| /* ------------------------------------------------------------------ |
| * 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: ms_synt.c |
| |
| ------------------------------------------------------------------------------ |
| REVISION HISTORY |
| |
| Description: Modified from original shareware code |
| |
| Description: Cleaned up a bit, not finished. |
| |
| Description: |
| Copied in code from pns_intensity_right.c, which has the same structure as |
| this file. Also, merged in code from ms_map_mask.c |
| |
| Description: |
| (1) Various optimizations (eliminated extra variables by making use of a |
| single temporary register throughout the code, etc.) |
| (2) Wrote pseudocode, pasted in correct function template, etc. |
| |
| Description: Unrolled loops to get speed up code |
| |
| ------------------------------------------------------------------------------ |
| INPUT AND OUTPUT DEFINITIONS |
| |
| Inputs: |
| wins_in_group = Number of windows in the current group. |
| [const Int] |
| |
| coef_per_win = Number of coefficients per window. |
| [const Int] |
| |
| num_bands = Number of scalefactor bands. |
| [const Int] |
| |
| band_length = Number of coefficients per scalefactor band. |
| [const Int] |
| |
| pFirst_Window_CoefsL = Array containing the spectral coefficients for |
| the left channel. |
| [Int32 *, length LN] |
| pFirst_Window_CoefsR = Array containing the spectral coefficients for |
| the right channel. |
| [Int32 *, length LN] |
| q_formatLeft = Array containing the q-format used to encode each |
| scalefactor band's data on the left channel. |
| [Int *, length MAXBANDS] |
| q_formatRight = Array containing the q-format used to encode each |
| scalefactor band's data on the right channel. |
| [Int *, length MAXBANDS] |
| |
| Local Stores/Buffers/Pointers Needed: |
| None |
| |
| Global Stores/Buffers/Pointers Needed: |
| None |
| |
| Outputs: |
| None |
| |
| Pointers and Buffers Modified: |
| pFirst_Window_CoefsL The coefficients in the group will be modified per the |
| formula for M/S stereo on each scalefactor band where |
| M/S stereo is active. |
| |
| pFirst_Window_CoefsR The coefficients in the group will be modified per the |
| formula for M/S stereo on each scalefactor band where |
| M/S stereo is active. |
| |
| q_formatLeft The q_format may be modified on scalefactor bands |
| where M/S stereo is active. |
| |
| q_formatRight The q_format may be modified on scalefactor bands |
| where M/S stereo is active. |
| |
| Local Stores Modified: |
| |
| Global Stores Modified: |
| |
| ------------------------------------------------------------------------------ |
| FUNCTION DESCRIPTION |
| |
| This module applies the formula for M/S coding to one grouped scalefactor |
| band. The ISO code has a similar function which applies M/S coding to an |
| entire frame. |
| |
| It is the calling function's responsibility to check the map_mask array, which |
| is filled by the function getmask. If a scalefactor band is identified as |
| using M/S stereo, the coefficients in that array are calculated using |
| the following formula... |
| |
| TempLeft = LeftCoefficient; |
| |
| LeftCoefficient = LeftCoefficient + RightCoefficient; |
| RightCoefficient = TempLeft - RightCoefficient; |
| |
| This function should be inlined if the compiler supports C99 inlining, |
| as this short function is only called by sfb_tools_ms(). |
| Therefore, inlining will not increase the code size. |
| |
| ------------------------------------------------------------------------------ |
| REQUIREMENTS |
| |
| |
| ------------------------------------------------------------------------------ |
| REFERENCES |
| |
| (1) ISO/IEC 14496-3:1999(E) |
| Part 3 |
| Subpart 4.6.7.1 M/S stereo |
| Subpart 4.6.2 ScaleFactors |
| |
| (2) 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. |
| |
| ------------------------------------------------------------------------------ |
| PSEUDO-CODE |
| |
| start_indx = 0; |
| |
| pCoefR = coefLeft; |
| pCoefL = coefRight; |
| |
| FOR (win_indx = wins_in_group; win_indx > 0; win_indx--) |
| |
| |
| tempInt = q_formatLeft[start_indx] - q_formatRight[start_indx]; |
| |
| IF (tempInt > 0) |
| THEN |
| |
| shift_left_chan = 1 + tempInt; |
| shift_right_chan = 1; |
| |
| q_formatLeft[start_indx] = (q_formatRight[start_indx] - 1); |
| q_formatRight[start_indx] = (q_formatRight[start_indx] - 1); |
| |
| ELSE |
| shift_left_chan = 1; |
| shift_right_chan = 1 - tempInt; |
| |
| q_formatRight[start_indx] = (q_formatLeft[start_indx] - 1); |
| q_formatLeft[start_indx] = (q_formatLeft[start_indx] - 1); |
| |
| ENDIF |
| |
| FOR (tempInt = band_length; tempInt > 0; tempInt--) |
| |
| temp_left = *(pCoefL) >> shift_left_chan; |
| temp_right = *(pCoefR) >> shift_right_chan; |
