Choose an API

LansonAI provides three live transcription APIs today, plus Voice Agent which is coming soon.

Decision table

Scenario	API	Endpoint	Who does VAD
Live captions / dialogue	Realtime WS	`WS /v1/audio/transcriptions/stream`	Server
Pre-segmented speech clips (e.g. voice UI)	Segment HTTP	`POST /v1/audio/transcriptions`	Client
Meeting / podcast file from URL	Batch jobs	`POST /v1/audio/transcriptions/jobs`	Server (time slice)
Voice agent	Voice Agent	Coming soon	—

::callout{icon="i-lucide-info" color="primary"} Segment vs Batch Segment = you already cut speech with client VAD; send multipart file, get 200 immediately. Batch = you have a long audio_url; get 202 + poll. Do not send silence to Segment — we transcribe whatever you POST. ::

Realtime Voice Context

When to use: text while the person is still speaking.

Live captions, real-time display

Continuous PCM stream; server-side VAD and utterance boundaries

Characteristics:

WebSocket full-duplex

PCM16LE / 16kHz / mono

Millisecond-level latency

→ Realtime Overview

Segment transcription (client VAD)

When to use: your app already detected speech boundaries (VAD) and has a short clip per utterance.

Voice clients that upload one WAV per utterance

OpenAI Whisper-compatible multipart/form-data

Synchronous 200 response

Characteristics:

No server-side silence filtering — silent clips are transcribed and billed

~800ms × up to 2 worker attempts per request; no HTTP auto-retry

On failure (502), client decides whether to resend

→ Segment API · Client-VAD guide

Batch jobs (recorded files)

When to use: complete audio file at a public URL; processing can take minutes.

Post-meeting / podcast processing

Server slices by time, concurrent chunk transcription, aggregation

Optional LLM review and webhook

Characteristics:

HTTP async (202 + poll)

workflow_id is cf_ + 64 hex (not UUID)

→ Recorded Overview · Batch Jobs API

Voice Agent

Status: Coming soon

Comparison

Dimension	Realtime WS	Segment HTTP	Batch jobs
Transport	WebSocket	HTTP POST	HTTP POST + GET poll
Latency	Milliseconds	~≤1.6s sync	Minutes (async)
Input	PCM16LE stream	Multipart `file`	JSON `audio_url`
Output	Event stream	Transcript JSON	Full job JSON
VAD	Server	Client	Server (slice)
Success code	WS events	200	202

Next steps