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|
//! Quadrature Mirror Filter used in various audio codecs like MPEG Audio.
///! 32-band QMF.
pub struct QMF {
hist: [f32; 1024],
pos: usize,
}
macro_rules! butterfly {
(in; $src0: expr, $src1: expr, $dst0: expr, $dst1: expr, $scale: expr) => {
$dst0 = $src0 + $src1;
$dst1 = ($src0 - $src1) * $scale;
};
(rev; $a: expr, $b: expr) => {
butterfly!(rev; $a, $b, std::f32::consts::FRAC_1_SQRT_2);
};
(rev; $a: expr, $b: expr, $scale: expr) => {
let tmp = $a + $b;
$b = ($a - $b) * $scale;
$a = tmp;
};
(scal; $a: expr, $b: expr) => {
butterfly!(scal; $a, $b, std::f32::consts::FRAC_1_SQRT_2);
};
(scal; $a: expr, $b: expr, $scale: expr) => {
let tmp = $a + $b;
$b = ($b - $a) * $scale;
$a = tmp;
};
}
macro_rules! postadd {
($tmp: expr, $a0: expr, $b0: expr, $c0: expr, $d0: expr, $a1: expr, $b1: expr, $c1: expr, $d1: expr) => {
$tmp[$c0] += $tmp[$d0];
$tmp[$c1] += $tmp[$d1];
$tmp[$a1] += $tmp[$c1];
$tmp[$c1] += $tmp[$b1];
$tmp[$b1] += $tmp[$d1];
}
}
fn dct32(src: &[f32; 32], dst: &mut [f32]) {
let mut tmp = [0.0f32; 32];
butterfly!(in; src[ 0], src[31], tmp[ 0], tmp[31], 0.50060299823519627);
butterfly!(in; src[ 1], src[30], tmp[ 1], tmp[30], 0.50547095989754365);
butterfly!(in; src[ 2], src[29], tmp[ 2], tmp[29], 0.51544730992262455);
butterfly!(in; src[ 3], src[28], tmp[ 3], tmp[28], 0.53104259108978413);
butterfly!(in; src[ 4], src[27], tmp[ 4], tmp[27], 0.55310389603444454);
butterfly!(in; src[ 5], src[26], tmp[ 5], tmp[26], 0.58293496820613389);
butterfly!(in; src[ 6], src[25], tmp[ 6], tmp[25], 0.62250412303566482);
butterfly!(in; src[ 7], src[24], tmp[ 7], tmp[24], 0.67480834145500568);
butterfly!(in; src[ 8], src[23], tmp[ 8], tmp[23], 0.74453627100229858);
butterfly!(in; src[ 9], src[22], tmp[ 9], tmp[22], 0.83934964541552681);
butterfly!(in; src[10], src[21], tmp[10], tmp[21], 0.97256823786196078);
butterfly!(in; src[11], src[20], tmp[11], tmp[20], 1.1694399334328847);
butterfly!(in; src[12], src[19], tmp[12], tmp[19], 1.4841646163141662);
butterfly!(in; src[13], src[18], tmp[13], tmp[18], 2.0577810099534108);
butterfly!(in; src[14], src[17], tmp[14], tmp[17], 3.407608418468719);
butterfly!(in; src[15], src[16], tmp[15], tmp[16], 10.190008123548033);
butterfly!(rev; tmp[ 0], tmp[15], 0.50241928618815568);
butterfly!(rev; tmp[ 1], tmp[14], 0.52249861493968885);
butterfly!(rev; tmp[ 2], tmp[13], 0.56694403481635769);
butterfly!(rev; tmp[ 3], tmp[12], 0.64682178335999008);
butterfly!(rev; tmp[ 4], tmp[11], 0.7881546234512502);
