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node-labstreaminglayer

Node.js bindings for Lab Streaming Layer (LSL) - A system for unified collection of measurement time series in research experiments.

Features

  • 🚀 High-performance FFI bindings using Koffi
  • 📊 Support for all LSL data types (float32, double64, string, int32, int16, int8, int64)
  • 🔄 Real-time streaming with sub-millisecond precision
  • 🔍 Stream discovery and resolution
  • 📝 Full metadata support via XML
  • 💻 Cross-platform support (Windows, macOS, Linux)
  • 📦 TypeScript support with full type definitions
  • 🧵 Thread-safe operations

Installation

npm install node-labstreaminglayer

Quick Start

Sending Data

import { StreamInfo, StreamOutlet } from 'node-labstreaminglayer';

// Create stream info
const info = new StreamInfo('MyStream', 'EEG', 8, 100, 'float32', 'uniqueid123');

// Create outlet and start streaming
const outlet = new StreamOutlet(info);

// Send data
const sample = [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0];
outlet.pushSample(sample);

Receiving Data

import { resolveStreams, StreamInlet } from 'node-labstreaminglayer';

// Find available streams
const streams = resolveStreams();

if (streams.length > 0) {
  // Connect to first stream
  const inlet = new StreamInlet(streams[0]);
  
  // Receive data
  const [sample, timestamp] = inlet.pullSample();
  console.log('Received:', sample, 'at', timestamp);
}

API Reference

Core Classes

StreamInfo

Stores the declaration of a data stream.

const info = new StreamInfo(
  name,           // Stream name
  type,           // Content type (e.g., 'EEG', 'Markers')
  channelCount,   // Number of channels
  nominalSrate,   // Sampling rate (Hz) or IRREGULAR_RATE
  channelFormat,  // Data type: 'float32', 'double64', 'string', etc.
  sourceId        // Unique source identifier (optional)
);

StreamOutlet

Makes streaming data available on the network.

const outlet = new StreamOutlet(info, chunkSize?, maxBuffered?);
outlet.pushSample(sample, timestamp?, pushthrough?);
outlet.pushChunk(samples, timestamp?, pushthrough?);
outlet.haveConsumers();
outlet.waitForConsumers(timeout);

StreamInlet

Receives streaming data from the network.

const inlet = new StreamInlet(info, maxBuflen?, maxChunklen?, recover?, processingFlags?);
const [sample, timestamp] = inlet.pullSample(timeout?);
const [samples, timestamps] = inlet.pullChunk(timeout?, maxSamples?);
inlet.timeCorrection(timeout?);
inlet.openStream(timeout?);
inlet.closeStream();

Stream Discovery

// Find all streams
const streams = resolveStreams(waitTime?);

// Find by property
const eegStreams = resolveByProp('type', 'EEG');

// Find by predicate (XPath)
const filtered = resolveByPred("name='MyStream' and type='EEG'");

// Continuous resolution
const resolver = new ContinuousResolver();
const currentStreams = resolver.results();

Constants

import { 
  IRREGULAR_RATE,  // 0.0 - for irregular sampling
  FOREVER,         // 32000000.0 - for infinite timeout
  proc_clocksync,  // Clock synchronization flag
  proc_dejitter,   // Dejitter timestamps flag
  proc_ALL        // All processing flags
} from 'node-labstreaminglayer';

Examples

The package includes several example scripts in the src/examples directory:

  • SendData.ts - Stream multi-channel data
  • ReceiveData.ts - Receive and display data
  • SendStringMarkers.ts - Send event markers
  • ReceiveStringMarkers.ts - Receive event markers
  • HandleMetadata.ts - Work with stream metadata

Run examples after building:

npm run build
node dist/examples/SendData.js

Building from Source

# Install dependencies
npm install

# Build TypeScript
npm run build

# Run tests
npm test

Platform Support

  • Windows: x64 and x86 (uses lsl_amd64.dll or lsl_i386.dll)
  • Linux: x64 (uses lsl.so)
  • macOS: x64 and ARM64 (uses lsl.dylib)

License

MIT

Credits

This package provides Node.js bindings for the Lab Streaming Layer (LSL) library.

Author

Haowen John Wei
GitHub: https://github.com/HaowenWeiJohn

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.