# Translation

<Note type="warning">Speech translation is an experimental feature.</Note>

The AI SDK provides the
[`experimental_streamTranslate`](/docs/reference/ai-sdk-core/stream-translate)
function to translate live speech into another language. Translation is a
streaming-only modality: models translate live source audio into
target-language audio and text.

`experimental_streamTranslate` is built on the speech translation model
specification (`Experimental_SpeechTranslationModelV4`).

<Note>
  Provider implementations of the speech translation model specification ship
  separately. Pass any model instance that implements
  `Experimental_SpeechTranslationModelV4` — see your provider's documentation
  for available translation models.
</Note>

```ts
import { experimental_streamTranslate as streamTranslate } from 'ai';

const result = streamTranslate({
  // any provider model instance that implements the experimental
  // speech translation model specification (Experimental_SpeechTranslationModelV4):
  model: translationModel,
  audio: audioStream, // ReadableStream<Uint8Array | string>
  inputAudioFormat: { type: 'audio/pcm', rate: 24000 },
  targetLanguage: 'es',
});

for await (const part of result.fullStream) {
  if (part.type === 'output-text-delta') {
    process.stdout.write(part.delta);
  }

  if (part.type === 'audio') {
    // translated audio chunk (Uint8Array or base64 string)
  }

  if (part.type === 'source-transcript-final') {
    console.log('source:', part.text);
  }
}

console.log(await result.translationText);
```

The `audio` stream must contain raw audio chunks. `Uint8Array` chunks are raw
bytes; `string` chunks are base64-encoded raw bytes. Always set
`inputAudioFormat` to match the chunks you send.

`targetLanguage` (and the optional `sourceLanguage`) are BCP-47-style language
tags (e.g. `en`, `es`, `fr-CA`). Supported values are provider-specific and
validated by the provider.

When `sourceLanguage` is absent, providers auto-detect the source language.

`fullStream` is a single-consumer live stream and can only be accessed once.
When you need both stream parts and final results, access `fullStream` first and
await the result promises while or after consuming it. Accessing a result
promise first consumes the stream internally, so `fullStream` is no longer
available. This avoids retaining an unbounded replay buffer for live audio.

To access the final translation metadata:

```ts
const sourceText = await result.sourceText; // final source-language transcript
const translationText = await result.translationText; // final translated text
const durationInSeconds = await result.durationInSeconds; // duration of the source audio in seconds, if available
const usage = await result.usage; // audio/text token usage, if reported
```

A translation stream is considered successful when at least one `audio` part
was emitted or the final output text is non-empty. For providers that produce
only audio output, `translationText` may resolve to an empty string.

## Stream parts

The `fullStream` yields the following part types:

- `audio`: a translated audio chunk in the target language.
- `output-text-delta`: an append-only translated text delta.
- `output-text-final`: final translated text for a provider-defined segment or
  utterance.
- `source-transcript-delta`: an append-only source transcript delta.
- `source-transcript-partial`: non-final source transcript text that may be
  revised by later parts.
- `source-transcript-final`: final source transcript text for a
  provider-defined segment or utterance.
- `raw`: raw provider chunks when `includeRawChunks` is enabled.
- `error`: stream errors.

Output text is append-only: providers stream `output-text-delta` parts and
finalize per-utterance with `output-text-final`. There is no partial/revision
part for output text by design for now.

## Settings

### Output audio format

Use `outputAudioFormat` to request a specific audio format for translated
audio chunks. When absent, the provider default output format is used.

```ts highlight="6"
import { experimental_streamTranslate as streamTranslate } from 'ai';

const result = streamTranslate({
  model: translationModel,
  audio: audioStream,
  inputAudioFormat: { type: 'audio/pcm', rate: 24000 },
  outputAudioFormat: { type: 'audio/pcm', rate: 24000 },
  targetLanguage: 'es',
});
```

