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Merge pull request #3310 from FearlessTobi/fast-resample

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audio_core: Switch to a faster interpolation technique
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bunnei 2020-02-22 01:54:40 -05:00 committed by GitHub
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2 changed files with 159 additions and 48 deletions
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194
src/audio_core/algorithm/interpolate.cpp
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@ -6,6 +6,7 @@
#include <algorithm>
#include <cmath>
#include <limits>
#include <vector>
#include "audio_core/algorithm/interpolate.h"
#include "common/common_types.h"
@ -13,13 +14,131 @@
namespace AudioCore {
/// The Lanczos kernel
static double Lanczos(std::size_t a, double x) {
if (x == 0.0)
return 1.0;
const double px = M_PI * x;
return a * std::sin(px) * std::sin(px / a) / (px * px);
}
constexpr std::array<s16, 512> curve_lut0 = {
6600, 19426, 6722, 3, 6479, 19424, 6845, 9, 6359, 19419, 6968, 15, 6239,
19412, 7093, 22, 6121, 19403, 7219, 28, 6004, 19391, 7345, 34, 5888, 19377,
7472, 41, 5773, 19361, 7600, 48, 5659, 19342, 7728, 55, 5546, 19321, 7857,
62, 5434, 19298, 7987, 69, 5323, 19273, 8118, 77, 5213, 19245, 8249, 84,
5104, 19215, 8381, 92, 4997, 19183, 8513, 101, 4890, 19148, 8646, 109, 4785,
19112, 8780, 118, 4681, 19073, 8914, 127, 4579, 19031, 9048, 137, 4477, 18988,
9183, 147, 4377, 18942, 9318, 157, 4277, 18895, 9454, 168, 4179, 18845, 9590,
179, 4083, 18793, 9726, 190, 3987, 18738, 9863, 202, 3893, 18682, 10000, 215,
3800, 18624, 10137, 228, 3709, 18563, 10274, 241, 3618, 18500, 10411, 255, 3529,
18436, 10549, 270, 3441, 18369, 10687, 285, 3355, 18300, 10824, 300, 3269, 18230,
10962, 317, 3186, 18157, 11100, 334, 3103, 18082, 11238, 351, 3022, 18006, 11375,
369, 2942, 17927, 11513, 388, 2863, 17847, 11650, 408, 2785, 17765, 11788, 428,
2709, 17681, 11925, 449, 2635, 17595, 12062, 471, 2561, 17507, 12198, 494, 2489,
17418, 12334, 517, 2418, 17327, 12470, 541, 2348, 17234, 12606, 566, 2280, 17140,
12741, 592, 2213, 17044, 12876, 619, 2147, 16946, 13010, 647, 2083, 16846, 13144,
675, 2020, 16745, 13277, 704, 1958, 16643, 13409, 735, 1897, 16539, 13541, 766,
1838, 16434, 13673, 798, 1780, 16327, 13803, 832, 1723, 16218, 13933, 866, 1667,
16109, 14062, 901, 1613, 15998, 14191, 937, 1560, 15885, 14318, 975, 1508, 15772,
14445, 1013, 1457, 15657, 14571, 1052, 1407, 15540, 14695, 1093, 1359, 15423, 14819,
1134, 1312, 15304, 14942, 1177, 1266, 15185, 15064, 1221, 1221, 15064, 15185, 1266,
1177, 14942, 15304, 1312, 1134, 14819, 15423, 1359, 1093, 14695, 15540, 1407, 1052,
14571, 15657, 1457, 1013, 14445, 15772, 1508, 975, 14318, 15885, 1560, 937, 14191,
15998, 1613, 901, 14062, 16109, 1667, 866, 13933, 16218, 1723, 832, 13803, 16327,
1780, 798, 13673, 16434, 1838, 766, 13541, 16539, 1897, 735, 13409, 16643, 1958,
704, 13277, 16745, 2020, 675, 13144, 16846, 2083, 647, 13010, 16946, 2147, 619,
12876, 17044, 2213, 592, 12741, 17140, 2280, 566, 12606, 17234, 2348, 541, 12470,
17327, 2418, 517, 12334, 17418, 2489, 494, 12198, 17507, 2561, 471, 12062, 17595,
2635, 449, 11925, 17681, 2709, 428, 11788, 17765, 2785, 408, 11650, 17847, 2863,
388, 11513, 17927, 2942, 369, 11375, 18006, 3022, 351, 11238, 18082, 3103, 334,
11100, 18157, 3186, 317, 10962, 18230, 3269, 300, 10824, 18300, 3355, 285, 10687,
