Mauch MIREX 2010

%

%CHORD2MIDINOTES Generate MIDI note values for a given chord symbol

% 

% [midinotes, success, errormessage] = chord2midinotes(chordsymbol, {verbose})

% 

% Obtains a set of midi note values for notes present in chord "chordsymbol".

% The voicing is built on the rootnote with all other degrees occuring 

% above in number order unless a bass degree is specified.

%

% In the case of the 'no chord' symbol 'N' function returns midinote -1

%

% Success = 1 if chord is converted correctly else 0.

% 

% If optional argument 'verbose' is 1, function prints any errormessage to 

% the screen.

%

% Returns:  midinotes (array of integers)

%           success (boolean)

%           errormessage (string)

%

%

% % Author: Christopher Harte,  August 2005

% 

% Copyright: Centre for Digital Music, Queen Mary University of London 2005 

%

% This file is part of the C4DM Chord Toolkit.  

%

% The C4DM Chord Toolkit 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.

%

% The C4DM Chord Toolkit 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 should have received a copy of the GNU General Public License

% along with the C4DM Toolkit; if not, write to the Free Software

% Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

%

function [midinotes, success,errormessage] = chord2midinotes(chordsymbol, verbose)

% set verbose default to 0

if nargin < 2

    verbose = 0;

end

errormessage = '';

mainlist = '';

success = 1;

midinotes = 0;

% parse the chordsymbol

[rootnote,shorthand,degreelist,bass, success, errormessage] = getchordinfo(chordsymbol);

if success

    %if 'no chord' then return -1

    if rootnote == 'N'

        midinotes = -1;

    else

        % get root's pitchclass with respect to middle C and calculate absolute

        % pitch of root in that octave   

        if success

        [rootpitchclass, success, errormessage] = note2pitchclass(rootnote);

        % midinote C4 = 60 so add pitchclass to calculate rootpitch

        rootpitch = 60 + rootpitchclass;

        end

        % combine shorthand and degreelist and obtain semitone values for each

        % degree

        if success

            [mainlist, success, errormessage] = addshort2list(shorthand, degreelist);

            if success

                [semitones,success,errormessage] = degrees2semitones(mainlist);

                % add rootpitch to obtain midinotes

                chordpitches = semitones + rootpitch;

            end

        end

        % Now find the bass note

        if success

            % if we haven't got a bass degree then play the rootnote as the

            % bassnote

            if isempty(bass)

                basspitchclass = rootpitchclass;

            else

                % otherwise convert the bassdegree to a note

                [bassnote,success,errormessage] = degree2note(bass, rootnote);

                if success

                    [basspitchclass, success, errormessage] = note2pitchclass(char(bassnote));

                end

            end

            if success

                % calculate bass note so that it is in the octave below the

                % rest of the chord i.e. add to C3 midinote 48

                basspitch = basspitchclass + 48;

                % Put midinote list together

                midinotes = [basspitch, rootpitch];

                for index = 1:length(chordpitches)

                    if chordpitches(index) ~= rootpitch

                       midinotes = [midinotes, chordpitches(index)];

                    end

                end

            end

        end

    end

%alter pitches for chords with high roots

if rootpitchclass > 6

    midinotes = midinotes-12;

end

end

if success == 0

    errormessage = [errormessage sprintf(['Error in chord2midinotes: Couldn''t convert chord"' chordsymbol '"\n'])];   

    if verbose ==1

       fprintf(1,errormessage);

    end

end