> ## Documentation Index > Fetch the complete documentation index at: https://docs.camb.ai/llms.txt > Use this file to discover all available pages before exploring further. # Live Transcription (Websocket) > Stream raw audio to CAMB over a single WebSocket and receive cumulative interim transcripts, word-level timing, and typed events. **Beta.** The live transcription WebSocket is generally available for testing but the schema, event shape, and error codes may change in backwards-incompatible ways before GA. Pin to the SDK versions you test against. ## What you get back After connect, the server emits a single `Ready` event, then streams `Results` messages as your audio is consumed. Each `Results` carries the **cumulative** transcript for the current utterance — replace your in-progress UI state with it rather than concatenating. The `is_final` flag tells interim refinements (`false`) apart from the frame that finalizes an utterance (`true`). After a final, **the next `Results` starts a brand-new utterance from an empty string** — so if you only ever overwrite your UI with the latest `transcript`, each new utterance erases the previous one. Show the interim frames as a live preview, then commit the text when `is_final` is `true` (the server also emits an `UtteranceEnd` boundary marker around the same point). Word-level timing (`channel.alternatives[0].words`, each entry with `word`/`start`/`end`/`confidence`) is populated only on the **final** frame (`is_final: true`); interim frames carry an empty `words` array. The `UtteranceEnd` marker also reports `last_word_end`. When the client stops sending audio, the connection closes cleanly with WebSocket close code `1000`. ## Supported source languages Pass any of the codes below as the `language` query parameter, or omit it to default to `en-us`. You can also pass the Languages enum name (`EN_US`) or its numeric ID. The model performs automatic language detection regardless of the value passed. | Code | Language | | :--------------- | :----------------------------------------------- | | `en-us` | English (United States) | | `af-za` | Afrikaans (South Africa) | | `am-et` | Amharic (Ethiopia) | | `ar-ae` | Arabic (United Arab Emirates) | | `ar-bh` | Arabic (Bahrain) | | `ar-dz` | Arabic (Algeria) | | `ar-eg` | Arabic (Egypt) | | `ar-iq` | Arabic (Iraq) | | `ar-jo` | Arabic (Jordan) | | `ar-kw` | Arabic (Kuwait) | | `ar-lb` | Arabic (Lebanon) | | `ar-ly` | Arabic (Libya) | | `ar-ma` | Arabic (Morocco) | | `ar-om` | Arabic (Oman) | | `ar-qa` | Arabic (Qatar) | | `ar-sa` | Arabic (Saudi Arabia) | | `ar-sy` | Arabic (Syria) | | `ar-tn` | Arabic (Tunisia) | | `ar-ye` | Arabic (Yemen) | | `az-az` | Azerbaijani (Latin, Azerbaijan) | | `bg-bg` | Bulgarian (Bulgaria) | | `bn-bd` | Bangla (Bangladesh) | | `bn-in` | Bengali (India) | | `bs-ba` | Bosnian (Bosnia And Herzegovina) | | `ca-es` | Catalan | | `cs-cz` | Czech (Czechia) | | `cy-gb` | Welsh (United Kingdom) | | `da-dk` | Danish (Denmark) | | `de-at` | German (Austria) | | `de-ch` | German (Switzerland) | | `de-de` | German (Germany) | | `el-gr` | Greek (Greece) | | `en-au` | English (Australia) | | `en-ca` | English (Canada) | | `en-gb` | English (United Kingdom) | | `en-hk` | English (Hong Kong Sar) | | `en-ie` | English (Ireland) | | `en-in` | English (India) | | `en-ke` | English (Kenya) | | `en-ng` | English (Nigeria) | | `en-nz` | English (New Zealand) | | `en-ph` | English (Philippines) | | `en-sg` | English (Singapore) | | `en-tz` | English (Tanzania) | | `en-za` | English (South Africa) | | `es-ar` | Spanish (Argentina) | | `es-bo` | Spanish (Bolivia) | | `es-cl` | Spanish (Chile) | | `es-co` | Spanish (Colombia) | | `es-cr` | Spanish (Costa Rica) | | `es-cu` | Spanish (Cuba) | | `es-do` | Spanish (Dominican Republic) | | `es-ec` | Spanish (Ecuador) | | `es-es` | Spanish (Spain) | | `es-gq` | Spanish (Equatorial Guinea) | | `es-gt` | Spanish (Guatemala) | | `es-hn` | Spanish (Honduras) | | `es-mx` | Spanish (Mexico) | | `es-ni` | Spanish (Nicaragua) | | `es-pa` | Spanish (Panama) | | `es-pe` | Spanish (Peru) | | `es-pr` | Spanish (Puerto Rico) | | `es-py` | Spanish (Paraguay) | | `es-sv` | Spanish (El Salvador) | | `es-us` | Spanish (United States) | | `es-uy` | Spanish (Uruguay) | | `es-ve` | Spanish (Venezuela) | | `et-ee` | Estonian (Estonia) | | `eu-es` | Basque | | `fa-ir` | Persian (Iran) | | `fi-fi` | Finnish (Finland) | | `fr-be` | French (Belgium) | | `fr-ca` | French (Canada) | | `fr-ch` | French (Switzerland) | | `fr-fr` | French (France) | | `gl-es` | Galician | | `gu-in` | Gujarati (India) | | `he-il` | Hebrew (Israel) | | `hi-in` | Hindi (India) | | `hr-hr` | Croatian (Croatia) | | `hu-hu` | Hungarian (Hungary) | | `hy-am` | Armenian (Armenia) | | `id-id` | Indonesian (Indonesia) | | `is-is` | Icelandic (Iceland) | | `it-it` | Italian (Italy) | | `ja-jp` | Japanese (Japan) | | `ka-ge` | Georgian (Georgia) | | `kk-kz` | Kazakh (Kazakhstan) | | `km-kh` | Khmer (Cambodia) | | `kn-in` | Kannada (India) | | `ko-kr` | Korean (Korea) | | `lo-la` | Lao (Laos) | | `lt-lt` | Lithuanian (Lithuania) | | `lv-lv` | Latvian (Latvia) | | `mk-mk` | Macedonian (North Macedonia) | | `ml-in` | Malayalam (India) | | `mn-mn` | Mongolian (Mongolia) | | `mr-in` | Marathi (India) | | `ms-my` | Malay (Malaysia) | | `mt-mt` | Maltese (Malta) | | `my-mm` | Burmese (Myanmar) | | `nb-no` | Norwegian (Bokmål, Norway) | | `ne-np` | Nepali (Nepal) | | `nl-be` | Dutch (Belgium) | | `nl-nl` | Dutch (Netherlands) | | `pa-in` | Punjabi (India) | | `pl-pl` | Polish (Poland) | | `ps-af` | Pashto (Afghanistan) | | `pt-br` | Portuguese (Brazil) | | `pt-pt` | Portuguese (Portugal) | | `ro-ro` | Romanian (Romania) | | `ru-ru` | Russian (Russia) | | `si-lk` | Sinhala (Sri Lanka) | | `sk-sk` | Slovak (Slovakia) | | `sl-si` | Slovenian (Slovenia) | | `so-so` | Somali (Somalia) | | `sq-al` | Albanian (Albania) | | `sr-rs` | Serbian (Cyrillic, Serbia) | | `su-id` | Sundanese (Indonesia) | | `sv-se` | Swedish (Sweden) | | `sw-ke` | Swahili (Kenya) | | `sw-tz` | Swahili (Tanzania) | | `ta-in` | Tamil (India) | | `ta-lk` | Tamil (Sri Lanka) | | `ta-my` | Tamil (Malaysia) | | `ta-sg` | Tamil (Singapore) | | `te-in` | Telugu (India) | | `th-th` | Thai (Thailand) | | `tl-ph` | Tagalog (Philippines) | | `tr-tr` | Turkish (Turkey) | | `uk-ua` | Ukrainian (Ukraine) | | `ur-in` | Urdu (India) | | `ur-pk` | Urdu (Pakistan) | | `uz-uz` | Uzbek (Latin, Uzbekistan) | | `vi-vn` | Vietnamese (Vietnam) | | `zh-cn` | Chinese (Mandarin, Simplified) | | `zh-cn-henan` | Chinese (Zhongyuan Mandarin Henan, Simplified) | | `zh-cn-liaoning` | Chinese (Northeastern Mandarin, Simplified) | | `zh-cn-shaanxi` | Chinese (Zhongyuan Mandarin Shaanxi, Simplified) | | `zh-cn-shandong` | Chinese (Jilu Mandarin, Simplified) | | `zh-cn-sichuan` | Chinese (Southwestern Mandarin, Simplified) | | `zh-hk` | Chinese (Cantonese, Traditional) | | `zh-tw` | Chinese (Taiwanese Mandarin, Traditional) | ## Sample Testing Script The CAMB SDKs wrap the protocol below behind a typed event dispatcher. The snippets here stream a WAV file at real-time pace so the server sees arrival patterns equivalent to a live microphone capture. For mic input, swap `FileAudioSource(...)` for `Microphone(...)