Basic Digital Audio Effects

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FIR Comb Filter MATLAB Code fircomb.m: CM0268 MATLAB DSP GRAPHICS 369 x=zeros(100,1);x(1)=1; % unit impulse signal of length 100 g=0.5; %Example gain Delayline=zeros(10,1); % memory allocation for length 10 for n=1:length(x); y(n)=x(n)+g*Delayline(10); Delayline=[x(n);Delayline(1:10-1)]; end; 1 ◭◭ ◮◮ ◭ ◮ Back Close
IIR Comb Filter This simulates a single delay: • Simulates endless reflections at both ends of cylinder. • We get an endless series of responses, y(n) to input, x(n). • The input signal circulates in delay line (delay time τ) that is fed back to the input.. • Each time it is fed back it is attenuated by g. • Input sometime scaled by c to compensate for high amplification of the structure. • The difference equation is simply: y(n) = Cx(n) + gy(n − M) • The transfer function is: c H(z) = 1 − gz −M with M = τ/f s CM0268 MATLAB DSP GRAPHICS 370 1 ◭◭ ◮◮ ◭ ◮ Back Close
Page 1 and 2: Digital Audio Effects Having learne
Page 3 and 4: Classifying Effects Audio effects c
Page 5 and 6: Shelving and Peak Filters Shelving
Page 7 and 8: Shelving Filters (Cont.) The gain,
Page 9 and 10: Peak Filters A first-order shelving
Page 11 and 12: Peak Filters Signal Flow Graph x(n)
Page 13 and 14: K = tan((pi * fc)/fs); V0 = 10ˆ(G/
Page 15 and 16: + (Kˆ2)/V0); a2 = (1 - root2/sqrt(
Page 17 and 18: %Do treble shelf filter fct = 600;
Page 19 and 20: Time-varying Filters Some common ef
Page 21 and 22: Time Varying Filter Implementation:
Page 23 and 24: The State Variable Filter Algorithm
Page 25 and 26: %%%%%%% EFFECT COEFFICIENTS %%%%%%%
Page 27 and 28: % write output wav files wavwrite(y
Page 29 and 30: Wah-wah Code Explained Three main p
Page 31 and 32: Wah-wah Code Explained (Cont.) Note
Page 33 and 34: Bandreject (BR)/Bandpass(BP) Filter
Page 35 and 36: Basic Delay Structure We build basi
Page 37: FIR Comb Filter Signal Flow Diagram
Page 41 and 42: IIR Comb Filter MATLAB Code iircomb
Page 43 and 44: Universal Comb Filter Parameters CM
Page 45 and 46: Vibrato - A Simple Delay Based Effe
Page 47 and 48: for n=1:(LEN-1) M=MODFREQ; MOD=sin(
Page 49 and 50: Vibrato MATLAB Code Explained Click
Page 51 and 52: Comb Filter Delay Effects: Flanger,
Page 53 and 54: % to avoid referencing of negative
Page 55 and 56: Modulation Modulation is the proces
Page 57 and 58: MATLAB Ring Modulation Two examples
Page 59 and 60: Amplitude Modulation Amplitude Modu
Page 61 and 62: Tremolo via Ring Modulation If you
Page 63 and 64: Limiter A Limiter is a device that
Page 65 and 66: MATLAB Limiter Example (Cont.) % do
Page 67 and 68: Compressors/Expanders Compressors a
Page 69 and 70: MATLAB Compressor/Expander (Cont.)
Page 71 and 72: Overdrive, Distortion and Fuzz Dist
Page 73 and 74: MATLAB Overdrive Example The MATLAB
Page 75 and 76: Distortion/Fuzz A non-linear functi
Page 77 and 78: MATLAB Fuzz Example (Cont.) An fuzz
Page 79 and 80: Panning The simple problem we addre
Page 81 and 82: MATLAB Panning Example The MATLAB c
Page 83 and 84: Reverb Reverberation (reverb for sh
Page 85 and 86: Reverb v. Echo Is reverb just a ser
Page 87 and 88: Reverb Simulations There are many w
Page 89 and 90:
Schroeder’s Reverberator (Cont.)
Page 91 and 92:
% add the scaled direct signal y =
Page 93 and 94:
MATLAB Schroeder Reverb (Cont.) The
Page 95 and 96:
% sum the ouptut of the 4 comb filt
Page 97 and 98:
Moorer’s Reverberator CM0268 MATL
Page 99 and 100:
MATLAB Moorer Reverb (Cont.) % send
Page 101 and 102:
MATLAB Moorer Reverb (Cont.) %set g
Page 103 and 104:
Convolution Reverb If the impulse r
Page 105 and 106:
Room Impulse Responses Apart from p
Page 107 and 108:
MATLAB Convolution Reverb (Cont.) A
Page 109 and 110:
MATLAB Convolution Reverb (Cont.) C
Page 111:
MATLAB Convolution Reverb (Cont.) Y
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Basic Digital Audio Effects

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