gusucode.com > 《MATLAB图像与视频处理实用案例详解》代码 > 《MATLAB图像与视频处理实用案例详解》代码/第 19 章 基于语音识别的信号灯图像模拟控制技术/voicebox/readwav.m
function [y,fs,wmode,fidx]=readwav(filename,mode,nmax,nskip)
%READWAV Read a .WAV format sound file [Y,FS,WMODE,FIDX]=(FILENAME,MODE,NMAX,NSKIP)
%
% Input Parameters:
%
% FILENAME gives the name of the file (with optional .WAV extension) or alternatively
% can be the FIDX output from a previous call to READWAV
% MODE specifies the following (*=default):
%
% Scaling: 's' Auto scale to make data peak = +-1
% 'r' Raw unscaled data (integer values)
% 'q' Scaled to make 0dBm0 be unity mean square
% 'p' * Scaled to make +-1 equal full scale
% 'o' Scale to bin centre rather than bin edge (e.g. 127 rather than 127.5 for 8 bit values)
% (can be combined with n+p,r,s modes)
% 'n' Scale to negative peak rather than positive peak (e.g. 128.5 rather than 127.5 for 8 bit values)
% (can be combined with o+p,r,s modes)
% 'g' Scale by the gain written by the "g" option in "writewav" to restore original level
% Offset: 'y' * Correct for offset in <=8 bit PCM data
% 'z' No offset correction
% File I/O: 'f' Do not close file on exit
% 'd' Look in data directory: voicebox('dir_data')
% Display; 'h' Print header information
% 'w' Plot waveform
% 'W' Plot spectrogram
% 'a' play audio (max 10 seconds)
% 'A' play all audio even if very long
%
% NMAX maximum number of samples to read (or -1 for unlimited [default])
% NSKIP number of samples to skip from start of file
% (or -1 to continue from previous read when FIDX is given instead of FILENAME [default])
%
% Output Parameters:
%
% Y data matrix of dimension (samples,channels)
% FS sample frequency in Hz
% WMODE mode string needed for WRITEWAV to recreate the data file
% FIDX Information row vector containing the element listed below.
%
% (1) file id
% (2) current position in file
% (3) dataoff byte offset in file to start of data
% (4) nsamp number of samples
% (5) nchan number of channels
% (6) nbyte bytes per data value
% (7) bits number of bits of precision
% (8) code Data format: 1=PCM, 2=ADPCM, 3=floating point, 6=A-law, 7=Mu-law
% (9) fs sample frequency
% (10) mask channel mask
% (11) gain gain factor in dB
%
% If no output parameters are specified, header information will be printed.
%
% For stereo data, y(:,1) is the left channel and y(:,2) the right
% The mask, if specified, is a bit field giving the channels present in the following order:
% 0=FL, 1=FR, 2=FC, 3=W, 4=BL, 5=BR, 6=FLC, 7=FRC, 8=BC, 9=SL, 10=SR, 11=TC, 12=TFL, 13=TFC, 14=TFR, 15=TBL, 16=TBC, 17=TBR
% where F=front, L=left, C=centre, W=woofer (low frequency), B=back, LC=left of centre, RC=right of centre, S=side, T=top
%
% See also WRITEWAV.
% *** Note on scaling ***
% If we want to scale signal values in the range +-1 to an integer in the
% range [-128,127] then we have four plausible choices corresponding to
% scale factors of (a) 127, (b) 127.5, (c) 128 or (d) 128.5 but each choice
% has disadvantages.
% For forward scaling: (c) and (d) cause clipping on inputs of +1.
% For reverse scaling: (a) and (b) can generate output values < -1.
% Any of these scalings can be selected via the mode input: (a) 'o', (b) default, (c) 'on', (d) 'n'
% Copyright (C) Mike Brookes 1998-2011
% Version: $Id: readwav.m,v 1.8 2011/05/02 16:51:08 dmb Exp $
%
% VOICEBOX is a MATLAB toolbox for speech processing.
% Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This program is free software; you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation; either version 2 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You can obtain a copy of the GNU General Public License from
% http://www.gnu.org/copyleft/gpl.html or by writing to
% Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Bugs/suggestions:
if nargin<1
error('Usage: [y,fs,wmode,fidx]=READWAV(filename,mode,nmax,nskip)'); end
if nargin<2
mode='p';
else
mode = [mode(:).' 'p'];
end
k=find((mode>='p') & (mode<='s'));
mno=all(mode~='o'); % scale to input limits not output limits
sc=mode(k(1));
z=128*all(mode~='z');
info=zeros(1,11);
if ischar(filename)
if any(mode=='d')
filename=fullfile(voicebox('dir_data'),filename);
end
fid=fopen(filename,'rb','l');
if fid == -1
fn=[filename,'.wav'];
fid=fopen(fn,'rb','l');
if fid ~= -1
filename=fn;
end
end
if fid == -1
error('Can''t open %s for input',filename);
end
info(1)=fid;
else
info=filename;
fid=info(1);
end
getdat= nargout>0 || any(lower(mode)=='w') || any(lower(mode)=='a');
mh=any(mode=='h') || ~getdat;
if ~info(3)
fseek(fid,8,-1); % read riff chunk
header=fread(fid,4,'*char')';
if ~strcmp(header,'WAVE')
fclose(fid);
error('File does not begin with a WAVE chunck');
end
if mh
fprintf('\nWAVE file: %s\n',filename);
end
fmtlen=-1;
datalen=-1;
instlen=-1;
factlen=-1;
riffmt='e'; % default is original wave file format
while datalen<0 % loop until FMT and DATA chuncks both found
header=fread(fid,4,'*char');
len=fread(fid,1,'ulong');
if mh
fprintf(' %s chunk: %d bytes\n',header,len);
end
if strcmp(header','fmt ') % ******* found FMT chunk *********
fmtlen=len; % remember the length
if len>16
riffmt='x'; % might be WAVEFORMATEX format
end
wavfmt=fread(fid,1,'short'); % format: 1=PCM, 6=A-law, 7-Mu-law
info(8)=wavfmt;
info(5)=fread(fid,1,'ushort'); % number of channels
fs=fread(fid,1,'ulong'); % sample rate in Hz
info(9)=fs; % sample rate in Hz
rate=fread(fid,1,'ulong'); % average bytes per second (ignore)
align=fread(fid,1,'ushort'); % block alignment in bytes (container size * #channels)
bps=fread(fid,1,'ushort'); % bits per sample
info(7)=bps;
% info(6)=ceil(info(7)/8); % round up to a byte count
info(6)=floor(align/info(5)); % assume block size/channels = container size
if info(8)==-2 % wave format extensible
cb=fread(fid,1,'ushort'); % extra bytes must be >=22
riffmt='X'; % WAVEFORMATEXTENSIBLE format
wfxsamp=fread(fid,1,'ushort'); % samples union
if wfxsamp>0
info(7)=wfxsamp; % valid bits per sample
end
info(10)=fread(fid,1,'ulong'); % channel mask
wfxguida=fread(fid,1,'ulong'); % GUID
wfxguidb=fread(fid,2,'ushort'); % GUID
wfxguidc=fread(fid,8,'uchar'); % GUID
if wfxguida<65536
info(8)=wfxguida; % turn it into normal wav format
end
fseek(fid,len-40,0); % skip to end of header
else
if align>0 && align<(info(6)+4)*info(5)
info(6)=ceil(align/info(5));
end
fseek(fid,len-16,0); % skip to end of header
end
if mh
fmttypes={'?' 'PCM' 'ADPCM' 'IEEE-float' '?' '?' 'A-law' '?-law' '?'};
fprintf(' Format: %d = %s',info(8),fmttypes{1+max(min(info(8),8),0)});
if wavfmt==-2
fprintf(' (%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x)\n',wfxguida,wfxguidb,wfxguidc);
else
fprintf('\n');
end
fprintf(' %d channels at %g kHz sample rate (%d kbytes/s)\n',info(5),fs/1000,rate/1000);
fprintf(' Mask=%x:',info(10));
spkpos={'FL' 'FR' 'FC' 'W' 'BL' 'BR' 'FLC' 'FRC' 'BC' 'SL' 'SR' 'TC' 'TFL' 'TFC' 'TFR' 'TBL' 'TBC' 'TBR'};
for i=1:18
if mod(floor(info(10)*pow2(1-i)),2)
fprintf([' ' spkpos{i}]);
end
end
fprintf('\n %d valid bits of %d per sample (%d byte block size)\n',info(7),bps,align);
end
elseif strcmp(header','fact') % ******* found FACT chunk *********
factlen=len;
if len<4
error('FACT chunk too short');
end
nsamp=fread(fid,1,'ulong'); % number of samples
fseek(fid,len-4,0); % skip to end of header
if mh
