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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: get_tns.c
+
+ Date: 10/25/2000
+
+------------------------------------------------------------------------------
+ REVISION HISTORY
+
+ Description: Modified from original shareware code
+
+ Description: Modified to pass variables by reference to eliminate use
+ of global variables.
+
+ Description: Brought code in-line with PV standards. Some minor
+ optimizations (count-down for loops, etc.) were made.
+
+ Description: Made cosmetic changes as suggested during review. Also,
+ changed calculation of s_mask and n_mask from table-based to being
+ calculated based on res_index. Also, the flag coef_res was changed
+ from having a range of [3,4] to having a range of [0,1], which corresponds
+ exactly with the true value that is passed via the bitstream.
+
+ Description: Modified to use more efficient TNS memory structure.
+
+ Description: Updated to reflect more efficient usage of memory by the TNS
+ filters.
+
+ Description: Updated the SW template to include the full pathname to the
+ source file and a slightly modified copyright header.
+
+ Description: Moved pInputStream to be the 2nd parameter, for a slight
+ optimization on some platforms.
+
+ Description: Moved pSfbTop outside of the loops, since its value does
+ not change.
+
+ Description: Replace some instances of getbits to get1bits
+ when only 1 bit is read.
+
+ Who: Date:
+ Description:
+
+------------------------------------------------------------------------------
+ INPUT AND OUTPUT DEFINITIONS
+
+ Inputs:
+ FrameInfo *pFrameInfo
+ Pointer to structure that holds information about each block.
+ (long block flag,
+ number of subblocks,
+ scalefactor bands per subblock, etc.)
+
+ BITS *pInputStream
+ Pointer to a BITS structure that is
+ passed on to function getbits to pull information from the bitstream.
+
+ TNS_Frame_info *pTnsFrameInfo
+ Pointer to filter data structure - to be populated by this function.
+
+ Local Stores/Buffers/Pointers Needed:
+ None
+
+ Global Stores/Buffers/Pointers Needed:
+ None
+
+ Outputs:
+ None
+
+ Pointers and Buffers Modified:
+ TNS_frame_info *pTnsFrameInfo
+
+ pTnsFrameInfo->n_filt = Number of tns filters to be applied to the data.
+
+ pTnsFrameInfo->filt[]->order = The order of each individual TNS filter.
+
+ pTnsFrameInfo->filt[]->coef_res = The resolution of the filter coefficients
+
+ pTnsFrameInfo->filt[]->start_band = start of spectral band
+
+ pTnsFrameInfo->filt[]->stop_band = end of spectral band
+
+ pTnsFrameInfo->filt[]->coef[] = Each filter's coefficients are filled with
+ data read from the input bitstream.
+
+ pTnsFrameInfo->filt[]->direction = A flag is set for each TNS filter.
+
+ If the direction flag (on the bitstream) = 0, then the filter
+ is applied to the block of spectral data in normal (upward) fashion.
+
+ If the direction flag (on the bitstream) = 1, then the filter
+ is applied in a reverse (downward) fashion.
+ (Starting with the last element in the block of data.)
+
+ The value stored in filt[]->direction maps the values [0,1] to [1,-1] for
+ a more intuitive storage of this flag's meaning.
+
+ Local Stores Modified:
+
+ Global Stores Modified:
+
+
+------------------------------------------------------------------------------
+ FUNCTION DESCRIPTION
+
+ This function reads the TNS filter information from the bitstream, and stores
+ the filter order, LPC coefficients, and the number of TNS filters to
+ be applied in the structure TNS_frame_info.
+
+------------------------------------------------------------------------------
+ REQUIREMENTS
+
+ This code should match the ISO code in functionality, with the exception
+ that coef_res has range of [0,1] (PV code) instead of [3,4] (ISO code)
+
+ coef_res is only used by tns_decode_coef.
+
+------------------------------------------------------------------------------
+ REFERENCES
+ (1) ISO/IEC 14496-3:1999(E)
+ Part 3
+ Subpart 4.6.8 (Temporal Noise Shaping)
+
+ (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
+
+
+------------------------------------------------------------------------------
+ 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 "get_tns.h"
+#include "s_mc_info.h"
+#include "s_frameinfo.h"
+#include "s_tnsfilt.h"
+#include "s_tns_frame_info.h"
+#include "s_bits.h"
+#include "ibstream.h"
+#include "e_window_sequence.h"
+#include "e_progconfigconst.h"
+
+#include "tns_decode_coef.h"
+
+
+/*----------------------------------------------------------------------------
+; MACROS
+; Define module specific macros here
+----------------------------------------------------------------------------*/
+#define SCALE_FACTOR_BAND_OFFSET(x) ( ((x) > 0) ? pSFB_top[(x)-1] : 0 )
+#define MINIMUM(x,y) ( ((x) < (y)) ? (x) : (y) )
+
+/*----------------------------------------------------------------------------
+; 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
+----------------------------------------------------------------------------*/
+/*
+ * The entries in the ensuing tables provide the maximum permissable
+ * number of scalefactor bands for each TNS filter. This value is effected
+ * by the sampling rate, and window type.
