| /* ------------------------------------------------------------------ |
| * Copyright (C) 1998-2009 PacketVideo |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either |
| * express or implied. |
| * See the License for the specific language governing permissions |
| * and limitations under the License. |
| * ------------------------------------------------------------------- |
| */ |
| /* |
| |
| Pathname: getmask.c |
| |
| ------------------------------------------------------------------------------ |
| REVISION HISTORY |
| |
| Description: Modified from original shareware code |
| |
| Description: Modified to pass variables by reference to eliminate use |
| of global variables. |
| Replaced for-loop style memory initialization with memset() |
| |
| Description: (1) Modified to bring code in-line with PV standard |
| (2) Removed multiple returns, Replaced multiple 'if's with |
| switch |
| |
| Description: (1) Modified per review comments |
| (2) increment pointer pMask after memset |
| |
| Description: Make the maximum number of bits requested from getbits |
| become a constant. |
| |
| Description: Typecast 1 to UInt32 for bitmask to avoid masking on a 16-bit |
| platform |
| |
| Description: Replace some instances of getbits to get9_n_lessbits |
| when the number of bits read is 9 or less. |
| |
| Who: Date: MM/DD/YYYY |
| Description: |
| |
| ------------------------------------------------------------------------------ |
| INPUT AND OUTPUT DEFINITIONS |
| |
| Inputs: |
| pFrameInfo = pointer to structure that holds information for current |
| frame, Type FrameInfo |
| |
| pInputStream= pointer to structure that holds input stream information |
| Type BITS |
| |
| pGroup = pointer to array that holds the stop window index for |
| each group in current frame, Type Int |
| |
| max_sfb = number of active sfbs for each window, Type Int |
| |
| mask[] = array that holds the MS_mask information |
| Type Int |
| |
| Local Stores/Buffers/Pointers Needed: |
| None |
| |
| Global Stores/Buffers/Pointers Needed: |
| None |
| |
| Outputs: |
| mask_present = 0 (no Mid/Side mixed) |
| 2 (Mid/Side mixed present for entire frame) |
| 1 (Mid/Side mixed information read from bitstream) |
| -1 (invalid mask_present read from bitstream) |
| |
| Pointers and Buffers Modified: |
| pMask contents replaced by MS information of each scalefactor band |
| |
| Local Stores Modified: |
| None |
| |
| Global Stores Modified: |
| None |
| |
| ------------------------------------------------------------------------------ |
| FUNCTION DESCRIPTION |
| |
| This function reads the Mid/Side(MS) mask information from the input |
| bitstream. If the mask_present field is equal to 2, the mask bits is set to |
| 1 for the entire frame. If mask_present has a value of 0, the function |
| returns 0, If mask_present is set to 1, the Mid/Side(MS) information is |
| read from the input stream. When mask_present is 3, an error code (-1) is |
| generated. |
| The Mid/Side(MS) information is later used for mixing the left and right |
| channel sounds. Each scalefactor band has its own MS information. |
| |
| (ISO comments: read a synthesis mask, read a synthesis mask uses |
| EXTENDED_MS_MASK and grouped mask ) |
| |
| ------------------------------------------------------------------------------ |
| REQUIREMENTS |
| |
| This function shall replace the contents of pMask with the MS information |
| of each scalefactor band |
| |
| ------------------------------------------------------------------------------ |
| REFERENCES |
| |
| (1) MPEG-2 NBC Audio Decoder |
| "This software module was originally developed by AT&T, Dolby |
| Laboratories, Fraunhofer Gesellschaft IIS in the course of development |
| of the MPEG-2 NBC/MPEG-4 Audio standard ISO/IEC 13818-7, 14496-1,2 and |
| 3. This software module is an implementation of a part of one or more |
| MPEG-2 NBC/MPEG-4 Audio tools as specified by the MPEG-2 NBC/MPEG-4 |
| Audio standard. ISO/IEC gives users of the MPEG-2 NBC/MPEG-4 Audio |
| standards free license to this software module or modifications thereof |
| for use in hardware or software products claiming conformance to the |
| MPEG-2 NBC/MPEG-4 Audio standards. Those intending to use this software |
| module in hardware or software products are advised that this use may |
| infringe existing patents. The original developer of this software |
| module and his/her company, the subsequent editors and their companies, |
| and ISO/IEC have no liability for use of this software module or |
| modifications thereof in an implementation. Copyright is not released |
| for non MPEG-2 NBC/MPEG-4 Audio conforming products.The original |
| developer retains full right to use the code for his/her own purpose, |
| assign or donate the code to a third party and to inhibit third party |
| from using the code for non MPEG-2 NBC/MPEG-4 Audio conforming products. |
| This copyright notice must be included in all copies or derivative |
| works." |
| Copyright(c)1996. |
| |
