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 48 #include "btstack_sbc_plc.h" 49 50 #define SAMPLE_FORMAT int16_t 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(SAMPLE_FORMAT *x, SAMPLE_FORMAT *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(SAMPLE_FORMAT *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], &y[n]); 111 if (Cn>maxCn){ 112 bestmatch=n; 113 maxCn = Cn; 114 } 115 } 116 return bestmatch; 117 } 118 119 static float AmplitudeMatch(SAMPLE_FORMAT *y, SAMPLE_FORMAT bestmatch) { 120 int i; 121 float sumx = 0; 122 float sumy = 0.000001f; 123 float sf; 124 125 for (i=0;i<SBC_FS;i++){ 126 sumx += absolute(y[SBC_LHIST-SBC_FS+i]); 127 sumy += absolute(y[bestmatch+i]); 128 } 129 sf = sumx/sumy; 130 // This is not in the paper, but limit the scaling factor to something reasonable to avoid creating artifacts 131 if (sf<0.75f) sf=0.75f; 132 if (sf>1.2f) sf=1.2f; 133 return sf; 134 } 135 136 static SAMPLE_FORMAT crop_sample(float val){ 137 float croped_val = val; 138 if (croped_val > 32767.0) croped_val= 32767.0; 139 if (croped_val < -32768.0) croped_val=-32768.0; 140 return (SAMPLE_FORMAT) croped_val; 141 } 142 143 uint8_t * btstack_sbc_plc_zero_signal_frame(void){ 144 return (uint8_t *)&indices0; 145 } 146 147 void btstack_sbc_plc_init(btstack_sbc_plc_state_t *plc_state){ 148 plc_state->nbf=0; 149 plc_state->bestlag=0; 150 memset(plc_state->hist,0,sizeof(plc_state->hist)); 151 } 152 153 void btstack_sbc_plc_bad_frame(btstack_sbc_plc_state_t *plc_state, SAMPLE_FORMAT *ZIRbuf, SAMPLE_FORMAT *out){ 154 float val; 155 int i = 0; 156 float sf = 1; 157 plc_state->nbf++; 158 159 if (plc_state->nbf==1){ 160 // Perform pattern matching to find where to replicate 161 plc_state->bestlag = PatternMatch(plc_state->hist); 162 // the replication begins after the template match 163 plc_state->bestlag += SBC_M; 164 165 // Compute Scale Factor to Match Amplitude of Substitution Packet to that of Preceding Packet 166 sf = AmplitudeMatch(plc_state->hist, plc_state->bestlag); 167 for (i=0;i<SBC_OLAL;i++){ 168 float left = ZIRbuf[i]; 169 float right = sf*plc_state->hist[plc_state->bestlag+i]; 170 val = left*rcos[i] + right*rcos[SBC_OLAL-1-i]; 171 plc_state->hist[SBC_LHIST+i] = crop_sample(val); 172 } 173 174 for (;i<SBC_FS;i++){ 175 val = sf*plc_state->hist[plc_state->bestlag+i]; 176 plc_state->hist[SBC_LHIST+i] = crop_sample(val); 177 } 178 179 for (;i<SBC_FS+SBC_OLAL;i++){ 180 float left = sf*plc_state->hist[plc_state->bestlag+i]; 181 float right = plc_state->hist[plc_state->bestlag+i]; 182 val = left*rcos[i-SBC_FS]+right*rcos[SBC_OLAL-1-i+SBC_FS]; 183 plc_state->hist[SBC_LHIST+i] = crop_sample(val); 184 } 185 186 for (;i<SBC_FS+SBC_RT+SBC_OLAL;i++){ 187 plc_state->hist[SBC_LHIST+i] = plc_state->hist[plc_state->bestlag+i]; 188 } 189 } else { 190 for (;i<SBC_FS+SBC_RT+SBC_OLAL;i++){ 191 plc_state->hist[SBC_LHIST+i] = plc_state->hist[plc_state->bestlag+i]; 192 } 193 } 194 for (i=0;i<SBC_FS;i++){ 195 out[i] = plc_state->hist[SBC_LHIST+i]; 196 } 197 198 // shift the history buffer 199 for (i=0;i<SBC_LHIST+SBC_RT+SBC_OLAL;i++){ 200 plc_state->hist[i] = plc_state->hist[i+SBC_FS]; 201 } 202 } 203 204 void btstack_sbc_plc_good_frame(btstack_sbc_plc_state_t *plc_state, SAMPLE_FORMAT *in, SAMPLE_FORMAT *out){ 205 float val; 206 int i = 0; 207 if (plc_state->nbf>0){ 208 for (i=0;i<SBC_RT;i++){ 209 out[i] = plc_state->hist[SBC_LHIST+i]; 210 } 211 212 for (i = SBC_RT;i<SBC_RT+SBC_OLAL;i++){ 213 float left = plc_state->hist[SBC_LHIST+i]; 214 float right = in[i]; 215 val = left*rcos[i-SBC_RT] + right*rcos[SBC_OLAL+SBC_RT-1-i]; 216 out[i] = (SAMPLE_FORMAT)val; 217 } 218 } 219 220 for (;i<SBC_FS;i++){ 221 out[i] = in[i]; 222 } 223 // Copy the output to the history buffer 224 for (i=0;i<SBC_FS;i++){ 225 plc_state->hist[SBC_LHIST+i] = out[i]; 226 } 227 // shift the history buffer 228 for (i=0;i<SBC_LHIST;i++){ 229 plc_state->hist[i] = plc_state->hist[i+SBC_FS]; 230 } 231 232 plc_state->nbf=0; 233 } 234