deepgram-reference-architecture

Deepgram Reference Architecture

Overview

Four reference architectures for Deepgram transcription at scale: synchronous REST for short files, async queue (BullMQ) for batch processing, WebSocket proxy for real-time streaming, and a hybrid router that auto-selects the best pattern based on audio duration.

Architecture Selection Guide

Pattern	Best For	Latency	Throughput	Complexity
Sync REST	Files <60s, low volume	Low	Low	Simple
Async Queue	Batch, files >60s	Medium	High	Medium
WebSocket Proxy	Live audio, real-time	Real-time	Medium	Medium
Hybrid Router	Mixed workloads	Varies	High	High
Callback	Files >5min, fire-and-forget	N/A	Very High	Low

Instructions

Step 1: Synchronous REST Pattern

import express from 'express';
import { createClient } from '@deepgram/sdk';

const app = express();
app.use(express.json());

const deepgram = createClient(process.env.DEEPGRAM_API_KEY!);

// Direct API call — best for short files (<60s)
app.post('/api/transcribe', async (req, res) => {
  const { url, model = 'nova-3', diarize = false } = req.body;

  try {
    const { result, error } = await deepgram.listen.prerecorded.transcribeUrl(
      { url },
      { model, smart_format: true, diarize, utterances: diarize }
    );
    if (error) return res.status(502).json({ error: error.message });

    res.json({
      transcript: result.results.channels[0].alternatives[0].transcript,
      confidence: result.results.channels[0].alternatives[0].confidence,
      duration: result.metadata.duration,
      request_id: result.metadata.request_id,
      utterances: diarize ? result.results.utterances : undefined,
    });
  } catch (err: any) {
    res.status(500).json({ error: err.message });
  }
});

Step 2: Async Queue Pattern (BullMQ)

import { Queue, Worker, Job } from 'bullmq';
import { createClient } from '@deepgram/sdk';
import Redis from 'ioredis';

const connection = new Redis(process.env.REDIS_URL ?? 'redis://localhost:6379');

// Producer: submit transcription jobs
const transcriptionQueue = new Queue('transcription', { connection });

async function submitJob(audioUrl: string, options: Record<string, any> = {}) {
  const job = await transcriptionQueue.add('transcribe', {
    audioUrl,
    model: options.model ?? 'nova-3',
    diarize: options.diarize ?? false,
    submittedAt: new Date().toISOString(),
  }, {
    attempts: 3,
    backoff: { type: 'exponential', delay: 5000 },
    removeOnComplete: { age: 86400 },  // Keep for 24h
  });

  console.log(`Job submitted: ${job.id}`);
  return job.id;
}

// Consumer: process transcription jobs
const deepgram = createClient(process.env.DEEPGRAM_API_KEY!);

const worker = new Worker('transcription', async (job: Job) => {
  const { audioUrl, model, diarize } = job.data;
  console.log(`Processing job ${job.id}: ${audioUrl}`);

  const { result, error } = await deepgram.listen.prerecorded.transcribeUrl(
    { url: audioUrl },
    { model, smart_format: true, diarize, utterances: diarize }
  );

  if (error) throw new Error(`Deepgram error: ${error.message}`);

  const output = {
    transcript: result.results.channels[0].alternatives[0].transcript,
    confidence: result.results.channels[0].alternatives[0].confidence,
    duration: result.metadata.duration,
    request_id: result.metadata.request_id,
  };

  // Store result (database, S3, etc.)
  console.log(`Job ${job.id} complete: ${output.duration}s audio`);
  return output;
}, {
  connection,
  concurrency: 10,     // Process 10 jobs simultaneously
  limiter: {
    max: 50,           // Max 50 per time window
    duration: 60000,   // Per minute
  },
});

worker.on('completed', (job) => console.log(`Completed: ${job.id}`));
worker.on('failed', (job, err) => console.error(`Failed: ${job?.id}`, err.message));

Step 3: WebSocket Proxy for Real-Time

import { WebSocketServer, WebSocket } from 'ws';
import { createClient, LiveTranscriptionEvents } from '@deepgram/sdk';

const wss = new WebSocketServer({ port: 8080 });

wss.on('connection', (clientWs: WebSocket) => {
  console.log('Client connected');

  const deepgram = createClient(process.env.DEEPGRAM_API_KEY!);
  const dgConnection = deepgram.listen.live({
    model: 'nova-3',
    smart_format: true,
    interim_results: true,
    utterance_end_ms: 1000,
    encoding: 'linear16',
    sample_rate: 16000,
    channels: 1,
  });

