/******************************************************************************
*
* Copyright 2022 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
******************************************************************************/
#include "ltpf.h"
#include "tables.h"
#include "ltpf_neon.h"
#include "ltpf_arm.h"
/* ----------------------------------------------------------------------------
* Resampling
* -------------------------------------------------------------------------- */
/**
* Resampling coefficients
* The coefficients, in fixed Q15, are reordered by phase for each source
* samplerate (coefficient matrix transposed)
*/
#ifndef resample_8k_12k8
static const int16_t h_8k_12k8_q15[8*10] = {
214, 417, -1052, -4529, 26233, -4529, -1052, 417, 214, 0,
180, 0, -1522, -2427, 24506, -5289, 0, 763, 156, -28,
92, -323, -1361, 0, 19741, -3885, 1317, 861, 0, -61,
0, -457, -752, 1873, 13068, 0, 2389, 598, -213, -79,
-61, -398, 0, 2686, 5997, 5997, 2686, 0, -398, -61,
-79, -213, 598, 2389, 0, 13068, 1873, -752, -457, 0,
-61, 0, 861, 1317, -3885, 19741, 0, -1361, -323, 92,
-28, 156, 763, 0, -5289, 24506, -2427, -1522, 0, 180,
};
#endif /* resample_8k_12k8 */
#ifndef resample_16k_12k8
static const int16_t h_16k_12k8_q15[4*20] = {
-61, 214, -398, 417, 0, -1052, 2686, -4529, 5997, 26233,
5997, -4529, 2686, -1052, 0, 417, -398, 214, -61, 0,
-79, 180, -213, 0, 598, -1522, 2389, -2427, 0, 24506,
13068, -5289, 1873, 0, -752, 763, -457, 156, 0, -28,
-61, 92, 0, -323, 861, -1361, 1317, 0, -3885, 19741,
19741, -3885, 0, 1317, -1361, 861, -323, 0, 92, -61,
-28, 0, 156, -457, 763, -752, 0, 1873, -5289, 13068,
24506, 0, -2427, 2389, -1522, 598, 0, -213, 180, -79,
};
#endif /* resample_16k_12k8 */
#ifndef resample_32k_12k8
static const int16_t h_32k_12k8_q15[2*40] = {
-30, -31, 46, 107, 0, -199, -162, 209, 430, 0,
-681, -526, 658, 1343, 0, -2264, -1943, 2999, 9871, 13116,
9871, 2999, -1943, -2264, 0, 1343, 658, -526, -681, 0,
430, 209, -162, -199, 0, 107, 46, -31, -30, 0,
-14, -39, 0, 90, 78, -106, -229, 0, 382, 299,
-376, -761, 0, 1194, 937, -1214, -2644, 0, 6534, 12253,
12253, 6534, 0, -2644, -1214, 937, 1194, 0, -761, -376,
299, 382, 0, -229, -106, 78, 90, 0, -39, -14,
};
#endif /* resample_32k_12k8 */
#ifndef resample_24k_12k8
static const int16_t h_24k_12k8_q15[8*30] = {
-50, 19, 143, -93, -290, 278, 485, -658, -701, 1396,
901, -3019, -1042, 10276, 17488, 10276, -1042, -3019, 901, 1396,
-701, -658, 485, 278, -290, -93, 143, 19, -50, 0,
-46, 0, 141, -45, -305, 185, 543, -501, -854, 1153,
1249, -2619, -1908, 8712, 17358, 11772, 0, -3319, 480, 1593,
-504, -796, 399, 367, -261, -142, 138, 40, -52, -5,
-41, -17, 133, 0, -304, 91, 574, -334, -959, 878,
1516, -2143, -2590, 7118, 16971, 13161, 1202, -3495, 0, 1731,
-267, -908, 287, 445, -215, -188, 125, 62, -52, -12,
-34, -30, 120, 41, -291, 0, 577, -164, -1015, 585,
1697, -1618, -3084, 5534, 16337, 14406, 2544, -3526, -523, 1800,
0, -985, 152, 509, -156, -230, 104, 83, -48, -19,
-26, -41, 103, 76, -265, -83, 554, 0, -1023, 288,
1791, -1070, -3393, 3998, 15474, 15474, 3998, -3393, -1070, 1791,
288, -1023, 0, 554, -83, -265, 76, 103, -41, -26,
-19, -48, 83, 104, -230, -156, 509, 152, -985, 0,
