comparison util/matlab_midi/piano_roll.m @ 81:a30e8bd6d948

matlab_midi scripts

+function [PR,t,nn] = piano_roll(Notes,vel,ts)
+%
+% Inputs:
+%  Notes: A 'notes' matrix as returned from midiInfo.m
+%  vel:   (optional) if vel==1, set value to note velocity instead of 1. (default 0)
+%  ts:    (optional) time step of one 'pixel' in seconds (default 0.01)
+%
+% Outputs:
+%  PR:    PR(ni,ti): value at note index ni, time index ti
+%  t:     t(ti):  time value in seconds at time index ti
+%  nn:    nn(ni): note number at note index ti
+%
+%   (i.e. t and nn provide 'real-world units' for PR)
+%
+
+% Copyright (c) 2009 Ken Schutte
+% more info at: http://www.kenschutte.com/midi
+
+if nargin < 2
+  vel = 0;
+end
+if nargin < 3
+  ts = 0.01;
+end
+
+Nnotes = size(Notes,1);
+
+n1 = round(Notes(:,5)/ts)+1;
+n2 = round(Notes(:,6)/ts)+1;
+
+if vel == 0
+  vals = ones(Nnotes,1);
+else
+  vals = Notes(:,4); % velocity
+end
+
+for i=1:Nnotes
+  PR(Notes(i,3), n1(i):n2(i)) = vals(i);
+end
+
+% create quantized time axis:
+t = linspace(0,max(Notes(:,6)),size(PR,2));
+% note axis:
+nn = min(Notes(:,3)):max(Notes(:,3));  
+% truncate to notes used:
+PR = PR(nn,:);