function rOut = id3parse(file)
%ID3PARSE Read meta-data about your digital media from an id3 tag
%
% Note that this file does NOT OFFICIALLY COMPLY with any standards
% established by id3.org or associated parties. This script is written
% based on the ID3v2.3 informal standard: http://www.id3.org/id3v2.3.0.html
%
% TAGFRAMES = ID3PARSE(FILENAME);
% Opens the file whose path is given by
% FILENAME for reading, reads the meta-data stored in the ID3 Tag, and
% returns it in the structure TAGFRAMES. The structure's fields represent
% the titles of the various "frames" of information stored in the tag, the
% values of which are the associated data. Recognized frame's are given
% user friendly names (e.g., the TPE1 frame is labeled as 'Artist', TCON
% frame is labeled 'Genre') and have their data converted as appropriate.
% Unrecognized frames use the given 4 character frame identifier and their
% values are given as text (which may or may not be appropriate, depending
% on the content of the frame).
%
% ID3 Tags are a standard which has largely been adopted throughout the
% digital media world as a means of storing meta data about digital media
% such as MP3 audio files and MPEG video files. ID3 Tags live in the byte
% sequence that makes up a file, usually at the beginning of the file
% (which is the only place I look for it in this script). They do not
% affect the remainder of the content in the file, for instance, and MP3
% file's ID3 tag cannot affect the audio data stored in the file. Data
% stored in an ID3 Tag can be wide ranging: from the Artists and Album
% names, to the copyright information, even synchronized lyrics that can be
% presented in time to the music.
%
% Data in the tag is broken into self contained units called frames. Each
% frame has an identifier associated with it, and some arbitrarirly
% formatted data. The identifier tells knowledgable programs how to parse
% the data stored in the tag. Many tags are simple to parse, for instance
% the TPE1 or "Artist" frame simply stores text. Other tags are more
% complicated because they store more complex data, for instance, an image
% of the album cover.
%
% id3.org maintains a list of widely recognized frame identifiers and
% information on how to parse the associated data. Many of the most
% commonly used tags appearing on that list are recognized by this script.
% Frame identifiers are limited to 4 characters, but frames recognized by
% this script will receive more user friendly names for display.
% Unrecognized frames (or frames I haven't gotten around to including in
% this file) use the frame identifier for display, and assume that the data
% is textual, which is a pretty safe bet for most common frames. If an
% error occurs parsing a particular frame, e.g., the data is not formatted
% the way I was expecting, a warning is issued and the frame is reutrned as
% though it was unrecognized.
%
% For official information (techinical and non-technical) regarding ID3
% Tags see: http://www.id3.org
% Release number: 2
% Current Date: September 01 2009
% Original Date: June 07 2005
% Original Author: Brian Mearns
% Contact: bmearns#coe.neu.edu
%
% Modifications Made By Gordon Forbes:
% Made the functions more robust to errors, by specifying:
% 1) That first 3 bytes must match the 'ID3' header
% 2) That file must exist
% 3) Corrected 'convertBytesToID3Size' Function
% 4) Made List of FrameIDs to Process so that errors can be bypassed
% 5) Put check on size of framedata, so erroneous frames don'r get read
if ~exist(file,'file')
rOut=[];
return
end
fid = fopen(file,'r');
%% HEADER
fileId = char(fread(fid,3,'uint8')');
if ~strcmp(fileId,'ID3')
fclose(fid);
rout=[];
return
end
majVersion = fread(fid,1,'uint8');
minVersion = fread(fid,1,'uint8');
headerFlags = fread(fid,1,'uint8');
headerFlags = dec2bin(headerFlags,8);
headerFlag_a = headerFlags(1) == '1'; %unsynchronized if set
headerFlag_b = headerFlags(2) == '1'; %extended header present if set
headerFlag_c = headerFlags(3) == '1'; %experimental if set.
tagSize = fread(fid,4,'uint8');
tagSize = convertBytesToID3Size(tagSize);
bytesRead = 0;
%% EXTENDED HEADER
if headerFlag_b
extHeaderSize = fread(fid,4,'uint8');
extHeaderSize = convertBytesToID3Size(extHeaderSize);
bytesRead = bytesRead + extHeaderSize + 4; %extHeaderSize does not index itself, it's own 4 bytes.
