A javascript based decoder for mp3 frame parsing supports id3

jsMp3dec.js

/*
 var net = require('net');
 var http = require('http');
 var listeners = [];
 var Meta = {};

 var streamer = http.createServer(function(req,res){
 res.write('ICY 200 OK\r\nicy-notice1:<BR>FUCK OFF <BR>icy-notice2:SHOUTcast Distributed Network Audio Server/posix v1.2.3<BR>icy-name:'+Meta.name+'\r\nicy-genre:'+Meta.genre+'\r\nicy-url:'+Meta.url+'\r\nContent-Type:audio/mpeg\r\nicy-pub:1\r\nicy-br:'+Meta.br+'\r\nicy-metaint:8192\r\n\r\n');
 listeners.push(res);
 });
 streamer.listen(7200);
 function handleMeta(data){
 if(data.indexOf('icy')> -1){
 //Media  Meta Data
 var arr = data.split('\n'); 
 for( item in arr ){
 var str = arr[item];
 str = str.split(':',2);
 str[0] = str[0].replace('icy-','');
 if(str[0] !== '' && str.length > 1)
 Meta[str[0]] = str[1];
 }
 console.dir(Meta);
 }
 }

 function handleStream(data){
 handleMeta(data);
 console.log(data);
 for (var i = listeners.length - 1; i > -1 ; i-- ) {
 listeners[i].write(data);
 }
 }

 var server = net.createServer(function(c) { //'connection' listener
 console.log('Connection');
 c.setEncoding('utf8');
 c.once('data',function(data){
 handleMeta(data);
 c.on('data',function(data){
 handleStream(data);
 });
 if(data.indexOf('cgcarls5')>-1){
 c.write('OK2\r\nicy-caps:11\r\n\r\n');
 }else{
 c.write('Invalid Password \r\n\r\n');
 }
 });
 c.on('end', function() {
 console.log('server disconnected');
 });
 });
 server.listen(8124, function() { //'listening' listener
 console.log('server bound');
 });
 */

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

// Mp3Id3Reader
// Supports Id3v2.3.0 fully
// TODO: Add id3v2.2.0
// TODO: Add id3v2.4.0
var id3Reader = function() {
	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 callback = null;
	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", //<--- Wait what the f ?
	"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);
	};

	function beginRead(err,fd,extern) {
		if(err) {
			console.dir(err);
			return;
		}
		var id3 = {};
		var _ext = extern;
		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() {
				if( _ext === false ) {
					fs.close(fd, function() {
						parseTags( raw_tags, function(parsed_tags) {
							id3.tags = parsed_tags;
							callback(id3);
						});
					});
				} else {
					parseTags( raw_tags , function( parsed_tags ) {
						id3.tags = parsed_tags;
						callback(id3);
					});
				}
			});
		});
	}

	/*
	 * @API - PUBLIC
	 */
	self.read = function (file,_callback,fd) {
		callback = _callback;
		if(fd === undefined) {
			fs.open(file,'r',beginRead);
		} else {
			beginRead(null,fd,true);
		}
	}
};
/* Singular Mp3 Reader */

// Loads of constants for binary reading
var ext = {

	_single_bit:[0xff,0x7f,0x3f,0x1f,0x0f,0x07,0x03,0x01],
	ver: {
		frame: {
			0:'MPEG 2.5',
			1:'Reserved',
			2:'MPEG 2',
			3:'MPEG 1'
		},
		layer: {
			0:'reserved',
			1:'Layer III',
			2:'Layer II',
			3:'Layer I'
		},
		bitrate: {
			/* Defines in Mpeg version  */
			/* Mpeg 1 */
			3: {
				/* defines the mpeg layer in the version */
				/* Layer 3 */
				1:[0,32,40,48,56,64,80,96,112,128,160,192,224,256,320,-1],
				/* Layer 2 */
				2:[0,32,48,56,64,80,96,112,128,160,192,224,256,320,384,-1],
				/* Layer 1 */
				3:[0,32,64,96,128,160,192,224,256,288,320,352,384,416,488,-1]
			},
			/* Mpeg version 2 */
			2: {
				/* Layer 1 */
				3:[0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,-1],
				/* Layer 2 */
				2:[0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,-1],
				/* Layer 3 */
				1:[0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,-1]
			},
			/* Mpeg version 2.5 */
			0: {
				/* Layer 1 */
				3:[0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,-1],
				/* Layer 2 */
				2:[0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,-1],
				/* Layer 3 */
				1:[0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,-1]
			}
		},
		samplerate: {
			3:[44100,48000,32000,-1], /* Mpeg 1 */
			2:[22050,24000,16000,-1], /* Mpeg 2 */
			0:[11025,12000,8000] /* Mpeg 2.5 */
		},
		channel:[
		'Stereo',
		'Joint Stereo',
		'Dual Channel',
		'Single Channel'
		],
		jsMode: {
			1:[['off','off'],['on','off'],['off','on'],['on','on']],
			2:[[4,31],[8,31],[12,31],[16,31]],
			3:[[4,31],[8,31],[12,31],[16,31]]
		},
		Emphasis:[
		'none',
		'50/15ms',
		'reserved',
		'CCIT J.17'
		],
		slot: {
			3:4,
			2:1,
			1:1
		},
		samplePerFrame: {
			3: {
				3:384,
				2:1152,
				1:1152
			},
			2: {
				3:384,
				2:1152,
				1:576,
			},
			0: {
				3:384,
				2:1152,
				1:576
			}
		}
	}
}

