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1 | use std::f32::consts; | |
2 | ||
3 | pub const MAX_BANDS: usize = 25; | |
4 | ||
5 | const CRITICAL_FREQS: [usize; MAX_BANDS] = [ | |
6 | 100, 200, 300, 400, 510, 630, 770, 920, | |
7 | 1080, 1270, 1480, 1720, 2000, 2320, 2700, 3150, | |
8 | 3700, 4400, 5300, 6400, 7700, 9500, 12000, 15500, | |
9 | 24500 | |
10 | ]; | |
11 | ||
12 | pub const RUN_TAB: [usize; 16] = [ 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 32, 64 ]; | |
13 | ||
14 | pub fn init_bands(srate: usize, len: usize, num_bands: &mut usize, bands: &mut [usize; MAX_BANDS + 1]) { | |
15 | *num_bands = 1; | |
16 | while *num_bands < CRITICAL_FREQS.len() && CRITICAL_FREQS[*num_bands - 1] < srate { | |
17 | *num_bands += 1; | |
18 | } | |
19 | bands[0] = 2; | |
20 | for i in 1..*num_bands { | |
21 | bands[i] = (CRITICAL_FREQS[i - 1] * len / srate) & !1; | |
22 | } | |
23 | bands[*num_bands] = len; | |
24 | } | |
25 | ||
26 | pub fn get_quants_table() -> [f32; 96] { | |
27 | let mut quants: [f32; 96] = [0.0; 96]; | |
28 | for i in 0..quants.len() { | |
29 | quants[i] = ((i as f32) * 0.0664 / consts::LOG10_E).exp(); | |
30 | } | |
31 | quants | |
32 | } |