@mcap/support

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.

The @mcap/support package provides utilities for working with MCAP files that use well-known compression formats, from Node.js and browsers.

Usage examples

$3

``ts
import { loadDecompressHandlers } from "@mcap/support";
import { BlobReadable } from "@mcap/browser";
import { McapIndexedReader } from "@mcap/core";

/**
* For , listen for "change" events.
*
* For drag & drop, listen for "drop" events. (Note that you must also listen for "dragover" events
* and call event.preventDefault(), to enable listening for drop events.)
*/
async function onChangeOrDrop(event: Event) {
let file: File | undefined;
if (event instanceof DragEvent) {
file = event.dataTransfer?.files[0];
event.preventDefault();
} else if (event.target instanceof HTMLInputElement) {
file = event.target.files?.[0];
} else {
throw new Error(Unexpected event type: ${event.type});
}
if (!file) {
throw new Error("No file selected");
}
const decompressHandlers = await loadDecompressHandlers();
const reader = await McapIndexedReader.Initialize({
readable: new BlobReadable(file),
decompressHandlers,
});
}
`

$3

`ts
import { loadDecompressHandlers } from "@mcap/support";
import { FileHandleReadable } from "@mcap/nodejs";
import { McapIndexedReader } from "@mcap/core";
import { open } from "fs/promises";

const decompressHandlers = await loadDecompressHandlers();
const fileHandle = await open("file.mcap", "r");
const reader = await McapIndexedReader.Initialize({
readable: new FileHandleReadable(fileHandle),
decompressHandlers,
});
`

License

@mcap/support` is licensed under the MIT License.

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