striplot.m

Speech Quantization_Compare SNRs of speech cs5 with mu-law companding and uniform quantization

function xmax = striplot(x, fs, n, ntick, xmax)
%STRIPLOT    plot long signal in horizontal strips     
%-------      ( good for multi-line speech wfms )
%
%  Usage:  striplot(X, FS, N)
%
%             plots waveform X with N pts/line. ALL traces 
%               are auto-scaled to the max signal value
%
%        FS = sampling rate (Hertz); used only for labeling
%
%    striplot(X, FS, N, NTICK)
%                    puts markers every NTICK samples
%    striplot(X, FS, N, NT, XMAX)
%                  uses XMAX as the value for scaling
%
%   NOTE: the x-axis is always labeled with (time) indices.
%         the y-axis labels are NOT AMPLITUDE, rather they
%         are the INDEX OFFSET to the start of each row.
%
%   see also STRIPS in Sig Proc Toolbox version 3

%---------------------------------------------------------------
% copyright 1994, by C.S. Burrus, J.H. McClellan, A.V. Oppenheim,
% T.W. Parks, R.W. Schafer, & H.W. Schussler.  For use with the book
% "Computer-Based Exercises for Signal Processing Using MATLAB"
% (Prentice-Hall, 1994).
%---------------------------------------------------------------

x = x(:);
if nargin < 5
   xmax = max(abs(x));      %% <-- default scaling
end
if nargin < 4
  ntick = 0;
end
if nargin < 3
  n = 400;        %% default:  50 msec @ 8 kHz
end
lenx = length(x);
nrows = ceil(lenx/n);
if lenx < n*nrows
   x(n*nrows) = 0;      %% <--- need to zero pad
   lenx = n*nrows;
end
del_t = 1/fs;
yscale = -n*del_t;
zeroy = yscale*[1;1]*[0:(nrows-1)];
half = 0.50;
offsets = (half*yscale)*[1;1]*ones(1,nrows);
sepy = [(zeroy-offsets) (zeroy(:,nrows)+(half*yscale)*[1;1])];
if ntick > 0 
   nnt   = [0:ntick:(lenx-1)];
   xtick = del_t*[1;1]*rem(nnt,n);
   ytick = yscale*( [1;1]*(fix(nnt/n)) + half*[1;-1]*ones(nnt) );
else
   xtick = 0; ytick = 0;
end
ends = del_t*[0;n-1];
scale = half/xmax;
x = reshape( x, n, nrows );
for i = 1:nrows
   x(:,i) = -yscale*scale*x(:,i) + yscale*(i-1);
end
plot( del_t*[0:(n-1)], x, '-b', ends, sepy, ':b',...
      ends, zeroy, '--b', xtick, ytick, ':b' );