auFile='taiwanUniversity.wav';
au=myAudioRead(auFile);
n=2; au.fs=au.fs/n; au.signal=au.signal(1:n:end, 1);    % Down sampling
index1=round(0.66*au.fs);
frameSize=256;
index2=index1+frameSize-1;
frame=au.signal(index1:index2);		% Take the frame for display
audiowrite('frame.wav', frame, au.fs);

subplot(2,1,1); plot(au.signal); grid on
xlabel('Sample index'); ylabel('Amplitude'); title(auFile);
%xlabel('取樣點索引值'); ylabel('波形振幅'); title(auFile);
axis([1, length(au.signal), -1 1]);
line(index1*[1 1], [-1 1], 'color', 'm', 'linewidth', 1);
line(index2*[1 1], [-1 1], 'color', 'm', 'linewidth', 1);
subplot(2,1,2); plot(frame, '.-'); grid on
xlabel('Sample index within the frame'); ylabel('Amplitude');
%xlabel('音框內的取樣點索引值'); ylabel('波形振幅');
axis([1, length(frame), -1 1]);
%boxOverlay([60.5 -0.7 52 1.4], 'r', 1, '音色：基本週期內的波形', 'top');
message=sprintf('Timbre:\nWaveform in a fundamental period');
boxOverlay([60.5 -0.5 52 1.2], 'r', 1, message, 'top');

subplot(211); loc1=get(gca, 'position');
subplot(212); loc2=get(gca, 'position');
%% ===== arrow 1 for closeup
x1=[loc1(1)+(index1(1)-1)/(length(au.signal)-1)*loc1(3), loc2(1)];
y1=[loc1(2), loc2(2)+loc2(4)];
ah=annotation('arrow', x1, y1, 'color', 'm', 'linewidth', 1);
%% ====== arrow 2 for closeup
x2=[loc1(1)+(index2-1)/(length(au.signal)-1)*loc1(3), loc2(1)+loc2(3)];
y2=[loc1(2), loc2(2)+loc2(4)];
ah=annotation('arrow', x2, y2, 'color', 'm', 'linewidth', 1);
%% Double arrow for fundamental period
axisLimit=axis;		% axisLimit=[1, 256, -1, 1]
xPos=[171, 223];
yPos=[0.65, 0.65];
xRel=loc2(1)+(xPos-axisLimit(1))/(axisLimit(2)-axisLimit(1))*loc2(3);
yRel=loc2(2)+(yPos-axisLimit(3))/(axisLimit(4)-axisLimit(3))*loc2(4);
ah=annotation('doublearrow', xRel, yRel, 'color', 'r');
textH=text(mean(xPos), mean(yPos), 'Fundamental period', 'horizontal', 'center', 'vertical', 'bottom');
%% Double arrow for volume
axisLimit=axis;		% axisLimit=[1, 256, -1, 1]
xPos=axisLimit(2)+[1, 1];
yPos=[min(frame), max(frame)];
xRel=loc2(1)+(xPos-axisLimit(1))/(axisLimit(2)-axisLimit(1))*loc2(3);
yRel=loc2(2)+(yPos-axisLimit(3))/(axisLimit(4)-axisLimit(3))*loc2(4);
ah=annotation('doublearrow', xRel, yRel, 'color', 'r');
textH=text(mean(xPos), mean(yPos), 'Volume', 'horizontal', 'center', 'vertical', 'top', 'rotation', 90);