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: getmask.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 Replaced for-loop style memory initialization with memset() 30 31 Description: (1) Modified to bring code in-line with PV standard 32 (2) Removed multiple returns, Replaced multiple 'if's with 33 switch 34 35 Description: (1) Modified per review comments 36 (2) increment pointer pMask after memset 37 38 Description: Make the maximum number of bits requested from getbits 39 become a constant. 40 41 Description: Typecast 1 to UInt32 for bitmask to avoid masking on a 16-bit 42 platform 43 44 Description: Replace some instances of getbits to get9_n_lessbits 45 when the number of bits read is 9 or less. 46 47 Who: Date: MM/DD/YYYY 48 Description: 49 50 ------------------------------------------------------------------------------ 51 INPUT AND OUTPUT DEFINITIONS 52 53 Inputs: 54 pFrameInfo = pointer to structure that holds information for current 55 frame, Type FrameInfo 56 57 pInputStream= pointer to structure that holds input stream information 58 Type BITS 59 60 pGroup = pointer to array that holds the stop window index for 61 each group in current frame, Type Int 62 63 max_sfb = number of active sfbs for each window, Type Int 64 65 mask[] = array that holds the MS_mask information 66 Type Int 67 68 Local Stores/Buffers/Pointers Needed: 69 None 70 71 Global Stores/Buffers/Pointers Needed: 72 None 73 74 Outputs: 75 mask_present = 0 (no Mid/Side mixed) 76 2 (Mid/Side mixed present for entire frame) 77 1 (Mid/Side mixed information read from bitstream) 78 -1 (invalid mask_present read from bitstream) 79 80 Pointers and Buffers Modified: 81 pMask contents replaced by MS information of each scalefactor band 82 83 Local Stores Modified: 84 None 85 86 Global Stores Modified: 87 None 88 89 ------------------------------------------------------------------------------ 90 FUNCTION DESCRIPTION 91 92 This function reads the Mid/Side(MS) mask information from the input 93 bitstream. If the mask_present field is equal to 2, the mask bits is set to 94 1 for the entire frame. If mask_present has a value of 0, the function 95 returns 0, If mask_present is set to 1, the Mid/Side(MS) information is 96 read from the input stream. When mask_present is 3, an error code (-1) is 97 generated. 98 The Mid/Side(MS) information is later used for mixing the left and right 99 channel sounds. Each scalefactor band has its own MS information. 100 101 (ISO comments: read a synthesis mask, read a synthesis mask uses 102 EXTENDED_MS_MASK and grouped mask ) 103 104 ------------------------------------------------------------------------------ 105 REQUIREMENTS 106 107 This function shall replace the contents of pMask with the MS information 108 of each scalefactor band 109 110 ------------------------------------------------------------------------------ 111 REFERENCES 112 113 (1) MPEG-2 NBC Audio Decoder 114 "This software module was originally developed by AT&T, Dolby 115 Laboratories, Fraunhofer Gesellschaft IIS in the course of development 116 of the MPEG-2 NBC/MPEG-4 Audio standard ISO/IEC 13818-7, 14496-1,2 and 117 3. This software module is an implementation of a part of one or more 118 MPEG-2 NBC/MPEG-4 Audio tools as specified by the MPEG-2 NBC/MPEG-4 119 Audio standard. ISO/IEC gives users of the MPEG-2 NBC/MPEG-4 Audio 120 standards free license to this software module or modifications thereof 121 for use in hardware or software products claiming conformance to the 122 MPEG-2 NBC/MPEG-4 Audio standards. Those intending to use this software 123 module in hardware or software products are advised that this use may 124 infringe existing patents. The original developer of this software 125 module and his/her company, the subsequent editors and their companies, 126 and ISO/IEC have no liability for use of this software module or 127 modifications thereof in an implementation. Copyright is not released 128 for non MPEG-2 NBC/MPEG-4 Audio conforming products.The original 129 developer retains full right to use the code for his/her own purpose, 130 assign or donate the code to a third party and to inhibit third party 131 from using the code for non MPEG-2 NBC/MPEG-4 Audio conforming products. 132 This copyright notice must be included in all copies or derivative 133 works." 134 Copyright(c)1996. 