# `SubtitleCue`

A timed caption: when it starts and ends, and its text.

Use it for subtitles, as WebVTT holds them.

## Shape

| Field | Type | Required? |
|---|---|---|
| `start` | [`Duration`](/docs/types/type-duration.md) | Yes |
| `end` | [`Duration`](/docs/types/type-duration.md) | Yes |
| `text` | `Text` | Yes |

Its parts keep these rules, and a value that breaks one fails with the rule's name:

- `start_not_negative`: start >= 0ms
- `end_after_start`: end > start
- `text_without_arrow`: text holds no `-->`

## Example

```jadpo
SubtitleCue { start: 1s end: 4s text: "Never drink liquid nitrogen." }
```

`text.parse(raw, as: SubtitleCue)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `00:00:01.000 --> 00:00:04.000`.

## Good to know

- Times count from the start of the media. The end must be after the start, and the text can't hold `-->`.
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it, so sort by one of its parts instead.

## In JSON

An object of its parts, in a request, a response or `json.write`:

```json
{"start":"PT1S","end":"PT4S","text":"Never drink liquid nitrogen."}
{"start":"PT1M5.25S","end":"PT1M7.5S","text":"— It will perforate your stomach.\n— You could die."}
{"start":"PT100H","end":"PT100H0.001S","text":"End"}
```

## Details

<details>
<summary>Text form, storage, how it is shown, and operations</summary>

`SubtitleCue` is in the group Media and visual, and has been in Jadpo since 0.1.0.

### Text form

`text.from` writes one standard text form, the same form `text.parse` reads back: `00:00:01.000 --> 00:00:04.000\nNever drink liquid nitrogen.`, `00:01:05.250 --> 00:01:07.500\n— It will perforate your stomach.\n— You could die.` and `100:00:00.000 --> 100:00:00.001\nEnd`.

### How it is stored

It is stored in 3 columns, each named for the field, `_` and its suffix. This is `00:01:05.250 --> 00:01:07.500\n— It will perforate your stomach.\n— You could die.`:

| Column | Type | Holds |
|---|---|---|
| `<field>_start` | `bigint` | `65250` |
| `<field>_end` | `bigint` | `67500` |
| `<field>_text` | `text` | `E'— It will perforate your stomach.\n— You could die.'` |

### How it is shown to people

`text.format(value, locale:)` shows it to people in their locale.

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `"00:00:01.000 --> 00:00:04.000\nNever drink liquid nitrogen."` | `"00:00:01.000 --> 00:00:04.000\nNever drink liquid nitrogen."` |
| `"00:01:05.250 --> 00:01:07.500\n— It will perforate your stomach.\n— You could die."` | `"00:01:05.250 --> 00:01:07.500\n— It will perforate your stomach.\n— You could die."` |
| `"100:00:00.000 --> 100:00:00.001\nEnd"` | `"100:00:00.000 --> 100:00:00.001\nEnd"` |

### Operations

It also takes `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. [How every standard type behaves](/docs/every-standard-type-meets-one-contract.md) says how they work.

</details>