| (2) ISO/IEC 14496-3: 1999(E) |
| Subpart 4 |
| p15 (Table 4.4.5 getmask) |
| |
| ------------------------------------------------------------------------------ |
| PSEUDO-CODE |
| |
| CALL getbits(LEN_MASK_PRES, pInputStream) |
| MODIFYING (pInputStream) |
| RETURNING (mask present information) |
| mask_present = mask present information |
| |
| SWITCH (mask_present) |
| |
| CASE (0): |
| BREAK; |
| |
| CASE (2): |
| nwin = pFrameInfo->num_win; |
| FOR(win = 0; win < nwin; win = *(pGroup++)) |
| |
| FOR(sfb = pFrameInfo->sfb_per_win[win]; sfb > 0; sfb--) |
| *(pMask++) = 1; |
| ENDFOR |
| |
| ENDFOR |
| |
| BREAK; |
| |
| CASE(1): |
| |
| nwin = pFrameInfo->num_win; |
| |
| nToDo = max_sfb; |
| |
| WHILE (nToDo > 0) |
| nCall = nToDo; |
| |
| IF (nCall > MAX_GETBITS) |
| THEN |
| nCall = MAX_GETBITS; |
| ENDIF |
| |
| tempMask = |
| getbits( |
| nCall, |
| pInputStream); |
| |
| bitmask = 1 << (nCall - 1); |
| FOR (sfb = nCall; sfb > 0; sfb--) |
| *(pMask++) = (tempMask & bitmask) >> (sfb - 1); |
| bitmask >>= 1; |
| ENDFOR |
| |
| nToDo -= nCall; |
| END WHILE |
| |
| pv_memset( |
| pMask, |
| 0, |
| (pFrameInfo->sfb_per_win[win]-max_sfb)*sizeof(*pMask)); |
| |
| ENDFOR (win) |
| |
| BREAK |
| |
| DEFAULT: |
| mask_present = -1 |
| |
| ENDSWITCH |
| |
| RETURN mask_present |
| |
| ------------------------------------------------------------------------------ |
| */ |
| |
| |
| /*---------------------------------------------------------------------------- |
| ; INCLUDES |
| ----------------------------------------------------------------------------*/ |
| #include "pv_audio_type_defs.h" |
| #include "huffman.h" |
| #include "aac_mem_funcs.h" |
| #include "e_maskstatus.h" |
| |
| /*---------------------------------------------------------------------------- |
| ; MACROS |
| ; Define module specific macros here |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; DEFINES |
| ; Include all pre-processor statements here. Include conditional |
| ; compile variables also. |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; LOCAL FUNCTION DEFINITIONS |
| ; Function Prototype declaration |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; LOCAL STORE/BUFFER/POINTER DEFINITIONS |
| ; Variable declaration - defined here and used outside this module |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; EXTERNAL FUNCTION REFERENCES |
| ; Declare functions defined elsewhere and referenced in this module |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES |
| ; Declare variables used in this module but defined elsewhere |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; FUNCTION CODE |
| ----------------------------------------------------------------------------*/ |
| Int getmask( |
| FrameInfo *pFrameInfo, |
| BITS *pInputStream, |
| Int group[], |
| Int max_sfb, |
| Int mask[]) |
| { |
| |
| Int win; /* window index */ |
| Int sfb; |
| Int mask_present; |
| Int *pMask; |
| Int *pGroup; |
| Int nwin; |
| Int nCall; |
| Int nToDo; |
| UInt32 tempMask; |
| UInt32 bitmask; |
| |
| pMask = mask; |
| pGroup = group; |
| |
| mask_present = |
| get9_n_lessbits( |
| LEN_MASK_PRES, |
| pInputStream); |
| |
| switch (mask_present) |
| { |
| case(MASK_NOT_PRESENT): |
| /* special EXTENDED_MS_MASK cases */ |
| /* no ms at all */ |
| break; |
| |
| case(MASK_ALL_FRAME): |
| /* MS for whole spectrum on, mask bits set to 1 */ |
| nwin = pFrameInfo->num_win; |
| for (win = 0; win < nwin; win = *(pGroup++)) |
| { |
| for (sfb = pFrameInfo->sfb_per_win[win]; sfb > 0; sfb--) |
| { |
| *(pMask++) = 1; /* cannot use memset for Int type */ |
| } |
| |
| } |
| |
| break; |
| |
| case(MASK_FROM_BITSTREAM): |
| /* MS_mask_present==1, get mask information*/ |
| nwin = pFrameInfo->num_win; |
| for (win = 0; win < nwin; win = *(pGroup++)) |
| { |
| /* |
| * the following code is equivalent to |
| * |
| * for(sfb = max_sfb; sfb > 0; sfb--) |
| * { |
| * *(pMask++) = |
| * getbits( |
| * LEN_MASK, |
| * pInputStream); |
| * } |
| * |
| * in order to save the calls to getbits, the above |
| * for-loop is broken into two parts |
| */ |
| |
| nToDo = max_sfb; |
| |
| while (nToDo > 0) |
| { |
| nCall = nToDo; |
| |
| if (nCall > MAX_GETBITS) |
| { |
| nCall = MAX_GETBITS; |
| } |
| |
| tempMask = |
| getbits( |
| nCall, |
| pInputStream); |
| |
| bitmask = (UInt32) 1 << (nCall - 1); |
| for (sfb = nCall; sfb > 0; sfb--) |
| { |
| *(pMask++) = (Int)((tempMask & bitmask) >> (sfb - 1)); |
| bitmask >>= 1; |
| } |
| |
| nToDo -= nCall; |
| } |
| |
| /* |
| * set remaining sfbs to zero |
| * re-use nCall to save one variable on stack |
| */ |
| |
| nCall = pFrameInfo->sfb_per_win[win] - max_sfb; |
| |
| |
| if (nCall >= 0) |
| { |
| pv_memset(pMask, |
| 0, |
| nCall*sizeof(*pMask)); |
| |
| pMask += nCall; |
| } |
| else |
| { |
| mask_present = MASK_ERROR; |
| break; |
| } |
| |
| |
| } /* for (win) */ |
| |
| break; |
| |
| default: |
| /* error */ |
| break; |
| |
| } /* switch (mask_present) */ |
| |
| return mask_present; |
| |
| } /* getmask */ |