135 136 (2) ISO/IEC 14496-3: 1999(E) 137 Subpart 4 138 p15 (Table 4.4.5 getmask) 139 140 ------------------------------------------------------------------------------ 141 PSEUDO-CODE 142 143 CALL getbits(LEN_MASK_PRES, pInputStream) 144 MODIFYING (pInputStream) 145 RETURNING (mask present information) 146 mask_present = mask present information 147 148 SWITCH (mask_present) 149 150 CASE (0): 151 BREAK; 152 153 CASE (2): 154 nwin = pFrameInfo->num_win; 155 FOR(win = 0; win < nwin; win = *(pGroup++)) 156 157 FOR(sfb = pFrameInfo->sfb_per_win[win]; sfb > 0; sfb--) 158 *(pMask++) = 1; 159 ENDFOR 160 161 ENDFOR 162 163 BREAK; 164 165 CASE(1): 166 167 nwin = pFrameInfo->num_win; 168 169 nToDo = max_sfb; 170 171 WHILE (nToDo > 0) 172 nCall = nToDo; 173 174 IF (nCall > MAX_GETBITS) 175 THEN 176 nCall = MAX_GETBITS; 177 ENDIF 178 179 tempMask = 180 getbits( 181 nCall, 182 pInputStream); 183 184 bitmask = 1 << (nCall - 1); 185 FOR (sfb = nCall; sfb > 0; sfb--) 186 *(pMask++) = (tempMask & bitmask) >> (sfb - 1); 187 bitmask >>= 1; 188 ENDFOR 189 190 nToDo -= nCall; 191 END WHILE 192 193 pv_memset( 194 pMask, 195 0, 196 (pFrameInfo->sfb_per_win[win]-max_sfb)*sizeof(*pMask)); 197 198 ENDFOR (win) 199 200 BREAK 201 202 DEFAULT: 203 mask_present = -1 204 205 ENDSWITCH 206 207 RETURN mask_present 208 209 ------------------------------------------------------------------------------ 210 */ 211 212 213 /*---------------------------------------------------------------------------- 214 ; INCLUDES 215 ----------------------------------------------------------------------------*/ 216 #include "pv_audio_type_defs.h" 217 #include "huffman.h" 218 #include "aac_mem_funcs.h" 219 #include "e_maskstatus.h" 220 221 /*---------------------------------------------------------------------------- 222 ; MACROS 223 ; Define module specific macros here 224 ----------------------------------------------------------------------------*/ 225 226 /*---------------------------------------------------------------------------- 227 ; DEFINES 228 ; Include all pre-processor statements here. Include conditional 229 ; compile variables also. 230 ----------------------------------------------------------------------------*/ 231 232 /*---------------------------------------------------------------------------- 233 ; LOCAL FUNCTION DEFINITIONS 234 ; Function Prototype declaration 235 ----------------------------------------------------------------------------*/ 236 237 /*---------------------------------------------------------------------------- 238 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 239 ; Variable declaration - defined here and used outside this module 240 ----------------------------------------------------------------------------*/ 241 242 /*---------------------------------------------------------------------------- 243 ; EXTERNAL FUNCTION REFERENCES 244 ; Declare functions defined elsewhere and referenced in this module 245 ----------------------------------------------------------------------------*/ 246 247 /*---------------------------------------------------------------------------- 248 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 249 ; Declare variables used in this module but defined elsewhere 250 ----------------------------------------------------------------------------*/ 251 252 /*---------------------------------------------------------------------------- 253 ; FUNCTION CODE 254 ----------------------------------------------------------------------------*/ 255 Int getmask( 256 FrameInfo *pFrameInfo, 257 BITS *pInputStream, 258 Int group[], 259 Int max_sfb, 260 Int mask[]) 261 { 262 263 Int win; /* window index */ 264 Int sfb; 265 Int mask_present; 266 Int *pMask; 267 Int *pGroup; 268 Int nwin; 269 Int nCall; 270 Int nToDo; 271 UInt32 tempMask; 272 UInt32 bitmask; 273 274 pMask = mask; 275 pGroup = group; 276 277 mask_present = 278 get9_n_lessbits( 279 LEN_MASK_PRES, 280 pInputStream); 281 282 switch (mask_present) 283 { 284 case(MASK_NOT_PRESENT): 285 /* special EXTENDED_MS_MASK cases */ 286 /* no ms at all */ 287 break; 288 289 case(MASK_ALL_FRAME): 290 /* MS for whole spectrum on, mask bits set to 1 */ 291 nwin = pFrameInfo->num_win; 292 for (win = 0; win < nwin; win = *(pGroup++)) 293 { 294 for (sfb = pFrameInfo->sfb_per_win[win]; sfb > 0; sfb--) 295 { 296 *(pMask++) = 1; /* cannot use memset for Int type */ 297 } 298 299 } 300 301 break; 302 303 case(MASK_FROM_BITSTREAM): 304 /* MS_mask_present==1, get mask information*/ 305 nwin = pFrameInfo->num_win; 306 for (win = 0; win < nwin; win = *(pGroup++)) 307 { 308 /* 309 * the following code is equivalent to 310 * 311 * for(sfb = max_sfb; sfb > 0; sfb--) 312 * { 313 * *(pMask++) = 314 * getbits( 315 * LEN_MASK, 316 * pInputStream); 317 * } 318 * 319 * in order to save the calls to getbits, the above 320 * for-loop is broken into two parts 321 */ 322 323 nToDo = max_sfb; 324 325 while (nToDo > 0) 326 { 327 nCall = nToDo; 328 329 if (nCall > MAX_GETBITS) 330 { 331 nCall = MAX_GETBITS; 332 } 333 334 tempMask = 335 getbits( 336 nCall, 337 pInputStream); 338 339 bitmask = (UInt32) 1 << (nCall - 1); 340 for (sfb = nCall; sfb > 0; sfb--) 341 { 342 *(pMask++) = (Int)((tempMask & bitmask) >> (sfb - 1)); 343 bitmask >>= 1; 344 } 345 346 nToDo -= nCall; 347 } 348 349 /* 350 * set remaining sfbs to zero 351 * re-use nCall to save one variable on stack 352 */ 353 354 nCall = pFrameInfo->sfb_per_win[win] - max_sfb; 355 356 357 if (nCall >= 0) 358 { 359 pv_memset(pMask, 360 0, 361 nCall*sizeof(*pMask)); 362 363 pMask += nCall; 364 } 365 else 366 { 367 mask_present = MASK_ERROR; 368 break; 369 } 370 371 372 } /* for (win) */ 373 374 break; 375 376 default: 377 /* error */ 378 break; 379 380 } /* switch (mask_present) */ 381 382 return mask_present; 383 384 } /* getmask */ 385
