1 /* 2 * Copyright (C) 2016 BlueKitchen GmbH 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the copyright holders nor the names of 14 * contributors may be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * 4. Any redistribution, use, or modification is done solely for 17 * personal benefit and not for any commercial purpose or for 18 * monetary gain. 19 * 20 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS 24 * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 27 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 30 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * Please inquire about commercial licensing options at 34 * [email protected] 35 * 36 */ 37 38 /* 39 * btstack_sbc_plc.c 40 * 41 */ 42 43 #include <stdint.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <fcntl.h> 48 #include <unistd.h> 49 50 #include "btstack_sbc_plc.h" 51 52 static uint8_t indices0[] = { 0xad, 0x00, 0x00, 0xc5, 0x00, 0x00, 0x00, 0x00, 0x77, 0x6d, 53 0xb6, 0xdd, 0xdb, 0x6d, 0xb7, 0x76, 0xdb, 0x6d, 0xdd, 0xb6, 0xdb, 0x77, 0x6d, 54 0xb6, 0xdd, 0xdb, 0x6d, 0xb7, 0x76, 0xdb, 0x6d, 0xdd, 0xb6, 0xdb, 0x77, 0x6d, 55 0xb6, 0xdd, 0xdb, 0x6d, 0xb7, 0x76, 0xdb, 0x6d, 0xdd, 0xb6, 0xdb, 0x77, 0x6d, 56 0xb6, 0xdd, 0xdb, 0x6d, 0xb7, 0x76, 0xdb, 0x6c}; 57 58 /* Raised COSine table for OLA */ 59 static float rcos[SBC_OLAL] = { 60 0.99148655f,0.96623611f,0.92510857f,0.86950446f, 61 0.80131732f,0.72286918f,0.63683150f,0.54613418f, 62 0.45386582f,0.36316850f,0.27713082f,0.19868268f, 63 0.13049554f,0.07489143f,0.03376389f,0.00851345f}; 64 65 // taken from http://www.codeproject.com/Articles/69941/Best-Square-Root-Method-Algorithm-Function-Precisi 66 // Algorithm: Babylonian Method + some manipulations on IEEE 32 bit floating point representation 67 static float sqrt3(const float x){ 68 union { 69 int i; 70 float x; 71 } u; 72 u.x = x; 73 u.i = (1<<29) + (u.i >> 1) - (1<<22); 74 75 // Two Babylonian Steps (simplified from:) 76 // u.x = 0.5f * (u.x + x/u.x); 77 // u.x = 0.5f * (u.x + x/u.x); 78 u.x = u.x + x/u.x; 79 u.x = 0.25f*u.x + x/u.x; 80 81 return u.x; 82 } 83 84 static float absolute(float x){ 85 if (x < 0) x = -x; 86 return x; 87 } 88 89 static float CrossCorrelation(int16_t *x, int16_t *y){ 90 float num = 0; 91 float den = 0; 92 float x2 = 0; 93 float y2 = 0; 94 int m; 95 for (m=0;m<SBC_M;m++){ 96 num+=((float)x[m])*y[m]; 97 x2+=((float)x[m])*x[m]; 98 y2+=((float)y[m])*y[m]; 99 } 100 den = (float)sqrt3(x2*y2); 101 return num/den; 102 } 103 104 static int PatternMatch(int16_t *y){ 105 float maxCn = -999999.0; /* large negative number */ 106 int bestmatch = 0; 107 float Cn; 108 int n; 109 for (n=0;n<SBC_N;n++){ 110 Cn = CrossCorrelation(&y[SBC_LHIST-SBC_M] /* x */, &y[n]); 111 if (Cn>maxCn){ 112 bestmatch=n; 113 maxCn = Cn; 114 } 115 } 116 return bestmatch; 117 } 118 119 120 static float AmplitudeMatch(int16_t *y, int16_t bestmatch) { 121 int i; 122 float sumx = 0; 123 float sumy = 0.000001f; 124 float sf; 125 126 for (i=0;i<SBC_FS;i++){ 127 sumx += absolute(y[SBC_LHIST-SBC_FS+i]); 128 sumy += absolute(y[bestmatch+i]); 129 } 130 sf = sumx/sumy; 131 /* This is not in the paper, but limit the scaling factor to