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 20 Pathname: pulse_nc.c 21 22 ------------------------------------------------------------------------------ 23 REVISION HISTORY 24 25 Description: Modified from original shareware code 26 27 Description: Modified to pass variables by reference to eliminate use 28 of global variables. 29 30 Description: Modified to bring code in-line with PV standards. 31 32 Description: Pass in max as input argument. 33 34 Description: Went back to the if-statement to check for max. 35 36 Who: Date: 37 Description: 38 39 ------------------------------------------------------------------------------ 40 INPUT AND OUTPUT DEFINITIONS 41 42 Inputs: 43 coef[] = Array of quantized spectral coefficents. 44 (Int []) 45 46 pPulseInfo = Pointer to structure which contains noiseless 47 encoding info, includes information about the pulse data, 48 pulse amplitude, etc. 49 (const PulseInfo *) 50 51 pLongFrameInfo = Pointer to structure that holds information about 52 each group. (long block flag, number of windows, 53 scalefactor bands per group, etc.) 54 55 Variable is named (pLongFrameInfo) because this function 56 is only used for LONG windows. 57 (FrameInfo *) 58 max = Pointer to the maximum value of coef[] 59 60 Local Stores/Buffers/Pointers Needed: 61 None 62 63 Global Stores/Buffers/Pointers Needed: 64 None 65 66 Outputs: 67 None 68 69 Pointers and Buffers Modified: 70 coef[] = coefficient contents are modified by the encoded pulse 71 72 Local Stores Modified: 73 74 Global Stores Modified: 75 76 ------------------------------------------------------------------------------ 77 FUNCTION DESCRIPTION 78 79 This function adds pulses to defined ranges of coefficients in the window, 80 for the case of LONG windows. The pulses are unsigned, so 81 negative coefficients subtract the pulse, and positive coefficients add it. 82 (The ampltiude of the coefficient is always increased by the pulse) 83 84 A maximum of 4 coefficients may be modified by a pulse, and these 85 coefficients must all occur in the same scalefactor band. 86 87 The number of pulse-encoded coefficients to be processed by this function 88 is communicated to this function via pPulseInfo->number_pulse 89 90 This value is equal to the actual number of pulses - 1. 91 (e.g if pPulseInfo->number_pulse == 0, one pulse is assumed) 92 This function must not be called if no pulse encoded data exists. 93 The function assumes that at least one pulse exists. 94 ------------------------------------------------------------------------------ 95 REQUIREMENTS 96 97 This module shall correctly add transmitted pulse(s) to the correct 98 coefficients in a LONG window. 99 100 ------------------------------------------------------------------------------ 101 REFERENCES 102 (1) ISO/IEC 14496-3:1999(E) 103 Part 3 104 Subpart 4.6.3.3 Decoding Process 105 106 (2) MPEG-2 NBC Audio Decoder 107 "This software module was originally developed by AT&T, Dolby 108 Laboratories, Fraunhofer Gesellschaft IIS in the course of development 109 of the MPEG-2 NBC/MPEG-4 Audio standard ISO/IEC 13818-7, 14496-1,2 and 110 3. This software module is an implementation of a part of one or more 111 MPEG-2 NBC/MPEG-4 Audio tools as specified by the MPEG-2 NBC/MPEG-4 112 Audio standard. ISO/IEC gives users of the MPEG-2 NBC/MPEG-4 Audio 113 standards free license to this software module or modifications thereof 114 for use in hardware or software products claiming conformance to the 115 MPEG-2 NBC/MPEG-4 Audio standards. Those intending to use this software 116 module in hardware or software products are advised that this use may 117 infringe existing patents. The original developer of this software 118 module and his/her company, the subsequent editors and their companies, 119 and ISO/IEC have no liability for use of this software module or 120 modifications thereof in an implementation. Copyright is not released 121 for non MPEG-2 NBC/MPEG-4 Audio conforming products.The original 122 developer retains full right to use the code for his/her own purpose, 123 assign or donate the code to a third party and to inhibit third party 124 from using the code for non MPEG-2 NBC/MPEG-4 Audio conforming products. 125 This copyright notice must be included in all copies or derivative 126 works." 127 Copyright(c)1996. 128 129 ------------------------------------------------------------------------------ 130 PSEUDO-CODE 131 132 index = pLongFrameInfo->win_sfb_top[0][pPulseInfo->pulse_start_sfb]; 133 134 pPulseOffset = &(pPulseInfo->pulse_offset[0]); 135 136 pPulseAmp = &(pPulseInfo->pulse_amp[0]); 137 138 pCoef = &(Coef[index]); 139 140 FOR (index = pPulseInfo->number_pulse; index >= 0; index--) 141 142 pCoef = pCoef + *(pPulseOffset); 143 pPulseOffset = pPulseOffset + 1; 144 145 IF (*pCoef > 0) 146 *(pCoef) = *(pCoef) + *(pPulseAmp); 147 pPulseAmp = pPulseAmp + 1; 148 ELSE 149 *(pCoef) = *(pCoef) - *(pPulseAmp); 150 pPulseAmp = pPulseAmp + 1; 151 ENDIF 152 153 ENDFOR 154 155 ------------------------------------------------------------------------------ 156 RESOURCES USED 157 When the code is written for a specific target processor the 158 the resources used should be documented below. 