1800, -523, -3526, 2544, 14406, 16337, 5534, -3084, -1618, 1697,
585, -1015, -164, 577, 0, -291, 41, 120, -30, -34,
-12, -52, 62, 125, -188, -215, 445, 287, -908, -267,
1731, 0, -3495, 1202, 13161, 16971, 7118, -2590, -2143, 1516,
878, -959, -334, 574, 91, -304, 0, 133, -17, -41,
-5, -52, 40, 138, -142, -261, 367, 399, -796, -504,
1593, 480, -3319, 0, 11772, 17358, 8712, -1908, -2619, 1249,
1153, -854, -501, 543, 185, -305, -45, 141, 0, -46,
};
#endif /* resample_24k_12k8 */
#ifndef resample_48k_12k8
static const int16_t h_48k_12k8_q15[4*60] = {
-13, -25, -20, 10, 51, 71, 38, -47, -133, -145,
-42, 139, 277, 242, 0, -329, -511, -351, 144, 698,
895, 450, -535, -1510, -1697, -521, 1999, 5138, 7737, 8744,
7737, 5138, 1999, -521, -1697, -1510, -535, 450, 895, 698,
144, -351, -511, -329, 0, 242, 277, 139, -42, -145,
-133, -47, 38, 71, 51, 10, -20, -25, -13, 0,
-9, -23, -24, 0, 41, 71, 52, -23, -115, -152,
-78, 92, 254, 272, 76, -251, -493, -427, 0, 576,
900, 624, -262, -1309, -1763, -954, 1272, 4356, 7203, 8679,
8169, 5886, 2767, 0, -1542, -1660, -809, 240, 848, 796,
292, -252, -507, -398, -82, 199, 288, 183, 0, -130,
-145, -71, 20, 69, 60, 20, -15, -26, -17, -3,
-6, -20, -26, -8, 31, 67, 62, 0, -94, -152,
-108, 45, 223, 287, 143, -167, -454, -480, -134, 439,
866, 758, 0, -1071, -1748, -1295, 601, 3559, 6580, 8485,
8485, 6580, 3559, 601, -1295, -1748, -1071, 0, 758, 866,
439, -134, -480, -454, -167, 143, 287, 223, 45, -108,
-152, -94, 0, 62, 67, 31, -8, -26, -20, -6,
-3, -17, -26, -15, 20, 60, 69, 20, -71, -145,
-130, 0, 183, 288, 199, -82, -398, -507, -252, 292,
796, 848, 240, -809, -1660, -1542, 0, 2767, 5886, 8169,
8679, 7203, 4356, 1272, -954, -1763, -1309, -262, 624, 900,
576, 0, -427, -493, -251, 76, 272, 254, 92, -78,
-152, -115, -23, 52, 71, 41, 0, -24, -23, -9,
};
#endif /* resample_48k_12k8 */
#ifndef resample_96k_12k8
static const int16_t h_96k_12k8_q15[2*120] = {
-3, -7, -10, -13, -13, -10, -4, 5, 15, 26,
33, 36, 31, 19, 0, -23, -47, -66, -76, -73,
-54, -21, 23, 70, 111, 139, 143, 121, 72, 0,
-84, -165, -227, -256, -240, -175, -67, 72, 219, 349,
433, 448, 379, 225, 0, -268, -536, -755, -874, -848,
-648, -260, 301, 1000, 1780, 2569, 3290, 3869, 4243, 4372,
4243, 3869, 3290, 2569, 1780, 1000, 301, -260, -648, -848,
-874, -755, -536, -268, 0, 225, 379, 448, 433, 349,
219, 72, -67, -175, -240, -256, -227, -165, -84, 0,
72, 121, 143, 139, 111, 70, 23, -21, -54, -73,
-76, -66, -47, -23, 0, 19, 31, 36, 33, 26,
15, 5, -4, -10, -13, -13, -10, -7, -3, 0,
-1, -5, -8, -12, -13, -12, -8, 0, 10, 21,
30, 35, 34, 26, 10, -11, -35, -58, -73, -76,
-65, -39, 0, 46, 92, 127, 144, 136, 100, 38,
-41, -125, -199, -246, -254, -214, -126, 0, 146, 288,
398, 450, 424, 312, 120, -131, -405, -655, -830, -881,
-771, -477, 0, 636, 1384, 2178, 2943, 3601, 4084, 4340,
4340, 4084, 3601, 2943, 2178, 1384, 636, 0, -477, -771,
-881, -830, -655, -405, -131, 120, 312, 424, 450, 398,
288, 146, 0, -126, -214, -254, -246, -199, -125, -41,
38, 100, 136, 144, 127, 92, 46, 0, -39, -65,
-76, -73, -58, -35, -11, 10, 26, 34, 35, 30,
21, 10, 0, -8, -12, -13, -12, -8, -5, -1,
};
#endif /* resample_96k_12k8 */
/**
* High-pass 50Hz filtering, at 12.8 KHz samplerate
* hp50 Biquad filter state
