mtags/parsers/id3v2frames.js

Media file tag parser

/*
 * Copyright (c) 2009 Opera Software ASA, António Afonso (antonio.afonso@opera.com)
 * Modified by António Afonso <antonio.afonso gmail.com>
 */

var ID3v2 = {};
ID3v2.readFrameData = exports.readFrameData = {};

var pictureType = [
  "32x32 pixels 'file icon' (PNG only)",
  "Other file icon",
  "Cover (front)",
  "Cover (back)",
  "Leaflet page",
  "Media (e.g. lable side of CD)",
  "Lead artist/lead performer/soloist",
  "Artist/performer",
  "Conductor",
  "Band/Orchestra",
  "Composer",
  "Lyricist/text writer",
  "Recording Location",
  "During recording",
  "During performance",
  "Movie/video screen capture",
  "A bright coloured fish",
  "Illustration",
  "Band/artist logotype",
  "Publisher/Studio logotype"
];

function getTextEncoding( bite ) {
  var charset;
  switch( bite )
  {
    case 0x00:
      charset = 'iso-8859-1';
      break;

    case 0x01:
      charset = 'utf-16';
      break;

    case 0x02:
      charset = 'utf-16be';
      break;

    case 0x03:
      charset = 'utf-8';
      break;
  }

  return charset;
}

function getTime( duration )
{
  var duration    = duration/1000,
      seconds     = Math.floor( duration ) % 60,
      minutes     = Math.floor( duration/60 ) % 60,
      hours       = Math.floor( duration/3600 );

  return {
    seconds : seconds,
            minutes : minutes,
            hours   : hours
  };
}

function formatTime( time )
{
  var seconds = time.seconds < 10 ? '0'+time.seconds : time.seconds;
  var minutes = (time.hours > 0 && time.minutes < 10) ? '0'+time.minutes : time.minutes;

  return (time.hours>0?time.hours+':':'') + minutes + ':' + seconds;
}

ID3v2.readFrameData['APIC'] = function readPictureFrame(offset, length, data, flags, v) {
  v = v || '3';

  var start = offset;
  var charset = getTextEncoding( data.getByteAt(offset) );
  switch( v ) {
    case '2':
      var format = data.getStringAt(offset+1, 3);
      offset += 4;
      break;

    case '3':
    case '4':
      var format = data.getStringWithCharsetAt(offset+1, length - (offset-start), charset);
      offset += 1 + format.bytesReadCount;
      break;
  }
  var bite = data.getByteAt(offset, 1);
  var type = pictureType[bite];
  var desc = data.getStringWithCharsetAt(offset+1, length - (offset-start), charset);

  offset += 1 + desc.bytesReadCount;

  return {
    "format" : format.toString(),
      "type" : type,
      "description" : desc.toString(),
      "data" : data.getBytesAt(offset, (start+length) - offset)
  };
};

ID3v2.readFrameData['COMM'] = function readCommentsFrame(offset, length, data) {
  var start = offset;
  var charset = getTextEncoding( data.getByteAt(offset) );
  var language = data.getStringAt( offset+1, 3 );
  var shortdesc = data.getStringWithCharsetAt(offset+4, length-4, charset);

  offset += 4 + shortdesc.bytesReadCount;
  var text = data.getStringWithCharsetAt( offset, (start+length) - offset, charset );

  return {
    language : language,
             short_description : shortdesc.toString(),
             text : text.toString()
  };
};

ID3v2.readFrameData['COM'] = ID3v2.readFrameData['COMM'];

ID3v2.readFrameData['PIC'] = function(offset, length, data, flags) {
  return ID3v2.readFrameData['APIC'](offset, length, data, flags, '2');
};

ID3v2.readFrameData['PCNT'] = function readCounterFrame(offset, length, data) {
  // FIXME: implement the rest of the spec
  return data.getInteger32At(offset);
};

ID3v2.readFrameData['CNT'] = ID3v2.readFrameData['PCNT'];

ID3v2.readFrameData['T*'] = function readTextFrame(offset, length, data) {
  var charset = getTextEncoding( data.getByteAt(offset) );

  return data.getStringWithCharsetAt(offset+1, length-1, charset).toString();
};

ID3v2.readFrameData['TCON'] = function readGenreFrame(offset, length, data) {
  var text = ID3v2.readFrameData['T*'].apply( this, arguments );
  return text.replace(/^\(\d+\)/, '');
};

ID3v2.readFrameData['TCO'] = ID3v2.readFrameData['TCON'];

//ID3v2.readFrameData['TLEN'] = function readLengthFrame(offset, length, data) {
//    var text = ID3v2.readFrameData['T*'].apply( this, arguments );
//    
//    return {
//        text : text,
//        parsed : formatTime( getTime(parseInt(text)) )
//    };
//};

ID3v2.readFrameData['USLT'] = function readLyricsFrame(offset, length, data) {
  var start = offset;
  var charset = getTextEncoding( data.getByteAt(offset) );
  var language = data.getStringAt( offset+1, 3 );
  var descriptor = data.getStringWithCharsetAt( offset+4, length-4, charset );

  offset += 4 + descriptor.bytesReadCount;
  var lyrics = data.getStringWithCharsetAt( offset, (start+length) - offset, charset );

  return {
    language : language,
             descriptor : descriptor.toString(),
             lyrics : lyrics.toString()
  };
};

ID3v2.readFrameData['ULT'] = ID3v2.readFrameData['USLT'];

// Exporting public functions.
// Adding all frame read methods to the exports object.
for (var tag in ID3v2.readFrameData) {
  exports.readFrameData[tag] = ID3v2.readFrameData[tag];
}