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4.1.1_r1
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external
aac
libSBRdec
src
env_dec.cpp
/* ----------------------------------------------------------------------------------------------------------- Software License for The Fraunhofer FDK AAC Codec Library for Android Copyright 1995 - 2012 Fraunhofer-Gesellschaft zur Frderung der angewandten Forschung e.V. All rights reserved. 1. INTRODUCTION The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio. This FDK AAC Codec software is intended to be used on a wide variety of Android devices. AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part of the MPEG specifications. Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer) may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners individually for the purpose of encoding or decoding bit streams in products that are compliant with the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec software may already be covered under those patent licenses when it is used for those licensed purposes only. Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality, are also available from Fraunhofer. Users are encouraged to check the Fraunhofer website for additional applications information and documentation. 2. COPYRIGHT LICENSE Redistribution and use in source and binary forms, with or without modification, are permitted without payment of copyright license fees provided that you satisfy the following conditions: You must retain the complete text of this software license in redistributions of the FDK AAC Codec or your modifications thereto in source code form. You must retain the complete text of this software license in the documentation and/or other materials provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form. You must make available free of charge copies of the complete source code of the FDK AAC Codec and your modifications thereto to recipients of copies in binary form. The name of Fraunhofer may not be used to endorse or promote products derived from this library without prior written permission. You may not charge copyright license fees for anyone to use, copy or distribute the FDK AAC Codec software or your modifications thereto. Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software and the date of any change. For modified versions of the FDK AAC Codec, the term "Fraunhofer FDK AAC Codec Library for Android" must be replaced by the term "Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android." 3. NO PATENT LICENSE NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer, ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with respect to this software. You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized by appropriate patent licenses. 4. DISCLAIMER This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, including but not limited to the implied warranties of merchantability and fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, or consequential damages, including but not limited to procurement of substitute goods or services; loss of use, data, or profits, or business interruption, however caused and on any theory of liability, whether in contract, strict liability, or tort (including negligence), arising in any way out of the use of this software, even if advised of the possibility of such damage. 