---
title: "McapChannel"
---
<!-- DO NOT EDIT! This file was auto-generated by crates/build/re_types_builder/src/codegen/docs/website.rs -->

⚠️ **This type is _unstable_ and may change significantly in a way that the data won't be backwards compatible.**
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`](https://rerun.io/docs/reference/types/archetypes/mcap_message) for individual messages within a channel,
[`archetypes.McapSchema`](https://rerun.io/docs/reference/types/archetypes/mcap_schema) for the data structure definitions, and the
[MCAP specification](https://mcap.dev/) for complete format details.

## Fields
### Required
* `id`: [`ChannelId`](../components/channel_id.md)
* `topic`: [`Text`](../components/text.md)
* `message_encoding`: [`Text`](../components/text.md)

### Optional
* `metadata`: [`KeyValuePairs`](../components/key_value_pairs.md)


## Can be shown in
* [DataframeView](../views/dataframe_view.md)

## API reference links
 * 🌊 [C++ API docs for `McapChannel`](https://ref.rerun.io/docs/cpp/stable/structrerun_1_1archetypes_1_1McapChannel.html)
 * 🐍 [Python API docs for `McapChannel`](https://ref.rerun.io/docs/python/stable/common/archetypes#rerun.archetypes.McapChannel)
 * 🦀 [Rust API docs for `McapChannel`](https://docs.rs/rerun/latest/rerun/archetypes/struct.McapChannel.html)

## Example

### Simple MCAP channel

snippet: archetypes/mcap_channel_simple

