Building a live caption, meeting or lecture app on Azure usually means picking more than one Speech product: real-time speech-to-text for captions, Speech Translation when you need another language on screen, and Conversation Transcription or a diarization add-on when you need speaker IDs. LecSync ships those pieces on a single WebSocket at one rate.
This article compares the LecSync Realtime Speech API with Azure AI Speech real-time paths for translation and speakers. Azure figures come from the official Retail Prices API and public Learn / pricing pages, read on October 9, 2026. LecSync figures come from the developers page and pricing docs.
The short answer
If the product needs live captions, a translation track and speaker labels together, LecSync returns all three over one connection for $0.006 per accepted audio minute ($0.36 per hour, Calculated). On Azure, Speech Translation alone is $2.50 per hour at the S1 retail meter, real-time STT is $1.00 per hour, and diarization is a separate enhanced add-on line. Azure is the stronger pick when you already live in Azure, need adjustable high concurrency, speech output / Live Interpreter, custom speech models, or an enterprise SLA posture.
What "one connection" means here
A one-connection realtime speech API opens a single stream that can return transcription, translation and speaker labels on the same socket, billed as one rate for accepted audio. A multi-service Azure build opens Speech-to-Text and/or Speech Translation (and optionally Conversation Transcription or enhanced diarization), each with its own meter, quota share and SDK surface. The first suits a thin client; the second suits teams already wiring Azure Speech SDKs and Translator.
Side-by-side facts (checked October 9, 2026)
| LecSync Realtime Speech API | Azure AI Speech (real-time) | |
|---|---|---|
| How you connect | One WebSocket after POST /v1/realtime/connect | Speech SDK / REST: Speech-to-Text, Speech Translation, ConversationTranscriber as separate entry points |
| Live captions | Included (60 languages) | S1 Speech To Text, $1.00/hr (Retail Prices API, eastus) |
| Live translation | Included, one language pair per stream, direction per segment | Speech Translation standard: speech→text (optional speech output); up to 2 target languages in that price; $2.50/hr (Retail Prices API + Learn) |
| Live speakers | speakers: true on the same stream | Conversation Transcription / real-time diarization; enhanced add-on $0.30/hr per feature on the Speech pricing page (us-east, Measured) |
| Live structured minutes | digest on the same socket | Not part of these Speech meters |
| Concurrent streams (default) | Product docs list regions; no public "100" default on the developers page | Free F0: 1; Standard S0: 100 combined for realtime STT + speech translation, adjustable |
| Real-time diarization session length | No 240-minute cap listed on LecSync public pages | Max 240 minutes per session (quotas page) |
| Billing grain | Accepted audio minutes (fractions of a second) | STT and Speech Translation billed in one-second increments |
| Free allotment | None on the public developers rate | 5 audio hours/month STT and Speech Translation on Free |
| SLA | Best-effort; no SLA today | Azure enterprise / SLA posture available for the platform |
Sources: Azure Speech pricing, Speech translation overview, quotas and limits, real-time diarization / conversation transcription, LecSync developers, LecSync pricing docs. Retail meters: Azure Retail Prices API, eastus, October 9, 2026.
How each side is wired
LecSync: one connect call
You authenticate, call POST https://api.lecsync.com/v1/realtime/connect, then open the returned WebSocket. Turning on translation, speakers and digest is configuration on that stream. Partial and final captions, translation tokens and speaker IDs share segment IDs and timestamps. First word latency is listed as 0.28 s; translation adds about 88 ms to the first token. Audio backlog is capped at 2 seconds. Regions today: dal, hz, jp2, ru2, uk.
The rate does not change when you enable those features: $0.006 per minute of accepted audio. Storage for 30 days, glossary and AI translation polish are on that same line. For how speaker fields and timestamps look in a meeting client, see the speakers and timestamps walkthrough. For flat versus add-on pricing across vendors, see the flat vs add-ons breakdown.
Azure: Speech Translation, STT and speakers as separate products
Speech Translation is a dedicated real-time API: audio in, transcript and translation out, with optional synthesized speech on the translation path. Microsoft's Learn page states the standard speech translation price covers up to two target languages; a third language goes through Azure Translator text translation. The Learn page's $2.50/hr example matches the S1 Speech Translation retail meter we read today.
Speech-to-Text alone covers captions without that translation meter. The S1 Speech To Text retail meter is $1.00 per hour in eastus.
Speakers for live multi-party audio go through Conversation Transcription / the real-time diarization quickstart (ConversationTranscriber, speaker IDs such as Guest-1). On the public Speech pricing page, Diarization sits under enhanced add-on features for real-time, priced per hour per feature; the live page amount for us-east on October 9, 2026 was $0.30. Quotas limit real-time diarization sessions to 240 minutes.
