mp3read

MP3READ Read MP3 (".mp3") sound file.
    Y=MP3READ(FILE) reads a MP3 file specified by the string FILE,
    returning the sampled data in Y. Amplitude values are in the range [-1,+1].
 
    [Y,FS,NBITS]=MP3READ(FILE) returns the sample rate (FS) in Hertz
    and the number of bits per sample (NBITS) used to encode the
    data in the file.
 
    Supports two channel encoded data, with up to 16 bits per sample.
 
    See also MP3WRITE, WAVWRITE, AUREAD, AUWRITE.

0001 function [Y,FS,NBITS] = mp3read(FILE)
0002 %MP3READ Read MP3 (".mp3") sound file.
0003 %    Y=MP3READ(FILE) reads a MP3 file specified by the string FILE,
0004 %    returning the sampled data in Y. Amplitude values are in the range [-1,+1].
0005 %
0006 %    [Y,FS,NBITS]=MP3READ(FILE) returns the sample rate (FS) in Hertz
0007 %    and the number of bits per sample (NBITS) used to encode the
0008 %    data in the file.
0009 %
0010 %    Supports two channel encoded data, with up to 16 bits per sample.
0011 %
0012 %    See also MP3WRITE, WAVWRITE, AUREAD, AUWRITE.
0013 
0014 %%%%%% Location of the ".exe" Files
0015 s = which('mp3read.m');
0016 ww = findstr('mp3read.m',s);
0017 location = s(1:ww-2);
0018 mpg123 = location;;
0019 mp3info = location;
0020 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0021 %%%%%% Data extraction from File using "mp3info.exe"%%%%%%%%%%%%%%
0022 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0023 % Q = samprate, u = #frames, r = bitrate, v = mpeg version (1/2/2.5)
0024 % C = Copyright, e = emph, E = CRC, L = layer, O = orig, o = mono, p = pad
0025 cmd = [mp3info,'\mp3info', ' -r a -p  "%Q %u %r %v * %C %e %E %L %O %o %p" "', FILE,'"'];
0026 w = mysystem(cmd);
0027 % Break into numerical and ascii parts by finding the delimiter (*)
0028 starpos = findstr(w,'*');
0029 nums = str2num(w(1:(starpos - 2)));
0030 strs = tokenize(w((starpos+2):end));
0031 SR = nums(1);                           %Sampling Rate
0032 nframes = nums(2);                      %Number of Frames
0033 nchans = 2 - strcmp(strs{6}, 'mono');   %Number of Channels
0034 layer = length(strs{4});                %MPEG Layer
0035 bitrate = nums(3)*1000;                 %MPEG Bitrate
0036 mpgv = nums(4);                         %MPEG Version
0037 %%%%Temporary file%%%%%%
0038 tmpfile = ['temp.wav'];
0039 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0040 %%%%%%%%%%%%%% Data Decoding  using "mpg123.exe"%%%%%%%%%%%%%%%%%%
0041 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0042 cmd = [mpg123,'\mpg123', ' -w ', tmpfile, ' ', '"',FILE,'"'];
0043 w = mysystem(cmd);
0044 % Load the data and delete temporary file
0045 [Y,FS,NBITS] = wavread(tmpfile);
0046 delete(tmpfile);
0047 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0048 function w = mysystem(cmd)
0049 % Run system command; report error; strip all but last line
0050 [s,w] = dos(cmd);
0051 if s ~= 0 
0052   error(['unable to execute ',cmd]);
0053 end
0054 % Keep just final line
0055 w = w((1+max([0,findstr(w,10)])):end);
0056 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0057 function a = tokenize(s)
0058 % Break space-separated string into cell array of strings
0059 % 2004-09-18 dpwe@ee.columbia.edu
0060 a = [];
0061 p = 1;
0062 n = 1;
0063 l = length(s);
0064 nss = findstr([s(p:end),' '],' ');
0065 for ns = nss
0066   % Skip initial spaces
0067   if ns == p
0068     p = p+1;
0069   else
0070     if p <= l
0071       a{n} = s(p:(ns-1));
0072       n = n+1;
0073       p = ns+1;
0074     end
0075   end
0076 end
0077