A simple ID3v2.3.0 Tag Reader written for node.js

Id3NodeReader.js

var fs = require('fs');
var Buffer = require('buffer').Buffer;

var id3Reader = new (function(){
  // Credits to esailja //
  var self = this;
  function id3Size( buffer ) {
	var integer = ( ( buffer[0] & 0x7F ) << 21 ) |
			  ( ( buffer[1] & 0x7F ) << 14 ) |
			  ( ( buffer[2] & 0x7F ) << 7 ) |
			  ( buffer[3] & 0x7F );
    return integer;
  }
  var PIC_TYPE = ["Other","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","Movie/video screen capture","A bright coloured fish","Illustration","Band/artist logotype","Publisher/Studio logotype","Band/Orchestra","Composer","Lyricist/text writer","Recording Location","During recording","During performance"];
  var GENRES = ["Blues","Classic Rock","Country","Dance","Disco","Funk","Grunge","Hip-Hop","Jazz","Metal","New Age","Oldies","Other","Pop","R&B","Rap","Reggae","Rock","Techno","Industrial","Alternative","Ska","Death Metal","Pranks","Soundtrack","Euro-Techno","Ambient","Trip-Hop","Vocal","Jazz+Funk","Fusion","Trance","Classical","Instrumental","Acid","House","Game","Sound Clip","Gospel","Noise","AlternRock","Bass","Soul","Punk","Space","Meditative","Instrumental Pop","Instrumental Rock","Ethnic","Gothic","Darkwave","Techno-Industrial","Electronic","Pop-Folk","Eurodance","Dream","Southern Rock","Comedy","Cult","Gangsta","Top 40","Christian Rap","Pop/Funk","Jungle","Native American","Cabaret","New Wave","Psychadelic","Rave","Showtunes","Trailer","Lo-Fi","Tribal","Acid Punk","Acid Jazz","Polka","Retro","Musical","Rock & Roll","Hard Rock","Folk","Folk-Rock","National Folk","Swing","Fast Fusion","Bebob","Latin","Revival","Celtic","Bluegrass","Avantgarde","Gothic Rock","Progressive Rock","Psychedelic Rock","Symphonic Rock","Slow Rock","Big Band","Chorus","Easy Listening","Acoustic","Humour","Speech","Chanson","Opera","Chamber Music","Sonata","Symphony","Booty Bass","Primus","Porn Groove","Satire","Slow Jam","Club","Tango","Samba","Folklore","Ballad","Power Ballad","Rhythmic Soul","Freestyle","Duet","Punk Rock","Drum Solo","A capella","Euro-House","Dance Hall"];
  var TAGS = {
    "AENC": "Audio encryption",
    "APIC": "Attached picture",
    "COMM": "Comments",
    "COMR": "Commercial frame",
    "ENCR": "Encryption method registration",
    "EQUA": "Equalization",
    "ETCO": "Event timing codes",
    "GEOB": "General encapsulated object",
    "GRID": "Group identification registration",
    "IPLS": "Involved people list",
    "LINK": "Linked information",
    "MCDI": "Music CD identifier",
    "MLLT": "MPEG location lookup table",
    "OWNE": "Ownership frame",
    "PRIV": "Private frame",
    "PCNT": "Play counter",
    "POPM": "Popularimeter",
    "POSS": "Position synchronisation frame",
    "RBUF": "Recommended buffer size",
    "RVAD": "Relative volume adjustment",
    "RVRB": "Reverb",
    "SYLT": "Synchronized lyric/text",
    "SYTC": "Synchronized tempo codes",
    "TALB": "Album",
    "TBPM": "BPM",
    "TCOM": "Composer",
    "TCON": "Genre",
    "TCOP": "Copyright message",
    "TDAT": "Date",
    "TDLY": "Playlist delay",
    "TENC": "Encoded by",
    "TEXT": "Lyricist",
    "TFLT": "File type",
    "TIME": "Time",
    "TIT1": "Content group description",
    "TIT2": "Title",
    "TIT3": "Subtitle",
    "TKEY": "Initial key",
    "TLAN": "Language(s)",
    "TLEN": "Length",
    "TMED": "Media type",
    "TOAL": "Original album",
    "TOFN": "Original filename",
    "TOLY": "Original lyricist",
    "TOPE": "Original artist",
    "TORY": "Original release year",
