fast-vad 0.2.1

Extremely fast voice activity detection in Rust with Python bindings and streaming mode support.
Documentation 
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//! Internal constants used by the filterbank and detector.

use wide::f32x8;

/// Number of FFT bins used during band-energy analysis.
///
/// [`BAND_BINS`] covers the range `[0, ANALYSIS_BINS)`, which spans 0-4 kHz
/// at 16 kHz sample rate. The Nyquist bin and everything above it are
/// intentionally excluded.
pub const ANALYSIS_BINS: usize = 128;

/// Number of logarithmic frequency bands in the filterbank.
pub const NUM_BANDS: usize = 8;

/// Half-open FFT-bin ranges for each of the eight filterbank bands.
pub static BAND_BINS: [(usize, usize); NUM_BANDS] = [
    (3, 6),
    (6, 12),
    (12, 19),
    (19, 32),
    (32, 51),
    (51, 77),
    (77, 108),
    (108, 128),
];

/// Logistic-regression weights applied to raw band energies.
pub static RAW_WEIGHTS: f32x8 = f32x8::new([
    0.01562034,  // raw_80-200
    0.20278303,  // raw_200-380
    0.09269018,  // raw_380-600
    -0.15091796, // raw_600-1k
    -0.01901991, // raw_1k-1.6k
    0.07493567,  // raw_1.6k-2.4k
    -0.08492067, // raw_2.4k-3.2k
    0.28920355,  // raw_3.2k-4k
]);

/// Logistic-regression weights applied to noise-normalized band energies.
pub static NORM_WEIGHTS: f32x8 = f32x8::new([
    0.17463323,  // norm_80-200
    0.543_774_2, // norm_200-380
    0.21194649,  // norm_380-600
    -0.00053826, // norm_600-1k
    0.10791918,  // norm_1k-1.6k
    -0.14064065, // norm_1.6k-2.4k
    0.33679298,  // norm_2.4k-3.2k
    0.152_284_6, // norm_3.2k-4k
]);

/// Logistic-regression weights applied to first-order temporal deltas.
pub static DELTA_WEIGHTS: f32x8 = f32x8::new([
    -0.18790886,  // delta_80-200
    -0.73869383,  // delta_200-380
    -0.30269337,  // delta_380-600
    0.15577473,   // delta_600-1k
    -0.07288475,  // delta_1k-1.6k
    0.05904672,   // delta_1.6k-2.4k
    -0.21098153,  // delta_2.4k-3.2k
    -0.363_977_5, // delta_3.2k-4k
]);

/// Logistic-regression weights applied to second-order temporal deltas.
pub static DELTA2_WEIGHTS: f32x8 = f32x8::new([
    0.08596912,  // delta2_80-200
    0.321_316_9, // delta2_200-380
    0.139_114,   // delta2_380-600
    -0.02363876, // delta2_600-1k
    0.04661002,  // delta2_1k-1.6k
    -0.00053802, // delta2_1.6k-2.4k
    0.10279381,  // delta2_2.4k-3.2k
    0.12189715,  // delta2_3.2k-4k
]);

/// Logistic-regression bias term.
pub static BIAS: f32 = -0.50482284;

/// Adaptation rate used when updating the running noise floor estimate.
pub const NOISE_FLOOR_ALPHA: f32 = 0.01;