Enabling Real-Time Media Transcription via Genesys Cloud Media API with TypeScript

What You Will Build

• A TypeScript service that activates real-time transcription on a Genesys Cloud media session, streams partial transcripts via WebSocket, redacts PII, tracks latency, and exposes a live captioning interface.
• This implementation uses the Genesys Cloud Media API (/api/v2/media/transcriptions) and the WebSocket API (/api/v2/websocket).
• The code is written in TypeScript targeting Node.js 18+ and uses native fetch and WebSocket with modern async/await patterns.

Prerequisites

• OAuth 2.0 Confidential Client registered in Genesys Cloud
• Required scopes: media:transcription, conversation:transcription:view, analytics:call:view
• Node.js 18+ with TypeScript 5.0+
• Dependencies: npm i @types/node uuid
• Access to a Genesys Cloud organization ID and a valid media session ID from an active call or WebRTC session

Authentication Setup

Genesys Cloud APIs require a bearer token obtained via the OAuth 2.0 client credentials flow. The following function handles token acquisition, caching, and automatic refresh when the token expires.

const OAUTH_TOKEN_URL = "https://api.mypurecloud.com/oauth/token";
let cachedToken: string | null = null;
let tokenExpiry: number = 0;

async function getAccessToken(clientId: string, clientSecret: string, grantType: string = "client_credentials"): Promise<string> {
  if (cachedToken && Date.now() < tokenExpiry - 60000) {
    return cachedToken;
  }

  const payload = new URLSearchParams({
    client_id: clientId,
    client_secret: clientSecret,
    grant_type: grantType,
    scope: "media:transcription conversation:transcription:view analytics:call:view"
  });

  const response = await fetch(OAUTH_TOKEN_URL, {
    method: "POST",
    headers: { "Content-Type": "application/x-www-form-urlencoded" },
    body: payload
  });

  if (!response.ok) {
    const errorBody = await response.text();
    throw new Error(`OAuth token request failed with status ${response.status}: ${errorBody}`);
  }

  const data = await response.json();
  cachedToken = data.access_token;
  tokenExpiry = Date.now() + (data.expires_in * 1000);
  return cachedToken;
}

Implementation

Step 1: Validate Media Session Attributes and Construct Activation Payload

Genesys Cloud requires transcription activation to specify language models, profanity filtering, and chunk sizes. You must also validate that the media session codec and region support real-time transcription. The platform currently supports en-US, es-ES, fr-FR, and de-DE with specific regional endpoints.

const SUPPORTED_REGIONS = ["us-east-1", "eu-west-1", "ap-southeast-2"];
const SUPPORTED_CODECS = ["opus", "g729", "pcmu", "pcma"];

interface TranscriptionConfig {
  mediaSessionId: string;
  language: string;
  profanityFilter: boolean;
  chunkSize: number;
  languageModel: string;
}

function validateSessionAttributes(sessionRegion: string, sessionCodec: string): void {
  if (!SUPPORTED_REGIONS.includes(sessionRegion)) {
    throw new Error(`Transcription is not available in region ${sessionRegion}`);
  }
  if (!SUPPORTED_CODECS.includes(sessionCodec)) {
    throw new Error(`Codec ${sessionCodec} does not support real-time transcription`);
  }
}

async function activateTranscription(
  orgId: string,
  accessToken: string,
  config: TranscriptionConfig
): Promise<void> {
  const url = `https://${orgId}.mypurecloud.com/api/v2/media/transcriptions`;
  
  const requestBody = {
    mediaSessionId: config.mediaSessionId,
    language: config.language,
    profanityFilter: config.profanityFilter,
    chunkSize: config.chunkSize,
    languageModel: config.languageModel
  };

  let retries = 0;
  const maxRetries = 3;
  let response: Response;

  do {
    response = await fetch(url, {
      method: "POST",
      headers: {
        "Authorization": `Bearer ${accessToken}`,
        "Content-Type": "application/json",
        "Accept": "application/json"
      },
      body: JSON.stringify(requestBody)
    });

