Struct McapChannel 

pub struct McapChannel {
    pub id: Option<SerializedComponentBatch>,
    pub topic: Option<SerializedComponentBatch>,
    pub message_encoding: Option<SerializedComponentBatch>,
    pub metadata: Option<SerializedComponentBatch>,
}

Archetype: A channel within an MCAP file that defines how messages are structured and encoded.

Channels in MCAP files group messages by topic and define their encoding format. Each channel has a unique identifier and specifies the message schema and encoding used for all messages published to that topic.

See also archetypes::McapMessage for individual messages within a channel, archetypes::McapSchema for the data structure definitions, and the MCAP specification for complete format details.

⚠️ This type is unstable and may change significantly in a way that the data won’t be backwards compatible.

Fields

id: Option<SerializedComponentBatch>

Unique identifier for this channel within the MCAP file.

Channel IDs must be unique within a single MCAP file and are used to associate messages with their corresponding channel definition.

topic: Option<SerializedComponentBatch>

The topic name that this channel publishes to.

Topics are hierarchical paths from the original robotics system (e.g., “/sensors/camera/image”) that categorize and organize different data streams. Topics are separate from Rerun’s entity paths, but they often can be mapped to them.

message_encoding: Option<SerializedComponentBatch>

The encoding format used for messages in this channel.

Common encodings include:

• ros1 - ROS1 message format
• cdr - Common Data Representation (CDR) message format, used by ROS2
• protobuf - Protocol Buffers
• json - JSON encoding

metadata: Option<SerializedComponentBatch>

Additional metadata for this channel stored as key-value pairs.

This can include channel-specific configuration, description, units, coordinate frames, or any other contextual information that helps interpret the data in this channel.

Implementations

impl McapChannel

pub fn descriptor_id() -> ComponentDescriptor

Returns the ComponentDescriptor for Self::id.

The corresponding component is crate::components::ChannelId.

pub fn descriptor_topic() -> ComponentDescriptor

Returns the ComponentDescriptor for Self::topic.

The corresponding component is crate::components::Text.

pub fn descriptor_message_encoding() -> ComponentDescriptor

Returns the ComponentDescriptor for Self::message_encoding.

The corresponding component is crate::components::Text.

pub fn descriptor_metadata() -> ComponentDescriptor

Returns the ComponentDescriptor for Self::metadata.

The corresponding component is crate::components::KeyValuePairs.

impl McapChannel

pub const NUM_COMPONENTS: usize = 4usize

The total number of components in the archetype: 3 required, 0 recommended, 1 optional

impl McapChannel

pub fn new( id: impl Into<ChannelId>, topic: impl Into<Text>, message_encoding: impl Into<Text>, ) -> McapChannel

Create a new McapChannel.

pub fn update_fields() -> McapChannel

Update only some specific fields of a McapChannel.

pub fn clear_fields() -> McapChannel

Clear all the fields of a McapChannel.

pub fn columns<I>( self, _lengths: I, ) -> Result<impl Iterator<Item = SerializedComponentColumn>, SerializationError>

where I: IntoIterator<Item = usize> + Clone,

Partitions the component data into multiple sub-batches.

Specifically, this transforms the existing SerializedComponentBatches data into SerializedComponentColumns instead, via SerializedComponentBatch::partitioned.

This makes it possible to use RecordingStream::send_columns to send columnar data directly into Rerun.

The specified lengths must sum to the total length of the component batch.

pub fn columns_of_unit_batches( self, ) -> Result<impl Iterator<Item = SerializedComponentColumn>, SerializationError>

Helper to partition the component data into unit-length sub-batches.

This is semantically similar to calling Self::columns with std::iter::take(1).repeat(n), where n is automatically guessed.

pub fn with_id(self, id: impl Into<ChannelId>) -> McapChannel

Unique identifier for this channel within the MCAP file.

Channel IDs must be unique within a single MCAP file and are used to associate messages with their corresponding channel definition.

pub fn with_many_id( self, id: impl IntoIterator<Item = impl Into<ChannelId>>, ) -> McapChannel

This method makes it possible to pack multiple crate::components::ChannelId in a single component batch.

This only makes sense when used in conjunction with Self::columns. Self::with_id should be used when logging a single row’s worth of data.

pub fn with_topic(self, topic: impl Into<Text>) -> McapChannel

The topic name that this channel publishes to.

