Merge pull request #30 from ltcptgeneral/pitchshiftenvelope

added half circles function
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khannuuuuur 2021-12-08 20:45:10 -08:00 committed by GitHub
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function x = generate_halfCircles(amplitude, frequency, phase, fs, duration, duty)
% Generates half circles.
% By Conner Hsu
% DOCUMENTATION:
% amplitude scales how tall the half circle is.
% phase shift is in number of periods
% fs is the sampling frequency: how many sample points per second
% duration is time in seconds
% duty cycle should be a number between 0 and 1.
% duty of 0 or less would return 0 for all sample points
% duty of 0.25 would return a half circle for first quarter of each cycle
% then return 0 for the remaining 3/4ths
% duty of 1 would return all +amplitude
% initialize local variables from input arguments
n = fs * duration; % number of samples (length of matrix)
dt = 1 / fs; % sampling period: time between two sample points
% initialize a one dimensional zero matrix to be populated
x = zeros(1, n);
% populate the matrix
for i = 1:n
t = i * dt; % time at the i'th sample
% periodic ramp from 0 to 1
% progression through a cycle
st = mod(frequency * t - phase, 1);
if(st < duty)
x(i) = sqrt((duty/2)^2-(st-duty/2)^2)/2*amplitude;
else
x(i) = 0;
end
end
%Testing code.
%t = 0:dt:duration;
%t(n) = [];
%plot(t, x);
sound(x, fs);
end