# Matlab help on audio processing

Discussion in 'Programmer's Corner' started by jeffcech, Sep 2, 2009.

1. ### jeffcech Thread Starter New Member

Sep 2, 2009
1
0
Hello everyone,

I need to calculate the number of spectral coefficients in an audio frame in matlab.

I only know that FrameSize = 144 * BitRate / (SampleRate + Padding).

But how do i look into individual frames and start counting?

2. ### kaankarabulut New Member

Oct 3, 2009
3
0
are you looking like that?
fft and filtering

clc
clear all

[x,Fs] = wavread( 'data1.wav' );

[b,a] = butter(13,2*[200 2000]/Fs,'bandpass');
figure, freqz(b,a,128,Fs)
y=filter(b,a,x) ;

Y1 = fft(x);
Pyy1 = abs(Y1)/length(Y1) ;
f1 = Fs * (0:length(Y1)/2) / length(Y1) ;
lf1 = length(f1);

Y2 = fft(y);
Pyy2 = abs(Y2)/length(Y2) ;
f2 = Fs * (0:length(Y2)/2) / length(Y2) ;
lf2 = length(f2);

figure,subplot(221)
plot(x)
title('Original voice signal')
xlabel('time domain')
subplot(223)
plot(f1,Pyy1(1:lf1))
axis([0 5000 0 0.002])
title('Original voice signal')
xlabel('frequency Hz.')
subplot(222)
plot(y)
title('after window voice signal')
xlabel('time domain')
subplot(224)
plot(f2,Pyy2(1:lf2))
axis([0 3000 0 0.002])
title('after window voice signal')
xlabel('frequency Hz.')
wavwrite(y,'datakaanafter.wav')