* xn Input sample, in fixed Q30
* return Filtered sample, in fixed Q30
*/
LC3_HOT static inline int32_t filter_hp50(
struct lc3_ltpf_hp50_state *hp50, int32_t xn)
{
int32_t yn;
const int32_t a1 = -2110217691, a2 = 1037111617;
const int32_t b1 = -2110535566, b2 = 1055267782;
yn = (hp50->s1 + (int64_t)xn * b2) >> 30;
hp50->s1 = (hp50->s2 + (int64_t)xn * b1 - (int64_t)yn * a1);
hp50->s2 = ( (int64_t)xn * b2 - (int64_t)yn * a2);
return yn;
}
/**
* Resample from 8 / 16 / 32 KHz to 12.8 KHz Template
* p Resampling factor with compared to 192 KHz (8, 4 or 2)
* h Arrange by phase coefficients table
* hp50 High-Pass biquad filter state
* x [-d..-1] Previous, [0..ns-1] Current samples, Q15
* y, n [0..n-1] Output `n` processed samples, Q14
*
* The `x` vector is aligned on 32 bits
* The number of previous samples `d` accessed on `x` is :
* d: { 10, 20, 40 } - 1 for resampling factors 8, 4 and 2.
*/
#if !defined(resample_8k_12k8) || !defined(resample_16k_12k8) \
|| !defined(resample_32k_12k8)
LC3_HOT static inline void resample_x64k_12k8(const int p, const int16_t *h,
struct lc3_ltpf_hp50_state *hp50, const int16_t *x, int16_t *y, int n)
{
const int w = 2*(40 / p);
x -= w - 1;
for (int i = 0; i < 5*n; i += 5) {
const int16_t *hn = h + (i % p) * w;
const int16_t *xn = x + (i / p);
int32_t un = 0;
for (int k = 0; k < w; k += 10) {
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
}
int32_t yn = filter_hp50(hp50, un);
*(y++) = (yn + (1 << 15)) >> 16;
}
}
#endif
/**
* Resample from 24 / 48 KHz to 12.8 KHz Template
* p Resampling factor with compared to 192 KHz (8 or 4)
* h Arrange by phase coefficients table
* hp50 High-Pass biquad filter state
* x [-d..-1] Previous, [0..ns-1] Current samples, Q15
* y, n [0..n-1] Output `n` processed samples, Q14
*
* The `x` vector is aligned on 32 bits
* The number of previous samples `d` accessed on `x` is :
* d: { 30, 60 } - 1 for resampling factors 8 and 4.
*/
#if !defined(resample_24k_12k8) || !defined(resample_48k_12k8) \
|| !defined(resample_96k_12k8)
LC3_HOT static inline void resample_x192k_12k8(const int p, const int16_t *h,
struct lc3_ltpf_hp50_state *hp50, const int16_t *x, int16_t *y, int n)
{
const int w = 2*(120 / p);
x -= w - 1;
for (int i = 0; i < 15*n; i += 15) {
const int16_t *hn = h + (i % p) * w;
const int16_t *xn = x + (i / p);
int32_t un = 0;
for (int k = 0; k < w; k += 15) {
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
un += *(xn++) * *(hn++);
}
int32_t yn = filter_hp50(hp50, un);
*(y++) = (yn + (1 << 15)) >> 16;
}
}
#endif
/**
* Resample from 8 Khz to 12.8 KHz
* hp50 High-Pass biquad filter state
* x [-10..-1] Previous, [0..ns-1] Current samples, Q15
* y, n [0..n-1] Output `n` processed samples, Q14
*
* The `x` vector is aligned on 32 bits
*/
#ifndef resample_8k_12k8
LC3_HOT static void resample_8k_12k8(
struct lc3_ltpf_hp50_state *hp50, const int16_t *x, int16_t *y, int n)
{
resample_x64k_12k8(8, h_8k_12k8_q15, hp50, x, y, n);
}
#endif /* resample_8k_12k8 */
/**
* Resample from 16 Khz to 12.8 KHz
* hp50 High-Pass biquad filter state
* x [-20..-1] Previous, [0..ns-1] Current samples, in fixed Q15
* y, n [0..n-1] Output `n` processed samples, in fixed Q14
*
* The `x` vector is aligned on 32 bits
