From 99987da72c5aea3dcfc42b2786a87d99d765fa23 Mon Sep 17 00:00:00 2001
From: rainydaysavings <eliseuamaro@protonmail.com>
Date: Mon, 28 Dec 2020 02:13:56 +0000
Subject: [PATCH] Tentative noise cancelling with FFT. PSD might help in
 identifying chirp sounds.

---
 TP3/DiogoEliseu_TP3_8.m | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 TP3/DiogoEliseu_TP3_8.m

diff --git a/TP3/DiogoEliseu_TP3_8.m b/TP3/DiogoEliseu_TP3_8.m
new file mode 100644
index 0000000..ba92712
--- /dev/null
+++ b/TP3/DiogoEliseu_TP3_8.m
@@ -0,0 +1,34 @@
+%% clean environment
+clear; close all; clc
+
+%% read input
+[signal, fs] = audioread("Canto1.mp3");
+
+%% Compute the FFT
+signal_length = length(signal);
+fhat = fft(signal, signal_length);
+PSD = fhat.*conj(fhat)/signal_length; % Power spectrum density
+%[S, freq, T, PSDlel] = spectrogram(signal, 128, 96, 128, Fs);
+% signal, window, noverlap, nfft, fs
+freq_vector = linspace(1, fs, signal_length);
+L = 1:floor(signal_length/2);
+
+cutoff_indices = abs(PSD)>0.002;
+PSD_clean = PSD.*cutoff_indices;
+fhat_filtered = cutoff_indices.*fhat;
+signal_filtered = ifft(fhat_filtered);
+
+figure(1)
+plot(PSD)
+
+figure(2)
+plot(PSD_clean)
+
+figure(3)
+plot(signal)
+
+figure(4)
+plot(signal_filtered)
+
+%% output
+audiowrite('restored.flac', signal_filtered, fs);
\ No newline at end of file