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Diffstat (limited to 'media/libstagefright/codecs/aacdec/intensity_right.cpp')
| -rw-r--r-- | media/libstagefright/codecs/aacdec/intensity_right.cpp | 457 |
1 files changed, 457 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/aacdec/intensity_right.cpp b/media/libstagefright/codecs/aacdec/intensity_right.cpp new file mode 100644 index 0000000..106298a --- /dev/null +++ b/media/libstagefright/codecs/aacdec/intensity_right.cpp @@ -0,0 +1,457 @@ +/* ------------------------------------------------------------------ + * 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: intensity_right.c + +------------------------------------------------------------------------------ + REVISION HISTORY + + Description: Modified per review comments. + + Description: Noticed that the code could be more efficient by + using some other method for storing the sign. The code was changed to + use a signed Int to store the table, and an adjustment of the q-format to + reflect the difference between the data being shifted by 16 and the table + being stored in q-15 format. + + Description: Updated pseudocode + + Description: When the multiplication of two 16-bits variables is stored in + an 32-bits variable, the result should be typecasted explicitly + to Int32 before it is stored. + *(pCoefRight++) = (Int32) tempInt2 * multiplier; + + Description: +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + + scalefactor = Multiplier used to scale the data extracted from the left + channel for use on the right. + [const Int] + + coef_per_win = Number of coefficients per window. + (128 for short, 1024 for long) + [const Int] + + sfb_per_win = Number of scalefactor bands per window. This should be + a number divisible by four. + [const Int] + + wins_in_group = The number of windows in the group being decoded. + This number falls within the range 1-8. + [const Int] + + band_length = The length of the scalefactor band being decoded. + This value is divisible by 4. + [const Int] + + codebook = Value that denotes which Huffman codebook was used for + the encoding of this grouped scalefactor band. + [const Int] + + ms_used = Flag that denotes whether M/S is active for this band. + [const Bool] + + q_formatLeft = The Q-format for the left channel's fixed-point spectral + coefficients, on a per-scalefactor band, non-grouped basis. + [const Int *, length MAXBANDS] + + q_formatRight = The Q-format for the right channel's fixed-point spectral + coefficients, on a per-scalefactor band, non-grouped basis. + [Int *, length MAXBANDS] + + coefLeft = Array containing the fixed-point spectral coefficients + for the left channel. + [const Int32 *, length 1024] + + coefRight = Array containing the fixed-point spectral coefficients + for the right channel. + [Int32 *, length 1024] + + Local Stores/Buffers/Pointers Needed: + intensity_factor = Table which stores the values of + 0.5^(0), 0.5^(1/4), 0.5^(2/4) and 0.5^(3/4) + [UInt, length 4] + + Global Stores/Buffers/Pointers Needed: + None + + Outputs: + None + + Pointers and Buffers Modified: + coefRight[] Contains the new spectral information + + q_formatRight[] Q-format may be updated with changed fixed-point + data in coefRight. + + Local Stores Modified: + None + + Global Stores Modified: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + This function applies Intensity Stereo, generating data on the right channel + that is derived from data on the Left. A scalefactor is applied using the + following formula... + + RightCh = LeftCh*0.5^(scalefactor/4) + + This function works for one scalefactor band, which may belong to a group. + (i.e. the same scalefactor band repeated across multiple windows belonging + to one group.) + +------------------------------------------------------------------------------ + REQUIREMENTS + + codebook must be either INTENSITY_HCB or INTENSITY_HCB2 when this function + is called. + + ms_used must be 1 when TRUE, 0 when FALSE. + + wins_in_group falls within the range [1-8] + +------------------------------------------------------------------------------ + REFERENCES + + (1) ISO/IEC 14496-3:1999(E) + Part 3 + Subpart 4.6.7.2.3 Decoding Process (Intensity Stereo) + + (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 + multiplier = codebook AND 0x1; + + multiplier = multiplier XOR ms_used; + + multiplier = multiplier << 1; + + multiplier = multiplier - 1; + + multiplier = multiplier * intensity_factor[scalefactor & 0x3]; + + scf_div_4 = (scalefactor >> 2); + + nextWinPtrUpdate = (coef_per_win - band_length); + + FOR (win_indx = wins_in_group; win_indx > 0; win_indx--) + + *(pQformatRight) = scf_div_4 + *(pQformatLeft) - 1; + + FOR (tempInt = band_length; tempInt > 0; tempInt--) + tempInt2 = (Int)(*(pCoefLeft) >> 16); + + *(pCoefRight) = tempInt2 * multiplier; + + pCoefRight = pCoefRight + 1; + pCoefLeft = pCoefLeft + 1; + + ENDFOR + + pCoefRight = pCoefRight + nextWinPtrUpdate; + pCoefLeft = pCoefLeft + nextWinPtrUpdate; + + pQformatRight = pQformatRight + sfb_per_win; + pQformatLeft = pQformatLeft + sfb_per_win; + 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 "intensity_right.h" +#include "e_huffmanconst.h" + +#include "fxp_mul32.h" +#include "aac_mem_funcs.