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clear;
show_graphs = false;
%%%%%%%%%%%%%%%
% "constants" %
%%%%%%%%%%%%%%%
% how many updates per second, determines the length of audio snippets
const_frames_per_second = 100;
const_Fs = 44100; % sample rate in Hz
const_te = 1/const_frames_per_second; % signal duration in seconds
const_samples_per_frame = ceil(const_Fs * const_te);
const_sample_range = 0:const_samples_per_frame-1;
% the smaller the value, the quicker the fade out
const_fade_speed = 0.975;
% signal "generator" - only gives the input for sin()
% it does not apply the sin function yet, see below for reasoning
signal_f = @(freq) (freq ./ const_Fs .* 2 .* pi .* const_sample_range);
% dimensions to use for detecting number of hands in frame
zero_hands = size(NaN(0,0));
one_hand = size(NaN(1,1));
two_hands = size(NaN(1,2));
deviceWriter = audioDeviceWriter('SampleRate', const_Fs, ...
'SupportVariableSizeInput', true, 'BufferSize', 3 * const_samples_per_frame);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% init matleap by calling for first frame %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
matleap_frame;
% runtime variables
P = NaN(1000000,3);
count = 1;
done = false;
frequency_pos = 0;
height_pos = 0;
offset = 0;
signal = sin(signal_f(0));
complete_signal = signal;
% time gestures, used for program termination
gesture_count = 0;
% main loop
while gesture_count < const_frames_per_second
frame = matleap_frame;
handCount = size(frame.hands);
% slowly decrease volume
height_pos = height_pos * const_fade_speed;
if isequal(one_hand, handCount)
%pos = frame.hands(1).palm.position;
pos = frame.hands(1).palm.stabilized_position;
frequency_pos = pos(1);
height_pos = max(150, height_pos);
P(count, 1:3) = pos;
count = count + 1;
if frame.gesture > 0
gesture_count = gesture_count + 1;
else
gesture_count = 0;
end
elseif isequal(two_hands, handCount)
gesture_count = 0;
%pos = frame.hands(1).palm.position;
pos = frame.hands(1).palm.stabilized_position;
frequency_pos = pos(1);
%y_one = pos(2);
P(count, 1:3) = pos;
count = count + 1;
%pos = frame.hands(2).palm.position;
pos = frame.hands(2).palm.stabilized_position;
%x_two = pos(1);
height_pos = pos(2);
else
% no hands, do nothing (or more than 2 (how?! :D))
gesture_count = 0;
end
% play current sound
[signal, offset] = get_theremin_sound_bit(frequency_pos, height_pos, offset, signal_f);
buffer_under_flow = deviceWriter(signal(:));
if buffer_under_flow ~= 0
disp("Buffer ran empty!");
end
complete_signal = [complete_signal signal];
end
release(deviceWriter)
%theremin_player = audioplayer(complete_signal, const_Fs);
%play(theremin_player);
if show_graphs == true
% extract values
x = P(:,1); % links (-) rechts (+) (LED zu uns)
y = P(:,2); % oben unten
z = P(:,3); % vorne (+) hinten (-) (LED zu uns)
% plot
figure("Position",[0,0, 1200, 2400]);
t = tiledlayout(4,1);
nexttile;
plot(x);
ylabel('left right');
nexttile;
plot(y);
ylabel('height');
nexttile;
plot(z);
ylabel('depth');
nexttile;
plot3(z,x,y);
xlabel('depth');
ylabel('left right');
zlabel('height');
%{
% Plot both audio channels
N = size(complete_signal,2); % Determine total number of samples in audio file
figure;
subplot(1,1,1);
stem(1:N, complete_signal(1,:));
title('Audio Channel');
% Plot the spectrum
df = const_Fs / N;
w = (-(N/2):(N/2)-1)*df;
y = fft(complete_signal(1,:), N) / N; % For normalizing, but not needed for our analysis
y2 = fftshift(y);
figure;
plot(w,abs(y2));
%}
end
disp('If you want to save your audio, run `audiowrite(<.wav filename>, complete_signal, const_Fs)`');
function [sound,offset] = get_theremin_sound_bit(x, y, offset, generator)
% the values used here are mostly empirical
volume = y / 1300;
% How it works:
% https://web.physics.ucsb.edu/~lecturedemonstrations/Composer/Pages/60.17.html
frequency = max(0.003, (x - 50) / 220) * 1000; % have at least 3Hz
% here we generate the array to put into sin(), but offset it with the
% the previous frames offset..
base = generator(frequency) + offset;
% ..which we take from here - doing so stops us from phase jumping
offset = base(end);
% at last, apply the volume
sound = sin(base) .* volume;
end
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