butterfly!(rev; tmp[ 5], tmp[10], 1.0606776859903471);
butterfly!(rev; tmp[ 6], tmp[ 9], 1.7224470982383342);
butterfly!(rev; tmp[ 7], tmp[ 8], 5.1011486186891553);
butterfly!(scal; tmp[16], tmp[31], 0.50241928618815568);
butterfly!(scal; tmp[17], tmp[30], 0.52249861493968885);
butterfly!(scal; tmp[18], tmp[29], 0.56694403481635769);
butterfly!(scal; tmp[19], tmp[28], 0.64682178335999008);
butterfly!(scal; tmp[20], tmp[27], 0.7881546234512502);
butterfly!(scal; tmp[21], tmp[26], 1.0606776859903471);
butterfly!(scal; tmp[22], tmp[25], 1.7224470982383342);
butterfly!(scal; tmp[23], tmp[24], 5.1011486186891553);
butterfly!(rev; tmp[ 0], tmp[ 7], 0.50979557910415918);
butterfly!(rev; tmp[ 1], tmp[ 6], 0.60134488693504529);
butterfly!(rev; tmp[ 2], tmp[ 5], 0.89997622313641557);
butterfly!(rev; tmp[ 3], tmp[ 4], 2.5629154477415055);
butterfly!(rev; tmp[16], tmp[23], 0.50979557910415918);
butterfly!(rev; tmp[17], tmp[22], 0.60134488693504529);
butterfly!(rev; tmp[18], tmp[21], 0.89997622313641557);
butterfly!(rev; tmp[19], tmp[20], 2.5629154477415055);
butterfly!(scal; tmp[ 8], tmp[15], 0.50979557910415918);
butterfly!(scal; tmp[ 9], tmp[14], 0.60134488693504529);
butterfly!(scal; tmp[10], tmp[13], 0.89997622313641557);
butterfly!(scal; tmp[11], tmp[12], 2.5629154477415055);
butterfly!(scal; tmp[24], tmp[31], 0.50979557910415918);
butterfly!(scal; tmp[25], tmp[30], 0.60134488693504529);
butterfly!(scal; tmp[26], tmp[29], 0.89997622313641557);
butterfly!(scal; tmp[27], tmp[28], 2.5629154477415055);
butterfly!(rev; tmp[ 0], tmp[ 3], 0.54119610014619701);
butterfly!(rev; tmp[ 1], tmp[ 2], 1.3065629648763764);
butterfly!(rev; tmp[ 8], tmp[11], 0.54119610014619701);
butterfly!(rev; tmp[ 9], tmp[10], 1.3065629648763764);
butterfly!(rev; tmp[16], tmp[19], 0.54119610014619701);
butterfly!(rev; tmp[17], tmp[18], 1.3065629648763764);
butterfly!(rev; tmp[24], tmp[27], 0.54119610014619701);
butterfly!(rev; tmp[25], tmp[26], 1.3065629648763764);
butterfly!(scal; tmp[ 4], tmp[ 7], 0.54119610014619701);
butterfly!(scal; tmp[ 5], tmp[ 6], 1.3065629648763764);
butterfly!(scal; tmp[12], tmp[15], 0.54119610014619701);
butterfly!(scal; tmp[13], tmp[14], 1.3065629648763764);
butterfly!(scal; tmp[20], tmp[23], 0.54119610014619701);
butterfly!(scal; tmp[21], tmp[22], 1.3065629648763764);
butterfly!(scal; tmp[28], tmp[31], 0.54119610014619701);
butterfly!(scal; tmp[29], tmp[30], 1.3065629648763764);
butterfly!(rev; tmp[ 0], tmp[ 1]);
butterfly!(rev; tmp[ 4], tmp[ 5]);
butterfly!(rev; tmp[ 8], tmp[ 9]);
butterfly!(rev; tmp[12], tmp[13]);
