How to make the json for an mp3 Metaplex programmable NFT

Question

What information would I put in a Metaplex programmable NFT's json if I wanted to make a music nft? Where should I put the link to the mp3 file and what can I leave unfilled out?

I have a current implementation based on these docs: https://docs.metaplex.com/programs/token-metadata/token-standard#token-standards

Here's what I have right now with some questions commented for specific fields:

{
    "name": "song name",
    "symbol": "SONGSYMBOL",
    "description": "song genre, posting date, etc.",
    "image": "URI to image",
    "animation_url": "URI to asset's animation",  // what's this?
    "external_url": "URI to external URL defininig asset",  // Would this just be a URL to my website?
    "attributes": [],
    "properties": {
        "files": [
          {
            "uri": "https://www.arweave.net/abcd5678?ext=png",   // what's the difference between this image and teh image above?
            "type": "image/png"
          },
          {
            "uri": "https://watch.videodelivery.net/9876jkl",   // what is this?
            "type": "unknown",
            "cdn": true
          },
          {
            "uri": "https://www.arweave.net/efgh1234?ext=mp4",  // what would I replace this with to make it an mp3?
            "type": "video/mp4"
          }
        ],
        "category": "video",
      }
}

Answer 1

For music NFTs, I'd include your .mp3 in the animation_url per Metaplex docs.

I'd probably add these song genre, posting date, etc. as attributes, e.g.:

    "attributes": [
        {
            "trait_type": "Genre",
            "value": "YOUR_GENRE"
        },
        {
            "trait_type": "Artist",
            "value": "YOUR_NAME"
        },
        {
            "trait_type": "Posting Date",
            "value": "2023-02-16"
        },
        {
            "trait_type": "License",
            "value": "Exclusive"
        }
    ],

And again in your files:

    "properties": {
        "files": [
            {
                "type": "audio/mp3",
                "uri": "YOUR_MP3"
            },
            {
                "type": "image/png",
                "uri": "URI_OF_A_COMPLIMENTARY_IMG"
            }
        ],
        "category": "audio",

    },

And yes, external_url is your website.

fully metadata would look something like this:

{
    "name": "YOURSONG_NAME",
    "symbol": "SONG",
    "description": "some description",
    "seller_fee_basis_points": 100,
    "external_url": "https://YOUR_WEBSITE",
    "attributes": [
        {
            "trait_type": "Genre",
            "value": "YOUR_GENRE"
        },
        {
            "trait_type": "Artist",
            "value": "YOUR_NAME"
        },
        {
            "trait_type": "Posting Date",
            "value": "2023-02-16"
        },
        {
            "trait_type": "License",
            "value": "Exclusive"
        }
    ],
    "animation_url": "URI_TO_YOUR_MP3",
    "image": "IMG_EG_ALBUM_ART",
    "properties": {
        "files": [
            {
                "type": "audio/mp3",
                "uri": "YOUR_MP3"
            },
            {
                "type": "image/png",
                "uri": "URI_OF_A_COMPLIMENTARY_IMG"
            }
        ],
        "category": "audio"
    }
}

FWIW, I don't think there's anything special here in the metadata re: programmable vs standard NFT. Examples of both here.