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 26.073 22 ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec 23 Available from http://www.3gpp.org 24 25 (C) 2004, 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 Pathname: ./audio/gsm-amr/c/src/enc_lag6.c 35 Functions: 36 37 Date: 02/05/2002 38 39 ------------------------------------------------------------------------------ 40 REVISION HISTORY 41 42 Description: Updated template used to PV coding template. 43 Changed to accept the pOverflow flag for EPOC compatibility. 44 45 Description: 46 (1) Removed optimization -- mult(i, 6, pOverflow) is NOT the same as adding 47 i to itself 6 times. The reason is because the mult function does a 48 right shift by 15, which will obliterate smaller numbers. 49 50 Description: Replaced "int" and/or "char" with OSCL defined types. 51 52 Description: 53 54 ------------------------------------------------------------------------------ 55 MODULE DESCRIPTION 56 57 58 ------------------------------------------------------------------------------ 59 */ 60 61 /*---------------------------------------------------------------------------- 62 ; INCLUDES 63 ----------------------------------------------------------------------------*/ 64 #include "enc_lag6.h" 65 #include "typedef.h" 66 #include "basic_op.h" 67 68 /*---------------------------------------------------------------------------- 69 ; MACROS 70 ; Define module specific macros here 71 ----------------------------------------------------------------------------*/ 72 73 /*---------------------------------------------------------------------------- 74 ; DEFINES 75 ; Include all pre-processor statements here. Include conditional 76 ; compile variables also. 77 ----------------------------------------------------------------------------*/ 78 79 /*---------------------------------------------------------------------------- 80 ; LOCAL FUNCTION DEFINITIONS 81 ; Function Prototype declaration 82 ----------------------------------------------------------------------------*/ 83 84 /*---------------------------------------------------------------------------- 85 ; LOCAL VARIABLE DEFINITIONS 86 ; Variable declaration - defined here and used outside this module 87 ----------------------------------------------------------------------------*/ 88 89 90 /* 91 ------------------------------------------------------------------------------ 92 FUNCTION NAME: Enc_lag6 93 ------------------------------------------------------------------------------ 94 INPUT AND OUTPUT DEFINITIONS 95 96 Inputs: 97 T0 -- Word16 -- Pitch delay 98 T0_frac -- Word16 -- Fractional pitch delay 99 T0_min -- Word16 -- minimum of search range 100 delta_flag -- Word16 -- Flag for 1st (or 3rd) subframe 101 102 Outputs: 103 pOverflow -- Pointer to Flag -- overflow indicator 104 105 Returns: 106 Word16 -- Return index of encoding 107 108 Global Variables Used: 109 None 110 111 Local Variables Needed: 112 None 113 114 ------------------------------------------------------------------------------ 115 FUNCTION DESCRIPTION 116 117 PURPOSE: Encoding of fractional pitch lag with 1/6 resolution. 118 119 DESCRIPTION: 120 First and third subframes: 121 -------------------------- 122 The pitch range is divided as follows: 123 17 3/6 to 94 3/6 resolution 1/6 124 95 to 143 resolution 1 125 126 The period is encoded with 9 bits. 127 For the range with fractions: 128 index = (T-17)*6 + frac - 3; 129 where T=[17..94] and frac=[-2,-1,0,1,2,3] 130 and for the integer only range 131 index = (T - 95) + 463; where T=[95..143] 132 133 Second and fourth subframes: 134 ---------------------------- 135 For the 2nd and 4th subframes a resolution of 1/6 is always used, 136 and the search range is relative to the lag in previous subframe. 137 If t0 is the lag in the previous subframe then 138 t_min=t0-5 and t_max=t0+4 and the range is given by 139 (t_min-1) 3/6 to (t_max) 3/6 140 141 The period in the 2nd (and 4th) subframe is encoded with 6 bits: 142 index = (T-(t_min-1))*6 + frac - 3; 143 where T=[t_min-1..t_max] and frac=[-2,-1,0,1,2,3] 144 145 Note that only 61 values are used. If the decoder receives 61, 62, 146 or 63 as the relative pitch index, it means that a transmission 147 error occurred and the pitch from previous subframe should be used. 148 149 ------------------------------------------------------------------------------ 150 REQUIREMENTS 151 152 None 153 154 ------------------------------------------------------------------------------ 155 REFERENCES 156 157 enc_lag6.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 158 159 ------------------------------------------------------------------------------ 160 PSEUDO-CODE 161 162 163 ------------------------------------------------------------------------------ 164 RESOURCES USED [optional] 165 166 When the code is written for a specific target processor the 167 the resources used should be documented below. 168 169 HEAP MEMORY USED: x bytes 170 171 STACK MEMORY USED: x bytes 172 173 CLOCK CYCLES: (cycle count equation for this function) + (variable 174 used to represent cycle count for each subroutine 175 called) 176 where: (cycle count variable) = cycle count for [subroutine 177 name] 178 179 ------------------------------------------------------------------------------ 180 CAUTION [optional] 181 [State any special notes, constraints or cautions for users of this function] 182 183 ------------------------------------------------------------------------------ 184 */ 185 186 Word16 Enc_lag6( /* o : Return index of encoding */ 187 Word16 T0, /* i : Pitch delay */ 188 Word16 T0_frac, /* i : Fractional pitch delay */ 189 Word16 T0_min, /* i : minimum of search range */ 190 Word16 delta_flag, /* i : Flag for 1st (or 3rd) subframe */ 191 Flag *pOverflow /* o : overflow indicator */ 192 ) 193 { 194 Word16 index; 195 Word16 i; 196 Word16 temp; 197 198 if (delta_flag == 0) /* if 1st or 3rd subframe */ 199 { 200 /* encode pitch delay (with fraction) */ 201 if (T0 <= 94) 202 { 203 /* index = T0*6 - 105 + T0_frac */ 204 i = 6 * T0 - 105; 205 206 index = add(i, T0_frac, pOverflow); 207 } 208 else 209 { 210 index = add(T0, 368, pOverflow); 211 } 212 213 } 214 else 215 /* if second or fourth subframe */ 216 { 217 /* index = 6*(T0-T0_min) + 3 + T0_frac */ 218 temp = sub(T0, T0_min, pOverflow); 219 220 i = add(temp, temp, pOverflow); 221 i = add(temp, i, pOverflow); 222 i = add(i, i, pOverflow); 223 224 i = add(i, 3, pOverflow); 225 226 index = add(i, T0_frac, pOverflow); 227 } 228 229 return index; 230 } 231
