dequant.cpp
1 /* ***** BEGIN LICENSE BLOCK ***** 2 * Version: RCSL 1.0/RPSL 1.0 3 * 4 * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. 5 * 6 * The contents of this file, and the files included with this file, are 7 * subject to the current version of the RealNetworks Public Source License 8 * Version 1.0 (the "RPSL") available at 9 * http://www.helixcommunity.org/content/rpsl unless you have licensed 10 * the file under the RealNetworks Community Source License Version 1.0 11 * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl, 12 * in which case the RCSL will apply. You may also obtain the license terms 13 * directly from RealNetworks. You may not use this file except in 14 * compliance with the RPSL or, if you have a valid RCSL with RealNetworks 15 * applicable to this file, the RCSL. Please see the applicable RPSL or 16 * RCSL for the rights, obligations and limitations governing use of the 17 * contents of the file. 18 * 19 * This file is part of the Helix DNA Technology. RealNetworks is the 20 * developer of the Original Code and owns the copyrights in the portions 21 * it created. 22 * 23 * This file, and the files included with this file, is distributed and made 24 * available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 25 * EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS ALL SUCH WARRANTIES, 26 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS 27 * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 28 * 29 * Technology Compatibility Kit Test Suite(s) Location: 30 * http://www.helixcommunity.org/content/tck 31 * 32 * Contributor(s): 33 * 34 * ***** END LICENSE BLOCK ***** */ 35 36 /************************************************************************************** 37 * Fixed-point MP3 decoder 38 * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com) 39 * June 2003 40 * 41 * dequant.c - dequantization, stereo processing (intensity, mid-side), short-block 42 * coefficient reordering 43 **************************************************************************************/ 44 45 #include "coder.h" 46 #include "assembly.h" 47 48 /************************************************************************************** 49 * Function: Dequantize 50 * 51 * Description: dequantize coefficients, decode stereo, reorder short blocks 52 * (one granule-worth) 53 * 54 * Inputs: MP3DecInfo structure filled by UnpackFrameHeader(), UnpackSideInfo(), 55 * UnpackScaleFactors(), and DecodeHuffman() (for this granule) 56 * index of current granule 57 * 58 * Outputs: dequantized and reordered coefficients in hi->huffDecBuf 59 * (one granule-worth, all channels), format = Q26 60 * operates in-place on huffDecBuf but also needs di->workBuf 61 * updated hi->nonZeroBound index for both channels 62 * 63 * Return: 0 on success, -1 if null input pointers 64 * 65 * Notes: In calling output Q(DQ_FRACBITS_OUT), we assume an implicit bias 66 * of 2^15. Some (floating-point) reference implementations factor this 67 * into the 2^(0.25 * gain) scaling explicitly. But to avoid precision 68 * loss, we don't do that. Instead take it into account in the final 69 * round to PCM (>> by 15 less than we otherwise would have). 