Default Standard concurrency is 100 combined requests across real-time speech-to-text and speech translation; Free is 1. Both are documented as adjustable. Azure also offers Live Interpreter for speech-to-speech, custom speech models and a wide Speech SDK surface — none of which LecSync tries to replace.
If you assemble STT plus a separate MT call yourself, the engineering trade-offs match the pattern in built-in translation vs a DIY STT + MT pipeline. Google's streaming limits and translation path are covered in the Google Cloud STT comparison.
What one hour and 1,000 hours cost
Assumptions: one hour of live audio with captions and a translation track. Prices are public list / retail meters on October 9, 2026. Enhanced diarization is shown only where speakers are required.
| Setup | Calculation | Per hour | 1,000 hours |
|---|---|---|---|
| LecSync (captions + translation + speakers + digest) | 60 × $0.006 | $0.36 | $360 |
| Azure Speech Translation (standard, up to 2 targets) | S1 retail | $2.50 | $2,500 |
| Azure Speech To Text only (no translation) | S1 retail | $1.00 | $1,000 |
| Azure Speech Translation + diarization add-on | $2.50 + $0.30 | $2.80 | $2,800 |
LecSync's $0.36 already includes speakers and live minutes. Azure's $2.50 Speech Translation line does not; add the enhanced diarization feature when you need live speaker IDs. Azure STT-only at $1.00/hr is still above LecSync's all-in list rate, but Free tier includes 5 audio hours per month for STT and for Speech Translation, and commitment tiers can change the effective rate at volume.
Where Azure is the better choice
- You are already on Azure. Speech SDKs, identity, regions and billing stay inside one cloud account. Wiring LecSync means a second vendor.
- High concurrent streams. Standard defaults to 100 combined realtime STT + speech translation requests and can be raised. That matters for a multi-room or multi-tenant backend.
- Speech out, not only text. Speech Translation can return synthesized speech; Live Interpreter covers speech-to-speech. LecSync returns text tracks on the socket.
- Custom speech models or pronunciation assessment. Those live in Azure's Speech portfolio as first-class options.
- Contractual SLA / enterprise posture. LecSync's pricing docs say availability is best-effort with no SLA today. Azure is the safer checkbox for many enterprise reviews.
- Light usage on Free. Five free audio hours a month of STT and of Speech Translation cover prototypes without a bill.
Where LecSync fits
LecSync is built for apps that show captions, a second language and who-spoke-when on one live screen: lecture clients, bilingual meeting UIs, classroom note apps. One connect call, one WebSocket, one $0.006/min rate. You do not open a second translation meter or an enhanced diarization line to get those fields.
Limits to plan for: no published SLA; backlog capped at 2 seconds; one language pair per stream; a dropped connection does not resume — you reconnect and segment numbering restarts.
FAQ
Is Azure Speech Translation the same meter as Speech To Text?
No. The Azure Retail Prices API lists separate S1 meters: Speech To Text at $1.00 per hour and Speech Translation at $2.50 per hour (eastus, October 9, 2026). Captions-only and captions-plus-translation are different billable products.
How many target languages does Azure Speech Translation include?
Microsoft's Speech translation overview says the standard speech translation price covers up to two target languages. A third language is billed through Azure Translator text translation. LecSync takes one configured language pair per stream and chooses direction per segment.
How do you get live speaker IDs on Azure?
Use Conversation Transcription / the real-time diarization path (ConversationTranscriber). Speaker IDs such as Guest-1 appear on transcribed events. On the Speech pricing page, Diarization is an enhanced real-time add-on billed per hour per feature ($0.30/hr on the us-east amount read October 9, 2026). Sessions for real-time diarization are capped at 240 minutes.
What does LecSync include in $0.006 per minute?
Realtime transcription (60 languages), realtime translation, timestamps, speaker separation, glossary, AI translation polish, live structured digest and 30-day storage, per the developers page. Enabling those options does not change the rate.
Which option is cheaper for live captions plus translation?
At public list prices on October 9, 2026, LecSync is $0.36 per hour (Calculated: 60 × $0.006). Azure Speech Translation is $2.50 per hour. For 1,000 hours that is $360 versus $2,500. Azure Free hours and commitment tiers can narrow the gap for light or negotiated volume.
Does LecSync publish an SLA?
Not today. The pricing docs describe best-effort availability. If your contract requires an SLA, Azure's platform posture is the clearer fit.
The short version
Choose by how many Azure Speech meters you are willing to operate. Captions, translation and speakers on one socket at $0.36 per hour point to LecSync. Azure wins when you need its SDKs, concurrency headroom, speech output, custom models or an enterprise SLA. Create a key in the LecSync developers console, open a stream, and read the API docs for the connect and message formats.