# Audio input

Send an audio clip to a chat model as a content part. The model answers in text. The exchange does not transcribe the clip for a model that cannot hear. Only an offer that declared audio input can win the job.

```json
{
  "role": "user",
  "content": [
    { "type": "text", "text": "what does the speaker ask for?" },
    { "type": "input_audio", "input_audio": { "data": "UklGR…", "format": "wav" } }
  ]
}
```

Audio is for Chat Completions only. The Messages API has no audio block.

## Examples

**Summarise a voice note.** Send a short recording and ask for the key points.

```json
{
  "role": "user",
  "content": [
    { "type": "text", "text": "Summarise this voice note in three bullet points." },
    { "type": "input_audio", "input_audio": { "data": "UklGR…", "format": "wav" } }
  ]
}
```

**Answer a spoken question.** Send the question as audio with no text. The model answers in text.

```json
{
  "role": "user",
  "content": [{ "type": "input_audio", "input_audio": { "data": "//uQxAAA…", "format": "mp3" } }]
}
```

To get the answer as audio, send the answer text to [Speech](https://inference.ai.exchange/docs/speech.md).

## Send audio

`data` is bare base64 or a `data:` URL. The exchange refuses a remote URL with `400 unsupported_content`.

| Field    | Meaning                           |
| -------- | --------------------------------- |
| `data`   | The bytes of the clip, in base64. |
| `format` | `wav`, `flac` or `mp3`.           |

An offer can accept fewer formats.

## Cost

The exchange reads the duration from the container header. It converts the duration to input tokens at 50 tokens for each second, unless the offer states its own table. The charge is the token count that the provider meters.

An offer can limit the length with `max_duration_seconds`, and the size with `max_bytes`.

## Troubleshooting

| Error                       | Cause                                   | Fix                                                |
| --------------------------- | --------------------------------------- | -------------------------------------------------- |
| `400 unsupported_parameter` | No offer for the model hears audio.     | Pick a model with `audio` in `input_modalities`.   |
| `400 unsupported_content`   | A URL, or a header that cannot be read. | Send the bytes as base64 in a supported container. |
| `413 request_too_large`     | The body is over 20 MB.                 | Send a shorter clip.                               |

To get the words of a clip, buy a transcript. See [Speech-to-text](https://inference.ai.exchange/docs/speech-to-text.md).

## Next steps

- [Modalities](https://inference.ai.exchange/docs/modalities.md): the map of all modalities.
- [Speech](https://inference.ai.exchange/docs/speech.md): make spoken audio.