70 * Equivalently, we can think of the dequantized coefficients as 71 * Q(DQ_FRACBITS_OUT - 15) with no implicit bias. 72 **************************************************************************************/ 73 int Dequantize(MP3DecInfo *mp3DecInfo, int gr) 74 { 75 int i, ch, nSamps, mOut[2]; 76 FrameHeader *fh; 77 SideInfo *si; 78 ScaleFactorInfo *sfi; 79 HuffmanInfo *hi; 80 DequantInfo *di; 81 CriticalBandInfo *cbi; 82 83 /* validate pointers */ 84 if (!mp3DecInfo || !mp3DecInfo->FrameHeaderPS || !mp3DecInfo->SideInfoPS || !mp3DecInfo->ScaleFactorInfoPS || 85 !mp3DecInfo->HuffmanInfoPS || !mp3DecInfo->DequantInfoPS) 86 return -1; 87 88 fh = (FrameHeader *)(mp3DecInfo->FrameHeaderPS); 89 90 /* si is an array of up to 4 structs, stored as gr0ch0, gr0ch1, gr1ch0, gr1ch1 */ 91 si = (SideInfo *)(mp3DecInfo->SideInfoPS); 92 sfi = (ScaleFactorInfo *)(mp3DecInfo->ScaleFactorInfoPS); 93 hi = (HuffmanInfo *)mp3DecInfo->HuffmanInfoPS; 94 di = (DequantInfo *)mp3DecInfo->DequantInfoPS; 95 cbi = di->cbi; 96 mOut[0] = mOut[1] = 0; 97 98 /* dequantize all the samples in each channel */ 99 for (ch = 0; ch < mp3DecInfo->nChans; ch++) { 100 hi->gb[ch] = DequantChannel(hi->huffDecBuf[ch], di->workBuf, &hi->nonZeroBound[ch], fh, 101 &si->sis[gr][ch], &sfi->sfis[gr][ch], &cbi[ch]); 102 } 103 104 /* joint stereo processing assumes one guard bit in input samples 105 * it's extremely rare not to have at least one gb, so if this is the case 106 * just make a pass over the data and clip to [-2^30+1, 2^30-1] 107 * in practice this may never happen 108 */ 109 if (fh->modeExt && (hi->gb[0] < 1 || hi->gb[1] < 1)) { 110 for (i = 0; i < hi->nonZeroBound[0]; i++) { 111 if (hi->huffDecBuf[0][i] < -0x3fffffff) hi->huffDecBuf[0][i] = -0x3fffffff; 112 if (hi->huffDecBuf[0][i] > 0x3fffffff) hi->huffDecBuf[0][i] = 0x3fffffff; 113 } 114 for (i = 0; i < hi->nonZeroBound[1]; i++) { 115 if (hi->huffDecBuf[1][i] < -0x3fffffff) hi->huffDecBuf[1][i] = -0x3fffffff; 116 if (hi->huffDecBuf[1][i] > 0x3fffffff) hi->huffDecBuf[1][i] = 0x3fffffff; 117 } 118 } 119 120 /* do mid-side stereo processing, if enabled */ 121 if (fh->modeExt >> 1) { 122 if (fh->modeExt & 0x01) { 123 /* intensity stereo enabled - run mid-side up to start of right zero region */ 124 if (cbi[1].cbType == 0) 125 nSamps = fh->sfBand->l[cbi[1].cbEndL + 1]; 126 else 127 nSamps = 3 * fh->sfBand->s[cbi[1].cbEndSMax + 1]; 128 } else { 129 /* intensity stereo disabled - run mid-side on whole spectrum */ 130 nSamps = MAX(hi->nonZeroBound[0], hi->nonZeroBound[1]); 131 } 132 MidSideProc(hi->huffDecBuf, nSamps, mOut); 133 } 134 135 /* do intensity stereo processing, if enabled */ 136 if (fh->modeExt & 0x01) { 137 nSamps = hi->nonZeroBound[0]; 138 if (fh->ver == MPEG1) { 139 IntensityProcMPEG1(hi->huffDecBuf, nSamps, fh, &sfi->sfis[gr][1], di->cbi, 140 fh->modeExt >> 1, si->sis[gr][1].mixedBlock, mOut); 141 } else { 142 IntensityProcMPEG2(hi->huffDecBuf, nSamps, fh, &sfi->sfis[gr][1], di->cbi, &sfi->sfjs, 143 fh->modeExt >> 1, si->sis[gr][1].mixedBlock, mOut); 144 } 145 } 146 147 /* adjust guard bit count and nonZeroBound if we did any stereo processing */ 148 if (fh->modeExt) { 149 hi->gb[0] = CLZ(mOut[0]) - 1; 150 hi->gb[1] = CLZ(mOut[1]) - 1; 151 nSamps = MAX(hi->nonZeroBound[0], hi->nonZeroBound[1]); 152 hi->nonZeroBound[0] = nSamps; 153 hi->nonZeroBound[1] = nSamps; 154 } 155 156 /* output format Q(DQ_FRACBITS_OUT) */ 157 return 0; 158 }