jsmediatags/build2/ByteArrayUtils.js

Media Tags Reader (ID3, MP4)

'use strict';

/**
 * Converts a string to a binary array
 */
var bin = function bin(string) {
  var binaryArray = new Array(string.length);

  for (var i = 0; i < string.length; i++) {
    binaryArray[i] = string.charCodeAt(i);
  }

  return binaryArray;
};
/**
 * Pads an array with \0 until it is size length.
 */


var pad = function pad(array, size) {
  for (var i = array.length; i < size; i++) {
    array.push(0);
  }

  return array;
}; // The ID3v2 tag/frame size is encoded with four bytes where the most
// significant bit (bit 7) is set to zero in every byte, making a total of 28
// bits. The zeroed bits are ignored, so a 257 bytes long tag is represented
// as $00 00 02 01.


var getSynchsafeInteger32 = function getSynchsafeInteger32(number) {
  // 0x7f = 0b01111111
  return [number >> 21 & 0x7f, number >> 14 & 0x7f, number >> 7 & 0x7f, number & 0x7f];
};

var getInteger32 = function getInteger32(number) {
  return [number >> 24 & 0xff, number >> 16 & 0xff, number >> 8 & 0xff, number & 0xff];
};

var getInteger24 = function getInteger24(number) {
  return [number >> 16 & 0xff, number >> 8 & 0xff, number & 0xff];
};

module.exports = {
  bin: bin,
  pad: pad,
  getSynchsafeInteger32: getSynchsafeInteger32,
  getInteger32: getInteger32,
  getInteger24: getInteger24
};