18369, 3441, 270, 10549, 18436, 3529, 255, 10411, 18500, 3618, 241, 10274, 18563,
3709, 228, 10137, 18624, 3800, 215, 10000, 18682, 3893, 202, 9863, 18738, 3987,
190, 9726, 18793, 4083, 179, 9590, 18845, 4179, 168, 9454, 18895, 4277, 157,
9318, 18942, 4377, 147, 9183, 18988, 4477, 137, 9048, 19031, 4579, 127, 8914,
19073, 4681, 118, 8780, 19112, 4785, 109, 8646, 19148, 4890, 101, 8513, 19183,
4997, 92, 8381, 19215, 5104, 84, 8249, 19245, 5213, 77, 8118, 19273, 5323,
69, 7987, 19298, 5434, 62, 7857, 19321, 5546, 55, 7728, 19342, 5659, 48,
7600, 19361, 5773, 41, 7472, 19377, 5888, 34, 7345, 19391, 6004, 28, 7219,
19403, 6121, 22, 7093, 19412, 6239, 15, 6968, 19419, 6359, 9, 6845, 19424,
6479, 3, 6722, 19426, 6600};
constexpr std::array<s16, 512> curve_lut1 = {
-68, 32639, 69, -5, -200, 32630, 212, -15, -328, 32613, 359, -26, -450,
32586, 512, -36, -568, 32551, 669, -47, -680, 32507, 832, -58, -788, 32454,
1000, -69, -891, 32393, 1174, -80, -990, 32323, 1352, -92, -1084, 32244, 1536,
-103, -1173, 32157, 1724, -115, -1258, 32061, 1919, -128, -1338, 31956, 2118, -140,
-1414, 31844, 2322, -153, -1486, 31723, 2532, -167, -1554, 31593, 2747, -180, -1617,
31456, 2967, -194, -1676, 31310, 3192, -209, -1732, 31157, 3422, -224, -1783, 30995,
3657, -240, -1830, 30826, 3897, -256, -1874, 30649, 4143, -272, -1914, 30464, 4393,
-289, -1951, 30272, 4648, -307, -1984, 30072, 4908, -325, -2014, 29866, 5172, -343,
-2040, 29652, 5442, -362, -2063, 29431, 5716, -382, -2083, 29203, 5994, -403, -2100,
28968, 6277, -424, -2114, 28727, 6565, -445, -2125, 28480, 6857, -468, -2133, 28226,
7153, -490, -2139, 27966, 7453, -514, -2142, 27700, 7758, -538, -2142, 27428, 8066,
-563, -2141, 27151, 8378, -588, -2136, 26867, 8694, -614, -2130, 26579, 9013, -641,
-2121, 26285, 9336, -668, -2111, 25987, 9663, -696, -2098, 25683, 9993, -724, -2084,
25375, 10326, -753, -2067, 25063, 10662, -783, -2049, 24746, 11000, -813, -2030, 24425,
11342, -844, -2009, 24100, 11686, -875, -1986, 23771, 12033, -907, -1962, 23438, 12382,
-939, -1937, 23103, 12733, -972, -1911, 22764, 13086, -1005, -1883, 22422, 13441, -1039,
-1855, 22077, 13798, -1072, -1825, 21729, 14156, -1107, -1795, 21380, 14516, -1141, -1764,
21027, 14877, -1176, -1732, 20673, 15239, -1211, -1700, 20317, 15602, -1246, -1667, 19959,
15965, -1282, -1633, 19600, 16329, -1317, -1599, 19239, 16694, -1353, -1564, 18878, 17058,
-1388, -1530, 18515, 17423, -1424, -1495, 18151, 17787, -1459, -1459, 17787, 18151, -1495,
-1424, 17423, 18515, -1530, -1388, 17058, 18878, -1564, -1353, 16694, 19239, -1599, -1317,
16329, 19600, -1633, -1282, 15965, 19959, -1667, -1246, 15602, 20317, -1700, -1211, 15239,
20673, -1732, -1176, 14877, 21027, -1764, -1141, 14516, 21380, -1795, -1107, 14156, 21729,
-1825, -1072, 13798, 22077, -1855, -1039, 13441, 22422, -1883, -1005, 13086, 22764, -1911,
-972, 12733, 23103, -1937, -939, 12382, 23438, -1962, -907, 12033, 23771, -1986, -875,
11686, 24100, -2009, -844, 11342, 24425, -2030, -813, 11000, 24746, -2049, -783, 10662,
25063, -2067, -753, 10326, 25375, -2084, -724, 9993, 25683, -2098, -696, 9663, 25987,
-2111, -668, 9336, 26285, -2121, -641, 9013, 26579, -2130, -614, 8694, 26867, -2136,
-588, 8378, 27151, -2141, -563, 8066, 27428, -2142, -538, 7758, 27700, -2142, -514,
7453, 27966, -2139, -490, 7153, 28226, -2133, -468, 6857, 28480, -2125, -445, 6565,
28727, -2114, -424, 6277, 28968, -2100, -403, 5994, 29203, -2083, -382, 5716, 29431,
