API reference

MCAP libraries are available for C++, Go, Python, Rust, Swift, and TypeScript. All libraries are tested for conformance with the MCAP specification.

Feature Matrix

	C++	Go	Python	Rust	Swift	TypeScript
Indexed unordered message reading	Yes	Yes	Yes	Yes	No	Yes
Timestamp-ordered message reading	Yes	Yes	Yes	No	Yes	Yes
Indexed metadata reading	Yes 1	Yes 1	Yes	Yes	Yes 1	Yes 1
Indexed attachment reading	Yes 1	Yes 1	Yes	Yes	Yes 1	Yes 1
Non-materialized attachment reading	Yes 2	No	No	Yes	No	No
Non-indexed reading	Yes	Yes	Yes	Yes	Yes	Yes
CRC validation	No	Yes	No	Yes	Yes	Yes
ROS1 wrapper	No	No	Yes	No	No	No
ROS2 wrapper	Yes 3	No	Yes 3	No	No	No
Protobuf wrapper	No	No	Yes	No	No	No
Record writing	Yes	Yes	Yes	Yes	Yes	Yes
Easy chunked writing	Yes	Yes	Yes	Yes	Yes	Yes
Automatic summary writing	Yes 4	Yes 4	Yes 4	Yes4	Yes 4	Yes 4

 ¹ These readers don’t have a single call to read an attachment or metadata record by name, but do allow you to read the summary, seek to that location, read a record and parse it.
 ² The C++ reader interface does not preclude one from backing it with a memory-mapped file. This could be used to implement message and attachment parsing without copying data into memory.
 ³ Using the MCAP Rosbag2 storage plugin.
 ⁴ All writers currently do not compute a CRC for the DataEnd record.