Sync API: Sub-300ms Context-Aware Transcription (Full Transcript)

A demo of Universal 3.5 Pro’s Sync API shows fast REST transcription with conversational context for better formatting of dates, cards, and addresses.
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[00:00:00] Speaker 1: With the Universal 3.5 Pro, we're really excited to introduce the new Sync API. This is a hybrid API that kind of meets in the middle between a real-time API and a pre-recorded API. Think push-to-talk, IVR routing, customized voice agents where you want complete control over the orchestration end-to-end. This is a great HTTP API where you can send in audio between 8 milliseconds and 120 seconds and then get back transcription immediately within 300 milliseconds. It supports prompting, language steering, key terms, and conversational context out of the box. In this demo, I'm going to showcase some of the conversation context features. Let's say that we're transcribing a customer service call. So this is a customized voice agent, you're handling the orchestration end-to-end, and you really just want really fast, accurate transcription. The Sync API is perfect for that. With conversation context, we can add in what the agent is asking of the user to steer the human transcription that is coming back. So let's add what is your birth date to the conversation context. Now I'm going to hold to talk and say my birth date and we'll see the formatting that is applied. 3490. So we can see here the model comes back with 3490 perfectly formatted as a date because it has the context, what is your birth date. We can also see here that we returned the transcription or generated the transcription within 360 milliseconds. So it's very fast and snappy. As soon as you let go of the request, we're going to be processing that and returning right back to you. There's no polling, there's no session management. It is a simple REST API to interact with. Let's try another example in conversation context. What is the expiration date of your card? So let's say this is a reservation or a customer service call and you have to provide information on your card. Now people can pronounce this in different ways. They might say December 12th in the year. They might say 12-28 in the year. And the model will have to infer the right formatting. I'm going to do shorthand and we'll see how the model does. 12-28. So we can see that this came back properly formatted as well. 12-28. We can see the inference turnaround time is under 300 milliseconds at 263 milliseconds. So it's really fast in what we generate. Let's try one more example. So this time we're going to give conversation context. What is your address? So when we say our address, the model should properly format it in a single turn. My address is 1-2-3 East Main Street, New York, New York, 1-1-0-2. So this came back saying my address is 1-2-3 East Main Street, New York, New York, 1-1-0-2. So it didn't split up these entities and it formatted it nicely for the agent. This is really a make or break it for an agent experience. Agents would likely get tripped up, run wrong formatting, have to ask the question over and over again, leading to a frustrated user and likely a poor voice agent experience. With the Sync API, again, you get rapid transcription with the most accurate model that we have on the market, allowing you sub 300 milliseconds turnaround time and complete control over the orchestration for your agent or transcription experience. We can't wait to see what you build with it and we're really looking forward to the feedback. Thanks.

ai AI Insights
Arow Summary
Universal 3.5 Pro introduces the Sync API, a hybrid between real-time and pre-recorded speech APIs designed for push-to-talk, IVR routing, and custom voice agents where developers control orchestration end-to-end. The HTTP REST API accepts audio chunks from ~8 ms up to 120 s and returns near-immediate transcription (typically sub-300 ms) without polling or session management. It supports prompting, language steering, key terms, and built-in conversational context. A demo shows that adding agent questions to conversation context (e.g., birth date, card expiration date, address) helps the model format short spoken inputs correctly (e.g., “3490” as a date, “12-28” as an expiration date, and a full address in one turn), improving agent UX and reducing user frustration.
Arow Title
Sync API Demo: Fast, Context-Steered Speech Transcription
Arow Keywords
Universal 3.5 Pro Remove
Sync API Remove
hybrid speech API Remove
REST API Remove
push-to-talk Remove
IVR routing Remove
voice agents Remove
speech-to-text Remove
real-time transcription Remove
low latency Remove
conversation context Remove
prompting Remove
language steering Remove
key terms Remove
orchestration Remove
customer service calls Remove
entity formatting Remove
expiration date Remove
address parsing Remove
Arow Key Takeaways
  • Sync API is a hybrid HTTP speech API bridging real-time and batch use cases for developer-orchestrated voice experiences.
  • It accepts very short to long audio (8 ms to 120 s) and returns transcriptions in ~300 ms, enabling snappy push-to-talk and IVR flows.
  • No polling or session management is required; it’s a straightforward REST interaction.
  • Built-in features include prompting, language steering, key terms, and conversational context to improve accuracy and formatting.
  • Providing agent question context helps the model infer correct entity formats (dates, card expiration, addresses), reducing agent errors and user frustration.
  • Designed for customized voice agents needing fast, accurate transcription and full orchestration control.
Arow Sentiments
Positive: The speaker is enthusiastic and promotional, emphasizing excitement, speed (sub-300 ms), simplicity (no polling/sessions), and improved user experience through accurate, context-aware formatting.
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