Factory contract

Factory is the song registry and ERC-721 contract. The wallet calling mintSong becomes both the recorded creator and the first token owner.

Mint an original

mintSong(uint256 licenseAmount, uint256 licensePrice,
    uint256 streamPrice, bool remixable, string metadataUri)
    returns (uint256 songId)

Input	Meaning
`licenseAmount`	Number of licenses available. Zero means none are available for purchase.
`licensePrice`	Price for one ongoing license, in the settlement token’s atomic units.
`streamPrice`	Stored playback rate. Setting it does not collect playback payments.
`remixable`	Whether the original permits licensed variations.
`metadataUri`	Nonempty URI for the song’s metadata. Use your final `ipfs://` URI.

Connect and read

Use publicClient, walletClient, account and evmContracts from Contracts stack. This ABI includes only the calls and event used below:

import { parseAbi, parseEventLogs } from 'viem';

const factoryAbi = parseAbi([
  'function getSong(uint256 songId) view returns ((uint256 licenseAmount, uint256 licensePrice, uint256 streamPrice, address creator, bool remixable, bool isRemix, uint256 parentSongId, string metadataUri) song)',
  'function mintSong(uint256 licenseAmount, uint256 licensePrice, uint256 streamPrice, bool remixable, string metadataUri) returns (uint256 songId)',
  'event SongMinted(uint256 indexed songId, address indexed creator, uint256 licenseAmount, uint256 licensePrice, uint256 streamPrice, bool remixable, string metadataUri)',
]);
const song = await publicClient.readContract({
  address: evmContracts.factory, abi: factoryAbi,
  functionName: 'getSong', args: [1n], // An existing ID on this deployment.
});
console.log(song.creator, song.licensePrice, song.metadataUri);

getSong returns fields in this order: licenseAmount, licensePrice, streamPrice, creator, remixable, isRemix, parentSongId, metadataUri. An original has isRemix = false and parentSongId = 0. The following call mints 20 licenses priced at 5 USDC each and a stored rate of 0.01 USDC. Set metadataUri to your final published URI:

const { request } = await publicClient.simulateContract({
  address: evmContracts.factory, abi: factoryAbi, account,
  functionName: 'mintSong',
  args: [20n, 5_000_000n, 10_000n, true, metadataUri],
});
const hash = await walletClient.writeContract(request);
// Store hash in your product before waiting for confirmation.
const receipt = await publicClient.waitForTransactionReceipt({ hash });
if (receipt.status !== 'success') throw new Error('Mint failed');

Confirm the minted song

The transaction hash and song ID are different values. Decode the Factory’s SongMinted event from the successful receipt:

const mints = parseEventLogs({ abi: factoryAbi, eventName: 'SongMinted',
  logs: receipt.logs.filter(log =>
    log.address.toLowerCase() === evmContracts.factory.toLowerCase()),
}).filter(event => event.args.creator.toLowerCase() === account.toLowerCase()
  && event.args.metadataUri === metadataUri);
if (mints.length !== 1) throw new Error('Expected one matching mint');
const mintedId = mints[0].args.songId;

Read getSong(mintedId) and confirm its creator, URI, isRemix = false and parentSongId = 0 before recording it in your catalog. If receipt confirmation was interrupted, recover the saved hash before submitting another mint.

Reads and creator updates

Call	Result or permission
`getSong(songId)`	Song terms and provenance. Reverts if absent.
`songExists(songId)`	Whether the song exists.
`getLicenseAmount(songId)`	Remaining allocation.
`getSongCreator(songId)`	Recorded creator.
`hasLicense(songId, user)`	Whether this address holds ongoing rights.
`canRemix(songId)`	Original is remixable and has allocation left. This checks availability, not the caller’s purchased rights.
`totalSongs()`	Number of minted songs. IDs start at 1.
`tokenURI(songId)`	Metadata URI.
`ownerOf`, `balanceOf`, `approve`, `getApproved`, `setApprovalForAll`, `isApprovedForAll`, `transferFrom`, `safeTransferFrom`	Standard ERC-721 ownership, approvals and transfers.
`supportsInterface(interfaceId)`, `name()`, `symbol()`	Interface and token identity.
`updatePricing(songId, newLicensePrice, newStreamPrice)`	Recorded creator only.
`updateMetadataUri(songId, newMetadataUri)`	Recorded creator only; URI must be nonempty.

To change prices, simulate the creator’s call, sign it and check the receipt:

const pricingAbi = parseAbi([
  'function updatePricing(uint256 songId, uint256 newLicensePrice, uint256 newStreamPrice)',
]);
const { request: pricingRequest } = await publicClient.simulateContract({
  address: evmContracts.factory, abi: pricingAbi, account,
  functionName: 'updatePricing', args: [mintedId, 6_000_000n, 10_000n],
});
const pricingHash = await walletClient.writeContract(pricingRequest);
const pricingReceipt = await publicClient.waitForTransactionReceipt({ hash: pricingHash });
if (pricingReceipt.status !== 'success') throw new Error('Price update failed');

For metadata, use parseAbi(['function updateMetadataUri(uint256 songId, string newMetadataUri)']), functionName: 'updateMetadataUri' and args: [mintedId, newMetadataUri] in the same sequence. Read the song again after either update. Transferring the token does not grant the new owner creator-only update permissions. Existing licenses survive a pricing change.

Events and errors

Watch SongMinted, LicenseConsumed, PricingUpdated and MetadataUriUpdated for song changes. ERC-721 transfers emit Transfer. Filter logs by the Factory address and identify mints by creator and metadata URI. SongNotFound, NotSongCreator, EmptyMetadataUri, SongNotRemixable and NoLicensesAvailable describe the common rejected calls. The Factory interface defines their full fields.

Restricted interface

mintRemix(licenseAmount, licensePrice, streamPrice, parentSongId, remixer, metadataUri) and consumeLicense(songId, licensee) require an authorized consumer or administrator. Use Remix’s public calls for license purchases and variations.authorizeConsumer(consumer), revokeConsumer(consumer) and transferAdmin(newAdmin) require the administrator. isAuthorizedConsumer(consumer) and getAdmin() are public reads. These permissions are not required to integrate the public mint, license and variation calls.

Factory interface · Deployed Factory addresses

Overview

Contracts

Programs

Mint an original

Connect and read

Confirm the minted song

Reads and creator updates

Events and errors

​Mint an original

​Connect and read

​Confirm the minted song

​Reads and creator updates

​Events and errors

Mint an original

Connect and read

Confirm the minted song

Reads and creator updates

Events and errors