fprintf(' %d samples = %.3g seconds\n',nsamp,nsamp/fs);
end
elseif strcmp(header','inst') % ******* found INST chunk *********
instlen=len;
if len<7
error('INST chunk too short');
end
inst=fread(fid,3,'schar');
info(11)=double(inst(3)); % gain in dB
if mh
fprintf(' Gain = %d dB\n',info(11));
end
fseek(fid,len-3,0); % skip to end of header
elseif strcmp(header','data') % ******* found DATA chunk *********
if fmtlen<0
fclose(fid);
error('File %s does not contain a FMT chunck',filename);
end
if factlen>3 && nsamp >0
info(4)=nsamp; % take data length from FACT chunk
else
info(4) = fix(len/(info(6)*info(5))); % number of samples
end
info(3)=ftell(fid); % start of data
datalen=len;
if mh
fprintf(' %d samples x %d channels x %d bytes/samp',info(4:6));
if prod(info(4:6))~=len
fprintf(' + %d padding bytes',len-prod(info(4:6)));
end
fprintf(' = %g sec\n',info(4)/fs);
end
else % ******* found unwanted chunk *********
fseek(fid,len,0);
end
end
else
fs=info(9);
end
if nargin<4 || nskip<0
nskip=info(2); % resume at current file position
end
ksamples=info(4)-nskip; % number of samples remaining
if nargin>2
if nmax>=0
ksamples=min(nmax,ksamples);
end
elseif ~getdat
ksamples=min(5,ksamples); % just read 5 samples so we can print the first few data values
end
if ksamples>0
info(2)=nskip+ksamples;
fseek(fid,info(3)+info(6)*info(5)*nskip,-1);
nsamples=info(5)*ksamples;
if any(info(8)==3) % floating point format
pk=1; % peak is 1
switch info(6)
case 4
y=fread(fid,nsamples,'float32');
case 8
y=fread(fid,nsamples,'float64');
otherwise
error('cannot read %d-byte floating point numbers',info(6));
end
else
if ~any(info(8)==[1 6 7])
sc='r'; % read strange formats in raw integer mode
end
pk=pow2(0.5,8*info(6))*(1+(mno/2-all(mode~='n'))/pow2(0.5,info(7))); % use modes o and n to determine effective peak
switch info(6)
case 1
y=fread(fid,nsamples,'uchar');
if info(8)==1
y=y-z;
elseif info(8)==6
y=pcma2lin(y,213,1);
pk=4032+mno*64;
elseif info(8)==7
y=pcmu2lin(y,1);
pk=8031+mno*128;
end
case 2
y=fread(fid,nsamples,'short');
case 3
y=fread(fid,3*nsamples,'uchar');
y=reshape(y,3,nsamples);
y=([1 256 65536]*y-pow2(fix(pow2(y(3,:),-7)),24)).';
case 4
y=fread(fid,nsamples,'long');
otherwise
error('cannot read %d-byte integers',info(6));
end
end
if sc ~= 'r'
if sc=='s'
sf=1/max(abs(y(:)));
elseif sc=='p'
sf=1/pk;
else
if info(8)==7
sf=2.03761563/pk;
else
sf=2.03033976/pk;
end
end
y=sf*y;
else % mode = 'r' - output raw values
if info(8)==1
y=y*pow2(1,info(7)-8*info(6)); % shift to get the bits correct
end
end
if any(mode=='g') && info(11)~=0
y=y*10^(info(11)/20); % scale by the gain
end
if info(5)>1
y = reshape(y,info(5),ksamples).';
end
else
y=[];
end
if all(mode~='f')
fclose(fid);
end
if nargout>2 % sort out the mode input for writing this format
wmode=char([riffmt sc 'z'-z/128]);
if factlen>0
wmode=[wmode 'E'];
end
if info(6)>1 && info(6)<5
cszc=' cCL';
wmode=[wmode cszc(info(6))];
end
switch info(8)
case 1 % PCM modes
if ~mno
wmode=[wmode 'o'];
end
if any(mode=='n')
wmode=[wmode 'n'];
end
wmode=[wmode num2str(info(7))];
case 3
if info(7)<=32
wmode = [wmode 'v'];
else
wmode = [wmode 'V'];
end
case 6
wmode = [wmode 'a'];
case 7
wmode = [wmode 'u'];
end
fidx=info;
end
[ns,nchan]=size(y);
if mh && ns>0
nsh=min(ns,5); % print first few samples
for i=1:nsh
fprintf(' %d:',i);
fprintf(' %.3g',y(i,:));
fprintf('\n');
end
end
if ns>0.01*fs
if any(lower(mode)=='a')
nsh=min(ns,10*fs+ns*any(mode=='A'));
soundsc(y(1:nsh,1:min(nchan,2)),fs);
end
if any(mode=='W')
spm='pJcbf ';
if any(mode=='w')
spm(end)='w';
end
clf;
if nchan>1
for i=nchan:-1:1
subplot(nchan,1,i)
spgrambw(y(:,i),fs,spm);
end
else
spgrambw(y,fs,spm);
end
elseif any(mode=='w')
clf;
if nchan>1
for i=nchan:-1:1
subplot(nchan,1,i)
plot((1:ns)/fs,y(:,i));
ylabel(['Chan ' num2str(i)]);
if i==nchan
xlabel('Time (s)');
end
end
else
plot((1:ns)/fs,y);
xlabel('Time (s)');
end
end
end