highpass_filter_t Struct Reference

High-pass filter settings and state. More...

#include <lib/audio/mixer.h>

Data Fields
float	cutoff_hz
	Cutoff frequency in Hz (frequencies below this are attenuated)
float	sample_rate
	Sample rate in Hz (set during initialization)
float	alpha
	Filter coefficient alpha (calculated from cutoff_hz)
float	prev_input
	Previous input sample (filter state)
float	prev_output
	Previous output sample (filter state)

Detailed Description

High-pass filter settings and state.

Implements first-order IIR high-pass filter to remove low-frequency noise, rumble, and DC offset. Useful for cleaning up microphone input.

FILTER BEHAVIOR:

• Attenuates frequencies below cutoff_hz
• Passes frequencies above cutoff_hz with minimal phase shift
• First-order design provides gentle rolloff (-6dB/octave)

Note

Filter state (prev_input, prev_output) must be preserved between samples for proper operation.

Definition at line 218 of file mixer.h.

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The documentation for this struct was generated from the following file:

• mixer.h