isFooter = function isFooter(data, offset) {
  /*
   * The footer is a copy of the header, but with a different identifier
   */
  if (offset + 10 <= data.length) {
    // look for '3DI' identifier
    if (data[offset] === 0x33 && data[offset + 1] === 0x44 && data[offset + 2] === 0x49) {
      // check version is within range
      if (data[offset + 3] < 0xff && data[offset + 4] < 0xff) {
        // check size is within range
        if (data[offset + 6] < 0x80 && data[offset + 7] < 0x80 && data[offset + 8] < 0x80 && data[offset + 9] < 0x80) {
          return true;
        }
      }
    }
  }

  return false;
}
Returns true if an ID3 footer can be found at offset in data
@param {Uint8Array} data - The data to search in
@param {number} offset - The offset at which to start searching
@return {boolean} - True if an ID3 footer is found