记录下我学习乐理知识，并使用MATLAB编写曲子

学习资料

MATLAB程序

钢琴各音名

% 记录各音符的音阶,一行为一组

% 升音符号
note_treble = {'A2','A2+','B2', ...
    'C1','C1+','D1','D1+','E1','F1','F1+','G1','G1+','A1','A1+','B1', ...
    'C','C+','D','D+','E','F','F+','G','G+','A','A+','B', ...
    'c','c+','d','d+','e','f','f+','g','g+','a','a+','b', ...
    'c1','c1+','d1','d1+','e1','f1','f1+','g1','g1+','a1','a1+','b1', ...
    'c2','c2+','d2','d2+','e2','f2','f2+','g2','g2+','a2','a2+','b2', ...
    'c3','c3+','d3','d3+','e3','f3','f3+','g3','g3+','a3','a3+','b3', ...
    'c4','c4+','d4','d4+','e4','f4','f4+','g4','g4+','a4','a4+','b4', ...
    'c5'};

% 降音符号
note_bass = {'A2','B2-','B2', ...
    'C1','D1-','D1','E1-','E1','F1','G1-','G1','A1-','A1','B1-','B1', ...
    'C','D-','D','E-','E','F','G-','G','A-','A','B-','B', ...
    'c','d-','d','e-','e','f','g-','g','a-','a','b-','b', ...
    'c1','d1-','d1','e1-','e1','f1','g1-','g1','a1-','a1','b1-','b1', ...
    'c2','d2-','d2','e2-','e2','f2','g2-','g2','a2-','a2','b2-','b2', ...
    'c3','d3-','d3','e3-','e3','f3','g3-','g3','a3-','a3','b3-','b3', ...
    'c4','d4-','d4','e4-','e4','f4','g4-','g4','a4-','a4','b4-','b4', ...
    'c5'};

乐谱

%  高音，57个
Treble = {'d1-','e1-','f1','c2','a1-', ... %1
    {'b1-','g1','e1-','c1'},'0',{'a1-','f1','e1-','c1'},'c1',...
    'd1-','e1-','f1','c2','a1-','f1',... %3
    {'b1-','g1','e1-','c1'},{'b1-','g1','e1-','c1'},'0',{'c2','a1-','f1','e1-'},'c2',...
    'a2-','e2-','f2','c3','a2-','f2',... %5
    {'b2-','g2','e2-','c2'},'0',{'a2-','f2','e2-','c2'},'c2',...
    'd2-','e2-','f2','c3','a2-','f2',... %7
    {'b2-','g2','e2-','c2'},{'b2-','g2','e2-','c2'},'0',{'c3','a2-','f2','e2-'},'c2', ...
    'd2-','e2-','f2','c3','a2-','f2',... $9
    {'b2-','g2','e2-','c2'},'0',{'a2-','f2','e2-','c2'},'a2-','b2-','c3',...
    'c3','a2-','a2-','f2'}; %11
% 节拍数
rhyT = [0.5 0.5 0.5 1.5 1 ...
    1 0.5 2 0.5 ...
    0.5 0.5 0.5 1 1 0.5 ...%3
    0.75 0.25 0.5 2 0.5 ...
    0.5 0.5 0.5 1 1 0.5 ...%5
    1 0.5 2 0.5 ...
    0.5 0.5 0.5 1 1 0.5 ...%7
    0.75 0.25 0.5 2 0.5 ...
    0.5 0.5 0.5 1 1 0.5 ...%9
    1 0.5 1 0.5*ones(1,3) ...
    1.5 0.5 1.5 0.5];

% 低音，58个
Bass = {{'a-','f'},'c1',... %1
    'b-','g','a-','0','a-',...
    {'a-','f'},'c1',... %3
    'b-','g','a-','c1',...
    'd-','0','d-','A-','d-','A-',... %5
    'c','0','F','f','F','c',...
    'B-','B-','0','0','c','d-','d-',... %7
    'c','c','F','G','A-','G',...
    'd-','0','d-','A-','d-','A-',... %9
    {'g','c'},'0','F','f','e-','d-','c',...
    'B-','B-','0','B-','F','c','d-'}; %11
rhyB = [2 2 ... % 1
    1 0.5 0.5 1 1 ... % 2
    2 2 ... % 3
    ones(1,4) ...
    1 0.5 1 0.5 0.5 0.5 ...
    1 0.5 1 0.5 0.5 0.5 ... % 6
    1 0.5*ones(1,6) ...
    1 0.5 1 0.5*ones(1,3) ... %8
    1 0.5 1 0.5*ones(1,3) ... % 9
    1 0.5*ones(1,6) ...
    1 0.5*ones(1,6)];

采样函数

function x = sampling(note,rhy,fs,speed,note_table)
% note音符 fs采样率 rhy节拍数 speed拍/分钟

%rhy*60/speed:该节拍所需时间
t = 1:(fs*rhy*60/speed); %采样间隔数量

if iscell(note) %多个钢琴键同时按
    num = numel(note); % 钢琴音数
    x = zeros(num, length(t));
    for i=1:num % 不用for,index会乱
        index = find(ismember(note_table, note{i}));
        p = index + 20;
        f = 440*2^((p-69)/12); %振动频率
        x(i,:) = sin(t/fs*pi).*cos(t/fs*pi*2*f);
    end
    x = sum(x)./num;
    x = x / max(x);
    return;
    
elseif note ~= '0' %一个钢琴键
    index = find(ismember(note_table, note));% 音符所在钢琴位置
    p = index + 20; %音阶
    f = 440*2^((p-69)/12); %振动频率
    x = sin(t/fs*pi).*cos(t/fs*pi*2*f);
    x = x / max(x);
    return;
    
else %休止符
    x = zeros(1,length(t));
    return;
end

end

主函数

%% 设定
fs= 44100;
speed = 100;

%% 高音采样
treble = [];
for i=1:length(Treble)
    x = sampling(Treble{i}, rhyT(i), fs, speed, note_bass); % 降A大调
    treble = [treble x];
end

%% 低音采样
bass = [];
for i=1:length(Bass)
    x = sampling(Bass{i}, rhyB(i), fs, speed, note_bass); % 降A大调
    bass = [bass x];
end

%% 合并高低音
% subplot(1,2,1),plot(treble);
% subplot(1,2,2),plot(bass);

song = treble + 0.5*bass;
song = song./max(song);
audiowrite('song.mp4',song,fs);
sound(song, fs);