5. CONTACT INFORMATION Fraunhofer Institute for Integrated Circuits IIS Attention: Audio and Multimedia Departments - FDK AAC LL Am Wolfsmantel 33 91058 Erlangen, Germany www.iis.fraunhofer.de/amm amm-info@iis.fraunhofer.de ----------------------------------------------------------------------------------------------------------- */ /*! \file \brief envelope decoding This module provides envelope decoding and error concealment algorithms. The main entry point is decodeSbrData(). \sa decodeSbrData(),\ref documentationOverview */ #include "env_dec.h" #include "env_extr.h" #include "transcendent.h" #include "genericStds.h" static void decodeEnvelope (HANDLE_SBR_HEADER_DATA hHeaderData, HANDLE_SBR_FRAME_DATA h_sbr_data, HANDLE_SBR_PREV_FRAME_DATA h_prev_data, HANDLE_SBR_PREV_FRAME_DATA h_prev_data_otherChannel); static void sbr_envelope_unmapping (HANDLE_SBR_HEADER_DATA hHeaderData, HANDLE_SBR_FRAME_DATA h_data_left, HANDLE_SBR_FRAME_DATA h_data_right); static void requantizeEnvelopeData (HANDLE_SBR_FRAME_DATA h_sbr_data, int ampResolution); static void deltaToLinearPcmEnvelopeDecoding (HANDLE_SBR_HEADER_DATA hHeaderData, HANDLE_SBR_FRAME_DATA h_sbr_data, HANDLE_SBR_PREV_FRAME_DATA h_prev_data); static void decodeNoiseFloorlevels (HANDLE_SBR_HEADER_DATA hHeaderData, HANDLE_SBR_FRAME_DATA h_sbr_data, HANDLE_SBR_PREV_FRAME_DATA h_prev_data); static void timeCompensateFirstEnvelope (HANDLE_SBR_HEADER_DATA hHeaderData, HANDLE_SBR_FRAME_DATA h_sbr_data, HANDLE_SBR_PREV_FRAME_DATA h_prev_data); static int checkEnvelopeData (HANDLE_SBR_HEADER_DATA hHeaderData, HANDLE_SBR_FRAME_DATA h_sbr_data, HANDLE_SBR_PREV_FRAME_DATA h_prev_data); #define SBR_ENERGY_PAN_OFFSET (12 << ENV_EXP_FRACT) #define SBR_MAX_ENERGY (35 << ENV_EXP_FRACT) #define DECAY ( 1 << ENV_EXP_FRACT) #if ENV_EXP_FRACT #define DECAY_COUPLING ( 1 << (ENV_EXP_FRACT-1) ) /*!< corresponds to a value of 0.5 */ #else #define DECAY_COUPLING 1 /*!< If the energy data is not shifted, use 1 instead of 0.5 */ #endif /*! \brief Convert table index */ static int indexLow2High(int offset, /*!< mapping factor */ int index, /*!< index to scalefactor band */ int res) /*!< frequency resolution */ { if(res == 0) { if (offset >= 0) { if (index < offset) return(index); else return(2*index - offset); } else { offset = -offset; if (index < offset) return(2*index+index); else return(2*index + offset); } } else return(index); } /*! \brief Update previous envelope value for delta-coding The current envelope values needs to be stored for delta-coding in the next frame. The stored envelope is always represented with the high frequency resolution. If the current envelope uses the low frequency resolution, the energy value will be mapped to the corresponding high-res bands. */ static void mapLowResEnergyVal(FIXP_SGL currVal, /*!< current energy value */ FIXP_SGL* prevData,/*!< pointer to previous data vector */ int offset, /*!< mapping factor */ int index, /*!< index to scalefactor band */ int res) /*!< frequeny resolution */ { if(res == 0) { if (offset >= 0) { if(index < offset) prevData[index] = currVal; else { prevData[2*index - offset] = currVal; prevData[2*index+1 - offset] = currVal; } } else { offset = -offset; if (index < offset) { prevData[3*index] = currVal; prevData[3*index+1] = currVal; prevData[3*index+2] = currVal; } else { prevData[2*index + offset] = currVal; prevData[2*index + 1 + offset] = currVal; } } } else prevData[index] = currVal; } /*! \brief Convert raw envelope and noisefloor data to energy levels This function is being called by