butterfly!(rev; tmp[16], tmp[17]);
butterfly!(rev; tmp[20], tmp[21]);
butterfly!(rev; tmp[24], tmp[25]);
butterfly!(rev; tmp[28], tmp[29]);
butterfly!(scal; tmp[ 2], tmp[ 3]);
butterfly!(scal; tmp[ 6], tmp[ 7]);
butterfly!(scal; tmp[10], tmp[11]);
butterfly!(scal; tmp[14], tmp[15]);
butterfly!(scal; tmp[18], tmp[19]);
butterfly!(scal; tmp[22], tmp[23]);
butterfly!(scal; tmp[26], tmp[27]);
butterfly!(scal; tmp[30], tmp[31]);
postadd!(tmp, 0, 1, 2, 3, 4, 5, 6, 7);
postadd!(tmp, 8, 9, 10, 11, 12, 13, 14, 15);
postadd!(tmp,16, 17, 18, 19, 20, 21, 22, 23);
postadd!(tmp,24, 25, 26, 27, 28, 29, 30, 31);
dst[ 0] = tmp[0];
dst[16] = tmp[1];
dst[ 8] = tmp[2];
dst[24] = tmp[3];
dst[ 4] = tmp[4];
dst[20] = tmp[5];
dst[12] = tmp[6];
dst[28] = tmp[7];
dst[ 2] = tmp[ 8] + tmp[12];
dst[18] = tmp[ 9] + tmp[13];
dst[10] = tmp[10] + tmp[14];
dst[26] = tmp[11] + tmp[15];
dst[ 6] = tmp[12] + tmp[10];
dst[22] = tmp[13] + tmp[11];
dst[14] = tmp[14] + tmp[ 9];
dst[30] = tmp[15];
tmp[24] += tmp[28];
tmp[28] += tmp[26];
tmp[26] += tmp[30];
tmp[30] += tmp[25];
tmp[25] += tmp[29];
tmp[29] += tmp[27];
tmp[27] += tmp[31];
dst[ 1] = tmp[16] + tmp[24];
dst[17] = tmp[17] + tmp[25];
dst[ 9] = tmp[18] + tmp[26];
dst[25] = tmp[19] + tmp[27];
dst[ 5] = tmp[20] + tmp[28];
dst[21] = tmp[21] + tmp[29];
dst[13] = tmp[22] + tmp[30];
dst[29] = tmp[23] + tmp[31];
dst[ 3] = tmp[24] + tmp[20];
dst[19] = tmp[25] + tmp[21];
dst[11] = tmp[26] + tmp[22];
dst[27] = tmp[27] + tmp[23];
dst[ 7] = tmp[28] + tmp[18];
dst[23] = tmp[29] + tmp[19];
dst[15] = tmp[30] + tmp[17];
dst[31] = tmp[31];
}
impl QMF {
///! Constructs a new `QMF` context.
pub fn new() -> Self {
Self {
hist: [0.0; 1024],
pos: 0,
}
}
///! Performs reconstruction of audio from provided sub-band samples.
pub fn synth(&mut self, src: &[f32; 32], dst: &mut [f32]) {
self.pos = self.pos.wrapping_sub(32) & 0x1FF;
dct32(src, &mut self.hist[self.pos..][..32]);
for i in 0..16 {
let mut acc = 0.0;
for j in (0..512).step_by(64) {
acc += QMF_WINDOW[i + j] * self.hist[(j + 16 + i + self.pos) & 0x1FF];
acc -= QMF_WINDOW[i + j + 32] * self.hist[(j + 16 + 32 - i + self.pos) & 0x1FF];
}
dst[i] = acc;
}
let mut acc = 0.0;
for j in (0..512).step_by(64) {
acc -= QMF_WINDOW[j + 32 + 16] * self.hist[(j + 32 + self.pos) & 0x1FF];
}
dst[16] = acc;
for i in 17..32 {
let mut acc = 0.0;
for j in (0..512).step_by(64) {
acc -= QMF_WINDOW[i + j] * self.hist[(j + 32 + 16 - i + self.pos) & 0x1FF];
acc -= QMF_WINDOW[i + j + 32] * self.hist[(j + 32 - 16 + i + self.pos) & 0x1FF];
}
dst[i] = acc;
}
}
///! Resets internal filter state.