    if (response.status === 429 && retries < maxRetries) {
      const retryAfter = parseInt(response.headers.get("Retry-After") || "5", 10);
      console.log(`Rate limited. Retrying in ${retryAfter} seconds...`);
      await new Promise(resolve => setTimeout(resolve, retryAfter * 1000));
      retries++;
    }
  } while (response.status === 429 && retries < maxRetries);

  if (!response.ok) {
    const errorText = await response.text();
    throw new Error(`Transcription activation failed with status ${response.status}: ${errorText}`);
  }

  console.log("Transcription activation successful. HTTP 201 Created.");
}

Expected Request:

POST /api/v2/media/transcriptions HTTP/1.1
Host: yourorg.mypurecloud.com
Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9...
Content-Type: application/json

{
  "mediaSessionId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "language": "en-US",
  "profanityFilter": true,
  "chunkSize": 1500,
  "languageModel": "conversational"
}

Expected Response:

{
  "id": "trans-987654321",
  "status": "active",
  "mediaSessionId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "createdTime": "2024-06-15T10:30:00.000Z"
}

Step 2: Initialize WebSocket Subscription with Sequence Tracking

Real-time transcription streams arrive over WebSocket. You must subscribe to the conversation:transcription topic and filter by media session ID. Sequence tracking prevents duplicate processing and detects packet loss.

interface TranscriptionEvent {
  eventType: string;
  eventSequence: number;
  mediaSessionId: string;
  transcript: string;
  isPartial: boolean;
  timestamp: string;
}

class TranscriptionStreamHandler {
  private ws: WebSocket | null = null;
  private expectedSequence: number = 0;
  private onEventCallback: (event: TranscriptionEvent) => void;
  private onPacketLossCallback: (lostCount: number) => void;

  constructor(
    onEvent: (event: TranscriptionEvent) => void,
    onPacketLoss: (lostCount: number) => void
  ) {
    this.onEventCallback = onEvent;
    this.onPacketLossCallback = onPacketLoss;
  }

  connect(orgId: string, mediaSessionId: string): void {
    const wsUrl = `wss://${orgId}.mypurecloud.com/api/v2/websocket`;
    this.ws = new WebSocket(wsUrl);

    this.ws.onopen = () => {
      const subscriptionPayload = {
        action: "subscribe",
        topics: ["conversation:transcription"],
        filter: { mediaSessionId }
      };
      this.ws?.send(JSON.stringify(subscriptionPayload));
      console.log("WebSocket connected and subscribed to conversation:transcription");
    };

    this.ws.onmessage = (event: MessageEvent) => {
      const messages = JSON.parse(event.data as string);
      for (const msg of messages) {
        if (msg.eventType === "transcription") {
          this.handleTranscriptionMessage(msg as TranscriptionEvent);
        }
      }
    };

    this.ws.onerror = (error) => console.error("WebSocket error:", error);
    this.ws.onclose = () => console.log("WebSocket connection closed");
  }

  private handleTranscriptionMessage(event: TranscriptionEvent): void {
    if (event.eventSequence > this.expectedSequence + 1) {
      const lost = event.eventSequence - this.expectedSequence - 1;
      this.onPacketLossCallback(lost);
      console.warn(`Packet loss detected. Lost ${lost} sequence(s).`);
    }
    this.expectedSequence = event.eventSequence;
    this.onEventCallback(event);
  }
}

Step 3: Process Stream Events with PII Redaction and Normalization

Partial transcripts contain raw audio-to-text output. You must normalize whitespace, collapse repeated characters, and redact personally identifiable information before forwarding to downstream systems.

