% sp: create gray-scale spectrogram
% Usage: h=sp(wave,rate,nfft,nsampf,nhop,pre,drng,title,ngray,clr);
% wave: input waveform
% rate: sample rate in Hz (default 8000 Hz)
% nfft: FFT window length (default: 256 samples)
% nsampf: number of samples per frame (default: 60)
% nhop: number of samples to hop to next frame
%           (default: 5 samples)
% pre: preemphasis factor (0-1) (default: 1)
% drng: dynamic range in dB (default: 80)
% title: title for graph (default: none)
% ngray: number of gray levels for colormap (default 48)
% clr: clearscreen flag; if set to 1, clear figure window (default 1)
% h: axes handles

% Peter Assmann - Oct 20, 1992/ Modified for Matlab 5.0 [PA, 6-15-97]
function h=sp(wave,rate,nfft,nsampf,nhop,pre,drng,string,ngray,clr);
if ~exist('rate','var'), rate=8000; end;
if ~exist('nfft','var'), nfft=256; end;
if ~exist('nsampf','var'), nsampf=60; end;
if ~exist('nhop','var'), nhop=5; end;
if ~exist('pre','var'), pre=1; end;
if ~exist('drng','var'), drng=80; end;
if ~exist('string','var'), string=''; end;
if ~exist('ngray','var'), ngray=64; end;
if ~exist('clr','var'), clr=0; end;
[n,m]=size(wave);
if n==1 & m>1, wave=wave'; n=m; end; % want row vector
w=(wave(1:n))/3276.8;
ms=n/rate*1000;
t=1:n;
t=t'/(rate/1000);
dur=max(t);
plotflag=0;
b=20.*log10(fftpsd(w,rate,nfft,nsampf,nhop,pre,plotflag)+eps)';
if clr,
    clf reset;
    h(2)=axes('Position',[0.13 0.11 0.775 0.65]);
end;
maxb=max(max(b));
b=(b-maxb)+drng;
i=find(b<0); b(i)=zeros(size(i))+eps;
imagesc([0 max(t)],[0 rate/2000],b,'EraseMode','normal');
colormap(hot.*copper);
axis manual on xy;
xlabel('Time (ms)');
ylabel('Frequency (kHz)');
set(gca,'XLim',[0 max(t)],...
    'YLim',[0 rate/2000],...
    'TickDir','Out','Box','On'); 

% plot waveform only if clr is selected..
if clr,
    h(1)=axes('pos',[0.13 0.8 0.775 0.15],...
        'Vis','Off','XLim',[0 ms]);
    wp(wave,length(wave),rate,string);
    set(h(1),'XLim',[0 ms],'FontSize',14);
    axis off tight;
    font(15);
    set(get(h(1),'title'),'VerticalAlignment','middle');
end;