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_400Hz_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 400 Hz. 56 Designed with cheby2 function in MATLAB. 57 Optimized for fixed-point to get the following frequency response: 58 59 frequency: 0Hz 100Hz 200Hz 300Hz 400Hz 630Hz 1.5kHz 3kHz 60 dB loss: -infdB -30dB -20dB -10dB -3dB +6dB +1dB 0dB 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] = {3660, -7320, 3660}; in Q12 68 int16 a[3] = {4096, 7320, -3540}; in Q12 69 70 float --> b[3] = {0.893554687, -1.787109375, 0.893554687}; 71 a[3] = {1.000000000, 1.787109375, -0.864257812}; 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 #include "pv_amr_wb_type_defs.h" 93 #include "pvamrwbdecoder_basic_op.h" 94 #include "pvamrwb_math_op.h" 95 #include "pvamrwbdecoder_acelp.h" 96 97 /*---------------------------------------------------------------------------- 98 ; MACROS 99 ; Define module specific macros here 100 ----------------------------------------------------------------------------*/ 101 102 103 /*---------------------------------------------------------------------------- 104 ; DEFINES 105 ; Include all pre-processor statements here. Include conditional 106 ; compile variables also. 107 ----------------------------------------------------------------------------*/ 108 109 /*---------------------------------------------------------------------------- 110 ; LOCAL FUNCTION DEFINITIONS 111 ; Function Prototype declaration 112 ----------------------------------------------------------------------------*/ 113 114 /*---------------------------------------------------------------------------- 115 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 116 ; Variable declaration - defined here and used outside this module 117 ----------------------------------------------------------------------------*/ 118 119 /*---------------------------------------------------------------------------- 120 ; EXTERNAL FUNCTION REFERENCES 121 ; Declare functions defined elsewhere and referenced in this module 122 ----------------------------------------------------------------------------*/ 123 124 /*---------------------------------------------------------------------------- 125 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 126 ; Declare variables used in this module but defined elsewhere 127 ----------------------------------------------------------------------------*/ 128 129 /*---------------------------------------------------------------------------- 130 ; FUNCTION CODE 131 ----------------------------------------------------------------------------*/ 132 /* Initialization of static values */ 133 134 void highpass_400Hz_at_12k8_init(int16 mem[]) 135 { 136 pv_memset((void *)mem, 0, 6*sizeof(*mem)); 137 } 138 139 /*---------------------------------------------------------------------------- 140 ; FUNCTION CODE 141 ----------------------------------------------------------------------------*/ 142 143 void highpass_400Hz_at_12k8( 144 int16 signal[], /* input signal / output is divided by 16 */ 145 int16 lg, /* lenght of signal */ 146 int16 mem[] /* filter memory [6] */ 147 ) 148 { 149 int16 i, x2; 150 int16 y2_hi, y2_lo, y1_hi, y1_lo, x0, x1; 151 int32 L_tmp1; 152 int32 L_tmp2; 153 154 y2_hi = mem[0]; 155 y2_lo = mem[1]; 156 y1_hi = mem[2]; 157 y1_lo = mem[3]; 158 x0 = mem[4]; 159 x1 = mem[5]; 160 161 for (i = 0; i < lg; i++) 162 { 163 164 /* y[i] = b[0]*x[i] + b[1]*x[i-1] + b[0]*x[i-2] */ 165 /* + a[0]*y[i-1] + a[1] * y[i-2]; */ 166 167 L_tmp1 = fxp_mac_16by16(y1_lo, 29280, 8192L); 168 L_tmp2 = fxp_mul_16by16(y1_hi, 29280); 169 L_tmp1 = fxp_mac_16by16(y2_lo, -14160, L_tmp1); 170 L_tmp2 = fxp_mac_16by16(y2_hi, -14160, L_tmp2); 171 x2 = x1; 172 x1 = x0; 173 x0 = signal[i]; 174 L_tmp2 = fxp_mac_16by16(x2, 915, L_tmp2); 175 L_tmp2 = fxp_mac_16by16(x1, -1830, L_tmp2); 176 L_tmp2 = fxp_mac_16by16(x0, 915, L_tmp2); 177 178 L_tmp1 = (L_tmp1 >> 13) + (L_tmp2 << 2); /* coeff Q12 --> Q13 */ 179 180 y2_hi = y1_hi; 181 y2_lo = y1_lo; 182 /* signal is divided by 16 to avoid overflow in energy computation */ 183 signal[i] = (int16)((L_tmp1 + 0x00008000) >> 16); 184 185 y1_hi = (int16)(L_tmp1 >> 16); 186 y1_lo = (int16)((L_tmp1 - (y1_hi << 16)) >> 1); 187 188 189 } 190 191 192 mem[0] = y2_hi; 193 mem[1] = y2_lo; 194 mem[2] = y1_hi; 195 mem[3] = y1_lo; 196 mem[4] = x0; 197 mem[5] = x1; 198 199 } 200 201 202
