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/* ------------------------------------------------------------------
* 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/calc_gsfb_table.c
------------------------------------------------------------------------------
REVISION HISTORY
Description: Modified from original shareware code
Description: (1) Modified to bring in-line with PV standards
(2) Removed if(pFrameInfo->islong), only short windows will
call this routine from getics.c
Description: Modified per review comments
Who: Date:
Description:
------------------------------------------------------------------------------
INPUT AND OUTPUT DEFINITIONS
Inputs:
pFrameInfo = pointer to structure that holds information for current
frame. Data type FrameInfo
group[] = array that contains the grouping information of short
windows (stop index of windows in each group).
Data type Int
Local Stores/Buffers/Pointers Needed:
None
Global Stores/Buffers/Pointers Needed:
None
Outputs:
None
Pointers and Buffers Modified:
pFrameInfo -> frame_sfb_top contains the cumulative bandwidth of
scalefactor bands in each group
Local Stores Modified:
None
Global Stores Modified:
None
------------------------------------------------------------------------------
FUNCTION DESCRIPTION
This function is only invoked when short windows are present. It calculates
the number of groups in one frame, and the scalefactor bandwidth of each
scalefactor band in each group.
All windows within one group share the same scalefactors and are interleaved
on a scalefactor band basis. Within each group, the actual length of one
scalefactor band equals to the number of windows times the number of
coefficients in a regular scalefactor band.
------------------------------------------------------------------------------
REQUIREMENTS
This function shall replace the contents of pFrameInfo->frame_sfb_top
with the cumulative bandwidth of each scalefactor band in each group
------------------------------------------------------------------------------
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 p54. 4.5.2.3.2 decoding process
------------------------------------------------------------------------------
PSEUDO-CODE
offset = 0;
group_idx = 0;
DO
pFrameInfo->group_len[group_idx] = group[group_idx] - offset;
offset = group[group_idx];
group_idx++;
WHILE (offset < NUM_SHORT_WINDOWS);
pFrameInfo->num_groups = group_idx;
pFrameSfbTop = pFrameInfo->frame_sfb_top;
offset = 0;
FOR (group_idx = 0; group_idx < pFrameInfo->num_groups; group_idx++)
len = pFrameInfo->group_len[group_idx];
FOR (sfb = 0; sfb < pFrameInfo->sfb_per_win[group_idx]; sfb++)
offset += pFrameInfo->sfb_width_128[sfb] * len;
*pFrameSfbTop++ = offset;
ENDFOR
ENDFOR
------------------------------------------------------------------------------
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 "huffman.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
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; 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 calc_gsfb_table(
FrameInfo *pFrameInfo,
Int group[])
{
Int group_idx;
Int offset;
Int *pFrameSfbTop;
Int *pSfbWidth128;
Int sfb;
Int nsfb;
Int len;
Int ngroups;
/* clear out the default values set by infoinit */
/* */
pv_memset(pFrameInfo->frame_sfb_top,
0,
MAXBANDS*sizeof(pFrameInfo->frame_sfb_top[0]));
/* */
/* first calculate the group length*/
offset = 0;
ngroups = 0;
do
{
pFrameInfo->group_len[ngroups] = group[ngroups] - offset;
offset = group[ngroups];
ngroups++;
}
while (offset < NUM_SHORT_WINDOWS);
/* calculate the cumulative scalefactor bandwidth for one frame */
pFrameInfo->num_groups = ngroups;
pFrameSfbTop = pFrameInfo->frame_sfb_top;
offset = 0;
for (group_idx = 0; group_idx < ngroups; group_idx++)
{
len = pFrameInfo->group_len[ group_idx];
nsfb = pFrameInfo->sfb_per_win[group_idx];
pSfbWidth128 = pFrameInfo->sfb_width_128;
for (sfb = nsfb; sfb > 0; sfb--)
{
offset += *pSfbWidth128++ * len;
*pFrameSfbTop++ = offset;
}
}
} /* calc_gsfb_table */
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