159 160 STACK USAGE: [stack count for this module] + [variable to represent 161 stack usage for each subroutine called] 162 163 where: [stack usage variable] = stack usage for [subroutine 164 name] (see [filename].ext) 165 166 DATA MEMORY USED: x words 167 168 PROGRAM MEMORY USED: x words 169 170 CLOCK CYCLES: [cycle count equation for this module] + [variable 171 used to represent cycle count for each subroutine 172 called] 173 174 where: [cycle count variable] = cycle count for [subroutine 175 name] (see [filename].ext) 176 177 ------------------------------------------------------------------------------ 178 */ 179 180 181 /*---------------------------------------------------------------------------- 182 ; INCLUDES 183 ----------------------------------------------------------------------------*/ 184 #include "pv_audio_type_defs.h" 185 #include "s_frameinfo.h" 186 #include "s_pulseinfo.h" 187 #include "pulse_nc.h" 188 189 /*---------------------------------------------------------------------------- 190 ; MACROS 191 ; Define module specific macros here 192 ----------------------------------------------------------------------------*/ 193 194 /*--------------------------------------------------------------------------- 195 ; DEFINES 196 ; Include all pre-processor statements here. Include conditional 197 ; compile variables also. 198 ----------------------------------------------------------------------------*/ 199 200 /*---------------------------------------------------------------------------- 201 ; LOCAL FUNCTION DEFINITIONS 202 ; Function Prototype declaration 203 ----------------------------------------------------------------------------*/ 204 205 /*---------------------------------------------------------------------------- 206 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 207 ; Variable declaration - defined here and used outside this module 208 ----------------------------------------------------------------------------*/ 209 210 /*---------------------------------------------------------------------------- 211 ; EXTERNAL FUNCTION REFERENCES 212 ; Declare functions defined elsewhere and referenced in this module 213 ----------------------------------------------------------------------------*/ 214 215 /*---------------------------------------------------------------------------- 216 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 217 ; Declare variables used in this module but defined elsewhere 218 ----------------------------------------------------------------------------*/ 219 220 /*---------------------------------------------------------------------------- 221 ; FUNCTION CODE 222 ----------------------------------------------------------------------------*/ 223 224 void pulse_nc( 225 Int16 coef[], 226 const PulseInfo *pPulseInfo, 227 const FrameInfo *pLongFrameInfo, 228 Int *max) 229 { 230 Int index; 231 232 Int16 *pCoef; 233 Int temp; 234 235 const Int *pPulseOffset; 236 const Int *pPulseAmp; 237 238 /*--- Find the scalefactor band where pulse-encoded data starts ---*/ 239 240 if (pPulseInfo->pulse_start_sfb > 0) 241 { 242 index = pLongFrameInfo->win_sfb_top[0][pPulseInfo->pulse_start_sfb - 1]; 243 } 244 else 245 { 246 index = 0; 247 } 248 249 /*------------------------------------------------------------------------- 250 Each pulse index is stored as an offset from the previous pulse 251 252 Example - here we have a sfb that is 20 coefficients in length: 253 254 [0][1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] 255 [ ][ ][ ][ ][ ][P][P][ ][ ][ ][ ][ ][ ][ ][ ][ P][ ][ ][ ][ P] 256 257 The array pointed to by pPulseOffset == [5][1][9][4] 258 259 pPulseAmp is of the same length as pPulseOffset, and contains 260 an individual pulse amplitude for each coefficient. 261 --------------------------------------------------------------------------*/ 262 263 pCoef = &(coef[index]); 264 265 pPulseOffset = &(pPulseInfo->pulse_offset[0]); 266 267 pPulseAmp = &(pPulseInfo->pulse_amp[0]); 268 269 for (index = pPulseInfo->number_pulse; index > 0; index--) 270 { 271 pCoef += *pPulseOffset++; 272 273 temp = *pCoef; 274 275 if (temp > 0) 276 { 277 temp += *(pPulseAmp++); 278 *pCoef = (Int16)temp; 279 if (temp > *max) 280 { 281 *max = temp; 282 } 283 } 284 else 285 { 286 temp -= *(pPulseAmp++); 287 *pCoef = (Int16)temp; 288 if (-temp > *max) 289 { 290 *max = -temp; 291 } 292 } 293 294 } /* for() */ 295 296 return; 297 298 } /* pulse_nc */ 299
