1. module jsmediatags
   1. function jsmediatags.Config (fileReader)
   2. function jsmediatags.Reader (file)
   3. function jsmediatags.read (location, callbacks)
   4. object jsmediatags.ByteArrayUtils
   5. object jsmediatags.ID3v2FrameReader
   6. object jsmediatags.StringUtils
2. module jsmediatags.ByteArrayUtils
   1. function jsmediatags.ByteArrayUtils.bin (string)
   2. function jsmediatags.ByteArrayUtils.getInteger24 (number)
   3. function jsmediatags.ByteArrayUtils.getInteger32 (number)
   4. function jsmediatags.ByteArrayUtils.getSynchsafeInteger32 (number)
   5. function jsmediatags.ByteArrayUtils.pad (array, size)
3. module jsmediatags.ID3v2FrameReader
   1. function jsmediatags.ID3v2FrameReader.getFrameReaderFunction (frameId)
4. module jsmediatags.StringUtils
   1. function jsmediatags.StringUtils.readNullTerminatedString (bytes, maxBytes)
   2. function jsmediatags.StringUtils.readUTF16String (bytes, bigEndian, maxBytes)
   3. function jsmediatags.StringUtils.readUTF8String (bytes, maxBytes)

module jsmediatags

function jsmediatags.Config (fileReader)

• description and source-code

  class Config {
    static addFileReader(fileReader) {
      mediaFileReaders.push(fileReader);
      return Config;
    }
  
    static addTagReader(tagReader) {
      mediaTagReaders.push(tagReader);
      return Config;
    }
  
    static removeTagReader(tagReader) {
      var tagReaderIx = mediaTagReaders.indexOf(tagReader);
  
      if (tagReaderIx >= 0) {
        mediaTagReaders.splice(tagReaderIx, 1);
      }
  
      return Config;
    }
  
    static EXPERIMENTAL_avoidHeadRequests() {
      XhrFileReader.setConfig({
        avoidHeadRequests: true
      });
    }
  
    static setDisallowedXhrHeaders(disallowedXhrHeaders) {
      XhrFileReader.setConfig({
        disallowedXhrHeaders: disallowedXhrHeaders
      });
    }
  
    static setXhrTimeoutInSec(timeoutInSec) {
      XhrFileReader.setConfig({
        timeoutInSec: timeoutInSec
      });
    }
  }

• example usage

  n/a

function jsmediatags.Reader (file)

• description and source-code

  class Reader {
  
    constructor(file) {
      this._file = file;
    }
  
    setTagsToRead(tagsToRead) {
      this._tagsToRead = tagsToRead;
      return this;
    }
  
    setFileReader(fileReader) {
      this._fileReader = fileReader;
      return this;
    }
  
    setTagReader(tagReader) {
      this._tagReader = tagReader;
      return this;
    }
  
    read(callbacks) {
      var FileReader = this._getFileReader();
      var fileReader = new FileReader(this._file);
      var self = this;
  
      fileReader.init({
        onSuccess: function () {
          self._getTagReader(fileReader, {
            onSuccess: function (TagReader) {
              new TagReader(fileReader).setTagsToRead(self._tagsToRead).read(callbacks);
            },
            onError: callbacks.onError
          });
        },
        onError: callbacks.onError
      });
    }
  
    _getFileReader() {
      if (this._fileReader) {
        return this._fileReader;
      } else {
        return this._findFileReader();
      }
    }
  
    _findFileReader() {
      for (var i = 0; i < mediaFileReaders.length; i++) {
        if (mediaFileReaders[i].canReadFile(this._file)) {
          return mediaFileReaders[i];
        }
      }
  
      throw new Error("No suitable file reader found for ", this._file);
    }
  
    _getTagReader(fileReader, callbacks) {
      if (this._tagReader) {
        var tagReader = this._tagReader;
        setTimeout(function () {
          callbacks.onSuccess(tagReader);
        }, 1);
      } else {
        this._findTagReader(fileReader, callbacks);
      }
    }
  
    _findTagReader(fileReader, callbacks) {
      // We don't want to make multiple fetches per tag reader to get the tag
      // identifier. The strategy here is to combine all the tag identifier
      // ranges into one and make a single fetch. This is particularly important
      // in file readers that have expensive loads like the XHR one.
      // However, with this strategy we run into the problem of loading the
      // entire file because tag identifiers might be at the start or end of
      // the file.
      // To get around this we divide the tag readers into two categories, the
      // ones that read their tag identifiers from the start of the file and the
      // ones that read from the end of the file.
      var tagReadersAtFileStart = [];
      var tagReadersAtFileEnd = [];
      var fileSize = fileReader.getSize();
  
      for (var i = 0; i < mediaTagReaders.length; i++) {
        var range = mediaTagReaders[i].getTagIdentifierByteRange();
        if (!isRangeValid(range, fileSize)) {
          continue;
        }
  
