rosbags.rosbag1

Rosbags support for rosbag1 files.

Readers and writers provide access to metadata and raw message content saved in the rosbag1 format.

Supported versions:

Rosbag1 v2.0

class rosbags.rosbag1.Reader(path)

Bases: object

Rosbag 1 version 2.0 reader.

This class is designed for a ROS2 world, it will automatically normalize message type names to be in line with their ROS2 counterparts.

Parameters:: path (str | Path)

close()

Close rosbag.

Return type:: None

property duration: int: Duration in nanoseconds between earliest and latest messages.

property end_time: int: Timestamp in nanoseconds after the latest message.

property message_count: int: Total message count.

messages(connections=(), start=None, stop=None)

Read messages from bag.

Parameters:

connections (Iterable[Connection]) – Iterable with connections to filter for. An empty iterable disables filtering on connections.
start (int | None) – Yield only messages at or after this timestamp (ns).
stop (int | None) – Yield only messages before this timestamp (ns).

Yields:

Tuples of connection, timestamp (ns), and rawdata.

Raises:

ReaderError – Bag not open or data corrupt.

Return type:

Generator[tuple[Connection, int, bytes], None, None]

open()

Open rosbag and read metadata.

Return type:: None

read_chunk()

Read chunk record header from current position.

Return type:: Chunk

read_chunk_info()

Read chunk info record from current position.

Return type:: ChunkInfo

read_connection()

Read connection record from current position.

Return type:: Connection

read_index_data(pos, indexes)

Read index data from position.

The implementation purposely avoids the generic Header class and its costly string processing.

Parameters:

pos (int) – Seek position.
indexes (dict[int, list[IndexData]]) – Accumulated index data.

Raises:

ReaderError – Record unreadable.

Return type:

None

property start_time: int: Timestamp in nanoseconds of the earliest message.

property topics: dict[str, TopicInfo]: Topic information.

exception rosbags.rosbag1.ReaderError

Bases: Exception

Reader Error.

class rosbags.rosbag1.Writer(path)

Bases: object

Rosbag1 writer.

This class implements writing of rosbag1 files in version 2.0. It should be used as a contextmanager.

Parameters:: path (Path | str)

class CompressionFormat(value, names=<not given>, *values, module=None, qualname=None, type=None, start=1, boundary=None)

Bases: IntEnum

Compession formats.

add_connection(topic, msgtype, *, typestore=None, msgdef=None, md5sum=None, callerid=None, latching=None)

Add a connection.

This function can only be called after opening a bag.

Parameters:

topic (str) – Topic name.
msgtype (str) – Message type.
typestore (Typestore | None) – Typestore.
msgdef (str | None) – Message definiton.
md5sum (str | None) – Message hash.
callerid (str | None) – Caller id.
latching (int | None) – Latching information.

Return type:

Connection

Returns:

Connection id.

Raises:

WriterError – Bag not open or identical topic previously registered.

close()

Close rosbag1 after writing.

Closes open chunks and writes index.

Return type:: None

open()

Open rosbag1 for writing.

Return type:: None

set_compression(fmt)

Enable compression on rosbag1.

This function has to be called before opening.

Parameters:: fmt (CompressionFormat) – Compressor to use, bz2 or lz4
Raises:: WriterError – Bag already open.
Return type:: None

write(connection, timestamp, data)

Write message to rosbag1.

Parameters:

connection (Connection) – Connection to write message to.
timestamp (int) – Message timestamp (ns).
data (bytes | memoryview) – Serialized message data.

Raises:

WriterError – Bag not open or connection not registered.

Return type:

None

write_chunk(chunk)

Write open chunk to file.

Return type:: None
Parameters:: chunk (WriteChunk)

static write_connection(connection, bio)

Write connection record.

Return type:

None

Parameters:

connection (Connection)
bio (BinaryIO)

exception rosbags.rosbag1.WriterError

Bases: Exception

Writer Error.