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Diffstat (limited to 'media/libstagefright/codecs/aacdec/get_ics_info.cpp')
| -rw-r--r-- | media/libstagefright/codecs/aacdec/get_ics_info.cpp | 608 |
1 files changed, 608 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/aacdec/get_ics_info.cpp b/media/libstagefright/codecs/aacdec/get_ics_info.cpp new file mode 100644 index 0000000..17204cc --- /dev/null +++ b/media/libstagefright/codecs/aacdec/get_ics_info.cpp @@ -0,0 +1,608 @@ +/* ------------------------------------------------------------------ + * 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: ./src/get_ics_info.c + +------------------------------------------------------------------------------ + REVISION HISTORY + + Description: Modified from original shareware code + + Description: Modified to pass variables by reference to eliminate use + of global variables. + + Description: Clean up code. + + Description: Fix comments before review, remove lpflag[] + + Description: Update per review comments, and match ISO/IEC 14496-3 + + Description: Update per peer review comments. + + Description: Remove "rollback" of used bits, since lt_decode is to change. + + Description: Replace some instances of getbits to get9_n_lessbits + when the number of bits read is 9 or less and get1bits + when only 1 bit is read. + + Who: Date: + Description: + +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + audioObjectType = MP4 Audio Object Type for the current song. Only if + this is set to LTP (MP4AUDIO_LTP) will long term + prediction bits be retrieved. Data type + tMP4AudioObjectType, which is an enumeration, which in + turn is an Int. + + pInputStream = pointer to a BITS structure, used by the function getbits + to provide data. This is the second parameter to this + function to match its position in getbits(). + Data type pointer to BITS structure + + common_window = field read in huffdecode, which tells whether information + is shared between the left and right channel. Long term + prediction (LTP) data is NOT shared even if its a common + window, so this flag is needed to see if another set of + LTP possibly needs to be read. If this flag is false, + pSecondLTPStatus is not touched, it could be NULL if + need be. Data type Bool, which is Int. + + pWindowSequence = pointer to where the the window type of the current + frame and channel should be placed, of data type + WINDOW_SEQUENCE, which is Int. It can take on one + of four values: ONLY_LONG_SEQUENCE, LONG_START_SEQUENCE, + EIGHT_SHORT_SEQUENCE, LONG_STOP_SEQUENCE, + + pWindowShape = pointer to where the window shape for the current frame + and channel should be placed, of data type WINDOW_SHAPE, + which is Int. It can take on the one of these two values: + SINE_WINDOW, KAISER_BESSEL_WINDOW. It is used in the + "filterbank" section of decoding. + + group = array that holds the index of the first window in each + group. Data type array of Int, eight elements. + + p_max_sfb = pointer to where the maximum number of scale factor bands + for the current frame and channel will be placed. Data + type of pointer to Int. + + p_winmap = array of pointers to all of the possible four window + configurations. This parameter did not need to be pointers, + and could be changed in the future. Data type array of pointers + to FrameInfo structures, length 4. + + pFirstLTPStatus = pointer to a structure where the first LTP + information will be stored. It would be confusing and wrong + to call this left LTP status since if common_window = FALSE, + this function will be called twice - once for the left, once + for the right. It could be done, but extra conditional code + would need to be done. + Data type pointer to LT_PRED_STATUS structure. + + pSecondLTPStatus = pointer to where the right channel of LTP + information will be stored only if common_window is non-zero. + Data type pointer to LT_PRED_STATUS structure. + + Local Stores/Buffers/Pointers Needed: None. + + Global Stores/Buffers/Pointers Needed: None. + + Outputs: + status = 0 implies no error occurred, non-zero otherwise. + + Pointers and Buffers Modified: + pInputStream contents are modified in such a way that the number of bits + read increases. + pWindowSequence contents are updated with the current window for this + frame and channel + group[] contents will be modified to grouping information. See getgroup + source code for a better description of what this is. + p_max_sfb contents will be updated with the maximum scale factor bands + for this frame and channel. + pFirstLTPStatus contents may be updated if the stream has long term + prediction information. + pSecondLTPStatus contents may be updated if common_window != 0 and LTP data + is present. + + + Local Stores Modified: None + + Global Stores Modified: None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + This function retrieves the individual channel stream (ICS) information + from the bitstream. The information read for the current + frame and channel is: + - window sequence + - window shape for use in the filter bank + - number of scale factor bands + - long term predication (LTP) information + - grouping information + + This function does NOT support MPEG2 style AAC Frequency Domain Predictor, + not to be confused with LTP (Long Term Prediction). If such data is found + to be on the file an error is generated. + +------------------------------------------------------------------------------ + REQUIREMENTS + + This function is not to use static or global data. + +------------------------------------------------------------------------------ + REFERENCES + + (1) ISO/IEC 14496-3:1999(E) Titled "Information technology - Coding + of audio-visual objects Part 3: Audio Subpart 4:" + Table 4.4.6 - Syntax of ics_info(), page 16. + + + (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 + + status = 0; + first_ltp_data_present = FALSE; + second_ltp_data_present = FALSE; + + + CALL getbits( + neededBits = LEN_ICS_RESERV + LEN_WIN_SEQ + LEN_WIN_SH, + pInputStream = pInputStream) + MODIFYING( pInputStream ) + RETURNING( temp = returnValue ) + + windowSequence = (temp >> LEN_WIN_SH) & ((0x1<<LEN_WIN_SEQ)-1); + + *pWindowShape = (temp) & ((0x1<<LEN_WIN_SH)-1); + + IF (windowSequence == EIGHT_SHORT_SEQUENCE) + THEN + CALL getbits( + neededBits = LEN_MAX_SFBS, + pInputStream = pInputStream) + MODIFYING(pInputStream) + RETURNING(local_max_sfb = returnValue) + + CALL getgroup( + group = group, + pInputStream = pInputStream) + MODIFYING(group) + MODIFYING(pInputStream) + RETURNING(nothing) + + + ELSE + + group[0] = 1; + + CALL getbits( + neededBits = LEN_MAX_SFBL + LEN_PREDICTOR_DATA_PRESENT, + pInputStream = pInputStream) + MODIFYING(pInputStream) + RETURNING(temp = returnValue) + + predictor_data_present = + (Bool) getbits( + LEN_BOOLEAN, + pInputStream); + + local_max_sfb = (Int)(temp >> LEN_PREDICTOR_DATA_PRESENT); + + predictor_data_present = + (Bool) (temp & ((0x1 << LEN_PREDICTOR_DATA_PRESENT)-1)); + + IF (local_max_sfb > allowed_max_sfb) + THEN + status = 1 + ELSEIF (audioObjectType == MP4AUDIO_LTP) + THEN + IF (predictor_data_present != FALSE) + THEN + CALL getbits( + neededBits = LEN_LTP_DATA_PRESENT, + pInputStream = pInputStream) + MODIFYING(pInputStream) + RETURNING(first_ltp_data_present = returnValue) + + IF (ltp_data_present != FALSE) + THEN + + CALL lt_decode( + win_type = windowSequence, + pInputStream = pInputStream, + max_sfb = local_max_sfb, + pLt_pred = pFirstLTPStatus) + MODIFYING(pInputStream) + MODIFYING(pFirstLTPStatus) + RETURNING(nothing) + + ENDIF + + IF (common_window != FALSE) + THEN + CALL getbits( + neededBits = LEN_LTP_DATA_PRESENT, + pInputStream = pInputStream) + MODIFYING(pInputStream) + RETURNING(second_ltp_data_present = returnValue) + + IF (second_ltp_data_present != FALSE) + THEN + + CALL lt_decode( + win_type = windowSequence, + pInputStream = pInputStream, + max_sfb = local_max_sfb, + pLt_pred = pSecondLTPStatus) + MODIFYING(pInputStream) + MODIFYING(pSecondLTPStatus) + RETURNING(nothing) + ENDIF + ENDIF + ENDIF + ELSE + IF (predictor_data_present != FALSE) + THEN + status = 1 + ENDIF + END IF + ENDIF + + pFirstLTPStatus->ltp_data_present = first_ltp_data_present; + + IF (common_window != FALSE) + THEN + pSecondLTPStatus->ltp_data_present = second_ltp_data_present; + ENDIF + + pFrameInfo = p_winmap[*p_wnd]; + IF (local_max_sfb > pFrameInfo->sfb_per_frame) + THEN + status = 1; + ENDIF + + *(p_max_sfb) = local_max_sfb; + + MODIFY(*(pWindowSequence)) + MODIFY(*(pWinShape)) + MODIFY(*(p_max_sfb)) + MODIFY(group[]) + MODIFY(*pInputStream) + MODIFY(*pFirstLTPStatus) + MODIFY(*pSecondLTPStatus) + RETURN (status); + + + +------------------------------------------------------------------------------ + RESOURCES USED + When the code is written for a specific target processor the + 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 "e_rawbitstreamconst.h" +#include "e_tmp4audioobjecttype.h" + +#include "s_bits.h" +#include "s_frameinfo.h" +#include "s_lt_pred_status.h" + +#include "ibstream.h" +#include "lt_decode.h" +#include "ltp_common_internal.h" /* For LEN_LTP_DATA_PRESENT constant */ + +#include "get_ics_info.h" +#include "huffman.h" /* For the declaration of getgroup */ + +/*---------------------------------------------------------------------------- +; MACROS +; Define module specific macros here +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; DEFINES +; Include all pre-processor statements here. Include conditional +; compile variables also. +----------------------------------------------------------------------------*/ + +#define LEN_PREDICTOR_DATA_PRESENT (1) + +/*---------------------------------------------------------------------------- +; LOCAL FUNCTION DEFINITIONS +; Function Prototype declaration +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL VARIABLE DEFINITIONS +; Variable declaration - defined here and used outside this module +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; EXTERNAL FUNCTION REFERENCES +; Declare functions defined elsewhere and referenced in this module +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; EXTERNAL VARIABLES REFERENCES +; Declare variables used in this module but defined elsewhere +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; FUNCTION CODE +----------------------------------------------------------------------------*/ + +Int get_ics_info( + const tMP4AudioObjectType audioObjectType, + BITS *pInputStream, + const Bool common_window, + WINDOW_SEQUENCE *pWindowSequence, + WINDOW_SHAPE *pWindowShape, + Int group[], + Int *p_max_sfb, + FrameInfo *p_winmap[], + LT_PRED_STATUS *pFirstLTPStatus, + LT_PRED_STATUS *pSecondLTPStatus) +{ + WINDOW_SEQUENCE windowSequence; + UInt temp; + Bool predictor_data_present; + UInt local_max_sfb; + UInt allowed_max_sfb; + Int status = SUCCESS; + Bool first_ltp_data_present = FALSE; + Bool second_ltp_data_present = FALSE; + + /* + * The following three calls to getbits have been replaced with one + * call for speed: + * + * getbits(LEN_ICS_RESERV, pInputStream); + * windowSequence = getbits(LEN_WIN_SEQ, pInputStream); + * *pWindowShape = getbits(LEN_WIN_SH, pInputStream); + * + */ + + temp = + get9_n_lessbits( + LEN_ICS_RESERV + LEN_WIN_SEQ + LEN_WIN_SH, + pInputStream); + + + windowSequence = (WINDOW_SEQUENCE)((temp >> LEN_WIN_SH) & ((0x1 << LEN_WIN_SEQ) - 1)); + + *pWindowShape = (WINDOW_SHAPE)((temp) & ((0x1 << LEN_WIN_SH) - 