1 /* ------------------------------------------------------------------ 2 * Copyright (C) 1998-2009 PacketVideo 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either 13 * express or implied. 14 * See the License for the specific language governing permissions 15 * and limitations under the License. 16 * ------------------------------------------------------------------- 17 */ 18 /**************************************************************************************** 19 Portions of this file are derived from the following 3GPP standard: 20 21 3GPP TS 26.173 22 ANSI-C code for the Adaptive Multi-Rate - Wideband (AMR-WB) speech codec 23 Available from http://www.3gpp.org 24 25 (C) 2007, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC) 26 Permission to distribute, modify and use this file under the standard license 27 terms listed above has been obtained from the copyright holder. 28 ****************************************************************************************/ 29 /* 30 ------------------------------------------------------------------------------ 31 32 33 34 Filename: highpass_50Hz_at_12k8.cpp 35 36 ------------------------------------------------------------------------------ 37 INPUT AND OUTPUT DEFINITIONS 38 39 int16 signal[], input signal / output is divided by 16 40 int16 lg, lenght of signal 41 int16 mem[] filter memory [6] 42 43 44 ------------------------------------------------------------------------------ 45 FUNCTION DESCRIPTION 46 47 2nd order high pass filter with cut off frequency at 31 Hz. 48 Designed with cheby2 function in MATLAB. 49 Optimized for fixed-point to get the following frequency response: 50 51 frequency: 0Hz 14Hz 24Hz 31Hz 37Hz 41Hz 47Hz 52 dB loss: -infdB -15dB -6dB -3dB -1.5dB -1dB -0.5dB 53 54 Algorithm: 55 56 y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2] 57 + a[1]*y[i-1] + a[2]*y[i-2]; 58 59 int16 b[3] = {4053, -8106, 4053}; in Q12 60 int16 a[3] = {8192, 16211, -8021}; in Q12 61 62 float --> b[3] = {0.989501953, -1.979003906, 0.989501953}; 63 a[3] = {1.000000000, 1.978881836, -0.979125977}; 64 65 66 ------------------------------------------------------------------------------ 67 REQUIREMENTS 68 69 70 ------------------------------------------------------------------------------ 71 REFERENCES 72 73 ------------------------------------------------------------------------------ 74 PSEUDO-CODE 75 76 ------------------------------------------------------------------------------ 77 */ 78 79 80 /*---------------------------------------------------------------------------- 81 ; INCLUDES 82 ----------------------------------------------------------------------------*/ 83 84 85 #include "pv_amr_wb_type_defs.h" 86 #include "pvamrwbdecoder_basic_op.h" 87 #include "pvamrwb_math_op.h" 88 #include "pvamrwbdecoder_cnst.h" 89 #include "pvamrwbdecoder_acelp.h" 90 91 92 /*---------------------------------------------------------------------------- 93 ; MACROS 94 ; Define module specific macros here 95 ----------------------------------------------------------------------------*/ 96 97 98 /*---------------------------------------------------------------------------- 99 ; DEFINES 100 ; Include all pre-processor statements here. Include conditional 101 ; compile variables also. 102 ----------------------------------------------------------------------------*/ 103 104 /*---------------------------------------------------------------------------- 105 ; LOCAL FUNCTION DEFINITIONS 106 ; Function Prototype declaration 107 ----------------------------------------------------------------------------*/ 108 109 /*---------------------------------------------------------------------------- 110 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 111 ; Variable declaration - defined here and used outside this module 112 ----------------------------------------------------------------------------*/ 113 114 /*---------------------------------------------------------------------------- 115 ; EXTERNAL FUNCTION REFERENCES 116 ; Declare functions defined elsewhere and referenced in this module 117 ----------------------------------------------------------------------------*/ 118 119 /*---------------------------------------------------------------------------- 120 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 121 ; Declare variables used in this module but defined elsewhere 122 ----------------------------------------------------------------------------*/ 123 124 /*---------------------------------------------------------------------------- 125 ; FUNCTION CODE 126 ----------------------------------------------------------------------------*/ 127 128 void highpass_50Hz_at_12k8_init(int16 mem[]) 129 { 130 pv_memset((void *)mem, 0, 6*sizeof(*mem)); 131 } 132 133 /*---------------------------------------------------------------------------- 134 ; FUNCTION CODE 135 ----------------------------------------------------------------------------*/ 136 137 void highpass_50Hz_at_12k8( 138 int16 signal[], /* input/output signal */ 139 int16 lg, /* lenght of signal */ 140 int16 mem[] /* filter memory [6] */ 141 ) 142 { 143 int16 i, x2; 144 int16 y2_hi, y2_lo, y1_hi, y1_lo, x0, x1; 145 int32 L_tmp1; 146 int32 L_tmp2; 147 int16 *pt_sign = signal; 148 149 y2_hi = mem[0]; 150 y2_lo = mem[1]; 151 y1_hi = mem[2]; 152 y1_lo = mem[3]; 153 x0 = mem[4]; 154 x1 = mem[5]; 155 156 157 for (i = lg; i != 0; i--) 158 { 159 160 /* y[i] = b[0]*x[i] + b[1]*x[i-1] + b[0]*x[i-2] */ 161 /* + a[0]*y[i-1] + a[1] * y[i-2]; */ 162 163 L_tmp1 = fxp_mac_16by16(y1_lo, 16211, 8192L); 164 L_tmp1 = fxp_mac_16by16(y2_lo, -8021, L_tmp1); 165 L_tmp2 = fxp_mul_16by16(y1_hi, 32422); 166 L_tmp2 = fxp_mac_16by16(y2_hi, -16042, L_tmp2); 167 168 x2 = x1; 169 x1 = x0; 170 x0 = *pt_sign; 171 L_tmp2 = fxp_mac_16by16(x2, 8106, L_tmp2); 172 L_tmp2 = fxp_mac_16by16(x1, -16212, L_tmp2); 173 L_tmp2 = fxp_mac_16by16(x0, 8106, L_tmp2); 174 175 176 L_tmp1 = ((L_tmp1 >> 14) + L_tmp2) << 2; 177 178 y2_hi = y1_hi; 179 y2_lo = y1_lo; 180 y1_hi = (int16)(L_tmp1 >> 16); 181 y1_lo = (int16)((L_tmp1 - (y1_hi << 16)) >> 1); 182 183 /* coeff Q14 --> Q15 with saturation */ 184 *(pt_sign++) = amr_wb_shl1_round(L_tmp1); 185 186 } 187 188 189 mem[0] = y2_hi; 190 mem[1] = y2_lo; 191 mem[2] = y1_hi; 192 mem[3] = y1_lo; 193 mem[4] = x0; 194 mem[5] = x1; 195 196 } 197 198