spRead

SPREAD Read HTK (".SP") sound file.
   Y=SPREAD(FILE) reads a SP file specified by the string FILE,
   returning the sampled data in Y. The ".SP" extension is appended
   if no extension is given.  Amplitude values are in the range [-1,+1].

   [Y,FS,NBITS,SAMPLEKIND]=SPREAD(FILE) returns the sample rate
   (FS) in Hertz, the number of bits per sample (NBITS) used to
   encode the data in the file, and the code indicating the sample kind.

   [...]=SPREAD(FILE,N) returns only the first N samples in the file.
   [...]=SPREAD(FILE,[N1 N2]) returns only samples N1 through N2 in the file.
   SIZ=SPREAD(FILE,'size') returns the size of the audio data contained
       in the file in place of the actual audio data, returning the
       SIZ=samples.

0001 function [y,Fs,bits,parmKind] = spread(file,ext)
0002 %SPREAD Read HTK (".SP") sound file.
0003 %   Y=SPREAD(FILE) reads a SP file specified by the string FILE,
0004 %   returning the sampled data in Y. The ".SP" extension is appended
0005 %   if no extension is given.  Amplitude values are in the range [-1,+1].
0006 %
0007 %   [Y,FS,NBITS,SAMPLEKIND]=SPREAD(FILE) returns the sample rate
0008 %   (FS) in Hertz, the number of bits per sample (NBITS) used to
0009 %   encode the data in the file, and the code indicating the sample kind.
0010 %
0011 %   [...]=SPREAD(FILE,N) returns only the first N samples in the file.
0012 %   [...]=SPREAD(FILE,[N1 N2]) returns only samples N1 through N2 in the file.
0013 %   SIZ=SPREAD(FILE,'size') returns the size of the audio data contained
0014 %       in the file in place of the actual audio data, returning the
0015 %       SIZ=samples.
0016 
0017 % Parse input arguments:
0018 nargchk(1,2,nargin);
0019 if nargin<2, ext=[]; end    % Default - read all samples
0020 exts = prod(size(ext));     % length of extent info
0021 if ~strncmp(lower(ext),'size',exts) & (exts > 2),
0022    error('Index range must be specified as a scalar or 2-element vector.');
0023 end
0024 if ~ischar(ext) & exts==1,
0025    if ext==0,
0026       ext='size';           % synonym for size
0027    else
0028       ext=[1 ext];          % Prepend start sample index
0029    end
0030 end
0031 
0032 % Open SP file.
0033 [fid,msg] = open_sp(file);
0034 error(msg);
0035 
0036 % ------------------------------------------------------------------------
0037 % Parse structure info for return to user:
0038 % ------------------------------------------------------------------------
0039 
0040 % The number of samples in file (4 bytes interger).
0041 nSamples = fread(fid,1,'int32');
0042 
0043 % The sample period in 100ns units (4 bytes interger).
0044 sampPeriod = fread(fid,1,'int32');
0045 
0046 % The number of bytes per sample (2 bytes interger).
0047 sampSize = fread(fid,1,'int16');
0048 
0049 % A code indicating the sample kind (2 bytes interger).
0050 parmKind = fread(fid,1,'int16');
0051 
0052 % Determine # bytes/sample.
0053 if (sampSize == 1),
0054    dtype='uchar'; % unsigned 8-bit
0055 elseif (sampSize == 2),
0056    dtype='short'; % signed 16-bit
0057 else
0058    error('Cannot read SP file formats with more than 16 bits per sample.');
0059 end
0060 
0061 % Return the sampled data.
0062 [y_tmp,cnt] = fread(fid,dtype);
0063 
0064 % Return the sample rate in Hertz.
0065 Fs = 1/(sampPeriod/10000000);
0066 
0067 % Return the number of bits per sample.
0068 % used to encode the data in the file.
0069 bits = sampSize*8;
0070 
0071 % Check whether the file is SP file or not.
0072 if (nSamples ~= cnt),
0073    error('Not a SP file.');
0074 end
0075 
0076 if strncmp(lower(ext),'size',exts) | (~isempty(ext) & all(ext==0)),
0077    % Caller doesn't want data - just data size:
0078    y = nSamples;
0079 
0080 else
0081   % Determine sample range to read:
0082   if isempty(ext),
0083      y = normal(y_tmp,sampSize);    % Return all samples.
0084   else  
0085      if prod(size(ext))~=2,
0086         error('Sample limit vector must have 2 elements.');
0087      end
0088      if ext(1)<1 | ext(2)>nSamples,
0089         error('Sample limits out of range.');
0090      end
0091      if ext(1)>ext(2),
0092         error('Sample limits must be given in ascending order.');
0093      end          
0094      y = normal(y_tmp(ext(1):ext(2)),sampSize);
0095   end
0096   
0097 end
0098 
0099 % ------------------------------------------------------------------------
0100 % Private functions:
0101 % ------------------------------------------------------------------------
0102 
0103 % ---------------------------------------------
0104 % OPEN_SP: Open a sp file for reading
0105 % ---------------------------------------------
0106 function [fid,msg] = open_sp(file)
0107 % Append .sp extension if it's missing:
0108 [pat,nam,ext] = fileparts(file);
0109 if isempty(ext),
0110   file = [file '.sp'];
0111 end
0112 [fid,msg] = fopen(file,'rb','l');   % Little-endian
0113 if fid == -1,
0114     msg = 'Cannot open file.';
0115 end
0116 return
0117 
0118 % ----------------------------------------------
0119 % NORMAL: Normalize data range. Min will hit -1,
0120 %         max will not quite hit +1.
0121 % ----------------------------------------------
0122 function [newData] = normal(Data,BytesPerSample)
0123 if (BytesPerSample == 1),
0124    newData = (Data-128)/128;  % [-1,1)
0125 else
0126    newData = Data/32768;  % [-1,1)
0127 end
0128 return