Ethereum smart contract for NFTs representing media that is Definitely Unique™

DefinitelyUniqueMediaBlock.sol

// SPDX-License-Identifier: CC0-1.0
pragma solidity ^0.8.11;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Counters.sol";

contract DefinitelyUniqueMediaBlock is ERC721, Ownable {
  using Counters for Counters.Counter;
  Counters.Counter private _lastTokenId;

  constructor() public ERC721("Definitely Unique Media Block", "DUMB") {
  }

  function mint() public onlyOwner returns (uint256) {
    _lastTokenId.increment();
    uint256 newTokenId = _lastTokenId.current();
    _safeMint(owner(), newTokenId);
    return newTokenId;
  }

  function tokenURI(uint256 /* tokenId */) public view virtual override returns (string memory) {
    // JSON metadata referencing an embedded 1x1 pixel PNG image
    return "data:application/json;base64,eyJuYW1lIjoiRGVmaW5pdGVseSBVbmlxdWUgTWVkaWEgQmxvY2siLCJkZXNjcmlwdGlvbiI6IkEgdG90YWxseSB1bmlxdWUgaW1hZ2UgdG9rZW4iLCJpbWFnZSI6ImRhdGE6aW1hZ2UvcG5nO2Jhc2U2NCxpVkJPUncwS0dnb0FBQUFOU1VoRVVnQUFBQUVBQUFBQkNBSUFBQUNRZDFQZUFBQUFERWxFUVZRSTEyUDQvLzgvQUFYK0F2N2N6Rm5uQUFBQUFFbEZUa1N1UW1DQyJ9";
  }
}