Struct bs1770::Power

pub struct Power(pub f32);

The mean of the squares of the K-weighted samples in a window of time.

K-weighted power is equivalent to K-weighted loudness, the only difference is one of scale: power is quadratic in sample amplitudes, whereas loudness units are logarithmic. loudness_lkfs and from_lkfs convert between power, and K-weighted Loudness Units relative to nominal Full Scale (LKFS).

The term “LKFS” (Loudness Units, K-Weighted, relative to nominal Full Scale) is used in BS.1770-4 to emphasize K-weighting, but the term is otherwise interchangeable with the more widespread term “LUFS” (Loudness Units, relative to Full Scale). Loudness units are related to decibels in the following sense: boosting a signal that has a loudness of -L_K LUFS by L_K dB (by multiplying the amplitude by 10^L_K/20) will bring the loudness to 0 LUFS.

K-weighting refers to a high-shelf and high-pass filter that model the effect that humans perceive a certain amount of power in low frequencies to be less loud than the same amount of power in higher frequencies. In this library the Power type is used exclusively to refer to power after applying K-weighting.

The nominal “full scale” is the range [-1.0, 1.0]. Because the power is the mean square of the samples, if no input samples exceeded the full scale, the power will be in the range [0.0, 1.0]. However, the power delivered by multiple channels, which is a weighted sum over individual channel powers, can exceed this range, because the weighted sum is not normalized.

Implementations

impl Power

pub fn from_lkfs(lkfs: f32) -> Power

Convert Loudness Units relative to Full Scale into a squared sample amplitude.

This is the inverse of loudness_lkfs.

pub fn loudness_lkfs(&self) -> f32

Return the loudness of this window in Loudness Units, K-weighted, relative to Full Scale.

This is the inverse of from_lkfs.

Trait Implementations

impl Clone for Power

fn clone(&self) -> Power

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Copy for Power

impl PartialEq<Power> for Power

fn eq(&self, other: &Power) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Power) -> bool

This method tests for !=.

impl PartialOrd<Power> for Power

fn partial_cmp(&self, other: &Power) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Power) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Power) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Power) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Power) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for Power