    "TOWN": "File owner",
    "TPE1": "Artist",
    "TPE2": "Band",
    "TPE3": "Conductor",
    "TPE4": "Interpreted, remixed, or otherwise modified by",
    "TPOS": "Part of a set",
    "TPUB": "Publisher",
    "TRCK": "Track number",
    "TRDA": "Recording dates",
    "TRSN": "Internet radio station name",
    "TRSO": "Internet radio station owner",
    "TSIZ": "Size",
    "TSRC": "ISRC (international standard recording code)",
    "TSSE": "Software/Hardware and settings used for encoding",
    "TYER": "Year",
    "TXXX": "User defined text information frame",
    "UFID": "Unique file identifier",
    "USER": "Terms of use",
    "USLT": "Unsychronized lyric/text transcription",
    "WCOM": "Commercial information",
    "WCOP": "Copyright/Legal information",
    "WOAF": "Official audio file webpage",
    "WOAR": "Official artist/performer webpage",
    "WOAS": "Official audio source webpage",
    "WORS": "Official internet radio station homepage",
    "WPAY": "Payment",
    "WPUB": "Publishers official webpage",
    "WXXX": "User defined URL link frame"
  };
  var special_tags = {
  	'APIC':function(raw){
  		var frame = {
  			txt_enc : raw.readUInt8(0)
  		}
  		var pos = raw.toString('ascii',1,(raw.length < 24)?raw.length:24).indexOf('\0');
  		frame.mime = raw.toString('ascii',1,pos+1);
  		pos += 2;
  		frame.type = PIC_TYPE[raw.readUInt8(pos++)] || 'unknown';
  		var desc = raw.toString('ascii',pos,pos+64); // Max 64 char comment
        var desc_pos = desc.indexOf('\0');
  		frame.desc = desc.substr(0,desc_pos);
  		pos +=  desc_pos + 1 ;// /0 is the last character which wont be counted xP
  		frame.img = fs.writeFileSync('art2.'+frame.mime.split('/')[1],raw.slice(pos,raw.length),'binary'); // Replace the art with unique ID .
  		return frame;
  	},
  	'TRCK':function(raw){
  		return raw.toString('ascii').replace(/\u0000/g,'') * 1;
  	},
  	'TYER':function(raw){
  		return raw.toString('ascii').replace(/\u0000/g,'') *1;
  	}
  }
  function parseTags (raw_tags,callback){
  	var max = raw_tags.length;
  	var pos = 0;
  	var parsed_tags = [];
    while( pos < max-10){
    	var TAG = {
    		NAME : raw_tags.toString('ascii',pos,pos+4),
    		SIZE : raw_tags.readUInt32BE(pos+4)
    	};
    	if( special_tags[TAG.NAME] !== undefined){
    	    TAG.content = special_tags[TAG.NAME](raw_tags.slice(pos+10,pos+10+TAG.SIZE)) || 'FUCK IN COMPLETE THE FUCKING FUNCTION';
    	}else{
    		TAG.content = raw_tags.toString('utf8',pos+10,pos+10+TAG.SIZE).replace(/\u0000/g,'');
    	}
    	if( TAGS[TAG.NAME] !== undefined && TAG.NAME !== 'PRIV'){
    		parsed_tags.push(TAG);
    	}
    	pos += (10+TAG.SIZE);
    }
    callback(parsed_tags);
  };
  /*
   * @API - PUBLIC
  */
  self.read = function (file,_callback){
  	var callback = _callback;
  	fs.open(file,'r',function(err,fd){
  		if(err){
  			console.dir(err);
  			return;
  		}
  		var id3 = {};
  		var header = new Buffer(10);
  		fs.read(fd,header,0,10,0,function(err,bytesRead,buff){
  			if( buff.toString('ascii',0,3) != 'ID3'){
  				console.log("Not an id3v2 ");
  				return;
  			}
  			id3.head = {
  				size:id3Size(buff.slice(6,10)),
  				ver:'2.'+buff.readUInt8(3)+'.'+buff.readUInt8(4)
  			};
  			var raw_tags = new Buffer(id3.head.size);
  			fs.read(fd,raw_tags,0,id3.head.size,null,function(){
  				fs.close(fd,function(){
  					parseTags( raw_tags,function(parsed_tags){
  					     id3.tags = parsed_tags;
  					     callback(id3);
  					});
  				});
  			});
  		});
  	});
  
  }
})();

// */