-2063, -362, 5442, 29652, -2040, -343, 5172, 29866, -2014, -325, 4908, 30072, -1984,
-307, 4648, 30272, -1951, -289, 4393, 30464, -1914, -272, 4143, 30649, -1874, -256,
3897, 30826, -1830, -240, 3657, 30995, -1783, -224, 3422, 31157, -1732, -209, 3192,
31310, -1676, -194, 2967, 31456, -1617, -180, 2747, 31593, -1554, -167, 2532, 31723,
-1486, -153, 2322, 31844, -1414, -140, 2118, 31956, -1338, -128, 1919, 32061, -1258,
-115, 1724, 32157, -1173, -103, 1536, 32244, -1084, -92, 1352, 32323, -990, -80,
1174, 32393, -891, -69, 1000, 32454, -788, -58, 832, 32507, -680, -47, 669,
32551, -568, -36, 512, 32586, -450, -26, 359, 32613, -328, -15, 212, 32630,
-200, -5, 69, 32639, -68};
constexpr std::array<s16, 512> curve_lut2 = {
3195, 26287, 3329, -32, 3064, 26281, 3467, -34, 2936, 26270, 3608, -38, 2811,
26253, 3751, -42, 2688, 26230, 3897, -46, 2568, 26202, 4046, -50, 2451, 26169,
4199, -54, 2338, 26130, 4354, -58, 2227, 26085, 4512, -63, 2120, 26035, 4673,
-67, 2015, 25980, 4837, -72, 1912, 25919, 5004, -76, 1813, 25852, 5174, -81,
1716, 25780, 5347, -87, 1622, 25704, 5522, -92, 1531, 25621, 5701, -98, 1442,
25533, 5882, -103, 1357, 25440, 6066, -109, 1274, 25342, 6253, -115, 1193, 25239,
6442, -121, 1115, 25131, 6635, -127, 1040, 25018, 6830, -133, 967, 24899, 7027,
-140, 897, 24776, 7227, -146, 829, 24648, 7430, -153, 764, 24516, 7635, -159,
701, 24379, 7842, -166, 641, 24237, 8052, -174, 583, 24091, 8264, -181, 526,
23940, 8478, -187, 472, 23785, 8695, -194, 420, 23626, 8914, -202, 371, 23462,
9135, -209, 324, 23295, 9358, -215, 279, 23123, 9583, -222, 236, 22948, 9809,
-230, 194, 22769, 10038, -237, 154, 22586, 10269, -243, 117, 22399, 10501, -250,
81, 22208, 10735, -258, 47, 22015, 10970, -265, 15, 21818, 11206, -271, -16,
21618, 11444, -277, -44, 21415, 11684, -283, -71, 21208, 11924, -290, -97, 20999,
12166, -296, -121, 20786, 12409, -302, -143, 20571, 12653, -306, -163, 20354, 12898,
-311, -183, 20134, 13143, -316, -201, 19911, 13389, -321, -218, 19686, 13635, -325,
-234, 19459, 13882, -328, -248, 19230, 14130, -332, -261, 18998, 14377, -335, -273,
18765, 14625, -337, -284, 18531, 14873, -339, -294, 18295, 15121, -341, -302, 18057,
15369, -341, -310, 17817, 15617, -341, -317, 17577, 15864, -340, -323, 17335, 16111,
-340, -328, 17092, 16357, -338, -332, 16848, 16603, -336, -336, 16603, 16848, -332,
-338, 16357, 17092, -328, -340, 16111, 17335, -323, -340, 15864, 17577, -317, -341,
15617, 17817, -310, -341, 15369, 18057, -302, -341, 15121, 18295, -294, -339, 14873,
18531, -284, -337, 14625, 18765, -273, -335, 14377, 18998, -261, -332, 14130, 19230,
-248, -328, 13882, 19459, -234, -325, 13635, 19686, -218, -321, 13389, 19911, -201,
-316, 13143, 20134, -183, -311, 12898, 20354, -163, -306, 12653, 20571, -143, -302,
12409, 20786, -121, -296, 12166, 20999, -97, -290, 11924, 21208, -71, -283, 11684,
21415, -44, -277, 11444, 21618, -16, -271, 11206, 21818, 15, -265, 10970, 22015,
47, -258, 10735, 22208, 81, -250, 10501, 22399, 117, -243, 10269, 22586, 154,
-237, 10038, 22769, 194, -230, 9809, 22948, 236, -222, 9583, 23123, 279, -215,
9358, 23295, 324, -209, 9135, 23462, 371, -202, 8914, 23626, 420, -194, 8695,
23785, 472, -187, 8478, 23940, 526, -181, 8264, 24091, 583, -174, 8052, 24237,
641, -166, 7842, 24379, 701, -159, 7635, 24516, 764, -153, 7430, 24648, 829,
-146, 7227, 24776, 897, -140, 7027, 24899, 967, -133, 6830, 25018, 1040, -127,
6635, 25131, 1115, -121, 6442, 25239, 1193, -115, 6253, 25342, 1274, -109, 6066,
