gusucode.com > 《MATLAB图像与视频处理实用案例详解》代码 > 《MATLAB图像与视频处理实用案例详解》代码/第 19 章 基于语音识别的信号灯图像模拟控制技术/voicebox/frq2midi.m
function [n,t]=frq2midi(f) %FRQ2MIDI Convert frequencies to musical note numbers [N,T]=(F) % notes are numbered in semitones with middle C being 60 % Note 69 (the A above middle C) has a frequency of 440 Hz. % These note numbers are used by MIDI. Note numbers are not necessarily % integers. % % t is a text representation of the note in which % C4# denotes C sharp in octave 4. Octave 4 goes % from middle C up to the B above middle C. For the white % notes on the piano, the third character is a space. % % Negative frequencies are equivalent to positive frequencies % except that flats will be used instead of sharps. Thus % C4# would become D4- % % see MIDI2FRQ for the inverse transform % Copyright (C) Mike Brookes 1998 % Version: $Id: frq2midi.m,v 1.4 2007/05/04 07:01:38 dmb Exp $ % % VOICEBOX is a MATLAB toolbox for speech processing. % 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 % http://www.gnu.org/copyleft/gpl.html or by writing to % Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% n=(69+12*log(abs(f)/440)/log(2)); if nargout > 1 m=round(n(:)); o=floor(m/12)-1; m=m-12*o+6*sign(f(:))-5; a=('CDDEEFGGAABBCCDDEFFGGAAB')'; b=(' - - - - - # # # # # ')'; t=setstr([a(m) mod(o,10)+'0' b(m)]); end