sbrDecoder_ParseElement() and provides two important algorithms: First the function decodes envelopes and noise floor levels as described in requantizeEnvelopeData() and sbr_envelope_unmapping(). The function also implements concealment algorithms in case there are errors within the sbr data. For both operations fractional arithmetic is used. Therefore you might encounter different output values on your target system compared to the reference implementation. */ void decodeSbrData (HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */ HANDLE_SBR_FRAME_DATA h_data_left, /*!< pointer to left channel frame data */ HANDLE_SBR_PREV_FRAME_DATA h_prev_data_left, /*!< pointer to left channel previous frame data */ HANDLE_SBR_FRAME_DATA h_data_right, /*!< pointer to right channel frame data */ HANDLE_SBR_PREV_FRAME_DATA h_prev_data_right)/*!< pointer to right channel previous frame data */ { FIXP_SGL tempSfbNrgPrev[MAX_FREQ_COEFFS]; int errLeft; /* Save previous energy values to be able to reuse them later for concealment. */ FDKmemcpy (tempSfbNrgPrev, h_prev_data_left->sfb_nrg_prev, MAX_FREQ_COEFFS * sizeof(FIXP_SGL)); decodeEnvelope (hHeaderData, h_data_left, h_prev_data_left, h_prev_data_right); decodeNoiseFloorlevels (hHeaderData, h_data_left, h_prev_data_left); if(h_data_right != NULL) { errLeft = hHeaderData->frameErrorFlag; decodeEnvelope (hHeaderData, h_data_right, h_prev_data_right, h_prev_data_left); decodeNoiseFloorlevels (hHeaderData, h_data_right, h_prev_data_right); if (!errLeft && hHeaderData->frameErrorFlag) { /* If an error occurs in the right channel where the left channel seemed ok, we apply concealment also on the left channel. This ensures that the coupling modes of both channels match and that we have the same number of envelopes in coupling mode. However, as the left channel has already been processed before, the resulting energy levels are not the same as if the left channel had been concealed during the first call of decodeEnvelope(). */ /* Restore previous energy values for concealment, because the values have been overwritten by the first call of decodeEnvelope(). */ FDKmemcpy (h_prev_data_left->sfb_nrg_prev, tempSfbNrgPrev, MAX_FREQ_COEFFS * sizeof(FIXP_SGL)); /* Do concealment */ decodeEnvelope (hHeaderData, h_data_left, h_prev_data_left, h_prev_data_right); } if (h_data_left->coupling) { sbr_envelope_unmapping (hHeaderData, h_data_left, h_data_right); } } /* Display the data for debugging: */ } /*! \brief Convert from coupled channels to independent L/R data */ static void sbr_envelope_unmapping (HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */ HANDLE_SBR_FRAME_DATA h_data_left, /*!< pointer to left channel */ HANDLE_SBR_FRAME_DATA h_data_right) /*!< pointer to right channel */ { int i; FIXP_SGL tempL_m, tempR_m, tempRplus1_m, newL_m, newR_m; SCHAR tempL_e, tempR_e, tempRplus1_e, newL_e, newR_e; /* 1. Unmap (already dequantized) coupled envelope energies */ for (i = 0; i < h_data_left->nScaleFactors; i++) { tempR_m = (FIXP_SGL)((LONG)h_data_right->iEnvelope[i] & MASK_M); tempR_e = (SCHAR)((LONG)h_data_right->iEnvelope[i] & MASK_E); tempR_e -= (18 + NRG_EXP_OFFSET); /* -18 = ld(UNMAPPING_SCALE / h_data_right->nChannels) */ tempL_m = (FIXP_SGL)((LONG)h_data_left->iEnvelope[i] & MASK_M); tempL_e = (SCHAR)((LONG)h_data_left->iEnvelope[i] & MASK_E); tempL_e -= NRG_EXP_OFFSET; /* Calculate tempRight+1 */ FDK_add_MantExp( tempR_m, tempR_e, FL2FXCONST_SGL(0.5f), 1, /* 1.0 */ &tempRplus1_m, &tempRplus1_e); FDK_divide_MantExp( tempL_m, tempL_e+1, /* 2 * tempLeft */ tempRplus1_m, tempRplus1_e, &newR_m, &newR_e ); if (newR_m >= ((FIXP_SGL)MAXVAL_SGL - ROUNDING)) { newR_m >>= 1; newR_e += 1; } newL_m = FX_DBL2FX_SGL(fMult(tempR_m,newR_m)); newL_e = tempR_e + newR_e; h_data_right->iEnvelope[i] = ((FIXP_SGL)((SHORT)(FIXP_SGL)(newR_m + ROUNDING) & MASK_M)) + (FIXP_SGL)((SHORT)(FIXP_SGL)(newR_e + NRG_EXP_OFFSET) & MASK_E); h_data_left->iEnvelope[i] = ((FIXP_SGL)((SHORT)(FIXP_SGL)(newL_m + ROUNDING) & MASK_M)) + (FIXP_SGL)((SHORT)(FIXP_SGL)(newL_e + NRG_EXP_OFFSET) & MASK_E); } /* 2. Dequantize and unmap coupled noise floor levels */ for (i = 0; i < hHeaderData->freqBandData.nNfb * h_data_left->frameInfo.nNoiseEnvelopes; i++) { tempL_e = (SCHAR)(6 - (LONG)h_data_left->sbrNoiseFloorLevel[i]); tempR_e = (SCHAR)((LONG)h_data_right->sbrNoiseFloorLevel[i] - 12) /*SBR_ENERGY_PAN_OFFSET*/; /* Calculate tempR+1 */ FDK_add_MantExp( FL2FXCONST_SGL(0.5f), 1+tempR_e, /* tempR */ FL2FXCONST_SGL(0.5f), 1, /* 1.0 */ &tempRplus1_m, &tempRplus1_e); /* Calculate 2*tempLeft/(tempR+1) */ FDK_divide_MantExp( FL2FXCONST_SGL(0.5f), tempL_e+2, /* 2 * tempLeft */ tempRplus1_m, tempRplus1_e, &newR_m, &newR_e ); /* if (newR_m >= ((FIXP_SGL)MAXVAL_SGL - ROUNDING)) { newR_m >>= 1; newR_e += 1; } */ /* L = tempR * R */ newL_m = newR_m; newL_e = newR_e + tempR_e; h_data_right->sbrNoiseFloorLevel[i] = ((FIXP_SGL)((SHORT)(FIXP_SGL)(newR_m + ROUNDING) & MASK_M)) + (FIXP_SGL)((SHORT)(FIXP_SGL)(newR_e + NOISE_EXP_OFFSET) & MASK_E); h_data_left->sbrNoiseFloorLevel[i] = ((FIXP_SGL)((SHORT)(FIXP_SGL)(newL_m + ROUNDING) & MASK_M)) + (FIXP_SGL)((SHORT)(FIXP_SGL)(newL_e + NOISE_EXP_OFFSET) & MASK_E); } } /*! \brief Simple alternative to the real SBR concealment If the real frameInfo is not available due to a frame loss, a replacement will be constructed with 1 envelope spanning the whole frame (FIX-FIX). The delta-coded energies are set to negative values, resulting in a fade-down. In case of coupling, the balance-channel will move towards the center. */ static void leanSbrConcealment(HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */ HANDLE_SBR_FRAME_DATA h_sbr_data, /*!< pointer to current data */ HANDLE_SBR_PREV_FRAME_DATA h_prev_data /*!< pointer to data of last frame */ ) { FIXP_SGL target; /* targeted level for sfb_nrg_prev during fade-down */ FIXP_SGL step; /* speed of fade */ int i; int currentStartPos = h_prev_data->stopPos - hHeaderData->numberTimeSlots; int currentStopPos = hHeaderData->numberTimeSlots; /* Use some settings of the previous frame */ h_sbr_data->ampResolutionCurrentFrame = h_prev_data->ampRes; h_sbr_data->coupling = h_prev_data->coupling; for(i=0;i
sbr_invf_mode[i] = h_prev_data->sbr_invf_mode[i]; /* Generate concealing control data */ h_sbr_data->frameInfo.nEnvelopes = 1; h_sbr_data->frameInfo.borders[0] = currentStartPos; h_sbr_data->frameInfo.borders[1] = currentStopPos; h_sbr_data->frameInfo.freqRes[0] = 1; h_sbr_data->frameInfo.tranEnv = -1; /* no transient */ h_sbr_data->frameInfo.nNoiseEnvelopes = 1; h_sbr_data->frameInfo.bordersNoise[0] = currentStartPos; h_sbr_data->frameInfo.bordersNoise[1] = currentStopPos; h_sbr_data->nScaleFactors = hHeaderData->freqBandData.nSfb[1]; /* Generate fake envelope data */ h_sbr_data->domain_vec[0] = 1; if (h_sbr_data->coupling == COUPLING_BAL) { target = (FIXP_SGL)SBR_ENERGY_PAN_OFFSET; step = (FIXP_SGL)DECAY_COUPLING; } else { target = FL2FXCONST_SGL(0.0f); step = (FIXP_SGL)DECAY; } if (hHeaderData->bs_info.ampResolution == 0) { target <<= 1; step <<= 1; } for (i=0; i < h_sbr_data->nScaleFactors; i++) { if (h_prev_data->sfb_nrg_prev[i] > target) h_sbr_data->iEnvelope[i] = -step; else h_sbr_data->iEnvelope[i] = step; } /* Noisefloor levels are always cleared ... */ h_sbr_data->domain_vec_noise[0] = 1; for (i=0; i < hHeaderData->freqBandData.nNfb; i++) h_sbr_data->sbrNoiseFloorLevel[i] = FL2FXCONST_SGL(0.0f); /* ... and so are the sines */ FDKmemclear(h_sbr_data->addHarmonics, MAX_FREQ_COEFFS); } /*! \brief Build reference energies and noise levels from bitstream elements */ static void decodeEnvelope (HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */ HANDLE_SBR_FRAME_DATA h_sbr_data, /*!< pointer to current data */ HANDLE_SBR_PREV_FRAME_DATA h_prev_data, /*!< pointer to data of last frame */ HANDLE_SBR_PREV_FRAME_DATA otherChannel /*!< other channel's last frame data */ ) { int i; int fFrameError = hHeaderData->frameErrorFlag; FIXP_SGL tempSfbNrgPrev[MAX_FREQ_COEFFS]; if (!fFrameError) { /* To avoid distortions after bad frames, set the error flag if delta coding in time occurs. However, SBR can take a little longer to come up again. */ if ( h_prev_data->frameErrorFlag ) { if (h_sbr_data->domain_vec[0] != 0) { fFrameError = 1; } } else { /* Check that the previous stop position and the current start position match. (Could be done in checkFrameInfo(), but the previous frame data is not available there) */ if ( h_sbr_data->frameInfo.borders[0] != h_prev_data->stopPos - hHeaderData->numberTimeSlots ) { /* Both the previous as well as the current frame are flagged to be ok, but they do not match! */ if (h_sbr_data->domain_vec[0] == 1) { /* Prefer concealment over delta-time coding between the mismatching frames */ fFrameError = 1; } else { /* Close the gap in time by triggering timeCompensateFirstEnvelope() */ fFrameError = 1; } } } } if (fFrameError) /* Error is detected */ { leanSbrConcealment(hHeaderData, h_sbr_data, h_prev_data); /* decode the envelope data to linear PCM */ deltaToLinearPcmEnvelopeDecoding (hHeaderData, h_sbr_data, h_prev_data); } else /*Do a temporary dummy decoding and check that the envelope values are within limits */ { if (h_prev_data->frameErrorFlag) { timeCompensateFirstEnvelope (hHeaderData, h_sbr_data, h_prev_data); if (h_sbr_data->coupling != h_prev_data->coupling) { /* Coupling mode has changed during concealment. The stored energy levels need to be converted. */ for (i = 0; i < hHeaderData->freqBandData.nSfb[1]; i++) { /* Former Level-Channel will be used for both channels */ if (h_prev_data->coupling == COUPLING_BAL) h_prev_data->sfb_nrg_prev[i] = otherChannel->sfb_nrg_prev[i]; /* Former L/R will be combined as the new Level-Channel */ else if (h_sbr_data->coupling == COUPLING_LEVEL) h_prev_data->sfb_nrg_prev[i] = (h_prev_data->sfb_nrg_prev[i] + otherChannel->sfb_nrg_prev[i]) >> 1; else if (h_sbr_data->coupling == COUPLING_BAL) h_prev_data->sfb_nrg_prev[i] = (FIXP_SGL)SBR_ENERGY_PAN_OFFSET; } } } FDKmemcpy (tempSfbNrgPrev, h_prev_data->sfb_nrg_prev, MAX_FREQ_COEFFS * sizeof (FIXP_SGL)); deltaToLinearPcmEnvelopeDecoding (hHeaderData, h_sbr_data, h_prev_data); fFrameError = checkEnvelopeData (hHeaderData, h_sbr_data, h_prev_data); if (fFrameError) { hHeaderData->frameErrorFlag = 1; FDKmemcpy (h_prev_data->sfb_nrg_prev, tempSfbNrgPrev, MAX_FREQ_COEFFS * sizeof (FIXP_SGL)); decodeEnvelope (hHeaderData, h_sbr_data, h_prev_data, otherChannel); return; } } requantizeEnvelopeData (h_sbr_data, h_sbr_data->ampResolutionCurrentFrame); hHeaderData->frameErrorFlag = fFrameError; } /*! \brief Verify that envelope energies are within the allowed range \return 0 if all is fine, 1 if an envelope value was too high */ static int checkEnvelopeData (HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */ HANDLE_SBR_FRAME_DATA h_sbr_data, /*!