/****************************************************************************** * * 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 */ /** * 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) 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 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, }; /* ---------------------------------------------------------------------------- * 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 (3.3.9.8) * 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 (3.3.9.7) * 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 (3.3.9.5-6) * 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 (3.3.9.7) * 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 = dt == LC3_DT_7M5 ? 96 : 128; 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); /* --- 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[n_12k8], v[n_12k8]; 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 = pitch_present && ((nc > 0.9f) || (nc > 0.84f && pitch_diff < 8 && nc_diff > -0.1f)); } else { data->active = 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 * -------------------------------------------------------------------------- */ /** * 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[w]; /* --- 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_NH(dt, sr); int dt_us = LC3_DT_US(dt); /* --- 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_SRATE_KHZ(sr) * 10 + 64) / 128; int nbits = (nbytes*8 * 10000 + (dt_us/2)) / dt_us; int g_idx = LC3_MAX(nbits / 80, 3 + (int)sr) - (3 + sr); bool active = data && data->active && g_idx < 4; int w = LC3_MAX(4, LC3_SRATE_KHZ(sr) / 4); float c[2*w]; 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 / (3 + dt); float x0[w]; if (active) memcpy(x0, x + nt-(w-1), (w-1) * sizeof(float)); if (!ltpf->active && active) synthesize[sr](xh, nh, pitch/4, ltpf->x, x, nt, c, 1); else if (ltpf->active && !active) synthesize[sr](xh, nh, ltpf->pitch/4, ltpf->x, x, nt, ltpf->c, -1); else if (ltpf->active && active && ltpf->pitch == pitch) synthesize[sr](xh, nh, pitch/4, ltpf->x, x, nt, c, 0); else if (ltpf->active && active) { synthesize[sr](xh, nh, ltpf->pitch/4, ltpf->x, x, nt, ltpf->c, -1); synthesize[sr](xh, nh, pitch/4, (x <= xh ? x + nh : x) - (w-1), x, nt, c, 1); } /* --- Remainder --- */ memcpy(ltpf->x, x + ns - (w-1), (w-1) * sizeof(float)); if (active) synthesize[sr](xh, nh, pitch/4, x0, 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); }