function normalizeAndRedact(rawText: string): string {
  let normalized = rawText
    .replace(/\s+/g, " ")
    .replace(/([.,!?])\s*/g, "$1")
    .trim();

  const piiPatterns: { pattern: RegExp; replacement: string }[] = [
    { pattern: /\b\d{3}-\d{2}-\d{4}\b/g, replacement: "[SSN]" },
    { pattern: /\b\d{3}[-.\s]?\d{3}[-.\s]?\d{4}\b/g, replacement: "[PHONE]" },
    { pattern: /\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b/g, replacement: "[EMAIL]" },
    { pattern: /\b\d{4}[-\s]?\d{4}[-\s]?\d{4}[-\s]?\d{4}\b/g, replacement: "[CC]" }
  ];

  for (const { pattern, replacement } of piiPatterns) {
    normalized = normalized.replace(pattern, replacement);
  }

  return normalized;
}

Step 4: Track Latency, Throughput, and Generate Audit Logs

Performance optimization requires measuring token throughput and transcription latency. Compliance requires structured audit logs for every processed segment.

interface AuditLogEntry {
  timestamp: string;
  mediaSessionId: string;
  sequence: number;
  rawLength: number;
  redactedLength: number;
  latencyMs: number;
  tokensProcessed: number;
  complianceFlag: string;
}

class PerformanceTracker {
  private auditLogs: AuditLogEntry[] = [];
  private totalTokens: number = 0;
  private startTime: number = Date.now();

  processEvent(event: TranscriptionEvent, redactedText: string): AuditLogEntry {
    const eventTime = new Date(event.timestamp).getTime();
    const processTime = Date.now();
    const latencyMs = processTime - eventTime;
    const tokens = redactedText.split(/\s+/).length;
    this.totalTokens += tokens;

    const logEntry: AuditLogEntry = {
      timestamp: new Date().toISOString(),
      mediaSessionId: event.mediaSessionId,
      sequence: event.eventSequence,
      rawLength: event.transcript.length,
      redactedLength: redactedText.length,
      latencyMs,
      tokensProcessed: tokens,
      complianceFlag: "PII_REDACTED"
    };

    this.auditLogs.push(logEntry);
    return logEntry;
  }

  getMetrics(): { avgLatencyMs: number; throughputTokensPerSec: number; totalLogs: number } {
    const elapsedSec = (Date.now() - this.startTime) / 1000;
    const avgLatency = this.auditLogs.length > 0
      ? this.auditLogs.reduce((sum, l) => sum + l.latencyMs, 0) / this.auditLogs.length
      : 0;
    return {
      avgLatencyMs: Math.round(avgLatency),
      throughputTokensPerSec: Math.round(this.totalTokens / elapsedSec),
      totalLogs: this.auditLogs.length
    };
  }

  exportAuditLogs(): AuditLogEntry[] {
    return [...this.auditLogs];
  }
}

Step 5: Expose Live Captioning Enabler Interface

External captioning systems require a standardized interface to consume normalized, redacted transcripts in real time. The following class exposes a callback-driven caption stream.

export class RealTimeTranscriptionService {
  private tracker: PerformanceTracker;
  private captionCallbacks: Array<(caption: string, isPartial: boolean) => void> = [];
  private streamHandler: TranscriptionStreamHandler;

  constructor() {
    this.tracker = new PerformanceTracker();
    this.streamHandler = new TranscriptionStreamHandler(
      (event) => this.handleTranscriptionEvent(event),
      (lost) => console.error(`Caption stream lost ${lost} packet(s)`)
    );
  }

  registerCaptionConsumer(callback: (caption: string, isPartial: boolean) => void): void {
    this.captionCallbacks.push(callback);
  }

  private handleTranscriptionEvent(event: TranscriptionEvent): void {
    const redacted = normalizeAndRedact(event.transcript);
    this.tracker.processEvent(event, redacted);
    
    for (const cb of this.captionCallbacks) {
      cb(redacted, event.isPartial);
    }
  }

  startStreaming(orgId: string, mediaSessionId: string): void {
    this.streamHandler.connect(orgId, mediaSessionId);
  }

  getMetrics() {
    return this.tracker.getMetrics();
  }

  getAuditLogs() {
    return this.tracker.exportAuditLogs();
  }
}

Complete Working Example

The following module combines authentication, activation, streaming, normalization, tracking, and captioning exposure into a single runnable service. Replace placeholder credentials with your Genesys Cloud OAuth client details.