< pointer to current data */ HANDLE_SBR_PREV_FRAME_DATA h_prev_data /*!< pointer to data of last frame */ ) { FIXP_SGL *iEnvelope = h_sbr_data->iEnvelope; FIXP_SGL *sfb_nrg_prev = h_prev_data->sfb_nrg_prev; int i = 0, errorFlag = 0; FIXP_SGL sbr_max_energy = (h_sbr_data->ampResolutionCurrentFrame == 1) ? SBR_MAX_ENERGY : (SBR_MAX_ENERGY << 1); /* Range check for current energies */ for (i = 0; i < h_sbr_data->nScaleFactors; i++) { if (iEnvelope[i] > sbr_max_energy) { errorFlag = 1; } if (iEnvelope[i] < FL2FXCONST_SGL(0.0f)) { errorFlag = 1; /* iEnvelope[i] = FL2FXCONST_SGL(0.0f); */ } } /* Range check for previous energies */ for (i = 0; i < hHeaderData->freqBandData.nSfb[1]; i++) { sfb_nrg_prev[i] = fixMax(sfb_nrg_prev[i], FL2FXCONST_SGL(0.0f)); sfb_nrg_prev[i] = fixMin(sfb_nrg_prev[i], sbr_max_energy); } return (errorFlag); } /*! \brief Verify that the noise levels are within the allowed range The function is equivalent to checkEnvelopeData(). When the noise-levels are being decoded, it is already too late for concealment. Therefore the noise levels are simply limited here. */ static void limitNoiseLevels(HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */ HANDLE_SBR_FRAME_DATA h_sbr_data) /*!< pointer to current data */ { int i; int nNfb = hHeaderData->freqBandData.nNfb; /* Set range limits. The exact values depend on the coupling mode. However this limitation is primarily intended to avoid unlimited accumulation of the delta-coded noise levels. */ #define lowerLimit ((FIXP_SGL)0) /* lowerLimit actually refers to the _highest_ noise energy */ #define upperLimit ((FIXP_SGL)35) /* upperLimit actually refers to the _lowest_ noise energy */ /* Range check for current noise levels */ for (i = 0; i < h_sbr_data->frameInfo.nNoiseEnvelopes * nNfb; i++) { h_sbr_data->sbrNoiseFloorLevel[i] = fixMin(h_sbr_data->sbrNoiseFloorLevel[i], upperLimit); h_sbr_data->sbrNoiseFloorLevel[i] = fixMax(h_sbr_data->sbrNoiseFloorLevel[i], lowerLimit); } } /*! \brief Compensate for the wrong timing that might occur after a frame error. */ static void timeCompensateFirstEnvelope (HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */ HANDLE_SBR_FRAME_DATA h_sbr_data, /*!< pointer to actual data */ HANDLE_SBR_PREV_FRAME_DATA h_prev_data) /*!< pointer to data of last frame */ { int i, nScalefactors; FRAME_INFO *pFrameInfo = &h_sbr_data->frameInfo; UCHAR *nSfb = hHeaderData->freqBandData.nSfb; int estimatedStartPos = h_prev_data->stopPos - hHeaderData->numberTimeSlots; int refLen, newLen, shift; FIXP_SGL deltaExp; /* Original length of first envelope according to bitstream */ refLen = pFrameInfo->borders[1] - pFrameInfo->borders[0]; /* Corrected length of first envelope (concealing can make the first envelope longer) */ newLen = pFrameInfo->borders[1] - estimatedStartPos; if (newLen <= 0) { /* An envelope length of <= 0 would not work, so we don't use it. May occur if the previous frame was flagged bad due to a mismatch of the old and new frame infos. */ newLen = refLen; estimatedStartPos = pFrameInfo->borders[0]; } deltaExp = FDK_getNumOctavesDiv8(newLen, refLen); /* Shift by -3 to rescale ld-table, 1-ampRes to enable coarser steps */ shift = (FRACT_BITS - 1 - ENV_EXP_FRACT + 1 - h_sbr_data->ampResolutionCurrentFrame - 3); deltaExp = deltaExp >> shift; pFrameInfo->borders[0] = estimatedStartPos; pFrameInfo->bordersNoise[0] = estimatedStartPos; if (h_sbr_data->coupling != COUPLING_BAL) { nScalefactors = (pFrameInfo->freqRes[0]) ? nSfb[1] : nSfb[0]; for (i = 0; i < nScalefactors; i++) h_sbr_data->iEnvelope[i] = h_sbr_data->iEnvelope[i] + deltaExp; } } /*! \brief Convert each envelope value from logarithmic to linear domain Energy levels are transmitted in powers of 2, i.e. only the exponent is extracted from the bitstream. Therefore, normally only integer exponents can occur. However during fading (in case of a corrupt bitstream), a fractional part can also occur. The data in the array iEnvelope is shifted left by ENV_EXP_FRACT compared to an integer representation so that numbers smaller than 1 can be represented. This function calculates a mantissa corresponding to the fractional part of the exponent for each reference energy. The array iEnvelope is converted in place to save memory. Input and output data must be interpreted differently, as shown in the below figure: \image html EnvelopeData.png The data is then used in calculateSbrEnvelope(). */ static void requantizeEnvelopeData (HANDLE_SBR_FRAME_DATA h_sbr_data, int ampResolution) { int i; FIXP_SGL mantissa; int ampShift = 1 - ampResolution; int exponent; /* In case that ENV_EXP_FRACT is changed to something else but 0 or 8, the initialization of this array has to be adapted! */ #if ENV_EXP_FRACT static const FIXP_SGL pow2[ENV_EXP_FRACT] = { FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 1))), /* 0.7071 */ FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 2))), /* 0.5946 */ FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 3))), FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 4))), FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 5))), FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 6))), FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 7))), FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 8))) /* 0.5013 */ }; int bit, mask; #endif for (i = 0; i < h_sbr_data->nScaleFactors; i++) { exponent = (LONG)h_sbr_data->iEnvelope[i]; #if ENV_EXP_FRACT exponent = exponent >> ampShift; mantissa = 0.5f; /* Amplify mantissa according to the fractional part of the exponent (result will be between 0.500000 and 0.999999) */ mask = 1; /* begin with lowest bit of exponent */ for ( bit=ENV_EXP_FRACT-1; bit>=0; bit-- ) { if (exponent & mask) { /* The current bit of the exponent is set, multiply mantissa with the corresponding factor: */ mantissa = (FIXP_SGL)( (mantissa * pow2[bit]) << 1); } /* Advance to next bit */ mask = mask << 1; } /* Make integer part of exponent right aligned */ exponent = exponent >> ENV_EXP_FRACT; #else /* In case of the high amplitude resolution, 1 bit of the exponent gets lost by the shift. This will be compensated by a mantissa of 0.5*sqrt(2) instead of 0.5 if that bit is 1. */ mantissa = (exponent & ampShift) ? FL2FXCONST_SGL(0.707106781186548f) : FL2FXCONST_SGL(0.5f); exponent = exponent >> ampShift; #endif /* Mantissa was set to 0.5 (instead of 1.0, therefore increase exponent by 1). Multiply by L=nChannels=64 by increasing exponent by another 6. => Increase exponent by 7 */ exponent += 7 + NRG_EXP_OFFSET; /* Combine mantissa and exponent and write back the result */ h_sbr_data->iEnvelope[i] = (FIXP_SGL)(((LONG)mantissa & MASK_M) | (exponent & MASK_E)); } } /*! \brief Build new reference energies from old ones and delta coded data */ static void deltaToLinearPcmEnvelopeDecoding (HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */ HANDLE_SBR_FRAME_DATA h_sbr_data, /*!