Crate hertz

useful functions for working with frame-rates, sample-rates, other rates, time durations, frequencies, etc and for keeping a constant framerate.

rate, sample rate, frame rate, fps, frequency, etc express the same concept and are therefore used interchangeably.

you can use hertz to compute the time resolution and frequency range that can be meaningfully analyzed by a short-time fourier transform of a signal:

extern crate hertz;

fn main() {
    let sample_rate = 44100;
    let window_size = 4096;
    let step_size = 512;

    // 11 hertz is the maximum frequency that can be meaningfully analyzed
    assert_eq!(
        11.,
        hertz::rayleigh(sample_rate as f64, window_size as f64).round());

    // 22050 hertz is the maximum frequency that can be meaningfully analyzed
    assert_eq!(
        22050.,
        hertz::nyquist(sample_rate as f64).round());

    // 12 ms is the time resolution we get when analyzing a 44100 hertz
    // signal with a step size of 512
    assert_eq!(
        12.,
        hertz::s_to_ms(hertz::cycles_per_second_to_seconds_per_cycle(
            sample_rate as f64,
            step_size as f64)).round());
}

you can use hertz to keep a constant framerate in a game or other computer graphics application:

fn main() {
    let frames_per_second: usize = 60;

    loop {
        let instant_at_frame_start = std::time::Instant::now();

        // here's where logic and rendering would go.
        // this is never called more than frames_per_second
        // times per second.

        hertz::sleep_for_constant_rate(
            frames_per_second, instant_at_frame_start);
    }
}

Functions

cycles_per_second_to_seconds_per_cycle

window duration in seconds sample_rate in hertz

fps_to_ns_per_frame

when given frames per second (or sample rate) returns the duration of a single frame

hertz_range

frequency range that can be modeled when taking the short time fourier transform of a signal with sample_rate with a sliding window of window_sizew. equivalent to rayleigh(sample_rate, window_size)..nyquist(sample_rate) increase the window size to increase the lower frequency increase the sample rate to increase the upper frequency

ms_to_ns

milliseconds to nanoseconds

ms_to_s

milliseconds to seconds

ns_to_ms

nanoseconds to milliseconds

ns_to_s

nanoseconds to seconds

nyquist

maximum frequency in hertz that can be meaningfully analyzed with a given sample rate https://en.wikipedia.org/wiki/Short-time_Fourier_transform#Explanation

rayleigh

minimum frequency in hertz that can be meaningfully analyzed with a given sample rate and window size https://en.wikipedia.org/wiki/Short-time_Fourier_transform#Rayleigh_frequency

s_to_ms

seconds to milliseconds

s_to_ns

seconds to nanoseconds

sleep_for_constant_rate

useful for keeping a constant framerate