*/
#ifndef resample_16k_12k8
LC3_HOT static void resample_16k_12k8(
struct lc3_ltpf_hp50_state *hp50, const int16_t *x, int16_t *y, int n)
{
resample_x64k_12k8(4, h_16k_12k8_q15, hp50, x, y, n);
}
#endif /* resample_16k_12k8 */
/**
* Resample from 32 Khz to 12.8 KHz
* hp50 High-Pass biquad filter state
* x [-30..-1] Previous, [0..ns-1] Current samples, in fixed Q15
* y, n [0..n-1] Output `n` processed samples, in fixed Q14
*
* The `x` vector is aligned on 32 bits
*/
#ifndef resample_32k_12k8
LC3_HOT static void resample_32k_12k8(
struct lc3_ltpf_hp50_state *hp50, const int16_t *x, int16_t *y, int n)
{
resample_x64k_12k8(2, h_32k_12k8_q15, hp50, x, y, n);
}
#endif /* resample_32k_12k8 */
/**
* Resample from 24 Khz to 12.8 KHz
* hp50 High-Pass biquad filter state
* x [-30..-1] Previous, [0..ns-1] Current samples, in fixed Q15
* y, n [0..n-1] Output `n` processed samples, in fixed Q14
*
* The `x` vector is aligned on 32 bits
*/
#ifndef resample_24k_12k8
LC3_HOT static void resample_24k_12k8(
struct lc3_ltpf_hp50_state *hp50, const int16_t *x, int16_t *y, int n)
{
resample_x192k_12k8(8, h_24k_12k8_q15, hp50, x, y, n);
}
#endif /* resample_24k_12k8 */
/**
* Resample from 48 Khz to 12.8 KHz
* hp50 High-Pass biquad filter state
* x [-60..-1] Previous, [0..ns-1] Current samples, in fixed Q15
* y, n [0..n-1] Output `n` processed samples, in fixed Q14
*
* The `x` vector is aligned on 32 bits
*/
#ifndef resample_48k_12k8
LC3_HOT static void resample_48k_12k8(
struct lc3_ltpf_hp50_state *hp50, const int16_t *x, int16_t *y, int n)
{
resample_x192k_12k8(4, h_48k_12k8_q15, hp50, x, y, n);
}
#endif /* resample_48k_12k8 */
/**
* Resample from 96 Khz to 12.8 KHz
* hp50 High-Pass biquad filter state
* x [-120..-1] Previous, [0..ns-1] Current samples, in fixed Q15
* y, n [0..n-1] Output `n` processed samples, in fixed Q14
*
* The `x` vector is aligned on 32 bits
*/
#ifndef resample_96k_12k8
LC3_HOT static void resample_96k_12k8(
struct lc3_ltpf_hp50_state *hp50, const int16_t *x, int16_t *y, int n)
{
resample_x192k_12k8(2, h_96k_12k8_q15, hp50, x, y, n);
}
#endif /* resample_96k_12k8 */
/**
* Resample to 6.4 KHz
* x [-3..-1] Previous, [0..n-1] Current samples
* y, n [0..n-1] Output `n` processed samples
*
* The `x` vector is aligned on 32 bits
*/
#ifndef resample_6k4
LC3_HOT static void resample_6k4(const int16_t *x, int16_t *y, int n)
{
static const int16_t h[] = { 18477, 15424, 8105 };
const int16_t *ye = y + n;
for (x--; y < ye; x += 2)
*(y++) = (x[0] * h[0] + (x[-1] + x[1]) * h[1]
+ (x[-2] + x[2]) * h[2]) >> 16;
}
#endif /* resample_6k4 */
/**
* LTPF Resample to 12.8 KHz implementations for each samplerates
*/
static void (* const resample_12k8[])
(struct lc3_ltpf_hp50_state *, const int16_t *, int16_t *, int ) =
{
[LC3_SRATE_8K ] = resample_8k_12k8,
[LC3_SRATE_16K ] = resample_16k_12k8,
[LC3_SRATE_24K ] = resample_24k_12k8,
[LC3_SRATE_32K ] = resample_32k_12k8,
[LC3_SRATE_48K ] = resample_48k_12k8,
[LC3_SRATE_48K_HR] = resample_48k_12k8,
[LC3_SRATE_96K_HR] = resample_96k_12k8,
};
/* ----------------------------------------------------------------------------
* Analysis
* -------------------------------------------------------------------------- */
/**
