Export Audio with Volume Automation

Dear Community,

I would like to print a sinewave with volume automation in mathlab. I am already able to print a stereo wave file with a fixed amplitude. Is it possible to set time points with corresponding amplitude values?

fs = 44100;

i=1/fs;

t = 0:i:2;

phi = 0;

A = 1;

f = 220.0000;

x = A*sin((2*pi*f*t) + phi);

f = 220.0000;

y = A*sin((2*pi*f*t) + phi);

stereo_mtx = [x(:), y(:)];

audiowrite('stereo sound 3.wav', stereo_mtx, fs);

Any help is much appreciated! Thanks

Answer 1

[Mathieu NOE]

hello Hans

this is my suggestion

fs = 44100; 
dt=1/fs; 
t = 0:dt:2;
phi = 0;
A = 1;
f = 220.0000;
x = A*sin((2*pi*f*t) + phi);
f = 220.0000;
y = A*sin((2*pi*f*t) + phi);

% define volume envelopp by time index + amplitude set points
tt = [0 0.5 1.5 2];
yt = [0 1 0.75 0]; % linear fade in / fade out demo
w = interp1(tt,yt,t); % create window of same length as signal 
y = y.*w; % apply window

stereo_mtx = [x(:), y(:)];
audiowrite('stereo sound 3.wav', stereo_mtx, fs);