pub fn reset(&mut self) {
self.hist = [0.0; 1024];
self.pos = 0;
}
}
impl Default for QMF {
fn default() -> Self {
Self::new()
}
}
const QMF_WINDOW: [f32; 512] = [
0.000000000, -0.000015259, -0.000015259, -0.000015259,
-0.000015259, -0.000015259, -0.000015259, -0.000030518,
-0.000030518, -0.000030518, -0.000030518, -0.000045776,
-0.000045776, -0.000061035, -0.000061035, -0.000076294,
-0.000076294, -0.000091553, -0.000106812, -0.000106812,
-0.000122070, -0.000137329, -0.000152588, -0.000167847,
-0.000198364, -0.000213623, -0.000244141, -0.000259399,
-0.000289917, -0.000320435, -0.000366211, -0.000396729,
-0.000442505, -0.000473022, -0.000534058, -0.000579834,
-0.000625610, -0.000686646, -0.000747681, -0.000808716,
-0.000885010, -0.000961304, -0.001037598, -0.001113892,
-0.001205444, -0.001296997, -0.001388550, -0.001480103,
-0.001586914, -0.001693726, -0.001785278, -0.001907349,
-0.002014160, -0.002120972, -0.002243042, -0.002349854,
-0.002456665, -0.002578735, -0.002685547, -0.002792358,
-0.002899170, -0.002990723, -0.003082275, -0.003173828,
0.003250122, 0.003326416, 0.003387451, 0.003433228,
0.003463745, 0.003479004, 0.003479004, 0.003463745,
0.003417969, 0.003372192, 0.003280640, 0.003173828,
0.003051758, 0.002883911, 0.002700806, 0.002487183,
0.002227783, 0.001937866, 0.001617432, 0.001266479,
0.000869751, 0.000442505, -0.000030518, -0.000549316,
-0.001098633, -0.001693726, -0.002334595, -0.003005981,
-0.003723145, -0.004486084, -0.005294800, -0.006118774,
-0.007003784, -0.007919312, -0.008865356, -0.009841919,
-0.010848999, -0.011886597, -0.012939453, -0.014022827,
-0.015121460, -0.016235352, -0.017349243, -0.018463135,
-0.019577026, -0.020690918, -0.021789551, -0.022857666,
-0.023910522, -0.024932861, -0.025909424, -0.026840210,
-0.027725220, -0.028533936, -0.029281616, -0.029937744,
-0.030532837, -0.031005859, -0.031387329, -0.031661987,
-0.031814575, -0.031845093, -0.031738281, -0.031478882,
0.031082153, 0.030517578, 0.029785156, 0.028884888,
0.027801514, 0.026535034, 0.025085449, 0.023422241,
0.021575928, 0.019531250, 0.017257690, 0.014801025,
0.012115479, 0.009231567, 0.006134033, 0.002822876,
-0.000686646, -0.004394531, -0.008316040, -0.012420654,
-0.016708374, -0.021179199, -0.025817871, -0.030609131,
-0.035552979, -0.040634155, -0.045837402, -0.051132202,
-0.056533813, -0.061996460, -0.067520142, -0.073059082,
-0.078628540, -0.084182739, -0.089706421, -0.095169067,
-0.100540161, -0.105819702, -0.110946655, -0.115921021,
-0.120697021, -0.125259399, -0.129562378, -0.133590698,
-0.137298584, -0.140670776, -0.143676758, -0.146255493,
-0.148422241, -0.150115967, -0.151306152, -0.151962280,
-0.152069092, -0.151596069, -0.150497437, -0.148773193,
-0.146362305, -0.143264771, -0.139450073, -0.134887695,
-0.129577637, -0.123474121, -0.116577148, -0.108856201,
0.100311279, 0.090927124, 0.080688477, 0.069595337,
0.057617187, 0.044784546, 0.031082153, 0.016510010,
0.001068115, -0.015228271, -0.032379150, -0.050354004,
-0.069168091, -0.088775635, -0.109161377, -0.130310059,