< pointer to current data */ HANDLE_SBR_PREV_FRAME_DATA h_prev_data) /*!< pointer to previous data */ { int i, domain, no_of_bands, band, freqRes; FIXP_SGL *sfb_nrg_prev = h_prev_data->sfb_nrg_prev; FIXP_SGL *ptr_nrg = h_sbr_data->iEnvelope; int offset = 2 * hHeaderData->freqBandData.nSfb[0] - hHeaderData->freqBandData.nSfb[1]; for (i = 0; i < h_sbr_data->frameInfo.nEnvelopes; i++) { domain = h_sbr_data->domain_vec[i]; freqRes = h_sbr_data->frameInfo.freqRes[i]; FDK_ASSERT(freqRes >= 0 && freqRes <= 1); no_of_bands = hHeaderData->freqBandData.nSfb[freqRes]; FDK_ASSERT(no_of_bands < (64)); if (domain == 0) { mapLowResEnergyVal(*ptr_nrg, sfb_nrg_prev, offset, 0, freqRes); ptr_nrg++; for (band = 1; band < no_of_bands; band++) { *ptr_nrg = *ptr_nrg + *(ptr_nrg-1); mapLowResEnergyVal(*ptr_nrg, sfb_nrg_prev, offset, band, freqRes); ptr_nrg++; } } else { for (band = 0; band < no_of_bands; band++) { *ptr_nrg = *ptr_nrg + sfb_nrg_prev[indexLow2High(offset, band, freqRes)]; mapLowResEnergyVal(*ptr_nrg, sfb_nrg_prev, offset, band, freqRes); ptr_nrg++; } } } } /*! \brief Build new noise levels from old ones and delta coded data */ static void decodeNoiseFloorlevels (HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */ HANDLE_SBR_FRAME_DATA h_sbr_data, /*!< pointer to current data */ HANDLE_SBR_PREV_FRAME_DATA h_prev_data) /*!< pointer to previous data */ { int i; int nNfb = hHeaderData->freqBandData.nNfb; int nNoiseFloorEnvelopes = h_sbr_data->frameInfo.nNoiseEnvelopes; /* Decode first noise envelope */ if (h_sbr_data->domain_vec_noise[0] == 0) { FIXP_SGL noiseLevel = h_sbr_data->sbrNoiseFloorLevel[0]; for (i = 1; i < nNfb; i++) { noiseLevel += h_sbr_data->sbrNoiseFloorLevel[i]; h_sbr_data->sbrNoiseFloorLevel[i] = noiseLevel; } } else { for (i = 0; i < nNfb; i++) { h_sbr_data->sbrNoiseFloorLevel[i] += h_prev_data->prevNoiseLevel[i]; } } /* If present, decode the second noise envelope Note: nNoiseFloorEnvelopes can only be 1 or 2 */ if (nNoiseFloorEnvelopes > 1) { if (h_sbr_data->domain_vec_noise[1] == 0) { FIXP_SGL noiseLevel = h_sbr_data->sbrNoiseFloorLevel[nNfb]; for (i = nNfb + 1; i < 2*nNfb; i++) { noiseLevel += h_sbr_data->sbrNoiseFloorLevel[i]; h_sbr_data->sbrNoiseFloorLevel[i] = noiseLevel; } } else { for (i = 0; i < nNfb; i++) { h_sbr_data->sbrNoiseFloorLevel[i + nNfb] += h_sbr_data->sbrNoiseFloorLevel[i]; } } } limitNoiseLevels(hHeaderData, h_sbr_data); /* Update prevNoiseLevel with the last noise envelope */ for (i = 0; i < nNfb; i++) h_prev_data->prevNoiseLevel[i] = h_sbr_data->sbrNoiseFloorLevel[i + nNfb*(nNoiseFloorEnvelopes-1)]; /* Requantize the noise floor levels in COUPLING_OFF-mode */ if (!h_sbr_data->coupling) { int nf_e; for (i = 0; i < nNoiseFloorEnvelopes*nNfb; i++) { nf_e = 6 - (LONG)h_sbr_data->sbrNoiseFloorLevel[i] + 1 + NOISE_EXP_OFFSET; /* +1 to compensate for a mantissa of 0.5 instead of 1.0 */ h_sbr_data->sbrNoiseFloorLevel[i] = (FIXP_SGL)( ((LONG)FL2FXCONST_SGL(0.5f)) + /* mantissa */ (nf_e & MASK_E) ); /* exponent */ } } }
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