From 6c7aa76b62f806106eb18a82c94540beb44512a9 Mon Sep 17 00:00:00 2001
From: Darell Chua Yun Da <darell27@gmail.com>
Date: Thu, 2 Dec 2021 13:44:57 +0800
Subject: [PATCH] Continuous Replay and Filter

Continuous Replay and Filter. Added a test main for people to easily test their filters.
---
 DarellsAnnex/DarellbandpassFilter.m | 20 ++++++++++++++++++++
 src/Main_test.m                     | 25 +++++++++++++++++++++++++
 src/play_continuous.m               |  9 +++++++++
 3 files changed, 54 insertions(+)
 create mode 100644 DarellsAnnex/DarellbandpassFilter.m
 create mode 100644 src/Main_test.m
 create mode 100644 src/play_continuous.m

diff --git a/DarellsAnnex/DarellbandpassFilter.m b/DarellsAnnex/DarellbandpassFilter.m
new file mode 100644
index 0000000..918358a
--- /dev/null
+++ b/DarellsAnnex/DarellbandpassFilter.m
@@ -0,0 +1,20 @@
+function output_y = DarellbandpassFilter(y,Fs,LOW,MED,HIGH)
+    Len = length(y);
+    F = Fs * (-Len/2 : (Len/2 - 1))/Len ;
+    Mod_Freq = fftshift(fft(y));
+    lenf = length(F);
+    output =  0 .* Mod_Freq; % zero array of len f
+    
+    for n = 1:lenf
+        if ((LOW < abs(F(n))) && HIGH > abs(F(n)))
+            output(n) = 1;
+        else
+            output(n) = 0;
+        end
+    end
+        
+    filtered_Mod_Freq = fftshift(Mod_Freq .* output);
+    
+    output_y = real(ifft(filtered_Mod_Freq));
+    
+end
\ No newline at end of file
diff --git a/src/Main_test.m b/src/Main_test.m
new file mode 100644
index 0000000..034d0f6
--- /dev/null
+++ b/src/Main_test.m
@@ -0,0 +1,25 @@
+%Basic Example test 
+%Written by Darell
+amplitude = 1;
+frequency = 200;
+phase = 0;
+fs = 44800;
+duration = 1;
+duty = 0;
+
+%example Sine Generation
+x = generate_sine(amplitude, frequency, phase, fs, duration, duty);
+x = x + generate_sine(amplitude, (frequency+5), phase, fs, duration, duty);
+
+%play over 5 counts, should hear both frequencies, 5 beats between the 2 frequencies
+playtime = 5;
+play_continuous(x, fs, playtime)
+
+LOW = 0;
+HIGH = frequency + 1;
+MED = "unused";
+x = DarellbandpassFilter(x,fs,LOW,MED,HIGH);
+
+%play over 5 counts, should only hear 200hz
+playtime = 5;
+play_continuous(x, fs, playtime)
\ No newline at end of file
diff --git a/src/play_continuous.m b/src/play_continuous.m
new file mode 100644
index 0000000..9b2828b
--- /dev/null
+++ b/src/play_continuous.m
@@ -0,0 +1,9 @@
+function play_continuous(wave, fs, time)
+%play_continuous: Darell Continuously Playing
+    soundfile = audioplayer(wave,fs);
+    countmax = time / (length(wave) / fs);
+    for count = 0:1:countmax %change to counts/while play button active
+        playblocking(soundfile);
+    end
+end
+