+ */
+
+const Int tns_max_bands_tbl_long_wndw[(1<<LEN_SAMP_IDX)] =
+ {31, /* 96000 Hz */
+ 31, /* 88200 Hz */
+ 34, /* 64000 Hz */
+ 40, /* 48000 Hz */
+ 42, /* 44100 Hz */
+ 51, /* 32000 Hz */
+ 46, /* 24000 Hz */
+ 46, /* 22050 Hz */
+ 42, /* 16000 Hz */
+ 42, /* 12000 Hz */
+ 42, /* 11025 Hz */
+ 39, /* 8000 Hz */
+ 0,
+ 0,
+ 0,
+ 0
+ };
+
+const Int tns_max_bands_tbl_short_wndw[(1<<LEN_SAMP_IDX)] =
+ {9, /* 96000 Hz */
+ 9, /* 88200 Hz */
+ 10, /* 64000 Hz */
+ 14, /* 48000 Hz */
+ 14, /* 44100 Hz */
+ 14, /* 32000 Hz */
+ 14, /* 24000 Hz */
+ 14, /* 22050 Hz */
+ 14, /* 16000 Hz */
+ 14, /* 12000 Hz */
+ 14, /* 11025 Hz */
+ 14, /* 8000 Hz */
+ 0,
+ 0,
+ 0,
+ 0
+ };
+
+/*
+ * For completeness, here are the table entries for object types that make
+ * use of PQF filter bank. We do not currently support this; these are
+ * given here only to ease future implementation.
+ *
+ * const Int tns_max_bands_tbl_long_wndw_PQF[(1<<LEN_SAMP_IDX)] =
+ * {28, ; 96000
+ * 28, ; 88200
+ * 27, ; 64000
+ * 26, ; 48000
+ * 26, ; 44100
+ * 26, ; 32000
+ * 29, ; 24000
+ * 29, ; 22050
+ * 23, ; 16000
+ * 23, ; 12000
+ * 23, ; 11025
+ * 19, ; 8000
+ * 0,
+ * 0,
+ * 0,
+ * 0};
+ *
+ * const Int tns_max_bands_tbl_short_wndw_PQF[(1<<LEN_SAMP_IDX)] =
+ * {7, ; 96000
+ * 7, ; 88200
+ * 7, ; 64000
+ * 6, ; 48000
+ * 6, ; 44100
+ * 6, ; 32000
+ * 7, ; 24000
+ * 7, ; 22050
+ * 8, ; 16000
+ * 8, ; 12000
+ * 8, ; 11025
+ * 7, ; 8000
+ * 0,
+ * 0,
+ * 0,
+ * 0};
+ */
+
+/*----------------------------------------------------------------------------
+; 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 get_tns(
+ const Int max_bands,
+ BITS * const pInputStream,
+ const WINDOW_SEQUENCE wnd_seq,
+ const FrameInfo * const pFrameInfo,
+ const MC_Info * const pMC_Info,
+ TNS_frame_info * const pTnsFrameInfo,
+ Int32 scratchTnsDecCoefMem[])
+{
+
+ const Int16 * const pSFB_top = pFrameInfo->win_sfb_top[0];
+
+ Int f;
+ Int t;
+ Int win;
+ UInt tempInt;
+
+ Int num_filt_bits;
+ Int num_order_bits;
+ Int num_start_band_bits;
+
+ Int top;
+ Int res;
+ Int res_index;
+ Int compress;
+
+ Int sfb_per_win;
+
+ Int32 *pLpcCoef;
+ Int32 *pStartLpcCoef;
+ Int s_mask;
+ Int n_mask;
+
+ Int tns_bands;
+ UInt max_order;
+ Int coef_res;
+
+
+ TNSfilt *pFilt;
+
+ if (wnd_seq != EIGHT_SHORT_SEQUENCE)
+ {
+ num_filt_bits = 2;
+ num_order_bits = 5;
+ num_start_band_bits = 6;
+
+ tns_bands = tns_max_bands_tbl_long_wndw[pMC_Info->sampling_rate_idx];
+
+ /*
+ * Definition from 14496-3:1999 doc. Our first encoder follows this rule,
+ * later encoders don't
+ */
+
+ if (pMC_Info->sampling_rate_idx > 4) /* if (sampling_rate <= 32000 */
+ {
+ max_order = 20;
+ }
+ else
+ {
+ max_order = 12;
+ }
+ }
+ else
+ {
+ num_filt_bits = 1;
+ num_order_bits = 3;
+ num_start_band_bits = 4;
+
+ tns_bands = tns_max_bands_tbl_short_wndw[pMC_Info->sampling_rate_idx];
+
+ max_order = 7;
+ }
+
+ /*
+ * After this branch, tns_bands will be equal to the minimum of
+ * the passed in variable, nbands, and the result from the
+ * tns_max_bands_tbl
+ */
+
+ if (max_bands < tns_bands)
+ {
+ tns_bands = max_bands;
+ }
+
+ sfb_per_win = pFrameInfo->sfb_per_win[0];
+
+ win = 0;
+
+ pLpcCoef = pTnsFrameInfo->lpc_coef;
+
+ pFilt = pTnsFrameInfo->filt;
+
+ do
+ {
+ tempInt = get9_n_lessbits(num_filt_bits,
+ pInputStream);
+
+ pTnsFrameInfo->n_filt[win] = tempInt;
+
+ if (tempInt != 0)
+ {
+ /*
+ * coef_res = [0, 1]
+ * Switch between a resolution of 3 and 4 bits respectively
+ *
+ * if coef_res = 0, the coefficients have a range of
+ *
+ * -4 -3 -2 -1 0 1 2 3
+ *
+ * if coef_res = 1, the coefficients have a range of
+ *
+ * -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
+ *
+ * The arrays in ./src/tns_tab.c are completely based on
+ * the value of coef_res.
