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](/docs/realtime)

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](/docs/api-reference/segment-transcription) · [Client-VAD guide](/docs/guides/client-vad-segments)

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](/docs/recorded) · [Batch Jobs API](/docs/api-reference/batch-jobs)

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

[Realtime Quickstart](/docs/realtime/quickstart)

[Client-VAD segments](/docs/guides/client-vad-segments)

[Transcribe Audio](/docs/recorded/transcribe-audio)

[Authentication](/docs/start/authentication)