* Return dot product of 2 vectors
* a, b, n The 2 vectors of size `n` (> 0 and <= 128)
* return sum( a[i] * b[i] ), i = [0..n-1]
*
* The size `n` of vectors must be multiple of 16, and less or equal to 128
*/
#ifndef dot
LC3_HOT static inline float dot(const int16_t *a, const int16_t *b, int n)
{
int64_t v = 0;
for (int i = 0; i < (n >> 4); i++)
for (int j = 0; j < 16; j++)
v += *(a++) * *(b++);
int32_t v32 = (v + (1 << 5)) >> 6;
return (float)v32;
}
#endif /* dot */
/**
* Return vector of correlations
* a, b, n The 2 vector of size `n` (> 0 and <= 128)
* y, nc Output the correlation vector of size `nc`
*
* The first vector `a` is aligned of 32 bits
* The size `n` of vectors is multiple of 16, and less or equal to 128
*/
#ifndef correlate
LC3_HOT static void correlate(
const int16_t *a, const int16_t *b, int n, float *y, int nc)
{
for (const float *ye = y + nc; y < ye; )
*(y++) = dot(a, b--, n);
}
#endif /* correlate */
/**
* Search the maximum value and returns its argument
* x, n The input vector of size `n`
* x_max Return the maximum value
* return Return the argument of the maximum
*/
LC3_HOT static int argmax(const float *x, int n, float *x_max)
{
int arg = 0;
*x_max = x[arg = 0];
for (int i = 1; i < n; i++)
if (*x_max < x[i])
*x_max = x[arg = i];
return arg;
}
/**
* Search the maximum weithed value and returns its argument
* x, n The input vector of size `n`
* w_incr Increment of the weight
* x_max, xw_max Return the maximum not weighted value
* return Return the argument of the weigthed maximum
*/
LC3_HOT static int argmax_weighted(
const float *x, int n, float w_incr, float *x_max)
{
int arg;
float xw_max = (*x_max = x[arg = 0]);
float w = 1 + w_incr;
for (int i = 1; i < n; i++, w += w_incr)
if (xw_max < x[i] * w)
xw_max = (*x_max = x[arg = i]) * w;
return arg;
}
/**
* Interpolate from pitch detected value
* x, n [-2..-1] Previous, [0..n] Current input
* d The phase of interpolation (0 to 3)
* return The interpolated vector
*
* The size `n` of vectors must be multiple of 4
*/
LC3_HOT static void interpolate(const int16_t *x, int n, int d, int16_t *y)
{
static const int16_t h4_q15[][4] = {
{ 6877, 19121, 6877, 0 }, { 3506, 18025, 11000, 220 },
{ 1300, 15048, 15048, 1300 }, { 220, 11000, 18025, 3506 } };
const int16_t *h = h4_q15[d];
int16_t x3 = x[-2], x2 = x[-1], x1, x0;
x1 = (*x++);
for (const int16_t *ye = y + n; y < ye; ) {
int32_t yn;
yn = (x0 = *(x++)) * h[0] + x1 * h[1] + x2 * h[2] + x3 * h[3];
*(y++) = yn >> 15;
yn = (x3 = *(x++)) * h[0] + x0 * h[1] + x1 * h[2] + x2 * h[3];
*(y++) = yn >> 15;
yn = (x2 = *(x++)) * h[0] + x3 * h[1] + x0 * h[2] + x1 * h[3];
*(y++) = yn >> 15;
yn = (x1 = *(x++)) * h[0] + x2 * h[1] + x3 * h[2] + x0 * h[3];
*(y++) = yn >> 15;
}
}
/**
* Interpolate autocorrelation
* x [-4..-1] Previous, [0..4] Current input
* d The phase of interpolation (-3 to 3)
* return The interpolated value
*/
LC3_HOT static float interpolate_corr(const float *x, int d)
{
static const float h4[][8] = {
{ 1.53572770e-02, -4.72963246e-02, 8.35788573e-02, 8.98638285e-01,
8.35788573e-02, -4.72963246e-02, 1.53572770e-02, },
{ 2.74547165e-03, 4.59833449e-03, -7.54404636e-02, 8.17488686e-01,
3.30182571e-01, -1.05835916e-01, 2.86823405e-02, -2.87456116e-03 },
