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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
```json
{
"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"
]
]
}
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