Low Fidelity Adaptive Filter Questions

[cebersp]

Hi,
it's been a while that I have done a project with Teensy, so after I had a look at Teensy Audio and OpenAudio I thought it might be wise to ask before I dive in...

• The goal is to analyse a mono audio signal for it's strongest frequency and filter the input to supress all the rest.
• I think, that the bandwidth to let through can be 4 musical notes, I have to try it out.
• Frequency range is 70Hz...1200Hz.
• The quality of the output does not need to be high.
• The phase of the output to the input should be variable
• Reaction time is not very critical. The filter should be adjusted perhaps within 50ms or so.
• The output shall be attenuated to form a noise gate and a compressor/limiter.

I would use a Teensy 3.5 using it's adc and dac. I wanted to use OpenAudio but it's graphical tool does not support adc and dac. (?)
Will T3.5 be strong enough for this?
I also have a Teensy 4.1. Where can I find info about an output filter for mqs?
Can I use delay for rather short delays to influence the phase?
I am not totally happy with fft1024 at 44100Hz as I would like to have better resolution at low frequencies and don't need the high frequencies. Is there a better way?

The ketch shows the idea:
The fft shall be used to find the strongest frequency and set the filters to form a bandpass. Also this frequency shall be used together with it's magnitude to set the amplifier. The frequency gives information about the delay to achieve a certain phase.

Thanks for any hints!!
Christof

 

[cebersp]

Ok, have begun to try it out...
Processor usage for T3.5 @ 120MHz with FFT1024 is 43 pc, so that's feasible.
Setting of the filters seems to work. Small delays to vary phase, less than a sampling block, seems possible.

Trying to use notefreq to detect the frequency. 72 pc processor usage with that.