+ */
+ res = get1bits(
+ pInputStream);
+
+ /* res is post-incremented for correct calculation of res_index */
+ coef_res = res++;
+
+ top = sfb_per_win;
+
+ for (f = pTnsFrameInfo->n_filt[win]; f > 0; f--)
+ {
+ tempInt = MINIMUM(top, tns_bands);
+
+ pFilt->stop_coef = SCALE_FACTOR_BAND_OFFSET(tempInt);
+
+ pFilt->stop_band = tempInt;
+
+ top -= get9_n_lessbits(num_start_band_bits,
+ pInputStream);
+
+ tempInt = MINIMUM(top, tns_bands);
+
+ pFilt->start_coef = SCALE_FACTOR_BAND_OFFSET(tempInt);
+
+ pFilt->start_band = tempInt;
+
+ tempInt = get9_n_lessbits(num_order_bits,
+ pInputStream);
+
+ pFilt->order = tempInt;
+
+ if (tempInt != 0)
+ {
+ if (tempInt > max_order)
+ {
+ pFilt->order = max_order;
+ }
+
+ /*
+ * This maps the bitstream's [0,1] to
+ * pFilt->direction = [1,-1]
+ */
+
+ tempInt = get1bits(pInputStream);
+
+ pFilt->direction = (-(Int)tempInt) | 0x1;
+
+ /*
+ * compress = [0,1]
+ * If compress is true, the MSB has
+ * been omitted from transmission (Ref. 1)
+ *
+ * For coef_res = 0, this limits the range of
+ * transmitted coefficients to...
+ *
+ * -2 -1 0 1
+ *
+ * For coef_res = 1, the coefficients have
+ * a range of...
+ *
+ * -4 -3 -2 -1 0 1 2 3
+ */
+ compress = get1bits(pInputStream);
+
+ /*
+ * res has a range of [1,2]
+ * compress has a range of [0,1]
+ * So (res - compress) has range [0,2];
+ */
+ res_index = res - compress;
+
+ s_mask = 2 << res_index;
+
+ /*
+ * If res_index = 0, grab 2 bits of data
+ * If res_index = 1, grab 3 bits of data
+ * If res_index = 2, grab 4 bits of data
+ */
+ res_index += 2;
+
+ pStartLpcCoef = pLpcCoef;
+
+ for (t = pFilt->order; t > 0; t--)
+ {
+ /*
+ * These are the encoded coefficients, which will
+ * later be decoded into LPC coefficients by
+ * the function tns_decode_coef()
+ */
+ tempInt = get9_n_lessbits(res_index,
+ pInputStream);
+
+ n_mask = -((Int)tempInt & s_mask);
+
+ /*
+ * n_mask is used to sign_extend the
+ * value, if it is negative.
+ *
+ */
+ *(pLpcCoef++) = tempInt | n_mask;
+ }
+
+ /* Decode the TNS coefficients */
+
+ tempInt = pFilt->stop_coef - pFilt->start_coef;
+
+ if (tempInt > 0)
+ {
+ pFilt->q_lpc =
+ tns_decode_coef(
+ pFilt->order,
+ coef_res,
+ pStartLpcCoef,
+ scratchTnsDecCoefMem);
+ }
+
+ } /* if (pTnsFilt->order != 0) */
+
+ pFilt++;
+
+ } /* END for (f=pTnsInfo->n_filt; f>0; f--, pTnsFilt++) */
+
+ } /* if (pTnsInfo->n_filt != 0) */
+
+ win++;
+
+ }
+ while (win < pFrameInfo->num_win);
+
+ return;
+
+} /* get_tns */
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