nips/29.md

NIP-29

Media Attachments

Media attachments (images, videos, and other files) may be added to events by including a URL in the event content, along with a matching imeta tag.

imeta ("inline metadata") tags add information about media URLs in the event's content. Each imeta tag SHOULD match a URL in the event content. Clients may replace imeta URLs with rich previews. imeta tags contain extra information about the media attachment, which clients can use to provide a better experience when loading previews.

The imeta tag is variadic, and each entry is a space-delimited key/value pair. Each imeta tag MUST have a url, and at least one other field. imeta may include any field specified by NIP 94. There SHOULD be only one imeta tag per url.

Example

{
  "content": "More image metadata tests don’t mind me https://nostr.build/i/my-image.jpg",
  "kind": 1,
  "tags": [
    [
      "imeta",
      "url https://nostr.build/i/my-image.jpg",
      "m image/jpeg",
      "blurhash eVF$^OI:${M{o#*0-nNFxakD-?xVM}WEWB%iNKxvR-oetmo#R-aen$",
      "dim 3024x4032",
      "alt A scenic photo overlooking the coast of Costa Rica",
      "x <sha256 hash as specified in NIP 94>",
      "fallback https://nostrcheck.me/alt1.jpg"
      "fallback https://void.cat/alt1.jpg"
    ]
  ]
}

Recommended client behavior

When uploading images during a new post, clients MAY include this metadata after the image is uploaded and included in the post.

When pasting urls during post composition, the client MAY download the image and add this metadata before the post is sent.