### Provider-Specific settings

Translation models often have provider or model-specific settings which you can
set using the `providerOptions` parameter.

```ts highlight="8-12"
import { experimental_streamTranslate as streamTranslate } from 'ai';

const result = streamTranslate({
  model: translationModel,
  audio: audioStream,
  inputAudioFormat: { type: 'audio/pcm', rate: 24000 },
  targetLanguage: 'es',
  providerOptions: {
    'provider-name': {
      // provider-specific options
    },
  },
});
```

### Abort Signals

Pass an `abortSignal` to cancel the translation:

```ts highlight="8"
import { experimental_streamTranslate as streamTranslate } from 'ai';

const result = streamTranslate({
  model: translationModel,
  audio: audioStream,
  inputAudioFormat: { type: 'audio/pcm', rate: 24000 },
  targetLanguage: 'es',
  abortSignal: AbortSignal.timeout(60_000), // abort after 1 minute
});
```

### Error Handling

When `experimental_streamTranslate` cannot produce a translation — no `audio`
part was emitted and the final output text is empty, or the stream ends
without a finish event — it errors with a
[`AI_NoTranslationGeneratedError`](/docs/reference/ai-sdk-errors/ai-no-translation-generated-error).

The error preserves the following information to help you log the issue:

- `response`: Metadata about the speech translation model response, including
  timestamp, model, and headers.
- `cause`: The cause of the error. You can use this for more detailed error
  handling.

```ts
import {
  experimental_streamTranslate as streamTranslate,
  NoTranslationGeneratedError,
} from 'ai';

try {
  const result = streamTranslate({
    model: translationModel,
    audio: audioStream,
    inputAudioFormat: { type: 'audio/pcm', rate: 24000 },
    targetLanguage: 'es',
  });

  console.log(await result.translationText);
} catch (error) {
  if (NoTranslationGeneratedError.isInstance(error)) {
    console.log('NoTranslationGeneratedError');
    console.log('Cause:', error.cause);
    console.log('Response:', error.response);
  }
}
```


## Navigation

- [Overview](/docs/ai-sdk-core/overview)
- [Generating Text](/docs/ai-sdk-core/generating-text)
- [Generating Structured Data](/docs/ai-sdk-core/generating-structured-data)
- [Tool Calling](/docs/ai-sdk-core/tools-and-tool-calling)
- [Model Context Protocol (MCP)](/docs/ai-sdk-core/mcp-tools)
- [MCP Apps](/docs/ai-sdk-core/mcp-apps)
- [Runtime and Tool Context](/docs/ai-sdk-core/runtime-and-tool-context)
- [Prompt Engineering](/docs/ai-sdk-core/prompt-engineering)
- [Settings](/docs/ai-sdk-core/settings)
- [Reasoning](/docs/ai-sdk-core/reasoning)
- [Embeddings](/docs/ai-sdk-core/embeddings)
- [Reranking](/docs/ai-sdk-core/reranking)
- [Image Generation](/docs/ai-sdk-core/image-generation)
- [Realtime](/docs/ai-sdk-core/realtime)
- [Transcription](/docs/ai-sdk-core/transcription)
- [Translation](/docs/ai-sdk-core/translation)
- [Speech](/docs/ai-sdk-core/speech)
- [Video Generation](/docs/ai-sdk-core/video-generation)
- [File Uploads](/docs/ai-sdk-core/file-uploads)
- [Language Model Middleware](/docs/ai-sdk-core/middleware)
- [Skill Uploads](/docs/ai-sdk-core/skill-uploads)
- [Provider & Model Management](/docs/ai-sdk-core/provider-management)
- [Error Handling](/docs/ai-sdk-core/error-handling)
- [Testing](/docs/ai-sdk-core/testing)
- [Telemetry](/docs/ai-sdk-core/telemetry)
- [DevTools](/docs/ai-sdk-core/devtools)
- [Lifecycle Callbacks](/docs/ai-sdk-core/lifecycle-callbacks)


[Full Sitemap](/sitemap.md)