{ -3.00125103e-03, 2.95038503e-02, -1.30305021e-01, 6.03297008e-01,
6.03297008e-01, -1.30305021e-01, 2.95038503e-02, -3.00125103e-03 },
{ -2.87456116e-03, 2.86823405e-02, -1.05835916e-01, 3.30182571e-01,
8.17488686e-01, -7.54404636e-02, 4.59833449e-03, 2.74547165e-03 },
};
const float *h = h4[(4+d) % 4];
float y = d < 0 ? x[-4] * *(h++) :
d > 0 ? x[ 4] * *(h+7) : 0;
y += x[-3] * h[0] + x[-2] * h[1] + x[-1] * h[2] + x[0] * h[3] +
x[ 1] * h[4] + x[ 2] * h[5] + x[ 3] * h[6];
return y;
}
/**
* Pitch detection algorithm
* ltpf Context of analysis
* x, n [-114..-17] Previous, [0..n-1] Current 6.4KHz samples
* tc Return the pitch-lag estimation
* return True when pitch present
*
* The `x` vector is aligned on 32 bits
*/
static bool detect_pitch(struct lc3_ltpf_analysis *ltpf,
const int16_t *x, int n, int *tc)
{
float rm1, rm2;
float r[98];
const int r0 = 17, nr = 98;
int k0 = LC3_MAX( 0, ltpf->tc-4);
int nk = LC3_MIN(nr-1, ltpf->tc+4) - k0 + 1;
correlate(x, x - r0, n, r, nr);
int t1 = argmax_weighted(r, nr, -.5f/(nr-1), &rm1);
int t2 = k0 + argmax(r + k0, nk, &rm2);
const int16_t *x1 = x - (r0 + t1);
const int16_t *x2 = x - (r0 + t2);
float nc1 = rm1 <= 0 ? 0 :
rm1 / sqrtf(dot(x, x, n) * dot(x1, x1, n));
float nc2 = rm2 <= 0 ? 0 :
rm2 / sqrtf(dot(x, x, n) * dot(x2, x2, n));
int t1sel = nc2 <= 0.85f * nc1;
ltpf->tc = (t1sel ? t1 : t2);
*tc = r0 + ltpf->tc;
return (t1sel ? nc1 : nc2) > 0.6f;
}
/**
* Pitch-lag parameter
* x, n [-232..-28] Previous, [0..n-1] Current 12.8KHz samples, Q14
* tc Pitch-lag estimation
* pitch The pitch value, in fixed .4
* return The bitstream pitch index value
*
* The `x` vector is aligned on 32 bits
*/
static int refine_pitch(const int16_t *x, int n, int tc, int *pitch)
{
float r[17], rm;
int e, f;
int r0 = LC3_MAX( 32, 2*tc - 4);
int nr = LC3_MIN(228, 2*tc + 4) - r0 + 1;
correlate(x, x - (r0 - 4), n, r, nr + 8);
e = r0 + argmax(r + 4, nr, &rm);
const float *re = r + (e - (r0 - 4));
float dm = interpolate_corr(re, f = 0);
for (int i = 1; i <= 3; i++) {
float d;
if (e >= 127 && ((i & 1) | (e >= 157)))
continue;
if ((d = interpolate_corr(re, i)) > dm)
dm = d, f = i;
if (e > 32 && (d = interpolate_corr(re, -i)) > dm)
dm = d, f = -i;
}
e -= (f < 0);
f += 4*(f < 0);
*pitch = 4*e + f;
return e < 127 ? 4*e + f - 128 :
e < 157 ? 2*e + (f >> 1) + 126 : e + 283;
}
/**
* LTPF Analysis
*/
bool lc3_ltpf_analyse(
enum lc3_dt dt, enum lc3_srate sr, struct lc3_ltpf_analysis *ltpf,
const int16_t *x, struct lc3_ltpf_data *data)
{
/* --- Resampling to 12.8 KHz --- */
int z_12k8 = sizeof(ltpf->x_12k8) / sizeof(*ltpf->x_12k8);
int n_12k8 = (1 + dt) * 32;
memmove(ltpf->x_12k8, ltpf->x_12k8 + n_12k8,
(z_12k8 - n_12k8) * sizeof(*ltpf->x_12k8));
int16_t *x_12k8 = ltpf->x_12k8 + (z_12k8 - n_12k8);
resample_12k8[sr](<pf->hp50, x, x_12k8, n_12k8);
x_12k8 -= (dt == LC3_DT_7M5 ? 44 : 24);
/* --- Resampling to 6.4 KHz --- */
int z_6k4 = sizeof(ltpf->x_6k4) / sizeof(*ltpf->x_6k4);
int n_6k4 = n_12k8 >> 1;
memmove(ltpf->x_6k4, ltpf->x_6k4 + n_6k4,
(z_6k4 - n_6k4) * sizeof(*ltpf->x_6k4));
int16_t *x_6k4 = ltpf->x_6k4 + (z_6k4 - n_6k4);
resample_6k4(x_12k8, x_6k4, n_6k4);
/* --- Enlarge for small frame size --- */
if (dt == LC3_DT_2M5) {