-0.152206421, -0.174789429, -0.198059082, -0.221984863,
-0.246505737, -0.271591187, -0.297210693, -0.323318481,
-0.349868774, -0.376800537, -0.404083252, -0.431655884,
-0.459472656, -0.487472534, -0.515609741, -0.543823242,
-0.572036743, -0.600219727, -0.628295898, -0.656219482,
-0.683914185, -0.711318970, -0.738372803, -0.765029907,
-0.791213989, -0.816864014, -0.841949463, -0.866363525,
-0.890090942, -0.913055420, -0.935195923, -0.956481934,
-0.976852417, -0.996246338, -1.014617920, -1.031936646,
-1.048156738, -1.063217163, -1.077117920, -1.089782715,
-1.101211548, -1.111373901, -1.120223999, -1.127746582,
-1.133926392, -1.138763428, -1.142211914, -1.144287109,
1.144989014, 1.144287109, 1.142211914, 1.138763428,
1.133926392, 1.127746582, 1.120223999, 1.111373901,
1.101211548, 1.089782715, 1.077117920, 1.063217163,
1.048156738, 1.031936646, 1.014617920, 0.996246338,
0.976852417, 0.956481934, 0.935195923, 0.913055420,
0.890090942, 0.866363525, 0.841949463, 0.816864014,
0.791213989, 0.765029907, 0.738372803, 0.711318970,
0.683914185, 0.656219482, 0.628295898, 0.600219727,
0.572036743, 0.543823242, 0.515609741, 0.487472534,
0.459472656, 0.431655884, 0.404083252, 0.376800537,
0.349868774, 0.323318481, 0.297210693, 0.271591187,
0.246505737, 0.221984863, 0.198059082, 0.174789429,
0.152206421, 0.130310059, 0.109161377, 0.088775635,
0.069168091, 0.050354004, 0.032379150, 0.015228271,
-0.001068115, -0.016510010, -0.031082153, -0.044784546,
-0.057617187, -0.069595337, -0.080688477, -0.090927124,
0.100311279, 0.108856201, 0.116577148, 0.123474121,
0.129577637, 0.134887695, 0.139450073, 0.143264771,
0.146362305, 0.148773193, 0.150497437, 0.151596069,
0.152069092, 0.151962280, 0.151306152, 0.150115967,
0.148422241, 0.146255493, 0.143676758, 0.140670776,
0.137298584, 0.133590698, 0.129562378, 0.125259399,
0.120697021, 0.115921021, 0.110946655, 0.105819702,
0.100540161, 0.095169067, 0.089706421, 0.084182739,
0.078628540, 0.073059082, 0.067520142, 0.061996460,
0.056533813, 0.051132202, 0.045837402, 0.040634155,
0.035552979, 0.030609131, 0.025817871, 0.021179199,
0.016708374, 0.012420654, 0.008316040, 0.004394531,
0.000686646, -0.002822876, -0.006134033, -0.009231567,
-0.012115479, -0.014801025, -0.017257690, -0.019531250,
-0.021575928, -0.023422241, -0.025085449, -0.026535034,
-0.027801514, -0.028884888, -0.029785156, -0.030517578,
0.031082153, 0.031478882, 0.031738281, 0.031845093,
0.031814575, 0.031661987, 0.031387329, 0.031005859,
0.030532837, 0.029937744, 0.029281616, 0.028533936,
0.027725220, 0.026840210, 0.025909424, 0.024932861,
0.023910522, 0.022857666, 0.021789551, 0.020690918,
0.019577026, 0.018463135, 0.017349243, 0.016235352,
0.015121460, 0.014022827, 0.012939453, 0.011886597,
0.010848999, 0.009841919, 0.008865356, 0.007919312,
0.007003784, 0.006118774, 0.005294800, 0.004486084,
0.003723145, 0.003005981, 0.002334595, 0.001693726,
0.001098633, 0.000549316, 0.000030518, -0.000442505,
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