Choose an API
Realtime, Segment, and Batch — when to use which.
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 | — |
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
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_idiscf_+ 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
Authentication
API key, session token, and browser-side security.
Realtime Overview
What the Realtime API does, input, output, and architecture.
Resources