nihav-rad/src/codecs/binkauddata.rs

   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 (band, &freq) in bands[1..*num_bands].iter_mut().zip(CRITICAL_FREQS.iter()) {
  21         *band = (freq * 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, quant) in quants.iter_mut().enumerate() {
  29         *quant = ((i as f32) * 0.0664 / consts::LOG10_E).exp();
  30     }
  31     quants
  32 }