Re: buffer (signal)?

[Sciss]

the description is here:

http://www.mathworks.com/access/helpdesk/help/toolbox/signal/buffer.html

meanwhile i started to write something based on that doc. beware as  
i'm absolutely bad with matlab/octave syntax and i stopped to  
implement it when it did it's job (see below) ;-)


%%% begin buffer.m

function [y, z, opt] = buffer( x, n, p, opt )
disp( "WARNING: buffer is a quick hack, don't use for continuous  
buffering" );

if nargin < 3, p = 0; end;
L = length(x);
if p <= 0
        if nargin < 4, skip = 0; else skip = opt; end;
        pre = [];
        m = floor((L-skip)/(n-p)) + (rem((L-skip),(n-p)) >= n);
        z = zeros( (L-skip) - m*(n-p) );
else
        if nargin < 4, pre = zeros( p, 1 ); else pre = opt; end;
        skip = 0;
        if strcmp( pre, 'nodelay' )
                pre = 0;
                m = floor((L-n)/(n-p))+1;
                z = zeros( L - ((m-1)*(n-p)+n) );
        else
                m = floor(L/(n-p));
                z = zeros( L - m*(n-p) );
        end;
end;
y = zeros( n, m );
q = n * m;
y(1:length(pre))=pre;
i = length(pre);
j = skip;
while (i < q && j < L)
        nn = min( min( n, q - i ), L - j );
        y((i+1):(i+nn))=x((j+1):(j+nn));
        i = i + n;
        j = j + n - p;
endwhile

%%% end buffer.m


i used this with a very interesting tool from

http://cosmal.ucsd.edu/cal/projects/CATbox/catbox.htm

--> the ConstQ spectrum analysis tool. all i had to change is to  
comment out the line

progressbar(i/N);

in cqgram.m since it produces some errors with gnuplot. i get  
impressive results, like:

x = auload( '/Users/rutz/Desktop/SineSweep.wav' );
cqgram( x, 16384, 16384-256, 32, 22050, 24, 44100 );


ciao, -sciss-




Am 10.04.2008 um 22:25 schrieb Ben Abbott:
> On Thursday, April 10, 2008, at 12:59PM, "Sciss" <address@hidden>  
> wrote:
> > hi,
> >
> > i am trying to run a function that was written for matlab. it breaks
> > because the function 'buffer' is missing, something that creates an
> > overlapped-chunk version of a vector. on octave-forge's documentation
> > site, it is stated:
> >
> > "buffer  [signal] -- not implemented"
> >
> > ... so i assume this function is missing? i installed the signal
> > package but no luck. any clues how i can get a 'buffer' function for
> > octave?
> >
> > thanks a lot! cheers, -sciss-
>
> From the most recent Matlab (7.6)
>
> > > which buffer
> 'buffer' not found.
> > >
>
> Apparently "buffer" is not a core Matlab function.
>
> By chance is the function you're looking for actually a class? ...  
> for example,
>
> http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do? 
> objectId=14087
>
> If not, can you tell us what "buffer" is supposed to do?
>
> Ben