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 Date: 05/08/2004 37 38 ------------------------------------------------------------------------------ 39 REVISION HISTORY 40 41 42 Description: 43 44 ------------------------------------------------------------------------------ 45 INPUT AND OUTPUT DEFINITIONS 46 47 int16 signal[], input signal / output is divided by 16 48 int16 lg, lenght of signal 49 int16 mem[] filter memory [6] 50 51 52 ------------------------------------------------------------------------------ 53 FUNCTION DESCRIPTION 54 55 2nd order high pass filter with cut off frequency at 31 Hz. 56 Designed with cheby2 function in MATLAB. 57 Optimized for fixed-point to get the following frequency response: 58 59 frequency: 0Hz 14Hz 24Hz 31Hz 37Hz 41Hz 47Hz 60 dB loss: -infdB -15dB -6dB -3dB -1.5dB -1dB -0.5dB 61 62 Algorithm: 63 64 y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2] 65 + a[1]*y[i-1] + a[2]*y[i-2]; 66 67 int16 b[3] = {4053, -8106, 4053}; in Q12 68 int16 a[3] = {8192, 16211, -8021}; in Q12 69 70 float --> b[3] = {0.989501953, -1.979003906, 0.989501953}; 71 a[3] = {1.000000000, 1.978881836, -0.979125977}; 72 73 74 ------------------------------------------------------------------------------ 75 REQUIREMENTS 76 77 78 ------------------------------------------------------------------------------ 79 REFERENCES 80 81 ------------------------------------------------------------------------------ 82 PSEUDO-CODE 83 84 ------------------------------------------------------------------------------ 85 */ 86 87 88 /*---------------------------------------------------------------------------- 89 ; INCLUDES 90 ----------------------------------------------------------------------------*/ 91 92 93 #include "pv_amr_wb_type_defs.h" 94 #include "pvamrwbdecoder_basic_op.h" 95 #include "pvamrwb_math_op.h" 96 #include "pvamrwbdecoder_cnst.h" 97 #include "pvamrwbdecoder_acelp.h" 98 99 100 /*---------------------------------------------------------------------------- 101 ; MACROS 102 ; Define module specific macros here 103 ----------------------------------------------------------------------------*/ 104 105 106 /*---------------------------------------------------------------------------- 107 ; DEFINES 108 ; Include all pre-processor statements here. Include conditional 109 ; compile variables also. 110 ----------------------------------------------------------------------------*/ 111 112 /*---------------------------------------------------------------------------- 113 ; LOCAL FUNCTION DEFINITIONS 114 ; Function Prototype declaration 115 ----------------------------------------------------------------------------*/ 116 117 /*---------------------------------------------------------------------------- 118 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 119 ; Variable declaration - defined here and used outside this module 120 ----------------------------------------------------------------------------*/ 121 122 /*---------------------------------------------------------------------------- 123 ; EXTERNAL FUNCTION REFERENCES 124 ; Declare functions defined elsewhere and referenced in this module 125 ----------------------------------------------------------------------------*/ 126 127 /*---------------------------------------------------------------------------- 128 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 129 ; Declare variables used in this module but defined elsewhere 130 ----------------------------------------------------------------------------*/ 131 132 /*---------------------------------------------------------------------------- 133 ; FUNCTION CODE 134 ----------------------------------------------------------------------------*/ 135 136 void highpass_50Hz_at_12k8_init(int16 mem[]) 137 { 138 pv_memset((void *)mem, 0, 6*sizeof(*mem)); 139 } 140 141 /*---------------------------------------------------------------------------- 142 ; FUNCTION CODE 143 ----------------------------------------------------------------------------*/ 144 145 void highpass_50Hz_at_12k8( 146 int16 signal[], /* input/output signal */ 147 int16 lg, /* lenght of signal */ 148 int16 mem[] /* filter memory [6] */ 149 ) 150 { 151 int16 i, x2; 152 int16 y2_hi, y2_lo, y1_hi, y1_lo, x0, x1; 153 int32 L_tmp1; 154 int32 L_tmp2; 155 int16 *pt_sign = signal; 156 157 y2_hi = mem[0]; 158 y2_lo = mem[1]; 159 y1_hi = mem[2]; 160 y1_lo = mem[3]; 161 x0 = mem[4]; 162 x1 = mem[5]; 163 164 165 for (i = lg; i != 0; i--) 166 { 167 168 /* y[i] = b[0]*x[i] + b[1]*x[i-1] + b[0]*x[i-2] */ 169 /* + a[0]*y[i-1] + a[1] * y[i-2]; */ 170 171 L_tmp1 = fxp_mac_16by16(y1_lo, 16211, 8192L); 172 L_tmp1 = fxp_mac_16by16(y2_lo, -8021, L_tmp1); 173 L_tmp2 = fxp_mul_16by16(y1_hi, 32422); 174 L_tmp2 = fxp_mac_16by16(y2_hi, -16042, L_tmp2); 175 176 x2 = x1; 177 x1 = x0; 178 x0 = *pt_sign; 179 L_tmp2 = fxp_mac_16by16(x2, 8106, L_tmp2); 180 L_tmp2 = fxp_mac_16by16(x1, -16212, L_tmp2); 181 L_tmp2 = fxp_mac_16by16(x0, 8106, L_tmp2); 182 183 184 L_tmp1 = ((L_tmp1 >> 14) + L_tmp2) << 2; 185 186 y2_hi = y1_hi; 187 y2_lo = y1_lo; 188 y1_hi = (int16)(L_tmp1 >> 16); 189 y1_lo = (int16)((L_tmp1 - (y1_hi << 16)) >> 1); 190 191 /* coeff Q14 --> Q15 with saturation */ 192 *(pt_sign++) = amr_wb_shl1_round(L_tmp1); 193 194 } 195 196 197 mem[0] = y2_hi; 198 mem[1] = y2_lo; 199 mem[2] = y1_hi; 200 mem[3] = y1_lo; 201 mem[4] = x0; 202 mem[5] = x1; 203 204 } 205 206
