AnsweredAssumed Answered

noisy biquad function <filter.h>

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



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