  // Forward Deepgram transcripts to client
  dgConnection.on(LiveTranscriptionEvents.Transcript, (data) => {
    const transcript = data.channel.alternatives[0]?.transcript;
    if (transcript && clientWs.readyState === WebSocket.OPEN) {
      clientWs.send(JSON.stringify({
        type: 'transcript',
        text: transcript,
        is_final: data.is_final,
        speech_final: data.speech_final,
      }));
    }
  });

  dgConnection.on(LiveTranscriptionEvents.UtteranceEnd, () => {
    if (clientWs.readyState === WebSocket.OPEN) {
      clientWs.send(JSON.stringify({ type: 'utterance_end' }));
    }
  });

  // Forward client audio to Deepgram
  clientWs.on('message', (data: Buffer) => {
    if (dgConnection.getReadyState() === 1) {
      dgConnection.send(data);
    }
  });

  // Cleanup on disconnect
  clientWs.on('close', () => {
    dgConnection.finish();
    console.log('Client disconnected');
  });

  dgConnection.on(LiveTranscriptionEvents.Error, (err) => {
    console.error('Deepgram error:', err.message);
    clientWs.close();
  });
});

console.log('WebSocket proxy on ws://localhost:8080');

Step 4: Hybrid Router

import { createClient } from '@deepgram/sdk';

class TranscriptionRouter {
  private client: ReturnType<typeof createClient>;
  private queue: typeof transcriptionQueue;

  constructor(apiKey: string, queue: any) {
    this.client = createClient(apiKey);
    this.queue = queue;
  }

  async route(audioUrl: string, options: {
    mode?: 'sync' | 'async' | 'callback' | 'auto';
    estimatedDuration?: number;  // seconds
    callbackUrl?: string;
    model?: string;
    diarize?: boolean;
  } = {}) {
    const mode = options.mode ?? 'auto';
    const duration = options.estimatedDuration ?? 0;

    // Auto-select based on duration
    const selectedMode = mode === 'auto'
      ? duration > 300 ? 'callback'   // >5 min: use callback
        : duration > 60 ? 'async'     // >60s: use queue
        : 'sync'                       // <60s: direct API
      : mode;

    console.log(`Routing: ${selectedMode} (est. ${duration}s)`);

    switch (selectedMode) {
      case 'sync':
        return this.syncTranscribe(audioUrl, options);
      case 'async':
        return this.asyncTranscribe(audioUrl, options);
      case 'callback':
        return this.callbackTranscribe(audioUrl, options);
    }
  }

  private async syncTranscribe(url: string, opts: any) {
    const { result, error } = await this.client.listen.prerecorded.transcribeUrl(
      { url },
      { model: opts.model ?? 'nova-3', smart_format: true, diarize: opts.diarize }
    );
    if (error) throw error;
    return { mode: 'sync', result };
  }

  private async asyncTranscribe(url: string, opts: any) {
    const jobId = await submitJob(url, opts);
    return { mode: 'async', jobId };
  }

  private async callbackTranscribe(url: string, opts: any) {
    const { result } = await this.client.listen.prerecorded.transcribeUrl(
      { url },
      { model: opts.model ?? 'nova-3', smart_format: true, callback: opts.callbackUrl }
    );
    return { mode: 'callback', requestId: result.metadata.request_id };
  }
}

Step 5: Architecture Diagram

                    ┌──────────────┐
                    │   Client     │
                    └──────┬───────┘
                           │
                    ┌──────▼───────┐
                    │   API Gateway │
                    │  /transcribe  │
                    └──────┬───────┘
                           │
                    ┌──────▼───────┐
                    │ Hybrid Router │
                    └──┬───┬───┬───┘
                       │   │   │
           ┌───────────┘   │   └───────────┐
           ▼               ▼               ▼
    ┌──────────┐   ┌──────────┐   ┌──────────┐
    │   Sync   │   │  Queue   │   │ Callback │
    │  (<60s)  │   │ (BullMQ) │   │  (>5min) │
    └────┬─────┘   └────┬─────┘   └────┬─────┘
         │              │              │
         └──────────┬───┘──────────────┘
                    │
            ┌───────▼──────┐
            │  Deepgram    │
            │  API         │
            └───────┬──────┘
                    │
            ┌───────▼──────┐
            │   Results    │
            │   Store      │
            └──────────────┘

Output

• Sync REST endpoint for short files
• BullMQ queue with workers for batch processing
• WebSocket proxy for real-time streaming
• Hybrid router with auto-mode selection
• Architecture diagram

Error Handling

Issue	Cause	Solution
Sync timeout on large file	Wrong pattern selected	Use async queue or callback
Queue backlog growing	Workers overloaded	Scale workers, increase concurrency
WebSocket disconnects	Network instability	Auto-reconnect with backoff
Callback not received	Endpoint unreachable	Check HTTPS, verify callback URL

Resources

• Deepgram Architecture Guide
• BullMQ Documentation
• WebSocket API