Getting Started

@elata-biosciences/biosignal-session is not published to npm yet. The API below reflects the source in the SDK repository and may change before the first release.

What it does

@elata-biosciences/biosignal-session records a biosignal session (EEG, PPG, rPPG metrics, and more) as a set of typed streams, chunked into self-contained Apache Arrow files. Recording is local-only: the package has no network client. It is built for reliability:

every chunk carries a CRC32C checksum and an idempotent (session, stream, sequence) identity
the recorder retries, applies backpressure, and never drops data silently
real gaps are recorded as explicit discontinuities, never interpolated

The model

Session ─┬─ Source   (headset, camera, synthetic)
         ├─ Stream   (eeg, ppg, optics, imu, rppg-metrics, ppg-metrics, …)
         │    └─ Chunk  (Arrow IPC file + CRC32C, sequence 0, 1, 2, …)
         └─ Event    (markers and annotations)

Time is session-relative integer microseconds, anchored once when the session starts.

Roles

A recording has two sides that talk over a MessagePort:

Side	Responsibility	Provided by this package
Recorder (your app)	Buffers samples, closes chunks, encodes Arrow, checksums, retries	Yes: `RecorderCore`, device adapters, a worker launcher
Host (trusted embedder)	Stores chunks durably and acknowledges each one	A reference in-memory host for tests (`createMemoryHost`)

Elata doesn’t host session recording yet. Today, use the package in your own host page, or with the in-memory host for development and tests.

Install

# Not on npm yet. This command works after the first release.
npm install @elata-biosciences/biosignal-session

Import	Contents
`@elata-biosciences/biosignal-session`	Contracts, protocol types, error codes, time helpers, CRC32C
`@elata-biosciences/biosignal-session/browser`	`RecorderCore`, handshake, Arrow encode/decode, device adapters, worker launcher
`@elata-biosciences/biosignal-session/testing`	Synthetic source, in-memory host, fake clock, recorder harness

Device adapters

Wrap the SDK objects you already use as recording sources:

createHeadbandSource(transport): a HeadbandTransport from eeg-web / eeg-web-ble
createRppgSource(options): an rppg-web session
createPpgSource(options): ppg-web metrics

Try it without hardware

The testing entry runs a full recording against an in-memory host with a seeded synthetic source. Hours of virtual signal run in seconds:

import {
  createRecorderHarness,
  createSyntheticSource,
} from '@elata-biosciences/biosignal-session/testing';

const h = createRecorderHarness();
const source = createSyntheticSource({ seed: 1234 });

await h.start();
await h.startSource(source);
source.pump(60_000);          // 60 s of synthetic EEG, rPPG, and PPG
await h.advance(60_000);
await source.stop();
await h.finalize();

h.core.state();               // "complete"

Read chunks back

Every chunk is a complete Arrow IPC file that carries its own schema and identity, so you can decode one on its own, in JavaScript or in Python with pyarrow:

import { decodeChunk, readFloat32Column } from '@elata-biosciences/biosignal-session/browser';

const { table, identity } = decodeChunk(bytes);
const tp9 = readFloat32Column(table, 'TP9');

Full guide

The step-by-step recording flow (clock anchor, handshake, opening streams, pushing samples, finalizing) and the host’s guarantees are in the recording guide. AI tools can read node_modules/@elata-biosciences/biosignal-session/llms.txt. To analyze what you record, see biosignal-analytics.

Overview

EEG Web SDK

EEG BLE Web SDK

Camera Web SDK

PPG Web SDK

Sessions and Analytics

Operations

Contributors

What it does

The model

Roles

Install

Device adapters

Try it without hardware

Read chunks back

Full guide

​What it does

​The model

​Roles

​Install

​Device adapters

​Try it without hardware

​Read chunks back

​Full guide

What it does

The model

Roles

Install

Device adapters

Try it without hardware

Read chunks back

Full guide