SmartSpectra SDKConfiguring Metrics
Request and read SmartSpectra metrics from the Node.js SDK.
The Node.js SDK passes requested metric codes through to the native SmartSpectra C++ SDK. Omitting requestedMetrics uses the default breathing bundle.
Breathing and Pulse
Request Metrics
Request the breathing bundle plus the cardio bundle (pulse rate, arterial pressure trace, HRV):
import { SmartSpectraSDK, breathingMetrics, cardioMetrics } from '@smartspectra/node-sdk';
const sdk = new SmartSpectraSDK({
apiKey: 'YOUR_API_KEY',
requestedMetrics: [...breathingMetrics, ...cardioMetrics],
});The bundle exports (breathingMetrics, cardioMetrics, faceMetrics, micromotionMetrics, edaMetrics) contain the MetricType integer codes defined in metric_types.proto. defaultSupportedMetrics is the bundle used when requestedMetrics is omitted (currently equal to breathingMetrics).
Read Metrics
Read the latest breathing and pulse samples from the metrics event:
import { decodeMetrics } from '@smartspectra/node-sdk';
sdk.on('metrics', (buf, timestampUs) => {
const metrics = decodeMetrics(buf) as any;
if (Buffer.isBuffer(metrics)) return;
const breathingRate = metrics.breathing?.rate?.at(-1)?.value;
const chestTrace = metrics.breathing?.upperTrace?.at(-1)?.value;
const abdomenTrace = metrics.breathing?.lowerTrace?.at(-1)?.value;
const pulseRate = metrics.cardio?.pulseRate?.at(-1)?.value;
});Cardio fields are empty unless you request a cardio metric such as PULSE_RATE.
Advanced
Combine bundles or hand-pick MetricType codes for finer control:
import {
SmartSpectraSDK, breathingMetrics, cardioMetrics, faceMetrics, edaMetrics,
} from '@smartspectra/node-sdk';
const sdk = new SmartSpectraSDK({
apiKey: 'YOUR_API_KEY',
requestedMetrics: [
...breathingMetrics,
...cardioMetrics,
...faceMetrics,
...edaMetrics,
],
});Read the advanced fields from the same decoded metrics object:
sdk.on('metrics', (buf, timestampUs) => {
const metrics = decodeMetrics(buf) as any;
if (Buffer.isBuffer(metrics)) return;
const pressureTrace = metrics.cardio?.arterialPressureTrace?.at(-1)?.value;
const hrvRmssd = metrics.cardio?.hrv?.at(-1)?.rmssd;
const edaTrace = metrics.eda?.trace?.at(-1)?.value;
const faceLandmarks = metrics.face?.landmarks?.at(-1)?.value;
const blinking = metrics.face?.blinking?.at(-1)?.detected;
const talking = metrics.face?.talking?.at(-1)?.detected;
const expression = metrics.face?.expression?.at(-1);
});Advanced Payload Shape
decodeMetrics returns the generated protobuf payload as a JavaScript object. Requested advanced metrics populate these fields:
type Metrics = {
breathing?: Breathing;
eda?: Eda;
face?: Face;
cardio?: Cardio;
};
type Cardio = {
pulseRate?: MeasurementWithConfidence[];
arterialPressureTrace?: MeasurementWithConfidence[];
hrv?: Hrv[];
};
type Hrv = {
rmssd: number;
meanNn: number;
sdnn: number;
baevsky: number;
timestamp: number;
confidence: number;
};
type Eda = {
trace?: Measurement[];
};
type Face = {
landmarks?: Landmarks[];
blinking?: DetectionStatus[];
talking?: DetectionStatus[];
expression?: Expression[];
};EDA may take longer to produce its first sample than breathing or cardio outputs. See Data Types for the complete protobuf schema.