Topics are hierarchical paths from the original robotics system (e.g., “/sensors/camera/image”) that categorize and organize different data streams. Topics are separate from Rerun’s entity paths, but they often can be mapped to them.

pub fn with_many_topic( self, topic: impl IntoIterator<Item = impl Into<Text>>, ) -> McapChannel

This method makes it possible to pack multiple crate::components::Text in a single component batch.

This only makes sense when used in conjunction with Self::columns. Self::with_topic should be used when logging a single row’s worth of data.

pub fn with_message_encoding( self, message_encoding: impl Into<Text>, ) -> McapChannel

The encoding format used for messages in this channel.

Common encodings include:

• ros1 - ROS1 message format
• cdr - Common Data Representation (CDR) message format, used by ROS2
• protobuf - Protocol Buffers
• json - JSON encoding

pub fn with_many_message_encoding( self, message_encoding: impl IntoIterator<Item = impl Into<Text>>, ) -> McapChannel

This method makes it possible to pack multiple crate::components::Text in a single component batch.

This only makes sense when used in conjunction with Self::columns. Self::with_message_encoding should be used when logging a single row’s worth of data.

pub fn with_metadata(self, metadata: impl Into<KeyValuePairs>) -> McapChannel

Additional metadata for this channel stored as key-value pairs.

This can include channel-specific configuration, description, units, coordinate frames, or any other contextual information that helps interpret the data in this channel.

pub fn with_many_metadata( self, metadata: impl IntoIterator<Item = impl Into<KeyValuePairs>>, ) -> McapChannel

This method makes it possible to pack multiple crate::components::KeyValuePairs in a single component batch.

This only makes sense when used in conjunction with Self::columns. Self::with_metadata should be used when logging a single row’s worth of data.

Trait Implementations

impl Archetype for McapChannel

fn name() -> ArchetypeName

The fully-qualified name of this archetype, e.g. rerun.archetypes.Points2D.

fn display_name() -> &'static str

Readable name for displaying in UI.

fn required_components() -> Cow<'static, [ComponentDescriptor]>

Returns all component descriptors that must be provided by the user when constructing this archetype.

fn recommended_components() -> Cow<'static, [ComponentDescriptor]>

Returns all component descriptors that should be provided by the user when constructing this archetype.

fn optional_components() -> Cow<'static, [ComponentDescriptor]>

Returns all component descriptors that may be provided by the user when constructing this archetype.

fn all_components() -> Cow<'static, [ComponentDescriptor]>

Returns all component descriptors that must, should and may be provided by the user when constructing this archetype.

fn from_arrow_components( arrow_data: impl IntoIterator<Item = (ComponentDescriptor, Arc<dyn Array>)>, ) -> Result<McapChannel, DeserializationError>

Given an iterator of Arrow arrays and their respective ComponentDescriptors, deserializes them into this archetype.

fn all_component_identifiers() -> impl Iterator<Item = ComponentIdentifier>

Utility method based on Self::all_components to return all component identifiers.

fn from_arrow( data: impl IntoIterator<Item = (Field, Arc<dyn Array>)>, ) -> Result<Self, DeserializationError>

where Self: Sized,

Given an iterator of Arrow arrays and their respective field metadata, deserializes them into this archetype.

impl AsComponents for McapChannel

fn as_serialized_batches(&self) -> Vec<SerializedComponentBatch>

Exposes the object’s contents as a set of SerializedComponentBatches.

fn to_arrow(&self) -> Result<Vec<(Field, Arc<dyn Array>)>, SerializationError>

Serializes all non-null Components of this bundle into Arrow arrays.

impl Clone for McapChannel

fn clone(&self) -> McapChannel

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for McapChannel

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for McapChannel

fn default() -> McapChannel

Returns the “default value” for a type.

impl PartialEq for McapChannel

fn eq(&self, other: &McapChannel) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl SizeBytes for McapChannel

fn heap_size_bytes(&self) -> u64

Returns how many bytes self uses on the heap.

fn total_size_bytes(&self) -> u64

Returns the total size of self in bytes, accounting for both stack and heap space.

fn stack_size_bytes(&self) -> u64

Returns the total size of self on the stack, in bytes.

fn is_pod() -> bool

Is Self just plain old data?

impl ArchetypeReflectionMarker for McapChannel

impl StructuralPartialEq for McapChannel