Buffer.prototype.ptr = 0; /* The position of read head in bits */

Buffer.prototype.getBits = function (bits) {
	var ptr = this.ptr;
	this.ptr += bits;

	var start = Math.floor(ptr/8);
	var end = Math.floor(this.ptr/8);
	var No_of_Bytes = Math.floor(bits/8);
	var _offset_start = ( ptr % 8);
	var _offset_end = 8 - (this.ptr % 8);
	if( _offset_end === 8) {
		end --;
	}
	var integer = 0;
	integer = (this[start] & ext._single_bit[_offset_start]);
	var i = start + 1;
	do {
		if(i < end )
			integer = ( (integer << 8) | this[i++] );
	} while(i < end-1 );
	if( No_of_Bytes > 0) {
		integer = (integer <<((8 - _offset_end%8))) | (this[end]>>(_offset_end%8));
	} else {
		integer = integer >> (_offset_end%8);
	}

	return integer;
};
Buffer.prototype.skip  = function(bits) {
	// done :-) // why wrapper , i dont know :P
	this.ptr += bits;
}
function mp3Reader () {
	'use_strict';
	var file = '';
	var meta = null;
	var fd = null;
	var self = this;
	var frames = 0;
	var Length = 0;
	var buffer = {
		head:new Buffer(4),
		body:null
	}
	var iter = 0;
	function readStream() {
		fs.read(fd,buffer.head,0,4,null, function(err,bytesRead) {
			if(err || iter > 5) {
				return;
			}
			iter++;
			var parsed = {};
			/* 0000 0000 0000 0000 0000 0000 0000 0000 *.
			* Sample
			*   F    F   F
			* Mpeg Version = 20th and 19th bit from right;
			* 0000 0000 0001 1000 0000 0000 0000 0000
			*
			* MPEG LAYER = 17th and 18th bit from right
			* 0000 0000 0000 0110 0000 0000 0000 0000
			* ----------0000 0110
			*
			* MPEG CRC
			* 0000 0000 0000 0001 0000 0000 0000 0000
			*           0000 0001 - 0x1;
			*
			* MPEG BITRATE INFORMATION
			* 0000 0000 0000 0000 1111 0000 0000 0000
			* ------------------- 1111 0000 = F0
			*
			* Sampler information
			*
			* 0000 0000 0000 0000 0000 1100 0000 0000
			* ------------------- 0000 1100 - C
			*
			* Padding bit
			* 0000 0000 0000 0000 0000 0010 0000 0000
			* --------------------0000 0010 - 2 ;
			*
			* Priv - 8th bit;
			*
			* Channel Mode
			*
			* 0000 0000 0000 0000 0000 0000 1100 0000
			* ------------------------------1100 0000 - C0
			*
			* JS ext
			* 0011 0000 - 30
			*
			* (C)
			* 0000 1000 - 8
			* (Origninal)
			* 0000 0100 - 4
			*/
			//
			// 1000 - 8 , 1001 - 9 , 1010 - A , 1011 - B , 1100 - 12
			if ( (buffer.head[0] & 0xff) !== 255 && (buffer.head[1] & 0xf0 >>> 4) !== 15 ) {
				console.log(Length);
				return; /* End of mp3 */
			}
			var ver = ( buffer.head[1] & 0x18)>>>3,
			layer = ( buffer.head[1]& 0x6 )>>>1,
			crc = ( buffer.head[1]&0x1 ),
			bitrate = ( buffer.head[2] & 0xF0 )>>>4,
			samplerate = ( buffer.head[2] & 0xC)>>>2,
			padding = ( buffer.head[2] & 0x2)>>>1,
			priv = ( buffer.head[2]& 0x1 ),
			channel = ( buffer.head[3] & 0xC0 )>>>6,
			jsExt =  ( buffer.head[3]& 0x30)>>> 4, /* joing stereo ext */
			cpyrite = ( buffer.head[3]& 0x9)>>> 3,
			orig = ( buffer.head[3] & 0x4 )>>>2,
			Emph = ( buffer.head[3] & 0x3 ),
			sample_per_frame =  ext.ver.samplePerFrame[ver][layer],

			frameSize = 144 * ( ext.ver.bitrate[ver][layer][bitrate]*1000 / ext.ver.samplerate[ver][samplerate] ) ;

			frameSize = Math.floor(frameSize) + ( (!!padding)?ext.ver.slot[layer]:0 );