x_12k8 -= n_12k8, x_6k4 -= n_6k4;
n_12k8 += n_12k8; n_6k4 += n_6k4;
}
/* --- Pitch detection --- */
int tc, pitch = 0;
float nc = 0;
bool pitch_present = detect_pitch(ltpf, x_6k4, n_6k4, &tc);
if (pitch_present) {
int16_t u[128], v[128];
data->pitch_index = refine_pitch(x_12k8, n_12k8, tc, &pitch);
interpolate(x_12k8, n_12k8, 0, u);
interpolate(x_12k8 - (pitch >> 2), n_12k8, pitch & 3, v);
nc = dot(u, v, n_12k8) / sqrtf(dot(u, u, n_12k8) * dot(v, v, n_12k8));
}
/* --- Activation --- */
if (ltpf->active) {
int pitch_diff =
LC3_MAX(pitch, ltpf->pitch) - LC3_MIN(pitch, ltpf->pitch);
float nc_diff = nc - ltpf->nc[0];
data->active = !lc3_hr(sr) && pitch_present &&
((nc > 0.9f) || (nc > 0.84f && pitch_diff < 8 && nc_diff > -0.1f));
} else {
data->active = !lc3_hr(sr) && pitch_present &&
( (dt == LC3_DT_10M || ltpf->nc[1] > 0.94f) &&
(ltpf->nc[0] > 0.94f && nc > 0.94f) );
}
ltpf->active = data->active;
ltpf->pitch = pitch;
ltpf->nc[1] = ltpf->nc[0];
ltpf->nc[0] = nc;
return pitch_present;
}
/* ----------------------------------------------------------------------------
* Synthesis
* -------------------------------------------------------------------------- */
/**
* Width of synthesis filter
*/
#define MAX_FILTER_WIDTH \
(LC3_MAX_SRATE_HZ / 4000)
/**
* Synthesis filter template
* xh, nh History ring buffer of filtered samples
* lag Lag parameter in the ring buffer
* x0 w-1 previous input samples
* x, n Current samples as input, filtered as output
* c, w Coefficients `den` then `num`, and width of filter
* fade Fading mode of filter -1: Out 1: In 0: None
*/
LC3_HOT static inline void synthesize_template(
const float *xh, int nh, int lag,
const float *x0, float *x, int n,
const float *c, const int w, int fade)
{
float g = (float)(fade <= 0);
float g_incr = (float)((fade > 0) - (fade < 0)) / n;
float u[MAX_FILTER_WIDTH];
/* --- Load previous samples --- */
lag += (w >> 1);
const float *y = x - xh < lag ? x + (nh - lag) : x - lag;
const float *y_end = xh + nh - 1;
for (int j = 0; j < w-1; j++) {
u[j] = 0;
float yi = *y, xi = *(x0++);
y = y < y_end ? y + 1 : xh;
for (int k = 0; k <= j; k++)
u[j-k] -= yi * c[k];
for (int k = 0; k <= j; k++)
u[j-k] += xi * c[w+k];
}
u[w-1] = 0;
/* --- Process by filter length --- */
for (int i = 0; i < n; i += w)
for (int j = 0; j < w; j++, g += g_incr) {
float yi = *y, xi = *x;
y = y < y_end ? y + 1 : xh;
for (int k = 0; k < w; k++)
u[(j+(w-1)-k)%w] -= yi * c[k];
for (int k = 0; k < w; k++)
u[(j+(w-1)-k)%w] += xi * c[w+k];
*(x++) = xi - g * u[j];
u[j] = 0;
}
}
/**
* Synthesis filter for each samplerates (width of filter)
*/
LC3_HOT static void synthesize_4(const float *xh, int nh, int lag,
const float *x0, float *x, int n, const float *c, int fade)
{
synthesize_template(xh, nh, lag, x0, x, n, c, 4, fade);
}
LC3_HOT static void synthesize_6(const float *xh, int nh, int lag,
const float *x0, float *x, int n, const float *c, int fade)
{
synthesize_template(xh, nh, lag, x0, x, n, c, 6, fade);
}
LC3_HOT static void synthesize_8(const float *xh, int nh, int lag,
const float *x0, float *x, int n, const float *c, int fade)
{
synthesize_template(xh, nh, lag, x0, x, n, c, 8, fade);
}
LC3_HOT static void synthesize_12(const float *xh, int nh, int lag,
