NIP-A0

Voice Messages

Status: Draft

This NIP defines new events kind: 1222 for root messages and kind: 1244 for reply messages to be used for short voice messages, typically up to 60 seconds in length.

Specification

Event Kind 1222 and Kind 1244

The kind: 1222 event is defined as follows:

• content: MUST be a URL pointing directly to an audio file.
  • The audio file SHOULD be in audio/mp4 (.m4a) format using AAC or Opus encoding. Clients MAY support other common audio formats like audio/ogg, audio/webm, or audio/mpeg (mp3), but audio/mp4 is recommended for broad compatibility and efficiency.
  • The audio duration SHOULD be no longer than 60 seconds. Clients publishing kind: 1222 events SHOULD enforce this limit or provide a clear warning to the user if exceeded.
• tags:
  • Tags MAY be included as per other NIPs (e.g., t for hashtags, g for geohash, etc.).

The kind: 1244 event is defined as follows:

• To be used for replies, kind: 1244 events MUST follow the structure of NIP-22.
• content: MUST be a URL pointing directly to an audio file.
  • The audio file SHOULD be in audio/mp4 (.m4a) format using AAC or Opus encoding. Clients MAY support other common audio formats like audio/ogg, audio/webm, or audio/mpeg (mp3), but audio/mp4 is recommended for broad compatibility and efficiency.
  • The audio duration SHOULD be no longer than 60 seconds. Clients publishing kind: 1222 events SHOULD enforce this limit or provide a clear warning to the user if exceeded.
• tags:
  • Tags MAY be included as per other NIPs (e.g., t for hashtags, g for geohash, etc.).

Visual representation with imeta (NIP-92) tag (optional)

The following imeta (NIP-92) tags MAY be included so clients can render a visual preview without having to download the audio file first:

• waveform: amplitude values over time, space separated full integers, less than 100 values should be enough to render a nice visual
• duration: audio length in seconds

Examples

Root Voice Message Example

{
  "content": "https://blossom.primal.net/5fe7df0e46ee6b14b5a8b8b92939e84e3ca5e3950eb630299742325d5ed9891b.mp4",
  "created_at": 1752501052,
  "id": "...",
  "kind": 1222,
  "pubkey": "...",
  "sig": "...",
  "tags": [
    [
      "imeta",
      "url https://blossom.primal.net/5fe7df0e46ee6b14b5a8b8b92939e84e3ca5e3950eb630299742325d5ed9891b.mp4",
      "waveform 0 7 35 8 100 100 49 8 4 16 8 10 7 2 20 10 100 100 100 100 100 100 15 100 100 100 25 60 5 4 3 1 0 100 100 15 100 29 88 0 33 11 39 100 100 19 4 100 42 35 5 0 1 5 0 0 11 38 100 94 17 11 44 58 5 100 100 100 55 14 72 100 100 57 6 1 14 2 16 100 100 40 16 100 100 6 32 14 13 41 36 16 14 6 3 0 1 2 1 6 0",
      "duration 8"
    ]
  ]
}