> **Experimental**
>
> `@aws-cdk/aws-medialive-alpha` is an [**experimental**](/stability) (alpha) package: its API may change in any release, without a major version bump.
# AncillaryCaptionSourceOptions

Options for an ancillary caption source.

- Stability: [Experimental](/cdk/api/stability.html)
- Source: [`lib/caption-selector.ts`](https://github.com/aws/aws-cdk/blob/v2.274.0-alpha.0/packages/@aws-cdk/aws-medialive-alpha/lib/caption-selector.ts#L103)

## Example

```ts
// The code below shows an example of how to instantiate this type.
// The values are placeholders you should change.
import * as medialive_alpha from '@aws-cdk/aws-medialive-alpha';
const ancillaryCaptionSourceOptions: medialive_alpha.AncillaryCaptionSourceOptions = {
  sourceChannelNumber: 123,
};
```

## Properties

- `sourceChannelNumber`: number — The captions channel (1-4) to extract from the ancillary captions.

  **Default:** MediaLive ignores the channel (passthrough)

  Required when
  converting to another caption format; ignored when passing through as embedded.