| |
| *(pCoefL++) = temp_left + temp_right; |
| *(pCoefR++) = temp_left - temp_right; |
| |
| ENDFOR |
| |
| tempInt = (coef_per_win - band_length); |
| |
| pCoefR = pCoefR + tempInt; |
| pCoefL = pCoefL + tempInt; |
| |
| start_indx = start_indx + num_bands; |
| |
| ENDFOR |
| |
| ------------------------------------------------------------------------------ |
| RESOURCES USED |
| When the code is written for a specific target processor the |
| resources used should be documented below. |
| |
| STACK USAGE: [stack count for this module] + [variable to represent |
| stack usage for each subroutine called] |
| |
| where: [stack usage variable] = stack usage for [subroutine |
| name] (see [filename].ext) |
| |
| DATA MEMORY USED: x words |
| |
| PROGRAM MEMORY USED: x words |
| |
| CLOCK CYCLES: [cycle count equation for this module] + [variable |
| used to represent cycle count for each subroutine |
| called] |
| |
| where: [cycle count variable] = cycle count for [subroutine |
| name] (see [filename].ext) |
| |
| ------------------------------------------------------------------------------ |
| */ |
| |
| |
| /*---------------------------------------------------------------------------- |
| ; INCLUDES |
| ----------------------------------------------------------------------------*/ |
| #include "pv_audio_type_defs.h" |
| #include "ms_synt.h" |
| #include "fxp_mul32.h" |
| #include "aac_mem_funcs.h" |
| #include "window_block_fxp.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 |
| ----------------------------------------------------------------------------*/ |
| |
| void ms_synt( |
| const Int wins_in_group, |
| const Int coef_per_win, |
| const Int num_bands, |
| const Int band_length, |
| Int32 coefLeft[], |
| Int32 coefRight[], |
| Int q_formatLeft[], |
| Int q_formatRight[]) |
| { |
| |
| Int32 *pCoefL = coefLeft; |
| Int32 *pCoefR = coefRight; |
| Int start_indx = 0; |
| |
| |
| if (band_length < 0 || band_length > LONG_WINDOW) |
| { |
| return; /* avoid any processing on error condition */ |
| } |
| |
| |
| Int nextWinPtrUpdate = (coef_per_win - band_length); |
| |
| for (Int win_indx = wins_in_group; win_indx > 0; win_indx--) |
| { |
| |
| if (q_formatRight[start_indx] < 31) |
| { |
| Int tempInt = q_formatLeft[start_indx] - q_formatRight[start_indx]; |
| |
| /* Normalize the left and right channel to the same q-format */ |
| if (tempInt > 0) |
| { |
| /* |
| * shift_left_chan and shift_right_chan each have an offset |
| * of 1. Even if the left and right channel share the same |
| * q-format, we must shift each by 1 to guard against |
| * overflow. |
| */ |
| Int shift_left_chan = 1 + tempInt; |
| |
| /* |
| * Following code line is equivalent to... |
| * q_formatLeft = q_formatRight - 1; |
| * q_formatRight = q_formatRight - 1; |
| */ |
| q_formatLeft[start_indx] = --(q_formatRight[start_indx]); |
| |
| |
| /* |
| * band_length is always an even number (check tables in pg.66 IS0 14496-3) |
| */ |
| |
| Int32 temp_left = *(pCoefL) >> shift_left_chan; |
| Int32 temp_right = *(pCoefR) >> 1; |
| |
| |
| |
| for (Int i = band_length; i != 0; i--) |
| { |
| *(pCoefL++) = temp_left + temp_right; |
| *(pCoefR++) = temp_left - temp_right; |
| temp_left = *(pCoefL) >> shift_left_chan; |
| temp_right = *(pCoefR) >> 1; |
| |
| } |
| |
| } |
| else |
| { |
| /* |
| * shift_left_chan and shift_right_chan each have an offset |
| * of 1. Even if the left and right channel share the same |
| * q-format, we must shift each by 1 to guard against |
| * overflow. |
| */ |
| Int shift_right_chan = 1 - tempInt; |
| |
| /* |
| * Following code line is equivalent to... |
| * q_formatRight = q_formatLeft - 1; |
| * q_formatLeft = q_formatLeft - 1; |
| */ |
| q_formatRight[start_indx] = --(q_formatLeft[start_indx]); |
| |
| /* |
| * band_length is always an even number (check tables in pg.66 IS0 14496-3) |
| */ |
| |
| Int32 temp_left = *(pCoefL) >> 1; |
| Int32 temp_right = *(pCoefR) >> shift_right_chan; |
| |
| for (Int i = band_length; i != 0; i--) |
| { |
| *(pCoefL++) = temp_left + temp_right; |
| *(pCoefR++) = temp_left - temp_right; |
| |
| temp_left = *(pCoefL) >> 1; |
| temp_right = *(pCoefR) >> shift_right_chan; |
| |
| } |
| } |
| |
| } |
| else |
| { |
| /* |
| * Nothing on right channel, just copy left into right |
| */ |
| q_formatRight[start_indx] = (q_formatLeft[start_indx]); |
| |
| pv_memcpy(pCoefR, pCoefL, band_length*sizeof(*pCoefR)); |
| pCoefR += band_length; |
| pCoefL += band_length; |
| } |
| |
| /* |
| * Increment the window pointers so they point |
| * to the next window in the group |
| */ |
| pCoefL += nextWinPtrUpdate; |
| pCoefR += nextWinPtrUpdate; |
| |
| start_indx += num_bands; |
| |
| } /* for (win_indx) */ |
| |
| return; |
| |
| } /* MS_synt */ |
