[Octave-bug-tracker] [bug #63440] [octave forge] (signal) sosfilt - NaN

[Charles Praplan]

Follow-up Comment #11, bug #63440 (project octave):

Hi Renato,
Unfortunately the function you want is not written. So you have to manage
without it.
Independently of this function, just run the following code to plot the
spectrum
before and after your while loop.
Although the while loop does its job of changing the crest factor, you will
see that is
adding some LF (white) noise to your signal.



close all
clear
clc

pkg load ltfat

sampling_rate = 44100;
length_fact = 30;
hpf = 40;
lpf = 400;
crest_factor = 6;
filter_order = 4;
rounding = 4;

typenoise = noise((length_fact/2)*sampling_rate, 1, 'pink');
%load typenoise.mat

[z, p, k] = butter(filter_order, [hpf/(sampling_rate/2),
lpf/(sampling_rate/2)]);
sos = zp2sos (z, p, k);
filtered = sosfilt(sos, typenoise);
normalized = filtered / (rms(filtered) / 10^(-crest_factor/20));
normalized_before_while_loop=normalized;

while crestfactor(normalized) > crest_factor
normalized(normalized > 0) = ((normalized(normalized > 0).^rounding) ./
((normalized(normalized > 0).^rounding) + 1)).^(1/rounding);
normalized(normalized < 0) = (((normalized(normalized < 0).^rounding) ./
((normalized(normalized < 0).^rounding) + 1)).^(1/rounding)) *-1;
rounding = rounding^2;
  if rounding > 100
    rounding = 100;
  end
  normalized = normalized / (rms(normalized) / 10^(-crest_factor/20));
end;

second_half = normalized * -1;
normalized = [[normalized]; [second_half]];

hist(normalized, 61);
xlabel('Amplitude');
ylabel('Samples');
grid on;

[spectra,freq] =
pwelch(normalized_before_while_loop,hann(length(normalized_before_while_loop)),0,length(normalized_before_while_loop),sampling_rate);
figure
loglog(freq,spectra)
[spectra,freq] =
pwelch(normalized,hann(length(normalized)),0,length(normalized),sampling_rate);
hold on
loglog(freq,spectra)
grid on
legend('spectrum before while loop', 'spectrum after while loop')
xlabel('[Hz]')
ylabel('Amplitude')



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