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 +----------------------------------------------------------------------------*/ +const Int16 intensity_factor[4] = +{ + 32767, /* (0.5^0.00)*2^15 - 1 (minus 1 for storage as type Int) */ + 27554, /* (0.5^0.25)*2^15 */ + 23170, /* (0.5^0.50)*2^15 */ + 19484 +}; /* (0.5^0.75)*2^15 */ + + +/*---------------------------------------------------------------------------- +; 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 intensity_right( + const Int scalefactor, + const Int coef_per_win, + const Int sfb_per_win, + const Int wins_in_group, + const Int band_length, + const Int codebook, + const Bool ms_used, + const Int q_formatLeft[], + Int q_formatRight[], + const Int32 coefLeft[], + Int32 coefRight[]) + +{ + const Int32 *pCoefLeft = coefLeft; + Int32 *pCoefRight = coefRight; + + const Int *pQformatLeft = q_formatLeft; + Int *pQformatRight = q_formatRight; + + Int multiplier; + Int scf_div_4; + Int nextWinPtrUpdate; + + /* + * The sign of the intensity multiplier obeys the following table... + * + * codebook | ms_used | multiplier + * -------------------------------------- + * INTENSITY_HCB | TRUE | -1 + * INTENSITY_HCB | FALSE | +1 + * INTENSITY_HCB2 | TRUE | +1 + * INTENSITY_HCB2 | FALSE | -1 + * + * In binary, the above table is represented as... + * + * codebook | ms_used | multiplier + * -------------------------------------- + * 1111b | 1 | -1 + * 1111b | 0 | +1 + * 1110b | 1 | +1 + * 1110b | 0 | -1 + * + */ + + /* + * Deriving the correct value for "multiplier" is illustrated + * below for all 4 possible combinations of codebook and ms_used + */ + + /* + * 1111b AND 0x1 = 1b + * 1111b AND 0x1 = 1b + * 1110b AND 0x1 = 0b + * 1110b AND 0x1 = 0b + */ + multiplier = (codebook & 0x1); + + /* + * 1b XOR 1 = 0b + * 1b XOR 0 = 1b + * 0b XOR 1 = 1b + * 0b XOR 0 = 0b + */ + multiplier ^= ms_used; + + /* + * 0b << 1 = 0 + * 1b << 1 = 2 + * 1b << 1 = 2 + * 0b << 1 = 0 + */ + multiplier <<= 1; + + /* + * 0 - 1 = -1 + * 2 - 1 = +1 + * 2 - 1 = +1 + * 0 - 1 = -1 + */ + multiplier--; + + multiplier *= intensity_factor[scalefactor & 0x3]; + + scf_div_4 = (scalefactor >> 2); + + /* + * Step through all the windows in this group, replacing this + * band in each window's spectrum with + * left-channel correlated data + */ + + nextWinPtrUpdate = (coef_per_win - band_length); + + for (Int win_indx = wins_in_group; win_indx > 0; win_indx--) + { + + /* + * Calculate q_formatRight + * + * q_formatLeft must be included, since the values + * on the right-channel are derived from the values + * on the left-channel. + * + * scalefactor/4 is included, since the intensity + * formula is RightCh = LeftCh*0.5^(scalefactor/4) + * + * powers of 0.5 increase the q_format by 1. + * (Another way to multiply something by 0.5^(x) + * is to increase its q-format by x.) + * + * Finally the q-format must be decreased by 1. + * The reason for this is because the table is stored + * in q-15 format, but we are shifting by 16 to do + * a 16 x 16 multiply. + */ + + *(pQformatRight) = scf_div_4 + *(pQformatLeft); + + /* + * reconstruct right intensity values + * + * to make things faster, this for loop + * can be partially unrolled, since band_length is a multiple + * of four. + */ + + + if (multiplier == 32767) + { + Int32 tempInt2 = *(pCoefLeft++); + Int32 tempInt22 = *(pCoefLeft++); + + for (Int tempInt = band_length >> 1; tempInt > 0; tempInt--) + { + *(pCoefRight++) = tempInt2; + *(pCoefRight++) = tempInt22; + tempInt2 = *(pCoefLeft++); + tempInt22 = *(pCoefLeft++); + } + + } + else + { + + Int32 tempInt2 = *(pCoefLeft++); + Int32 tempInt22 = *(pCoefLeft++); + for (Int tempInt = band_length >> 1; tempInt > 0; tempInt--) + { + *(pCoefRight++) = fxp_mul32_by_16(tempInt2, multiplier) << 1; + *(pCoefRight++) = fxp_mul32_by_16(tempInt22, multiplier) << 1; + tempInt2 = *(pCoefLeft++); + tempInt22 = *(pCoefLeft++); + } + } + + /* + * Set pCoefRight and pCoefLeft to the beginning of + * this sfb in the next window in the group. + */ + + pCoefRight += nextWinPtrUpdate; + pCoefLeft += (nextWinPtrUpdate - 2); + + /* + * Update pQformatRight and pQformatLeft to this sfb in + * in the next window in the group. + */ + + pQformatRight += sfb_per_win; + pQformatLeft += sfb_per_win; + + } /* for (win_indx) */ + + +} /* void intensity_right */ |