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noisy biquad function <filter.h>

Question asked by infraSonic on Jun 13, 2016
Latest reply on Oct 7, 2016 by infraSonic

Hi,

 

I'm using the biquad function from <filter.h> and process 19 sections with 8 samples at a time.

 

The output is as expected so the filtering works fine, however I get some noise.

 

The noise seems to come from low frequencies, so a kick bass adds a hissing noise which is disturbing and not use-able like this.

 

Even if I set all biquad coeffs to unity gain (b2=0, b1=0, b0=1, a2=0, a1=0) the output is still noisy.

 

When I use my own function to calculate the filtered output of the same set of biquad coeffs I dont get the noise, but I need the speed of the SIMD optimized biquad function..

 

Should this function be suitable for audio processing?

 

What are the preconditions I should meet before calling this function?

 

Before calling the biquad function I set the state array to 0 and dont touch it anymore like the manual (visualdsp++ 5.0 runtime lib Manual) states

 

Is there anything else I can check?

 

 

I'm working with Visualdsp++ update 10, target is an ADSP-21369

 

Thanks,

 

Vincent

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