> ## Documentation Index
> Fetch the complete documentation index at: https://docs.spatialreal.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Audio Format and Sample Rate

> Audio input format requirements and sample rate configuration across platforms.

SpatialReal services accept **mono 16-bit PCM (`s16le`)** audio. The sample rate is configured at SDK initialization and must match the audio your application sends.

## Audio Input Requirements

| Property     | Value                                                               |
| ------------ | ------------------------------------------------------------------- |
| Sample Rate  | One of `8000`, `16000`, `22050`, `24000`, `32000`, `44100`, `48000` |
| Channels     | `1` (mono)                                                          |
| Bit Depth    | `16-bit`                                                            |
| Format       | Raw PCM bytes                                                       |
| PCM Encoding | `s16le`                                                             |

<Note>
  If your source audio uses stereo channels, floating point samples, compressed codecs, or an unsupported sample rate, convert it before sending it to SpatialReal.
</Note>

## What Is [`s16le`](https://trac.ffmpeg.org/wiki/audio%20types)?

* `s16` means each audio sample is a signed 16-bit integer.
* `le` means the bytes are stored in little-endian order.
* `mono` means the stream contains a single channel only.

## Supported Sample Rates

| Sample Rate | Common Use Case                                |
| ----------- | ---------------------------------------------- |
| `8000` Hz   | Telephony, low-bandwidth voice                 |
| `16000` Hz  | Speech recognition, voice assistants (default) |
| `22050` Hz  | Low-quality speech synthesis                   |
| `24000` Hz  | Common TTS output (OpenAI, ElevenLabs)         |
| `32000` Hz  | Wideband audio                                 |
| `44100` Hz  | CD-quality audio                               |
| `48000` Hz  | Professional audio, WebRTC default             |

<Warning>
  Sending audio at a sample rate that doesn't match your SDK configuration will produce distorted or silent playback. Always ensure the configured rate matches your audio source.
</Warning>

## How to Choose a Sample Rate

* Use `16000` Hz (default) for most speech-driven integrations — it balances quality and bandwidth well.
* Match your TTS provider's native output rate to avoid resampling. For example, many TTS services output at `24000` Hz.
* In RTC Mode, the sample rate is typically governed by the RTC framework (e.g., LiveKit defaults to `48000` Hz).

<Note>
  The sample rate only affects audio sent to the driving service. The avatar's rendered animation quality is independent of sample rate.
</Note>

## Configuration

Set the sample rate when initializing the client-side SDK through the `AudioFormat` parameter.

<Tabs>
  <Tab title="Web">
    ```typescript theme={null}
    await AvatarSDK.initialize({
      appId: 'YOUR_APP_ID',
      audioFormat: { channelCount: 1, sampleRate: 16000 },
      // ...
    });
    ```
  </Tab>

  <Tab title="iOS">
    ```swift theme={null}
    AvatarSDK.initialize(
        appID: "YOUR_APP_ID",
        configuration: Configuration(
            environment: .intl,
            audioFormat: AudioFormat(sampleRate: 16000),
            drivingServiceMode: .sdk,
            logLevel: .warning
        )
    )
    ```
  </Tab>

  <Tab title="Android">
    ```kotlin theme={null}
    AvatarSDK.initialize(
        context = applicationContext,
        appId = "YOUR_APP_ID",
        configuration = Configuration(
            environment = Environment.Intl,
            audioFormat = AudioFormat(16000),
            drivingServiceMode = DrivingServiceMode.SDK,
            logLevel = LogLevel.INFO
        )
    )
    ```
  </Tab>
</Tabs>

## Before Sending Audio

Before sending audio to the SDK or service, make sure your pipeline outputs:

* a supported sample rate
* mono audio
* 16-bit signed PCM samples
* raw PCM bytes rather than WAV headers or compressed audio frames

For a practical overview of common audio encodings and container formats, see the [FFmpeg audio types reference](https://trac.ffmpeg.org/wiki/audio%20types).