Envelope Example

Updated Main Test to include Envelope Example

README.md

@@ -6,7 +6,7 @@
  
  ## Function Prototypes
  
- function x = generate_wave(amplitude, frequency, phase, fs, duration, duty)
+function x = generate_wave(amplitude, frequency, phase, fs, duration, duty)
  
 fuction x = envelope(input, fs, period, attack , decay, sustain, release)
 where attack, decay, sustain release are percentages between 0 to 1 of the period

src/DarellEnvelope.m

@@ -0,0 +1,37 @@
+function output = DarellEnvelope(input, Fs, attack,decay,sustain,release) %percentages for attack, decay, sustain, release
+    len = length(input);
+    T = (len-1)/Fs;
+    attacktime = attack * T * Fs;
+    decaytime = attacktime + decay * T * Fs;
+    sustaintime = (T - (release * T))* Fs;
+    
+    x = 0:1/Fs:T;
+    y = 0 .* x; %create zero array of y of len x
+    output = y;%create zero array of output of len x
+    tcounter = 1;
+    %attack phase
+    while tcounter <= attacktime
+        y(tcounter) = (1/attacktime) * tcounter;
+        tcounter = tcounter+1;
+    end
+    istart = tcounter;
+    while tcounter<= decaytime
+        y(tcounter) = 1 - (((1-sustain)/(decay * T * Fs)) * (tcounter - istart));
+        tcounter = tcounter+1;
+    end
+
+    while tcounter<= sustaintime
+        y(tcounter) = sustain;
+        tcounter = tcounter+1;
+    end
+    istart = tcounter;
+    while tcounter < (T * Fs)
+        y(tcounter) = sustain - ((sustain/(release * T * Fs)) * (tcounter - istart));
+        tcounter = tcounter+1;
+    end
+    
+    for counter = 1:1:len
+        output(counter) = y(counter) * input(counter);
+    end
+    
+end

src/Main_test.m

@@ -23,3 +23,13 @@ x = DarellbandpassFilter(x,fs,LOW,MED,HIGH);
 %play over 5 counts, should only hear 200hz
 playtime = 5;
 play_continuous(x, fs, playtime)
+
+attack = 0.2;
+decay = 0.2;
+sustain = 0.2;
+release = 0.1;
+
+x = DarellEnvelope(x, fs, attack,decay,sustain,release);
+%play over 5 counts, should only hear 200hz
+playtime = 5;
+play_continuous(x, fs, playtime)