Crate hertz

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

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

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

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 ns_at_frame_start = hertz::current_time_ns();

        // 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, ns_at_frame_start);
    }
}

Functions

current_time_ns	returns the current timestamp in nanoseconds
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