1)); + + /* + * This pointer should not be NULL as long as the initialization code + * has been run, so the test for NULL has been removed. + */ + allowed_max_sfb = p_winmap[windowSequence]->sfb_per_win[0]; + + if (windowSequence == EIGHT_SHORT_SEQUENCE) + { + local_max_sfb = get9_n_lessbits(LEN_MAX_SFBS, + pInputStream); + + getgroup( + group, + pInputStream); + + if (local_max_sfb > allowed_max_sfb) + { + status = 1; /* ERROR CODE - needs to be updated */ + } + + } /* end of TRUE of if (windowSequence == EIGHT_SHORT_SEQUENCE) */ + else + { + /* There is only one group for long windows. */ + group[0] = 1; + + /* + * The window is long, get the maximum scale factor bands, + * and get long term prediction info. + * + * Reference [1] states that the audioObjectType is first tested, + * then the predictor_data_present is read on either branch of the + * if (audioObjectType == MP4AUDIO_LTP). Instead, this code combines + * the two calls on both branches into one before the + * if, and then in turn combines with another call to getbits, all + * in the name of speed. + * + * This would be the individual calls, without checking the number + * of scale factor bands: + * + * local_max_sfb = + * (Int) getbits( + * LEN_MAX_SFBL, + * pInputStream); + * + * if (audioObjectType == MP4AUDIO_LTP) + * { + * predictor_data_present = + * (Bool) getbits( + * LEN_PREDICTOR_DATA_PRESENT, + * pInputStream); + * + * ..... (read LTP data) + * + * } + * else + * { + * + * predictor_data_present = + * (Bool) getbits( + * LEN_PREDICTOR_DATA_PRESENT, + * pInputStream); + * + * ..... (its an error for this library) + * } + */ + temp = + get9_n_lessbits( + LEN_MAX_SFBL + LEN_PREDICTOR_DATA_PRESENT, + pInputStream); + + local_max_sfb = (Int)(temp >> LEN_PREDICTOR_DATA_PRESENT); + + predictor_data_present = + (Bool)(temp & ((0x1 << LEN_PREDICTOR_DATA_PRESENT) - 1)); + + if (local_max_sfb > allowed_max_sfb) + { + status = 1; /* ERROR CODE - needs to be updated */ + } + else if (audioObjectType == MP4AUDIO_LTP) + { + /* + * Note that the predictor data bit has already been + * read. + */ + + /* + * If the object type is LTP, the predictor data is + * LTP. If the object type is not LTP, the predictor data + * is so called "frequency predictor data", which is not + * supported by this implementation. Refer to (1) + */ + if (predictor_data_present != FALSE) + { + first_ltp_data_present = + (Bool) get1bits(/* LEN_LTP_DATA_PRESENT,*/ + pInputStream); + + if (first_ltp_data_present != FALSE) + { + lt_decode( + windowSequence, + pInputStream, + local_max_sfb, + pFirstLTPStatus); + } + if (common_window != FALSE) + { + second_ltp_data_present = + (Bool) get1bits(/* LEN_LTP_DATA_PRESENT,*/ + pInputStream); + + if (second_ltp_data_present != FALSE) + { + lt_decode( + windowSequence, + pInputStream, + local_max_sfb, + pSecondLTPStatus); + } + } /* if (common_window != FALSE) */ + + } /* if (predictor_data_present != FALSE) */ + + } /* else if (audioObjectType == MP4AUDIO_LTP) */ + else + { + /* + * Note that the predictor data bit has already been + * read. + */ + + /* + * The object type is not LTP. If there is data, its + * frequency predictor data, not supported by this + * implementation. + */ + if (predictor_data_present != FALSE) + { + status = 1; /* ERROR CODE UPDATE LATER */ + } /* if (predictor_data_present != FALSE) */ + + } /* end of "else" clause of if (audioObjectType == MP4AUDIO_LTP) */ + + } /* if (windowSequence == EIGHT_SHORT_SEQUENCE) [FALSE branch] */ + + + /* + * Save all local copies. + */ + pFirstLTPStatus->ltp_data_present = first_ltp_data_present; + if (common_window != FALSE) + { + pSecondLTPStatus->ltp_data_present = second_ltp_data_present; + } + + *p_max_sfb = local_max_sfb; + + *pWindowSequence = windowSequence; + + return (status); + +} /* get_ics_info */ + |