%TODO: parse ext header more
extHeader = fread(fid,extHeaderSize,'uint8');
end
%% FRAMES
frames = struct();
valid_frame_headers=gen_valid_frame_headers;
while bytesRead < tagSize;
frameId = char(fread(fid,4,'uint8')');
bytesRead = bytesRead + 4;
% frameIds must be made up of A-Z and 0-9
% if not, assume we've reached our padding.
if double(frameId(1)) == 0
bytesRead = tagSize;
else
frameSize = fread(fid,4,'uint8');
bytesRead = bytesRead + 4;
frameSize = convertBytesToID3Size(frameSize);
frameFlags = fread(fid,2,'uint8');
bytesRead = bytesRead + 2;
frameFlags = dec2bin(frameFlags,8);
frameReadOnly = frameFlags(1,3) == '1';
frameCompressed = frameFlags(2,1) == '1';
frameEncrypted = frameFlags(2,2) == '1';
frameGrouping = frameFlags(2,3) == '1';
if frameCompressed
frameCompressedSize = fread(fid,4,'uint8');
bytesRead = bytesRead + 4;
frameCompressedSize = convertBytesToID3Size(frameCompressedSize);
frameSize = frameSize - 4;
end
if frameEncrypted
frameEncryptionMethod = fread(fid,1,'uint8');
bytesRead = bytesRead + 1;
frameSize = frameSize - 1;
end
if frameGrouping
frameGroupingID = fread(fid,1,'uint8');
bytesRead = bytesRead + 1;
frameSize = frameSize - 1;
end
if frameSize<tagSize
frameData = fread(fid,frameSize,'uint8')';
bytesRead = bytesRead + frameSize;
for k=1:length(valid_frame_headers)
if strcmp(valid_frame_headers{k},frameId)
frames = proccessFrame(frames,frameId,frameData);
break;
end
end
end
end
end%while...
fclose(fid);
rOut = frames;
end%function...id3parse...
%% proccessFrame ******************************************************
function frames = proccessFrame(frames,frameId,frameData)
% FRAMES is the struct to store the frames in
% FRAMEID is the 4 byte text id for the frame
% FRAMEDATA is the frame's data bytes
try
if strncmp(frameId,'T',1)
textEncoding = frameData(1);
frameData = frameData(2:end);
idx = find(frameData == 0);
if isempty(idx)
idx = length(frameData);
else
idx = min(idx(1),length(frameData));
end
frameData = frameData(1:idx);
switch frameId
%% TIT2
case 'TIT2'
frameName = 'Title';
frames = setfield(frames,frameName,char(frameData));
%% TALB
case 'TALB'
frameName = 'Album';
frames = setfield(frames,frameName,char(frameData));
%% TBPM
case 'TBPM'
frameName = 'Beats per minute';
frames = setfield(frames,frameName,char(frameData));
%% TCOM
case 'TCOM'
frameName = 'Composer';
composers = parseID3List(char(frameData));
frames = setfield(frames,frameName,composers);
%% TCON
case 'TCON'
frameName = 'Genre';
genres = {};
while ~isempty(frameData)
idx = find(frameData == ')');
genreCode = frameData(2:idx(1)-1);
genreCode = str2num(char(genreCode));
genre = getGenre(genreCode);
refinement = [];
if isempty(idx) || idx(1) < length(frameData)
frameData = frameData(idx+1:end);
%look for an open paren followed by something OTHER
%THAN an open paren, and preceeded by either the
%beginning of the line or something OTHER THAN an open
%paren.
idx = regexp(char(frameData),'(?:[^\(]|^)(\()[^\(]');
if isempty(idx)
idx = length(frameData)
end
refinement = frameData(1:idx);
if(idx < length(frameData))
frameData = frameData(idx+1:end);
else
frameData = [];
end
else
frameData = [];
end
refinement = strrep(char(refinement),'((','(');
if length(refinement) > 0
refinement = [': ',refinement];
end
genre = [genre{:},refinement]
genres = [genres;genre];
end
frames = setfield(frames,frameName,genres);
%% TCOP
case 'TCOP'
frameName = 'Copyright';
frames = setfield(frames,frameName,['Copyright ',char(frameData)]);
%% TDAT
case 'TDAT'
frameName = 'Recording_Date';
frames = setfield(frames,frameName,[char(frameData(1:2)),'-',char(frameData(3:4))] );
%% TDLY
case 'TDLY'
frameName = 'Playlist_Delay';
frames = setfield(frames,frameName,char(frameData));
%% TENC
case 'TENC'
frameName = 'Encoded_By';
frames = setfield(frames,frameName,char(frameData));
%% TPE1
case 'TPE1'
frameName = 'Artist';
artists = parseID3List(char(frameData));
frames = setfield(frames,frameName,artists);
%% TPE2
case 'TPE2'
frameName = 'Band';
frames = setfield(frames,frameName,char(frameData));
%% TPE3
case 'TPE3'
frameName = 'Conductor';
frames = setfield(frames,frameName,char(frameData));
%% TPE4
case 'TPE4'
frameName = 'Interpreted_By';