        if (range.offset >= 0 && range.offset < fileSize / 2 || range.offset < 0 && range.offset < -fileSize / 2) {
          tagReadersAtFileStart.push(mediaTagReaders[i]);
        } else {
          tagReadersAtFileEnd.push(mediaTagReaders[i]);
        }
      }
  
      var tagsLoaded = false;
      var loadTagIdentifiersCallbacks = {
        onSuccess: function () {
          if (!tagsLoaded) {
            // We're expecting to load two sets of tag identifiers. This flag
            // indicates when the first one has been loaded.
            tagsLoaded = true;
            return;
          }
  
          for (var i = 0; i < mediaTagReaders.length; i++) {
            var range = mediaTagReaders[i].getTagIdentifierByteRange();
            if (!isRangeValid(range, fileSize)) {
              continue;
            }
  
            try {
              var tagIndentifier = fileReader.getBytesAt(range.offset >= 0 ? range.offset : range.offset + fileSize, range.length);
            } catch (ex) {
              if (callbacks.onError) {
                callbacks.onError({
                  "type": "fileReader",
                  "info": ex.message
                });
                return;
              }
            }
  
            if (mediaTagReaders[i].canReadTagFormat(tagIndentifier)) {
              callbacks.onSuccess(mediaTagReaders[i]);
              return;
            }
          }
  
          if (callbacks.onError) {
            callbacks.onError({
              "type": "tagFormat",
              "info": "No suitable tag reader found"
            });
          }
        },
        onError: callbacks.onError
      };
  
      this._loadTagIdentifierRanges(fileReader, tagReadersAtFileS ...

• example usage

  ...
  });
  ```
  
  ```javascript
  // Advanced API
  var jsmediatags = require("jsmediatags");
  
  new jsmediatags.Reader("http://www.example.com/music-file.mp3")
  .setTagsToRead(["title", "artist"])
  .read({
    onSuccess: function(tag) {
      console.log(tag);
    },
    onError: function(error) {
      console.log(':(', error.type, error.info);
  ...

function jsmediatags.read (location, callbacks)

• description and source-code

  function read(location, callbacks) {
    new Reader(location).read(callbacks);
  }

• example usage

  ...
  
  Run `npm install jsmediatags --save` to install.
  
