?? midi2frq.m
字號:
function f=midi2frq(n,s)
%MIDI2FRQ Convert musical note numbers to frequencies F=(N,S)
% s is: 'e' equal tempered (default)
% 'p' pythagorean scale
% 'j' just intonation
%
% notes are numbered in semitones with middle C being 60
% On the equal tempered scale, note 69 (the A above middle C)
% has a frequency of 440 Hz.
%
% see FRQ2NOTE for the inverse transform
% Pythagorean
% sharps 1 2187/2048 9/8 19683/16384 81/64 4/3 729/512 3/2 6561/4096 27/16 59049/32768 243/128 2
% flats 1 256/243 9/8 32/27 81/64 4/3 1024/729 3/2 128/81 27/16 16/9 243/128 2
%
% Just Intonation
% sharps 1 25/24 9/8 75/64 5/4 4/3 45/32 3/2 25/16 5/3 225/128 15/8 2
% flats 1 16/15 9/8 6/5 5/4 4/3 108/75 3/2 8/5 5/3 18/10 15/8 2
% Copyright (C) Mike Brookes 1997
%
% Last modified Tue May 12 16:14:26 1998
%
% VOICEBOX 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
% ftp://prep.ai.mit.edu/pub/gnu/COPYING-2.0 or by writing to
% Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
if nargin > 1
if s(1)=='p'
r=[256/243 9/8 32/27 81/64 4/3 729/512 3/2 128/81 27/16 16/9 243/128];
elseif s(1)=='j'
r=[16/15 9/8 6/5 5/4 4/3 36/25 3/2 8/5 5/3 9/5 15/8];
else
r=0;
end
if r(1)
c=[0 0 12*log(r)/log(2)-(1:11) 0];
nm=mod(n,12);
na=floor(nm);
nb=nm-na;
f=440*exp((n+c(na+2).*(1-nb)+c(na+3).*nb-69)*log(2)/12);
else
f=440*exp((n-69)*log(2)/12);
end
else
f=440*exp((n-69)*log(2)/12);
end
?? 快捷鍵說明
復制代碼
Ctrl + C
搜索代碼
Ctrl + F
全屏模式
F11
切換主題
Ctrl + Shift + D
顯示快捷鍵
?
增大字號
Ctrl + =
減小字號
Ctrl + -