NIP-61
======

Danmaku
-------

`draft` `optional`

This NIP defines a new kind of event, `2333`, for danmaku.

Danmaku is a subtitle system in online videos where users post comments synchronized with the video timeline. It's also used in music, podcasts, and other media.

### Format

The format uses a regular event kind `2333`.

The `.content` of these events is the content of the danmaku comment.

The list of tags are as follows:
* `i` (required) universally unique identifier of the video. The format is `<platform (lowercase)>:<identity>` where `<platform>` is the platform of the video and `<identity>` is the unique identifier of the video on that platform. For example, a YouTube video with the identifier `aA-jiiepOrE` would have the identifier `youtube:aA-jiiepOrE`.
* `time` (required) the time of the video when the danmaku comment is sent in seconds.
* `duration` (optional) the duration of the danmaku comment shown in seconds.
* `speed` (optional) the speed of the danmaku comment in pixels per second.
* `color` (optional) the color of the danmaku comment in hexadecimal format.
* `mode` (optional) the display mode of the danmaku comment. The following values are possible:
  * `rtl` the danmaku comment scrolls from right to left.
  * `top` the danmaku comment is displayed at the top of the screen.
  * `bottom` the danmaku comment is displayed at the bottom of the screen.

Any other styling tags are allowed. And, client implementations should ignore any tags they do not understand.

### Example

```jsonc
{
  "id": "<...>",
  "pubkey": "<...>",
  "kind": 2333,
  "tags": [
    ["i", "youtube:aA-jiiepOrE"],
    ["time", "3.018597"],
    ["color", "#FFFFFF"],
    ["mode", "rtl"]
  ],
  "content": "Hello Nostr!",
  "sig": "<...>",
  "created_at": 1713368851
}
```