%%%%%  beat_demo1.m   %%%%%%%%
%
%  The illusion of a quickening beat is created by superimposing beats
%  in geometric relation to each other (self-similar) and changing the 
%  amplitude so the mind picks out the beat with the strongest amplitude.
%
%

%%  Initialization

%fs = 44100;      % sampling frequency
%nu = 220;        % tone
%num_beats = 5;   % number of "harmonics"
%r = 1.25;        % beats per second of first "harmonic"

%len = 15;        % number of beats of the sample (of the first "harmonic")


beat_size = floor (fs/(2^(num_beats-1) * r));
     %% beat_size is the size of the smallest drum beat (as defined by num_beats parameter)

beat = zeros ((num_beats+1), (2^(num_beats-1) * beat_size * len));
env = beat (1:num_beats, :);


t = (1:2^(num_beats-1)*beat_size)/fs;
tone = sin (2 * pi * nu * t);

for I = 1:num_beats

    a = beat_size * 2^(num_beats-I);
    b = floor (0.1 * a);
    perc_filter1 = t(1:b) * 1/t(b);
    perc_filter2 = exp ((t(b+1) - t(b+1:a)) *3*2^I);
    perc_filter = [perc_filter1 perc_filter2];   %  The percussive filter (makes the tone sound like a drum)

   

    env (I, :) = 1 - abs ((I-1)/(num_beats-1)*2^(num_beats-1)*beat_size*len - (0:2^(num_beats-1)*beat_size*len-1)) / (2^(num_beats-1)*beat_size*len-1);

    beat(I, :) = repmat (perc_filter (1:a).*tone(1:a), 1, 2^(I-1) * len);
    beat(num_beats+1,:) = beat(num_beats+1,:) + beat(I, :).*env (I, :);

end
    soundsc (beat(num_beats+1, :), fs)
     subplot (envs)
     plot ((0:2^(num_beats-1)*beat_size*len-1)/(2^(num_beats-1)*beat_size * len -1)*100, env)
     axis ([0.0 100 0.0 1])
     xlabel ('Percentage of Time')
     ylabel ('Amplitude')
     title ('Envelopes')

     
     subplot (wav_form)
     plot ((0:2^(num_beats-1)*beat_size*len-1)/fs, beat (num_beats+1,:))
     xlabel ('Percentage of Time')
     ylabel ('Amplitude')
     title ('Wave Form')
     



%    plot ((0:2^(num_beats-1)*beat_size*len-1)/(2^(num_beats-1)*beat_size * len -1)*100, env (1, :))
%     xlabel ('Percentage of Time');
%     ylabel ('Amplitude')
%     title ('Envelopes')
%     print -djpeg90 'diagram2.1.jpg'

%    plot ((0:2^(num_beats-1)*beat_size*len-1)/(2^(num_beats-1)*beat_size * len -1)*100, env (1:2, :))
%     xlabel ('Percentage of Time');
%     ylabel ('Amplitude')
%     title ('Envelopes')
%     print -djpeg90 'diagram2.2.jpg'


%    plot ((0:2^(num_beats-1)*beat_size*len-1)/(2^(num_beats-1)*beat_size * len -1)*100, env (1:3, :))
%     xlabel ('Percentage of Time');
%     ylabel ('Amplitude')
%     title ('Envelopes')
%     print -djpeg90 'diagram2.3.jpg'


%    plot ((0:2^(num_beats-1)*beat_size*len-1)/(2^(num_beats-1)*beat_size * len -1)*100, env (1:4, :))
%     xlabel ('Percentage of Time');
%     ylabel ('Amplitude')
%     title ('Envelopes')
%     print -djpeg90 'diagram2.4.jpg'


%    plot ((0:2^(num_beats-1)*beat_size*len-1)/(2^(num_beats-1)*beat_size * len -1)*100, env)
%     xlabel ('Percentage of Time');
%     ylabel ('Amplitude')
%     title ('Envelopes')
%     axis ([0 100 0 1])
%     print -djpeg90 'diagram2.5.jpg'


%plot ((1:2^(num_beats-1)*beat_size*len), env(1:2, :))
%plot ((1:2^(num_beats-1)*beat_size*len), env(1:3, :))
%plot ((1:2^(num_beats-1)*beat_size*len), env(1:4, :)
%plot ((1:2^(num_beats-1)*beat_size*len), env)