57 lines
2.1 KiB
Matlab
57 lines
2.1 KiB
Matlab
function output = muffled_effect_schluep(input, Fs, LOW, MED, HIGH)
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% muffled_effect_schluep: Outputs a muffled version of the the original input
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% sound in the time domain. This makes it sound as if the audio is being
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% played in another room.
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% Try this function out with "Strong_Bassline.mp3".
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% CONTRIBUTORS:
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% Nicolas Schluep: Function Author
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% DOCUMENTATION:
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% input: The input sound in the time-domain.
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% Fs: The sampling rate of the input signal. A typical value is 44100 Hz.
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% HIGH: The maximum frequency that the low-pass filter will let pass. A
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% typical value for this variable is 1000 Hz.
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non_stereophonic = input(:, 1); % Removes the sterophonic property of the input sound
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% by just taking the first column of data.
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Len = length(non_stereophonic);
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F = Fs * ((-Len/2) : ((Len/2) - 1)) / Len; % Creating the array of frequencies
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% which the FFT Shifted version of the signal can be plotted against.
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inputFreq = fftshift(fft(non_stereophonic)); % Creates the Fourier Transform of the
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% input signal. fftshift() makes it such that the zero frequency is at the
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% center of the array.
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lowPassFilter = zeros(1, length(inputFreq));
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% Creating Low Pass Filter
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for i = 1:length(lowPassFilter)
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if abs(F(i)) < HIGH
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lowPassFilter(i) = 1;
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else
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lowPassFilter(i) = 0;
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end
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end
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lowPassedInput = inputFreq .* transpose(lowPassFilter); %Apply the low-pass filter.
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% Adding a slight reverb effect.
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realOutput = real(ifft(fftshift(lowPassedInput)));
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delay = 0.001; % The delay of the sound in seconds.
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index = round(delay*Fs); % Find the first index where sound should start playing
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% by multiplying the delay by the sampling frequency.
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delayedOutput = [zeros(index, 1); realOutput]; % Adds "index" zeros to the front of the
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% "realOutput" vector to create a slightly delayed version of the signal.
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delayedOutput = delayedOutput(1:length(realOutput)); % Truncates the "delayedOutput"
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% vector so that it can be added to the "realOutput" vector.
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output = (realOutput + delayedOutput) ./ 2.0; % Adds the "realOutput" and "delayedOutput"
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% vectors to create a reverb effect. Divides by 2 to avoid clipping
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% effects.
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