Struct LowpassFilter 

pub struct LowpassFilter<T> { /* private fields */ }

A first-order lowpass filter compatible with f32 and f64.

It can consume and filter items one-by-one (iterator-style API) or operate on slices (LowpassFilter::run_slice).

It is mandatory to operate on values in range -1.0..=1.0, which is also the default in DSP.

More Info

• https://en.wikipedia.org/wiki/Low-pass_filter#Simple_infinite_impulse_response_filter

Implementations

impl<T: Sample> LowpassFilter<T>

pub fn new(sample_rate_hz: T, cutoff_frequency_hz: T) -> Self

Create a new lowpass filter.

Arguments

• sample_rate_hz: Sample rate in Hz (e.g., 48000.0).
• cutoff_frequency_hz: Cutoff frequency in Hz (e.g., 1000.0).

pub fn run(&mut self, input: T) -> T

Filter a single sample and return the filtered result.

It is mandatory to operate on values in range -1.0..=1.0, which is also the default in DSP. The returned value is also guaranteed to be in that range.

pub fn run_slice(&mut self, samples: &mut [T])

Filter a whole slice of samples in-place.

Matches calling Self::run per sample up to tiny floating point rounding differences (roughly 1e-6 for f32), but is significantly faster. The filter state is updated, so consecutive calls compose, also when mixed with Self::run.

Math

Unrolling y[n] = alpha * x[n] + beta * y[n-1] over a block of samples yields

y[i] = beta^(i+1) * prev + sum(alpha * beta^(i-j) * x[j] for j <= i)

so within a block, samples only depend on the state prev from before the block and can be computed in parallel, which enables compiler auto-vectorization (SIMD). Only prev propagates serially between blocks.

Arguments

• samples: Samples to filter in-place, in range -1.0..=1.0.

pub const fn reset(&mut self)

Reset the internal filter state.

Trait Implementations

impl<T: Clone> Clone for LowpassFilter<T>

fn clone(&self) -> LowpassFilter<T>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for LowpassFilter<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.