From c386637809bf5660c2d23a452c3d1b78176b916e Mon Sep 17 00:00:00 2001
From: TurtleEmperorx <anuragjadhavnis@gmail.com>
Date: Thu, 9 Dec 2021 01:30:51 -0800
Subject: [PATCH] Added Target Dampen and Amplify functions

Amplify or dampen an area around the target frequencies. It can handle dual channel audio (like the strong bassline)
---
 src/AnuragDampenTarget.m   | 52 ++++++++++++++++++++++++++++++++++++++
 src/AnuragEnchanceTarget.m | 52 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+)
 create mode 100644 src/AnuragDampenTarget.m
 create mode 100644 src/AnuragEnchanceTarget.m

diff --git a/src/AnuragDampenTarget.m b/src/AnuragDampenTarget.m
new file mode 100644
index 0000000..29d3576
--- /dev/null
+++ b/src/AnuragDampenTarget.m
@@ -0,0 +1,52 @@
+function output_x = AnuragDampenTarget(x, Fs,TARGET, AreaPercentage) 
+%Dampen a range of frequencies a percentage around the target frequency
+%Also maintain the other frequencies so that the target is muted
+%percentage is expressed as a number between 0 and 1.
+%target is the midpoint of the frequency range to dampen
+%x and Fs are the signal and frequency
+% CONTRIBUTORS:
+% Anurag Jadhav: function creator
+
+%   Detailed explanation goes here
+    [dim,len] = size(x); %get length of the input
+    F = Fs * ((-len/2) : ((len/2) - 1)) / len;
+    lenf = length(F);
+    Mod_Freq = ifft(fft(x)); %Fourier Transform of the input signal
+    output =  zeros([1,lenf]); % zero array of size Mod_freq
+    if(dim == 2) %check for dual channel audio
+       F = [F;F]; 
+       output = [output;output];
+    end
+    %set the bounds
+    lowerBound = (1-AreaPercentage) * TARGET;
+    upperBound = (1+AreaPercentage) * TARGET;
+%% Dampen the target frequencies and maintain the others
+    if(dim == 2) %iterate through both channels if track is dual channel
+        for n = 1:lenf
+            if ((lowerBound < abs(F(1,n))) && abs(F(1,n)) < upperBound)
+              output(1,n) = 1;
+            else
+              output(1,n) = 0.5;
+            end
+        end
+        for n = 1:lenf
+            if ((lowerBound < abs(F(2,n))) && abs(F(2,n)) < upperBound)
+              output(2,n) = 1;
+            else
+              output(2,n) = .5;
+            end
+        end
+    else %iterate onnly once for monochannel
+        for n = 1:lenf
+            if ((lowerBound < abs(F(n))) && abs(F(n)) < upperBound)
+                output(n) = 1;
+            else
+                output(n) = .5;
+            end
+        end
+    end
+%%Filter the original signal and transform 
+    filtered_Mod_Freq = fftshift(Mod_Freq .* output);
+    output_x = real(ifft(filtered_Mod_Freq));
+
+end
\ No newline at end of file
diff --git a/src/AnuragEnchanceTarget.m b/src/AnuragEnchanceTarget.m
new file mode 100644
index 0000000..33923ce
--- /dev/null
+++ b/src/AnuragEnchanceTarget.m
@@ -0,0 +1,52 @@
+function output_x = AnuragEnchanceTarget(x, Fs,TARGET, AreaPercentage) 
+%Amplify a range of frequencies a percentage around the target frequency
+%Also damnpen the other frequencies so that the target is easier to hear
+%percentage is expressed as a number between 0 and 1.
+%target is the midpoint of the frequency range to amplify
+%x and Fs are the signal and frequency
+% CONTRIBUTORS:
+% Anurag Jadhav: function creator
+
+%   Detailed explanation goes here
+    [dim,len] = size(x); %get length of the input
+    F = Fs * ((-len/2) : ((len/2) - 1)) / len;
+    lenf = length(F);
+    Mod_Freq = ifft(fft(x)); %Fourier Transform of the input signal
+    output =  zeros([1,lenf]); % zero array of size Mod_freq
+    if(dim == 2) %check for dual channel audio
+       F = [F;F]; 
+       output = [output;output];
+    end
+    %set the bounds
+    lowerBound = (1-AreaPercentage) * TARGET;
+    upperBound = (1+AreaPercentage) * TARGET;
+%% Amplify the target frequencies and dampen the others
+    if(dim == 2) %iterate through both channels if track is dual channel
+        for n = 1:lenf
+            if ((lowerBound < abs(F(1,n))) && abs(F(1,n)) < upperBound)
+              output(1,n) = 2;
+            else
+              output(1,n) = 0.75;
+            end
+        end
+        for n = 1:lenf
+            if ((lowerBound < abs(F(2,n))) && abs(F(2,n)) < upperBound)
+              output(2,n) = 2;
+            else
+              output(2,n) = 0.75;
+            end
+        end
+    else %iterate onnly once for monochannel
+        for n = 1:lenf
+            if ((lowerBound < abs(F(n))) && abs(F(n)) < upperBound)
+                output(n) = 2;
+            else
+                output(n) = 0.75;
+            end
+        end
+    end
+%%Filter the original signal and transform 
+    filtered_Mod_Freq = fftshift(Mod_Freq .* output);
+    output_x = real(ifft(filtered_Mod_Freq));
+
+end
\ No newline at end of file