofthe project and strengthen the ecosystem.