something reasonable to avoid creating artifacts */ 132 if (sf<0.75f) sf=0.75f; 133 if (sf>1.2f) sf=1.2f; 134 return sf; 135 } 136 137 static int16_t crop_to_int16(float val){ 138 float croped_val = val; 139 if (croped_val > 32767.0) croped_val= 32767.0; 140 if (croped_val < -32768.0) croped_val=-32768.0; 141 return (int16_t) croped_val; 142 } 143 144 uint8_t * btstack_sbc_plc_zero_signal_frame(void){ 145 return (uint8_t *)&indices0; 146 } 147 148 void btstack_sbc_plc_init(btstack_sbc_plc_state_t *plc_state){ 149 plc_state->nbf=0; 150 plc_state->bestlag=0; 151 memset(plc_state->hist,0,sizeof(plc_state->hist)); 152 } 153 154 void btstack_sbc_plc_bad_frame(btstack_sbc_plc_state_t *plc_state, int16_t *ZIRbuf, int16_t *out){ 155 float val; 156 int i = 0; 157 float sf = 1; 158 159 plc_state->nbf++; 160 161 if (plc_state->nbf==1){ 162 /* Perform pattern matching to find where to replicate */ 163 plc_state->bestlag = PatternMatch(plc_state->hist); 164 /* the replication begins after the template match */ 165 plc_state->bestlag += SBC_M; 166 167 /* Compute Scale Factor to Match Amplitude of Substitution Packet to that of Preceding Packet */ 168 sf = AmplitudeMatch(plc_state->hist, plc_state->bestlag); 169 for (i=0;i<SBC_OLAL;i++){ 170 float left = ZIRbuf[i]; 171 float right = sf*plc_state->hist[plc_state->bestlag+i]; 172 val = left*rcos[i] + right*rcos[SBC_OLAL-1-i]; 173 plc_state->hist[SBC_LHIST+i] = crop_to_int16(val); 174 } 175 176 for (;i<SBC_FS;i++){ 177 val = sf*plc_state->hist[plc_state->bestlag+i]; 178 plc_state->hist[SBC_LHIST+i] = crop_to_int16(val); 179 } 180 181 for (;i<SBC_FS+SBC_OLAL;i++){ 182 float left = sf*plc_state->hist[plc_state->bestlag+i]; 183 float right = plc_state->hist[plc_state->bestlag+i]; 184 val = left*rcos[i-SBC_FS]+right*rcos[SBC_FS+SBC_OLAL-1-i]; 185 plc_state->hist[SBC_LHIST+i] = crop_to_int16(val); 186 } 187 188 for (;i<SBC_FS+SBC_RT+SBC_OLAL;i++){ 189 plc_state->hist[SBC_LHIST+i] = plc_state->hist[plc_state->bestlag+i]; 190 } 191 192 } else { 193 for (i=0;i<SBC_FS+SBC_RT+SBC_OLAL;i++){ 194 plc_state->hist[SBC_LHIST+i] = plc_state->hist[plc_state->bestlag+i]; 195 } 196 } 197 for (i=0;i<SBC_FS;i++){ 198 out[i] = plc_state->hist[SBC_LHIST+i]; 199 } 200 201 /* shift the history buffer */ 202 for (i=0;i<SBC_LHIST+SBC_RT+SBC_OLAL;i++){ 203 plc_state->hist[i] = plc_state->hist[i+SBC_FS]; 204 } 205 206 } 207 208 void btstack_sbc_plc_good_frame(btstack_sbc_plc_state_t *plc_state, int16_t *in, int16_t *out){ 209 float val; 210 int i = 0; 211 if (plc_state->nbf>0){ 212 for (i=0;i<SBC_RT;i++){ 213 out[i] = plc_state->hist[SBC_LHIST+i]; 214 } 215 216 for (;i<SBC_RT+SBC_OLAL;i++){ 217 float left = plc_state->hist[SBC_LHIST+i]; 218 float right = in[i]; 219 val = left*rcos[i-SBC_RT] + right*rcos[SBC_OLAL-1-i+SBC_RT]; 220 out[i] = (int16_t)val; 221 } 222 } 223 for (;i<SBC_FS;i++){ 224 out[i] = in[i]; 225 } 226 227 /*Copy the output to the history buffer */ 228 for (i=0;i<SBC_FS;i++){ 229 plc_state->hist[SBC_LHIST+i] = out[i]; 230 } 231 /* shift the history buffer */ 232 for (i=0;i<SBC_LHIST;i++){ 233 plc_state->hist[i] = plc_state->hist[i+SBC_FS]; 234 } 235 236 plc_state->nbf=0; 237 } 238