# Live Captions card

> Canonical HTML: https://screenrig.ai/docs/cards/live-captions/

Rolling supplied captions with optional translated text.

Timed transcript snapshots appear with speaker labels, interim and final revisions, and translations supplied in the selected language. Later revisions replace earlier text, while long captions retain their latest words. Old or expired transcript content clears, with updates delivered via existing card-data updates. In Primetime, a gentle entrance and slow waveform linework accompany captions without compromising readability.

## Live card

This card is drawn in your browser by the same code the Players run, with sample data.

Category: Messages. Tags: Events and venues, Schools and campuses, News and announcements.

## Layouts

This fullscreen card fills the whole screen in landscape or portrait and is not placed as a corner, chip, or strip.

Layouts: full. Forms: landscape, portrait.

[Card layouts, themes and publishing](/docs/cards/). [Browse the cards](/apps/#cards).

## Data and privacy

This card uses its configured properties and live card data.

Supplied speech transcripts; use an appropriate destination and audience for the transcript. Expired and stale snapshots clear their displayed text.

## Properties

For theme, background, accent and position, see [Common properties](/docs/cards/#common-properties).

Set static properties in `params`. Bind `data` to a project card data key for live values; that document holds only dynamic properties. Without a data key, put the complete configuration in `params`. Nested rows describe the contents of their parent property.

### Static properties

| Name | Type | Default | Values and limits | Description |
| --- | --- | --- | --- | --- |
| `title` | string | `"Live captions"` | maxLength: `100` |  |
| `displayLanguage` | string | `""` | maxLength: `35` |  |
| `translationFallback` | string | `"source"` | `"source"`, `"hide"` |  |
| `lines` | integer | `3` | minimum: `1`; maximum: `4` |  |
| `historySeconds` | integer | `12` | minimum: `3`; maximum: `60` |  |
| `staleSeconds` | integer | `15` | minimum: `3`; maximum: `120` |  |
| `defaultDurationSeconds` | integer | `5` | minimum: `1`; maximum: `30` |  |
| `maxCharsPerCaption` | integer | `160` | minimum: `40`; maximum: `300` |  |

### Dynamic properties

| Name | Type | Default | Values and limits | Description |
| --- | --- | --- | --- | --- |
| `session` | object, null | `null` | additionalProperties: `false` | One supplied transcript snapshot. Existing card-data change delivery refreshes it; the card does not capture audio or generate translations. |
| `session.id` | string |  | minLength: `1`; maxLength: `100`; Required |  |
| `session.updatedAt` | string |  | maxLength: `64`; Required |  |
| `session.endedAt` | string | `""` | maxLength: `64` |  |
| `session.language` | string | `""` | maxLength: `35` |  |
| `session.segments` | array |  | maxItems: `100`; Required |  |
| `session.segments[].id` | string |  | minLength: `1`; maxLength: `80`; Required |  |
| `session.segments[].start` | string |  | maxLength: `64`; Required |  |
| `session.segments[].end` | string | `""` | maxLength: `64` |  |
| `session.segments[].text` | string |  | maxLength: `2000`; Required |  |
| `session.segments[].speaker` | string | `""` | maxLength: `60` |  |
| `session.segments[].language` | string | `""` | maxLength: `35` |  |
| `session.segments[].revision` | integer | `0` | minimum: `0`; maximum: `1000000` |  |
| `session.segments[].final` | boolean | `true` |  |  |
| `session.segments[].translations` | array | `[]` | maxItems: `8` |  |
| `session.segments[].translations[].language` | string |  | minLength: `1`; maxLength: `35`; Required |  |
| `session.segments[].translations[].text` | string |  | maxLength: `2000`; Required |  |

## Canvas example

Add this item to a playlist page’s `primitives`. [Publish the playlist and assign a screen](/docs/cards/#publish-a-card-canvas).

```json
{
  "id": "live-captions",
  "primitive": "card",
  "card": "live-captions",
  "major": 1,
  "params": {
    "theme": "neomustard"
  },
  "rect": {
    "x": 0,
    "y": 0,
    "width": 1920,
    "height": 1080
  },
  "layer": 0,
  "content_fit": "fill",
  "data": "example-key"
}
```

## Write live data

The canvas example binds its `data` field to `example-key`. That value is a data key: a name this canvas item chooses, not the name of the card. Give each canvas item its own key when items should show different data, or share one key when they should show the same data. Keys are scoped to the project, follow the K/V key grammar, and cannot start with `feed:`.

Create this document before showing the card, then replace it to update the screen without republishing. Writes to a key that live canvas items bind are checked against each bound card’s dynamic properties. Use the same project as the playlist.

Save the document as `card-data.json`. The CLI reads the document itself, with no wrapper:

```json
{
  "session": null
}
```

```console
screenrig card-data put example-key --file card-data.json
```

Or call the API directly. The API wraps the same document in a `document` field. An agent token already names its project, so no project header is sent; if you send `ScreenRig-Project`, it must match the token’s project. Supply your API authorization through the environment; see [API authentication](/docs/authentication/).

```console
curl --request PUT "https://api.screenrig.ai/api/card-data/example-key" \
  --header "Authorization: Bearer $SCREENRIG_TOKEN" \
  --header "Content-Type: application/json" \
  --data '{"document":{"session":null}}'
```