			Length += sample_per_frame/ext.ver.samplerate[ver][samplerate];

			/*
			 console.log('Version : ',ext.ver.frame[ver]);
			 console.log('Layer : ',ext.ver.layer[layer]);
			 console.log('Bitrate : ',ext.ver.bitrate[ver][layer][bitrate],'kbps');
			 console.log('CRC : ',!!crc);
			 console.log('SampleRate : ',ext.ver.samplerate[ver][samplerate]);
			 console.log('Channel : ',ext.ver.channel[channel]);
			 console.log('Mode Ext : ',(channel===1)? ext.ver.jsMode[layer][jsExt] :null);
			 console.log('Copyrighted : ',!!cpyrite);
			 console.log('Original : ',!!orig);
			 console.log('Emph : ',ext.ver.Emphasis[Emph]);
			 console.log('Padding : ',!!padding);
			 console.log('FrameSize :',frameSize);
			 // */
			var body = new Buffer( frameSize - 4 ); // we already read the 4 bytes :P
			fs.read(fd,body,0,frameSize - 4 ,null, function(err,bytesRead) {
				if(err) {
					console.dir(err);
					return;
				}
				if(crc) {
					var checksum = body.getBits(16);
				}
				if(channel < 2) {
					/* Not single */
					/* Mpeg Layer III */
					if( layer === 1) {
						var main_data_end =  body.getBits(9),
						priv_bits = body.getBits(3),
						scfsi = [[
						body.getBits(1),
						body.getBits(1),
						body.getBits(1),
						body.getBits(1),/* shifting this will be an overkill son */
						],[
						body.getBits(1),
						body.getBits(1),
						body.getBits(1),
						body.getBits(1),/* shifting this will be an overkill son */
						]],
						grn = [
						[{},{}],[{},{}]
						];
						for(var gr = 0 ; gr < 2 ; gr++ ) {
							for( var ch = 0 ; ch < 2 ; ch++) {
								grn[gr][ch].part2_3_length = body.getBits(12);
								grn[gr][ch].bigvalues = body.getBits(9);
								grn[gr][ch].global_gain = body.getBits(8);
								grn[gr][ch].scalefac_comp = body.getBits(4);
								grn[gr][ch].blocksplit_flag = !!(body.getBits(1));
								if(grn[gr][ch].blocksplit_flag) {
									grn[gr][ch].blocktype = body.getBits(2);
									grn[gr][ch].switch_point = body.getBits(1);
									grn[gr][ch].region = [];
									grn[gr][ch].sub_block_gain = [];
									for(var region = 0 ; region < 2 ; region++) {
										grn[gr][ch].region[region] = body.getBits(5);
									}
									for(var win = 0 ; win < 3 ; win ++) {
										grn[gr][ch].sub_block_gain[win] = body.getBits(3);
									}
								} else {
									grn[gr][ch].region = [];
									grn[gr][ch].reg = [];
									for(var region = 0 ; region < 3 ; region++) {
										grn[gr][ch].region[region] = body.getBits(5);
									}
									grn[gr][ch].reg = {
										region_address1:body.getBits(4),
										region_address2:body.getBits(3)
									};
								}
							}
						}
						for(var gr = 0; gr < 2 ; gr++ ) {
							for(var ch =0; ch < 2 ;ch++) {
								if( grn[gr][ch].blocksplit_flag === 1 && grn[gr][ch].blocktype == 2) {
									grn[gr][ch].scalefac = [];
									for(cb = 0; cb  < grn[gr][ch].switch_point ; cb++) {
										grn[gr][ch].scalefac[cb] = body.getBits(1);
									}
								}
							}
						}

					}
					console.log('Main Data Length',main_data_end);
					console.log('scfsi',scfsi);
					console.dir(grn[0][0]);

				} else {
					/* Yeah now its single :-(  */

				}
				readStream();
			})
		});
	}

	self.load = function ( _file ) {
		file = _file;
		fs.open(file,'r', function(err,_fd) {
			if(err) {
				return;
			}
			fd = _fd;
			new id3Reader().read(file, function(tags) {
				meta = tags;
				console.dir(tags);
				readStream();
			},fd);
		});
	}
};

var f1 = new mp3Reader();
f1.load('dah.mp3');