import { RealTimeTranscriptionService } from "./transcriptionService";
import { getAccessToken } from "./auth";
import { validateSessionAttributes, activateTranscription } from "./activation";

async function main() {
  const ORG_ID = "your-org-id";
  const CLIENT_ID = "your-client-id";
  const CLIENT_SECRET = "your-client-secret";
  const MEDIA_SESSION_ID = "a1b2c3d4-e5f6-7890-abcd-ef1234567890";
  const SESSION_REGION = "us-east-1";
  const SESSION_CODEC = "opus";

  try {
    console.log("Initializing transcription pipeline...");
    
    const token = await getAccessToken(CLIENT_ID, CLIENT_SECRET);
    
    validateSessionAttributes(SESSION_REGION, SESSION_CODEC);
    
    await activateTranscription(ORG_ID, token, {
      mediaSessionId: MEDIA_SESSION_ID,
      language: "en-US",
      profanityFilter: true,
      chunkSize: 1500,
      languageModel: "conversational"
    });

    const service = new RealTimeTranscriptionService();
    
    service.registerCaptionConsumer((caption, isPartial) => {
      const status = isPartial ? "[PARTIAL]" : "[FINAL]";
      console.log(`${status} Caption: ${caption}`);
    });

    service.startStreaming(ORG_ID, MEDIA_SESSION_ID);

    setInterval(() => {
      const metrics = service.getMetrics();
      console.log(`Metrics -> Avg Latency: ${metrics.avgLatencyMs}ms | Throughput: ${metrics.throughputTokensPerSec} tok/s | Logs: ${metrics.totalLogs}`);
    }, 10000);

  } catch (error) {
    console.error("Pipeline initialization failed:", error);
    process.exit(1);
  }
}

main();

Common Errors & Debugging

Error: HTTP 401 Unauthorized

• Cause: Expired or invalid OAuth token, missing Authorization header, or incorrect client credentials.
• Fix: Verify the token cache logic returns a fresh token when expires_in has passed. Ensure the Authorization header uses the exact format Bearer <token>.
• Code Fix: The getAccessToken function automatically refreshes tokens when Date.now() >= tokenExpiry - 60000.

Error: HTTP 403 Forbidden

• Cause: Missing required OAuth scopes on the client credentials grant.
• Fix: Add media:transcription and conversation:transcription:view to the client scope configuration in the Genesys Cloud admin console. Update the scope parameter in the token request.
• Code Fix: Modify the scope string in getAccessToken to include both scopes.

Error: HTTP 429 Too Many Requests

• Cause: Exceeding the Genesys Cloud API rate limit for transcription activation or WebSocket subscriptions.
• Fix: Implement exponential backoff with Retry-After header parsing. The activation function already includes a retry loop that respects the Retry-After header.
• Code Fix: Ensure the retry loop does not exceed maxRetries. Log the delay and adjust request frequency if sustained 429s occur.

Error: WebSocket 1006 Abnormal Closure

• Cause: Network interruption, missing subscription acknowledgment, or invalid filter syntax.
• Fix: Verify the subscription payload matches the exact schema. Add reconnection logic with a 5-second delay.
• Code Fix: Wrap this.ws = new WebSocket(wsUrl) in a reconnect function that triggers on onclose when event.code !== 1000.

Error: Sequence Gap Detection Fails

• Cause: Multiple WebSocket connections subscribing to the same topic, causing interleaved sequences.
• Fix: Ensure only one active subscription per media session. Reset expectedSequence on stream restart.
• Code Fix: Add a resetSequence() method and call it during stream reinitialization.

Official References

• Genesys Cloud Media Transcription API Documentation
• Genesys Cloud WebSocket API Documentation
• Genesys Cloud OAuth 2.0 Documentation
• Genesys Cloud JS SDK Reference