const float *x0, float *x, int n, const float *c, int fade)
{
synthesize_template(xh, nh, lag, x0, x, n, c, 12, fade);
}
static void (* const synthesize[])(const float *, int, int,
const float *, float *, int, const float *, int) =
{
[LC3_SRATE_8K ] = synthesize_4,
[LC3_SRATE_16K] = synthesize_4,
[LC3_SRATE_24K] = synthesize_6,
[LC3_SRATE_32K] = synthesize_8,
[LC3_SRATE_48K] = synthesize_12,
};
/**
* LTPF Synthesis
*/
void lc3_ltpf_synthesize(enum lc3_dt dt, enum lc3_srate sr, int nbytes,
lc3_ltpf_synthesis_t *ltpf, const lc3_ltpf_data_t *data,
const float *xh, float *x)
{
int nh = lc3_ns(dt, sr) + lc3_nh(dt, sr);
/* --- Filter parameters --- */
int p_idx = data ? data->pitch_index : 0;
int pitch =
p_idx >= 440 ? (((p_idx ) - 283) << 2) :
p_idx >= 380 ? (((p_idx >> 1) - 63) << 2) + (((p_idx & 1)) << 1) :
(((p_idx >> 2) + 32) << 2) + (((p_idx & 3)) << 0) ;
pitch = (pitch * lc3_ns(LC3_DT_10M, sr) + 64) / 128;
int nbits = (nbytes*8 * (1 + LC3_DT_10M)) / (1 + dt);
if (dt == LC3_DT_2M5)
nbits = (6 * nbits + 5) / 10;
if (dt == LC3_DT_5M)
nbits -= 160;
int g_idx = LC3_MAX(nbits / 80, (int)(3 + sr)) - (3 + sr);
bool active = data && data->active && g_idx < 4;
int w = LC3_MAX(4, lc3_ns_4m[sr] >> 4);
float c[2 * MAX_FILTER_WIDTH];
for (int i = 0; i < w; i++) {
float g = active ? 0.4f - 0.05f * g_idx : 0;
c[ i] = g * lc3_ltpf_cden[sr][pitch & 3][(w-1)-i];
c[w+i] = 0.85f * g * lc3_ltpf_cnum[sr][LC3_MIN(g_idx, 3)][(w-1)-i];
}
/* --- Transition handling --- */
int ns = lc3_ns(dt, sr);
int nt = ns / (1 + dt);
float x0[2][MAX_FILTER_WIDTH];
memcpy(x0[0], ltpf->x, (w-1) * sizeof(float));
memcpy(ltpf->x, x + ns - (w-1), (w-1) * sizeof(float));
if (active)
memcpy(x0[1], x + nt-(w-1), (w-1) * sizeof(float));
if (!ltpf->active && active)
synthesize[sr](xh, nh, pitch/4, x0[0], x, nt, c, 1);
else if (ltpf->active && !active)
synthesize[sr](xh, nh, ltpf->pitch/4, x0[0], x, nt, ltpf->c, -1);
else if (ltpf->active && active && ltpf->pitch == pitch)
synthesize[sr](xh, nh, pitch/4, x0[0], x, nt, c, 0);
else if (ltpf->active && active) {
synthesize[sr](xh, nh, ltpf->pitch/4, x0[0], x, nt, ltpf->c, -1);
synthesize[sr](xh, nh, pitch/4,
(x <= xh ? x + nh : x) - (w-1), x, nt, c, 1);
}
/* --- Remainder --- */
if (active && ns > nt)
synthesize[sr](xh, nh, pitch/4, x0[1], x + nt, ns-nt, c, 0);
/* --- Update state --- */
ltpf->active = active;
ltpf->pitch = pitch;
memcpy(ltpf->c, c, 2*w * sizeof(*ltpf->c));
}
/* ----------------------------------------------------------------------------
* Bitstream data
* -------------------------------------------------------------------------- */
/**
* LTPF disable
*/
void lc3_ltpf_disable(struct lc3_ltpf_data *data)
{
data->active = false;
}
/**
* Return number of bits coding the bitstream data
*/
int lc3_ltpf_get_nbits(bool pitch)
{
return 1 + 10 * pitch;
}
/**
* Put bitstream data
*/
void lc3_ltpf_put_data(lc3_bits_t *bits,
const struct lc3_ltpf_data *data)
{
lc3_put_bit(bits, data->active);
lc3_put_bits(bits, data->pitch_index, 9);
}
/**
* Get bitstream data
*/
void lc3_ltpf_get_data(lc3_bits_t *bits,
struct lc3_ltpf_data *data)
{
data->active = lc3_get_bit(bits);
data->pitch_index = lc3_get_bits(bits, 9);
}