` (Python) or `Microphone.fromBrowser` / `Microphone.fromNode` (TypeScript) — see the [Live Transcription tutorial](/tutorials/live-transcription-with-sdk). ```python Python theme={null} # pip install camb-sdk import asyncio import os import wave from camb.client import CambAI from camb.live_transcription import FileAudioSource, ServerMessageType async def main(audio_path: str = "sample.wav") -> None: with wave.open(audio_path, "rb") as wf: sample_rate, channels = wf.getframerate(), wf.getnchannels() client = CambAI(api_key=os.environ["CAMB_API_KEY"]) session = await client.live_transcription.connect( model="boli-v5", language="en-us", encoding="linear16", sample_rate=sample_rate, channels=channels, ) @session.on(ServerMessageType.READY) def _(_): print("Ready: streaming audio...") @session.on(ServerMessageType.RESULTS) def _(msg): text = msg.transcript.strip() if not text: return # Interim frames print as they arrive; commit the final on its own # line so the next utterance doesn't overwrite it. if not msg.is_final: print(f"[Interim] {text}\n", end="", flush=True) else: print(f"\r\033[K{text}\n", end="", flush=True) @session.on(ServerMessageType.CLOSED) def _(info): print(f"\nClosed: code={info.code}") async with session: await session.stream_audio(FileAudioSource(audio_path, real_time=True)) asyncio.run(main()) ``` ```typescript TypeScript theme={null} // npm install @camb-ai/sdk ws import fs from "node:fs"; import { CambClient, ServerMessageType } from "@camb-ai/sdk"; // Minimal WAV reader — returns { sampleRate, channels, bitsPerSample, pcm }. function readWav(path: string) { const buf = fs.readFileSync(path); let o = 12, sr = 0, ch = 0, bps = 0, dStart = -1, dLen = 0; while (o < buf.length - 8) { const id = buf.toString("ascii", o, o + 4); const size = buf.readUInt32LE(o + 4); if (id === "fmt ") { ch = buf.readUInt16LE(o + 10); sr = buf.readUInt32LE(o + 12); bps = buf.readUInt16LE(o + 22); } else if (id === "data") { dStart = o + 8; dLen = size; break; } o += 8 + size; } return { sampleRate: sr, channels: ch, bitsPerSample: bps, pcm: buf.subarray(dStart, dStart + dLen) }; } const { sampleRate, channels, bitsPerSample, pcm } = readWav("sample.wav"); const client = new CambClient({ apiKey: process.env.CAMB_API_KEY! }); const session = await client.liveTranscription.connect({ model: "boli-v5", language: "en-us", encoding: "linear16", sampleRate, channels, }); session.on(ServerMessageType.Ready, () => console.log("Ready: streaming audio...")); session.on(ServerMessageType.Results, (m) => { const text = m.transcript.trim(); if (!text) return; // Interim frames print as they arrive; commit the final on its own line. if (!m.isFinal) process.stdout.write(`[Interim] ${text}\n`); else process.stdout.write(`\r\x1b[K${text}\n`); }); session.on(ServerMessageType.Closed, (i) => console.log(`\nClosed: code=${i.code}`)); // Real-time-paced send so the server sees live arrival patterns. const bytesPerSec = sampleRate * channels * (bitsPerSample / 8); const chunk = Math.floor(bytesPerSec / 10); // 100 ms const t0 = Date.now(); let sent = 0; for (let i = 0; i < pcm.length; i += chunk) { await session.sendAudio(pcm.subarray(i, i + chunk)); sent += chunk; const drift = (sent / bytesPerSec) * 1000 - (Date.now() - t0); if (drift > 0) await new Promise((r) => setTimeout(r, drift)); } await session.close(); await session.waitUntilClosed(); ``` ### Timeout The Live Transcription API has an internal timeout of 1 hour. Please add retries to handle/create further connections. ### Raw protocol (no SDK) If you cannot use the SDKs, the wire protocol is small enough to drive directly. Open `wss://realtime.camb.ai/streaming-transcription/listen?...