/* ------------------------------------------------------------------ * 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 */