/* ------------------------------------------------------------------ * 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: pns_left.c ------------------------------------------------------------------------------ REVISION HISTORY Description: Modified from original shareware code Description: Brought code in-line with PV standards. Merged PNS and Intensity blocks into one function. Modified routine to interface with a fixed-point implementation. Modified variable names for clarity. Improved for-loop structure that was previously checking the codebook used in each scale factor band multiple times. Description: Added some comments for clarity. Description: Changed strategy for q-format. Q-format for SFBs should not be grouped. Description: Function had to be modified to obey new interpretation of the sfb_prediction_used flag. LTP takes precedence, and PNS should not be executed when a collision occurs between these two tools. Description: (1) Added flag "ltp_data_present" (2) Where feasible, I updated the code to resemble right_ch_sfb_tools_ms.c Just for conformance, readability. Description: Added include file - "e_huffmanconst.h" Description: The same "Factors" pointer indexing problem that existed in right_ch_sfb_tools_ms also existed here in pns_left.c Description: Modified how groups and windows are handled, as the multigroup case was not correct Who: Date: Description: ------------------------------------------------------------------------------ INPUT AND OUTPUT DEFINITIONS Inputs: const FrameInfo *pFrameInfo = Pointer to structure that holds information about each group. (long block flag, number of windows, scalefactor bands per group, etc.) const Int group[] = Array that contains indexes of the the first window in the next group. const Int codebook_map[] = Array that denotes which Huffman codebook was used for the encoding of each scalefactor band. const Int factors[] = Array of scalefactors Int sfb_prediction_used[] = Flag that denotes the activation of long term prediction on a sfb basis. Bool ltp_data_present = Flag that denotes whether LTP is active for the entire frame. If this flag is FALSE, sfb_prediction_used is garbage. Int32 spectral_coef[] = Array of pointers pointing to the spectral coef's for the LEFT channel. Int q_format[] = Q-format for the information pointed to by spectral_coef. Indexed by scalefactor band. Int32 *pCurrentSeed = Pointer to the current seed for the random number generator. (gen_rand_vector) Local Stores/Buffers/Pointers Needed: Global Stores/Buffers/Pointers Needed: Outputs: Pointers and Buffers Modified: Int32 spectral_coef[] = Contains the new spectral information Local Stores Modified: Global Stores Modified: ------------------------------------------------------------------------------ FUNCTION DESCRIPTION The function steps through each scalefactor band in the group, and checks for the use of Huffman codebook NOISE_HCB. When a SFB utilizing NOISE_HCB is detected, the band in every window in the group has its spectral information filled with scaled random data. The scaled random data is generated by the function gen_rand_vector. ------------------------------------------------------------------------------ REQUIREMENTS This module shall replace bands that were encoded with the Huffman codebook NOISE_HCB with random noise as returned from gen_rand_vector(). The result shall be perceptually indistinguishable from the result obtained by the ISO decoder. ------------------------------------------------------------------------------ REFERENCES (1) ISO/IEC 14496-3:1999(E) Part 3 Subpart 4.5.5 Figures Subpart 4.6.2 ScaleFactors Subpart 4.6.12 Perceptual Noise Substituion (PNS) (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 pFirst_Window_Coefs = spectral_coef; window_start = 0; tot_sfb = 0; DO num_bands = pFrameInfo->sfb_per_win[window_start]; pBand = pFrameInfo->win_sfb_top[window_start]; partition = *(pGroup); pGroup = pGroup + 1; band_start = 0; coef_per_win = pFrameInfo->coef_per_win[window_start]; wins_in_group = (partition - window_start); FOR (sfb = num_bands; sfb > 0; sfb--) band_stop = *pBand; pBand = pBand + 1; IF (*(pCodebookMap++) == NOISE_HCB ) tempInt = sfb_prediction_used[tot_sfb] AND ltp_data_present; IF (tempInt == FALSE) pWindow_Coef = pFirst_Window_Coefs + band_start; band_length = (band_stop - band_start); start_indx = tot_sfb; tempInt = *(pFactors); FOR (win_indx = wins_in_group; win_indx > 0; win_indx--) CALL gen_rand_vector( pWindow_CoefR, band_length, pCurrentSeed, tempInt); MODIFYING pWindow_CoefR = scaled random noise pCurrentSeed = current state of the random noise generator. RETURNING q_format[start_indx] = q-format for this sfb. pWindow_Coef = pWindow_Coef + coef_per_win; start_indx = start_indx + pFrameInfo->sfb_per_win[win_indx]; ENDFOR ENDIF ENDIF band_start = band_stop; tot_sfb = tot_sfb + 1; pFactors = pFactors + 1; ENDFOR coef_per_win = coef_per_win * wins_in_group; wins_in_group = wins_in_group - 1; tot_sfb = tot_sfb + num_bands * wins_in_group; pFactors = pFactors + num_bands * wins_in_group; pFirst_Window_Coefs = pFirst_Window_Coefs + coef_per_win; window_start = partition; WHILE (partition < pFrameInfo->num_win); ------------------------------------------------------------------------------ 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 "pns_left.h" #include "e_huffmanconst.h" #include "gen_rand_vector.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 pns_left( const FrameInfo *pFrameInfo, const Int group[], const Int codebook_map[], const Int factors[], const Int sfb_prediction_used[], const Bool ltp_data_present, Int32 spectral_coef[], Int q_format[], Int32 *pCurrentSeed) { Int tot_sfb; Int start_indx; Int sfb; Int band_stop; const Int16 *pBand; const Int *pCodebookMap = &(codebook_map[0]); const Int *pGroup = &(group[0]); const Int *pFactors = &(factors[0]); Int tempInt; Int32 *pWindow_Coef; Int32 *spec; Int partition; Int win_indx; tot_sfb = 0; spec = spectral_coef; /* PNS goes by group */ win_indx = 0; partition = 0; do { Int num_bands = pFrameInfo->sfb_per_win[partition]; pBand = pFrameInfo->win_sfb_top[partition]; /*---------------------------------------------------------- Partition is equal to the first window in the next group { Group 0 }{ Group 1 }{ Group 2 }{Group 3} [win 0][win 1][win 2][win 3][win 4][win 5][win 6][win 7] pGroup[0] = 2 pGroup[1] = 5 pGroup[2] = 7 pGroup[3] = 8 -----------------------------------------------------------*/ partition = *pGroup++; /* partition = index of last sbk in group */ do { Int band_start = 0; for (sfb = 0; sfb < num_bands; sfb++) { band_stop = pBand[sfb]; /* band is offset table, band_stop is last coef in band */ Int band_length = band_stop - band_start; if (pCodebookMap[sfb] == NOISE_HCB) { tempInt = sfb_prediction_used[tot_sfb] & ltp_data_present; if (tempInt == FALSE) { /* generate random noise */ pWindow_Coef = spec + band_start; tempInt = pFactors[sfb]; start_indx = tot_sfb++; /* reconstruct noise substituted values */ /* generate random noise */ q_format[start_indx] = gen_rand_vector(pWindow_Coef, band_length, pCurrentSeed, tempInt); } /* if (sfb_prediction_used[tot_sfb] == FALSE) */ } /* if (*(pCodebookMap++) == NOISE_HCB) */ else { tot_sfb ++; /* update absolute sfb counter */ } band_start = band_stop; } /* for (sfb) */ spec += pFrameInfo->coef_per_win[win_indx++]; pFactors += num_bands; } while (win_indx < partition); pCodebookMap += pFrameInfo->sfb_per_win[win_indx-1]; } while (partition < pFrameInfo->num_win); return; } /* pns */