` with the `x-api-key` header, send binary PCM frames matching the `encoding` / `sample_rate` / `channels` query string, optionally send `{"type":"KeepAlive"}` during silence, and finish with `{"type":"CloseStream"}`. The server returns `{"type":"Ready"}` once, then `{"type":"Results", ...}` frames carrying the cumulative transcript (`"is_final": false` for interim refinements, `true` on the frame that finalizes each utterance), and closes with WebSocket code `1000` on a clean shutdown. ## AsyncAPI ````yaml api-reference/websockets/asyncapi.json listen id: listen title: Listen description: '' servers: - id: production protocol: wss host: realtime.camb.ai bindings: [] variables: - id: model description: Transcription model to use. defaultValue: boli-v5 allowedValues: - boli-v5 - boli-v5-transcribe examples: [] - id: language description: >- Source language hint. The dropdown lists every supported source language; you may also pass the Languages enum name (`EN_US`) or its numeric ID. Omit to use the default (`en-us`); the model also performs automatic language detection regardless of the value passed. defaultValue: en-us allowedValues: - en-us - af-za - am-et - ar-ae - ar-bh - ar-dz - ar-eg - ar-iq - ar-jo - ar-kw - ar-lb - ar-ly - ar-ma - ar-om - ar-qa - ar-sa - ar-sy - ar-tn - ar-ye - az-az - bg-bg - bn-bd - bn-in - bs-ba - ca-es - cs-cz - cy-gb - da-dk - de-at - de-ch - de-de - el-gr - en-au - en-ca - en-gb - en-hk - en-ie - en-in - en-ke - en-ng - en-nz - en-ph - en-sg - en-tz - en-za - es-ar - es-bo - es-cl - es-co - es-cr - es-cu - es-do - es-ec - es-es - es-gq - es-gt - es-hn - es-mx - es-ni - es-pa - es-pe - es-pr - es-py - es-sv - es-us - es-uy - es-ve - et-ee - eu-es - fa-ir - fi-fi - fr-be - fr-ca - fr-ch - fr-fr - gl-es - gu-in - he-il - hi-in - hr-hr - hu-hu - hy-am - id-id - is-is - it-it - ja-jp - ka-ge - kk-kz - km-kh - kn-in - ko-kr - lo-la - lt-lt - lv-lv - mk-mk - ml-in - mn-mn - mr-in - ms-my - mt-mt - my-mm - nb-no - ne-np - nl-be - nl-nl - pa-in - pl-pl - ps-af - pt-br - pt-pt - ro-ro - ru-ru - si-lk - sk-sk - sl-si - so-so - sq-al - sr-rs - su-id - sv-se - sw-ke - sw-tz - ta-in - ta-lk - ta-my - ta-sg - te-in - th-th - tl-ph - tr-tr - uk-ua - ur-in - ur-pk - uz-uz - vi-vn - zh-cn - zh-cn-henan - zh-cn-liaoning - zh-cn-shaanxi - zh-cn-shandong - zh-cn-sichuan - zh-hk - zh-tw examples: [] - id: encoding description: >- Audio encoding of the bytes you send. Supported: `linear16` (PCM16 LE), `linear32` (PCM32 LE), `alaw` (G.711 A-law), `mulaw` (G.711 µ-law). defaultValue: linear16 allowedValues: - linear16 - linear32 - alaw - mulaw examples: [] - id: sample_rate description: >- Sample rate (Hz) of the audio you send. The server resamples internally; any rate is accepted. defaultValue: '16000' allowedValues: [] examples: [] - id: channels description: >- Number of audio channels in the bytes you send. Multi-channel input is downmixed to mono server-side. defaultValue: '1' allowedValues: [] examples: [] address: /streaming-transcription/listen parameters: [] bindings: [] operations: - &ref_2 id: clientSendAudio title: Client send audio description: Client sends audio bytes and control messages type: send messages: - &ref_6 id: AudioChunk contentType: application/octet-stream payload: - type: string format: binary x-parser-schema-id: name: Binary Audio Frame description: Raw audio bytes in the encoding declared on the query string. headers: [] jsonPayloadSchema: type: string format: binary x-parser-schema-id: title: Binary Audio Frame description: Raw audio bytes in the encoding declared on the query string. example: '{}' bindings: [] extensions: - id: x-parser-unique-object-id value: AudioChunk - &ref_7 id: CloseStream contentType: application/json payload: - name: Close Stream description: Signal end of input. The server flushes and closes the connection. type: object properties: - name: type type: string description: CloseStream required: true headers: [] jsonPayloadSchema: type: object properties: type: type: string const: CloseStream x-parser-schema-id: required: - type x-parser-schema-id: title: Close Stream description: Signal end of input. The server flushes and closes the connection. example: |- { "type": "" } bindings: [] extensions: - id: x-parser-unique-object-id value: CloseStream - &ref_8 id: KeepAlive contentType: application/json payload: - name: Keep Alive description: Optional heartbeat. The server accepts and ignores the contents. type: object properties: - name: type type: string description: KeepAlive required: true headers: [] jsonPayloadSchema: type: object properties: type: type: string const: KeepAlive x-parser-schema-id: required: - type x-parser-schema-id: title: Keep Alive description: Optional heartbeat. The server accepts and ignores the contents. example: |- { "type": "" } bindings: [] extensions: - id: x-parser-unique-object-id value: KeepAlive bindings: [] extensions: &ref_0 - id: x-parser-unique-object-id value: listen - &ref_1 id: serverSendEvents title: Server send events description: >- Server sends a Ready event followed by interim transcripts, and may emit an Error event before closing on a failure. type: receive messages: - &ref_3 id: Ready contentType: application/json payload: - name: Server Ready description: >- Emitted once after the upstream transcription session is established. type: object properties: - name: type type: string description: Ready required: true headers: [] jsonPayloadSchema: type: object properties: type: type: string const: Ready x-parser-schema-id: required: - type x-parser-schema-id: title: Server Ready description: Emitted once after the upstream transcription session is established. example: |- { "type": "" } bindings: [] extensions: - id: x-parser-unique-object-id value: Ready - &ref_4 id: TranscriptResult contentType: application/json payload: - name: Interim Transcription Result description: >- Cumulative interim transcript. Each event carries the full transcript-so-far for the current utterance — update your UI by replacing the previous interim, not by concatenating. The current release emits interim results only (`is_final` is always `false`); when input stops, the connection closes cleanly with WebSocket code `1000`. type: object properties: - name: type type: string description: Results required: true - name: is_final type: boolean description: Always `false` in the current release. required: false - name: start type: number description: Seconds since session start at which this segment begins. required: false - name: duration type: number description: Segment duration in seconds. May be `0` for interim deltas. required: false - name: channel type: object required: true properties: - name: alternatives type: array required: false properties: - name: transcript type: string required: false - name: confidence type: number required: false - name: words type: array required: false properties: - name: word type: string required: false - name: start type: number required: false - name: end type: number required: false - name: confidence type: number required: false - name: metadata type: object required: false properties: - name: request_id type: string required: false - name: model_uuid type: string required: false - name: model_info type: object required: false properties: - name: name type: string required: false - name: version type: string required: false headers: [] jsonPayloadSchema: type: object properties: type: type: string const: Results x-parser-schema-id: is_final: type: boolean description: Always `false` in the current release. x-parser-schema-id: start: type: number description: Seconds since session start at which this segment begins. x-parser-schema-id: duration: type: number description: Segment duration in seconds. May be `0` for interim deltas. x-parser-schema-id: channel: type: object properties: alternatives: type: array items: type: object properties: transcript: type: string x-parser-schema-id: confidence: type: number format: float x-parser-schema-id: words: type: array items: type: object properties: word: type: string x-parser-schema-id: start: type: number x-parser-schema-id: end: type: number x-parser-schema-id: confidence: type: number x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: metadata: type: object properties: request_id: type: string x-parser-schema-id: model_uuid: type: string x-parser-schema-id: model_info: type: object properties: name: type: string x-parser-schema-id: version: type: string x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: required: - type - channel x-parser-schema-id: title: Interim Transcription Result description: >- Cumulative interim transcript. Each event carries the full transcript-so-far for the current utterance — update your UI by replacing the previous interim, not by concatenating. The current release emits interim results only (`is_final` is always `false`); when input stops, the connection closes cleanly with WebSocket code `1000`. example: No examples found bindings: [] extensions: - id: x-parser-unique-object-id value: TranscriptResult - &ref_5 id: ServerError contentType: application/json payload: - name: Server Error description: >- Emitted when the server cannot continue the session (for example: invalid query parameters, upstream model failure, or unsupported audio encoding). After emitting `Error`, the server closes the connection with a non-1000 WebSocket close code. type: object properties: - name: type type: string description: Error required: true - name: code type: string description: >- Stable, machine-readable error identifier (for example `invalid_encoding`, `model_unavailable`). required: false - name: message type: string description: Human-readable explanation safe to surface to end-users. required: true headers: [] jsonPayloadSchema: type: object properties: type: type: string const: Error x-parser-schema-id: code: type: string description: >- Stable, machine-readable error identifier (for example `invalid_encoding`, `model_unavailable`). x-parser-schema-id: message: type: string description: Human-readable explanation safe to surface to end-users. x-parser-schema-id: required: - type - message x-parser-schema-id: title: Server Error description: >- Emitted when the server cannot continue the session (for example: invalid query parameters, upstream model failure, or unsupported audio encoding). After emitting `Error`, the server closes the connection with a non-1000 WebSocket close code. example: |- { "type": "", "code": "", "message": "" } bindings: [] extensions: - id: x-parser-unique-object-id value: ServerError bindings: [] extensions: *ref_0 sendOperations: - *ref_1 receiveOperations: - *ref_2 sendMessages: - *ref_3 - *ref_4 - *ref_5 receiveMessages: - *ref_6 - *ref_7 - *ref_8 extensions: - id: x-parser-unique-object-id value: listen securitySchemes: [] ````