  ```javascript
  // Simple API - will fetch all tags
  var jsmediatags = require("jsmediatags");
  
  jsmediatags.read("./music-file.mp3", {
    onSuccess: function(tag) {
      console.log(tag);
    },
    onError: function(error) {
      console.log(':(', error.type, error.info);
    }
  });
  ...

module jsmediatags.ByteArrayUtils

function jsmediatags.ByteArrayUtils.bin (string)

• description and source-code

  bin = function (string) {
    var binaryArray = new Array(string.length);
    for (var i = 0; i < string.length; i++) {
      binaryArray[i] = string.charCodeAt(i);
    }
    return binaryArray;
  }

• example usage

  n/a

function jsmediatags.ByteArrayUtils.getInteger24 (number)

• description and source-code

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

• example usage

  n/a

function jsmediatags.ByteArrayUtils.getInteger32 (number)

• description and source-code

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

• example usage

  n/a

function jsmediatags.ByteArrayUtils.getSynchsafeInteger32 (number)

• description and source-code

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

• example usage

  n/a

function jsmediatags.ByteArrayUtils.pad (array, size)

• description and source-code

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

• example usage

  n/a

module jsmediatags.ID3v2FrameReader

function jsmediatags.ID3v2FrameReader.getFrameReaderFunction (frameId)

• description and source-code

  getFrameReaderFunction = function (frameId) {
    if (frameId in frameReaderFunctions) {
      return frameReaderFunctions[frameId];
    } else if (frameId[0] === "T") {
      // All frame ids starting with T are text tags.
      return frameReaderFunctions["T*"];
    } else if (frameId[0] === "W") {
      // All frame ids starting with W are url tags.
      return frameReaderFunctions["W*"];
    } else {
      return null;
    }
  }

• example usage

  ...
  // (after unsynchronisation && encryption)
  if (flags && flags.format.data_length_indicator) {
    // var frameDataSize = frameData.getSynchsafeInteger32At(frameDataOffset);
    frameDataOffset += 4;
    frameSize -= 4;
  }
  
  var readFrameFunc = ID3v2FrameReader.getFrameReaderFunction(frameId);
  var parsedData = readFrameFunc ? readFrameFunc(frameDataOffset, frameSize, frameData, flags) : null;
  var desc = this._getFrameDescription(frameId);
  
  var frame = {
    id: frameId,
    size: frameSize,
    description: desc,
  ...

module jsmediatags.StringUtils

function jsmediatags.StringUtils.readNullTerminatedString (bytes, maxBytes)

• description and source-code

  readNullTerminatedString = function (bytes, maxBytes) {
    var arr = [];
    maxBytes = maxBytes || bytes.length;
    for (var i = 0; i < maxBytes;) {
      var byte1 = bytes[i++];
      if (byte1 == 0x00) {
        break;
      }
      arr[i - 1] = String.fromCharCode(byte1);
    }
    return new InternalDecodedString(arr.join(""), i);
  }

• example usage

  ...
        break;
  
      case "utf-8":
        string = StringUtils.readUTF8String(bytes);
        break;
  
      default:
        string = StringUtils.readNullTerminatedString(bytes);
        break;
    }
  
    return string;
  }
  
  getCharAt(offset) {
  ...

function jsmediatags.StringUtils.readUTF16String (bytes, bigEndian, maxBytes)

• description and source-code

  readUTF16String = function (bytes, bigEndian, maxBytes) {
    var ix = 0;
    var offset1 = 1,
        offset2 = 0;
  
    maxBytes = Math.min(maxBytes || bytes.length, bytes.length);
  
    if (bytes[0] == 0xFE && bytes[1] == 0xFF) {
      bigEndian = true;
      ix = 2;
    } else if (bytes[0] == 0xFF && bytes[1] == 0xFE) {
      bigEndian = false;
      ix = 2;
    }
    if (bigEndian) {
      offset1 = 0;
      offset2 = 1;
    }
  
    var arr = [];
    for (var j = 0; ix < maxBytes; j++) {
      var byte1 = bytes[ix + offset1];
      var byte2 = bytes[ix + offset2];
      var word1 = (byte1 << 8) + byte2;
      ix += 2;
      if (word1 == 0x0000) {
        break;
      } else if (byte1 < 0xD8 || byte1 >= 0xE0) {
        arr[j] = String.fromCharCode(word1);
      } else {
        var byte3 = bytes[ix + offset1];
        var byte4 = bytes[ix + offset2];
        var word2 = (byte3 << 8) + byte4;
        ix += 2;
        arr[j] = String.fromCharCode(word1, word2);
      }
    }
    return new InternalDecodedString(arr.join(""), ix);
  }

• example usage

  ...
      var bytes = this.getBytesAt(offset, length);
      var string;
  
      switch ((charset || '').toLowerCase()) {
  case "utf-16":
  case "utf-16le":
  case "utf-16be":
    string = StringUtils.readUTF16String(bytes, charset === "utf-16be");
    break;
  
  case "utf-8":
    string = StringUtils.readUTF8String(bytes);
    break;
  
  default:
  ...

function jsmediatags.StringUtils.readUTF8String (bytes, maxBytes)

• description and source-code

  readUTF8String = function (bytes, maxBytes) {
    var ix = 0;
    maxBytes = Math.min(maxBytes || bytes.length, bytes.length);
  
    if (bytes[0] == 0xEF && bytes[1] == 0xBB && bytes[2] == 0xBF) {
      ix = 3;
    }
  
    var arr = [];
    for (var j = 0; ix < maxBytes; j++) {
      var byte1 = bytes[ix++];
      if (byte1 == 0x00) {
        break;
      } else if (byte1 < 0x80) {
        arr[j] = String.fromCharCode(byte1);
      } else if (byte1 >= 0xC2 && byte1 < 0xE0) {
        var byte2 = bytes[ix++];
        arr[j] = String.fromCharCode(((byte1 & 0x1F) << 6) + (byte2 & 0x3F));
      } else if (byte1 >= 0xE0 && byte1 < 0xF0) {
        var byte2 = bytes[ix++];
        var byte3 = bytes[ix++];
        arr[j] = String.fromCharCode(((byte1 & 0xFF) << 12) + ((byte2 & 0x3F) << 6) + (byte3 & 0x3F));
      } else if (byte1 >= 0xF0 && byte1 < 0xF5) {
        var byte2 = bytes[ix++];
        var byte3 = bytes[ix++];
        var byte4 = bytes[ix++];
        var codepoint = ((byte1 & 0x07) << 18) + ((byte2 & 0x3F) << 12) + ((byte3 & 0x3F) << 6) + (byte4 & 0x3F) - 0x10000;
        arr[j] = String.fromCharCode((codepoint >> 10) + 0xD800, (codepoint & 0x3FF) + 0xDC00);
      }
    }
    return new InternalDecodedString(arr.join(""), ix);
  }

• example usage

  ...
    case "utf-16":
    case "utf-16le":
    case "utf-16be":
      string = StringUtils.readUTF16String(bytes, charset === "utf-16be");
      break;
  
    case "utf-8":
      string = StringUtils.readUTF8String(bytes);
      break;
  
    default:
      string = StringUtils.readNullTerminatedString(bytes);
      break;
  }
  ...