25440, 1357, -103, 5882, 25533, 1442, -98, 5701, 25621, 1531, -92, 5522, 25704,
1622, -87, 5347, 25780, 1716, -81, 5174, 25852, 1813, -76, 5004, 25919, 1912,
-72, 4837, 25980, 2015, -67, 4673, 26035, 2120, -63, 4512, 26085, 2227, -58,
4354, 26130, 2338, -54, 4199, 26169, 2451, -50, 4046, 26202, 2568, -46, 3897,
26230, 2688, -42, 3751, 26253, 2811, -38, 3608, 26270, 2936, -34, 3467, 26281,
3064, -32, 3329, 26287, 3195};
std::vector<s16> Interpolate(InterpolationState& state, std::vector<s16> input, double ratio) {
if (input.size() < 2)
@ -30,40 +149,39 @@ std::vector<s16> Interpolate(InterpolationState& state, std::vector<s16> input,
ratio = 1.0;
}
if (ratio != state.current_ratio) {
const double cutoff_frequency = std::min(0.5 / ratio, 0.5 * ratio);
state.nyquist = CascadingFilter::LowPass(std::clamp(cutoff_frequency, 0.0, 0.4), 3);
state.current_ratio = ratio;
const int step = static_cast<int>(ratio * 0x8000);
const std::array<s16, 512>& lut = [step] {
if (step > 0xaaaa) {
return curve_lut0;
}
state.nyquist.Process(input);
constexpr std::size_t taps = InterpolationState::lanczos_taps;
const std::size_t num_frames = input.size() / 2;
std::vector<s16> output;
output.reserve(static_cast<std::size_t>(input.size() / ratio + 4));
double& pos = state.position;
auto& h = state.history;
for (std::size_t i = 0; i < num_frames; ++i) {
std::rotate(h.begin(), h.end() - 1, h.end());
h[0][0] = input[i * 2 + 0];
h[0][1] = input[i * 2 + 1];
while (pos <= 1.0) {
double l = 0.0;
double r = 0.0;
for (std::size_t j = 0; j < h.size(); j++) {
const double lanczos_calc = Lanczos(taps, pos + j - taps + 1);
l += lanczos_calc * h[j][0];
r += lanczos_calc * h[j][1];
if (step <= 0x8000) {
return curve_lut1;
}
output.emplace_back(static_cast<s16>(std::clamp(l, -32768.0, 32767.0)));
output.emplace_back(static_cast<s16>(std::clamp(r, -32768.0, 32767.0)));
return curve_lut2;
}();
pos += ratio;
}
pos -= 1.0;
std::vector<s16> output(static_cast<std::size_t>(input.size() / ratio));
int in_offset = 0;
for (std::size_t out_offset = 0; out_offset < output.size(); out_offset += 2) {
const int lut_index = (state.fraction >> 8) * 4;
const int l = input[(in_offset + 0) * 2 + 0] * lut[lut_index + 0] +
input[(in_offset + 1) * 2 + 0] * lut[lut_index + 1] +
input[(in_offset + 2) * 2 + 0] * lut[lut_index + 2] +
input[(in_offset + 3) * 2 + 0] * lut[lut_index + 3];
const int r = input[(in_offset + 0) * 2 + 1] * lut[lut_index + 0] +
input[(in_offset + 1) * 2 + 1] * lut[lut_index + 1] +
input[(in_offset + 2) * 2 + 1] * lut[lut_index + 2] +
input[(in_offset + 3) * 2 + 1] * lut[lut_index + 3];
const int new_offset = state.fraction + step;
in_offset += new_offset >> 15;
state.fraction = new_offset & 0x7fff;
output[out_offset + 0] = static_cast<s16>(std::clamp(l >> 15, SHRT_MIN, SHRT_MAX));
output[out_offset + 1] = static_cast<s16>(std::clamp(r >> 15, SHRT_MIN, SHRT_MAX));
}
return output;

9
src/audio_core/algorithm/interpolate.h
View file

@ -6,19 +6,12 @@
#include <array>
#include <vector>
#include "audio_core/algorithm/filter.h"
#include "common/common_types.h"
namespace AudioCore {
struct InterpolationState {
static constexpr std::size_t lanczos_taps = 4;
static constexpr std::size_t history_size = lanczos_taps * 2 - 1;
double current_ratio = 0.0;
CascadingFilter nyquist;
std::array<std::array<s16, 2>, history_size> history = {};
double position = 0;
int fraction = 0;
};
/// Interpolates input signal to produce output signal.