frames = setfield(frames,frameName,char(frameData));
%% TLEN
case 'TLEN'
frameName = 'Length';
ms = str2num(char(frameData));
s = floor(ms/1000);
ms = ms - s*1000;
m = floor(s/60);
s = s - 60*m;
ms = int2str(ms);
if length(ms) < 2
ms = ['0',ms];
end
s = int2str(s);
if length(s) < 2
s = ['0',s];
end
m = int2str(m);
frames = setfield(frames,frameName,sprintf('%s:%s.%s',m,s,ms));
%% TPUB
case 'TPUB'
frameName = 'Publisher';
frames = setfield(frames,frameName,char(frameData));
%% TPOS
case 'TPOS'
frameName = 'Part_of_set';
idx = find(frameData == '/');
if isempty(idx)
idx = length(frameData)+1;
end
part = char(frameData(1:idx-1));
of = '';
if idx < length(frameData)
of = [' of ', char(frameData(idx+1:end))];
end
val = [part, of];
frames = setfield(frames,frameName,val);
%% TRCK
case 'TRCK'
frameName = 'Track';
idx = find(frameData == '/');
if isempty(idx)
idx = length(frameData)+1;
end
part = char(frameData(1:idx-1));
of = '';
if idx < length(frameData)
of = [' of ', char(frameData(idx+1:end))];
end
val = [part, of];
frames = setfield(frames,frameName,val);
%% TYER
case 'TYER'
frameName = 'Recording_Year';
frames = setfield(frames,frameName,char(frameData));
%% CUSTOM TEXT FRAME
otherwise
frames = setfield(frames,frameId,char(frameData));
end%switch frameId
else
switch frameId
%% UFID
case 'UFID'
idx = find(frameData == 0);
ownerIdentifier = char(frameData(1:idx-1));
identifier = frameData(idx+1:end);
frameName = 'Unique_File_Identifier';
if isfield(frames,frameName)
ufid = frames.(frameName);
else
ufid = {}
end
ufid = [ufid;{ownerIdentifier,identifier}];
frames.(frameName) = ufid;
%% PRIV
case 'PRIV'
idx = find(frameData == 0);
ownerIdentifier = char(frameData(1:idx-1));
identifier = frameData(idx+1:end);
frameName = 'Private_frame';
if isfield(frames,frameName)
priv = frames.(frameName);
else
priv = {};
end
priv = [priv;{ownerIdentifier,identifier}];
frames = setfield(frames,frameName,priv);
%% MCDI
case 'MCDI'
frameName = 'Music_CD_identifier';
frames = setfield(frames,frameName,char(frameData));
%% UNKNOWN FRAME
otherwise
frames = setField(frames,frameId,char(frameData));
end%switch frameId
end%if...else...
catch
warning('ID3Parser:IllFormat:Frame','Error parsing the following frame: %s',frameId);
frames = setField(frames,frameId,char(frameData));
end
end%function ... proccessFrame...
%% parseID3List *********************************************************
function cellArray = parseID3List(List)
cellArray = regexp(List,'([^\/]*)\/','tokens');
cellArray = [cellArray{:},regexp(List,'\/([^\/]*)$','tokens','once')];
if isempty(cellArray)
cellArray = List;
end
end%function ... parseID3List...
%% convertBytesToID3Size ********************************************
function the_size = convertBytesToID3Size(bytes)
bytes = dec2bin(bytes,8);
bytes(:,1) = []; % remove most significant bit
the_size =bin2dec([bytes(1,:) bytes(2,:) bytes(3,:) bytes(4,:)]);
end%function ... convertBytesToID3Size...
%% getGenre *************************************************************
function genre = getGenre(idx)
persistent genres;
if isempty(genres)
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' ,
};
end
genre = genres(idx+1);
end%function ... getGenre...
function out = gen_valid_frame_headers
out{1}='TALB';
out{end+1}='TBPM';
out{end+1}='TCOM';
%out{end+1}='TCON'; % TCON Was giving warning, so I removed It
out{end+1}='TCOP';
out{end+1}='TDAT';
out{end+1}='TDLY';
out{end+1}='TENC';
out{end+1}='TEXT';
out{end+1}='TFLT';
out{end+1}='TIME';
out{end+1}='TIT1';
out{end+1}='TIT2';
out{end+1}='TIT3';
out{end+1}='TKEY';
out{end+1}='TLAN';
out{end+1}='TLEN';
out{end+1}='TMED';
out{end+1}='TOAL';
out{end+1}='TOFN';
out{end+1}='TOLY';
out{end+1}='TOPE';
out{end+1}='TORY';
out{end+1}='TOWN';
out{end+1}='TPE1';
out{end+1}='TPE2';
out{end+1}='TPE3';
out{end+1}='TPE4';
out{end+1}='TPOS';
out{end+1}='TPUB';
out{end+1}='TRCK';
out{end+1}='TRDA';
out{end+1}='TRSN';
out{end+1}='TRSO';
out{end+1}='TSIZ';
out{end+1}='TSRC';
out{end+1}='TSSE';
out{end+1}='TYER';
out{end+1}='WCOM';
out{end+1}='WCOP';
out{end+1}='WOAF';
out{end+1}='WOAR';
out{end+1}='WOAS';
out{end+1}='WORS';
out{end+1}='WPAY';
out{end+1}='WPUB';
end%function ... gen_valid_frame_headers...
