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Diffstat (limited to 'circuitpython/lib/mp3/src/dequant.c')
| -rw-r--r-- | circuitpython/lib/mp3/src/dequant.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/circuitpython/lib/mp3/src/dequant.c b/circuitpython/lib/mp3/src/dequant.c new file mode 100644 index 0000000..b989b7d --- /dev/null +++ b/circuitpython/lib/mp3/src/dequant.c @@ -0,0 +1,158 @@ +/* ***** BEGIN LICENSE BLOCK ***** + * Version: RCSL 1.0/RPSL 1.0 + * + * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. + * + * The contents of this file, and the files included with this file, are + * subject to the current version of the RealNetworks Public Source License + * Version 1.0 (the "RPSL") available at + * http://www.helixcommunity.org/content/rpsl unless you have licensed + * the file under the RealNetworks Community Source License Version 1.0 + * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl, + * in which case the RCSL will apply. You may also obtain the license terms + * directly from RealNetworks. You may not use this file except in + * compliance with the RPSL or, if you have a valid RCSL with RealNetworks + * applicable to this file, the RCSL. Please see the applicable RPSL or + * RCSL for the rights, obligations and limitations governing use of the + * contents of the file. + * + * This file is part of the Helix DNA Technology. RealNetworks is the + * developer of the Original Code and owns the copyrights in the portions + * it created. + * + * This file, and the files included with this file, is distributed and made + * available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER + * EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS ALL SUCH WARRANTIES, + * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS + * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. + * + * Technology Compatibility Kit Test Suite(s) Location: + * http://www.helixcommunity.org/content/tck + * + * Contributor(s): + * + * ***** END LICENSE BLOCK ***** */ + +/************************************************************************************** + * Fixed-point MP3 decoder + * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com) + * June 2003 + * + * dequant.c - dequantization, stereo processing (intensity, mid-side), short-block + * coefficient reordering + **************************************************************************************/ + +#include "coder.h" +#include "assembly.h" + +/************************************************************************************** + * Function: Dequantize + * + * Description: dequantize coefficients, decode stereo, reorder short blocks + * (one granule-worth) + * + * Inputs: MP3DecInfo structure filled by UnpackFrameHeader(), UnpackSideInfo(), + * UnpackScaleFactors(), and DecodeHuffman() (for this granule) + * index of current granule + * + * Outputs: dequantized and reordered coefficients in hi->huffDecBuf + * (one granule-worth, all channels), format = Q26 + * operates in-place on huffDecBuf but also needs di->workBuf + * updated hi->nonZeroBound index for both channels + * + * Return: 0 on success, -1 if null input pointers + * + * Notes: In calling output Q(DQ_FRACBITS_OUT), we assume an implicit bias + * of 2^15. Some (floating-point) reference implementations factor this + * into the 2^(0.25 * gain) scaling explicitly. But to avoid precision + * loss, we don't do that. Instead take it into account in the final + * round to PCM (>> by 15 less than we otherwise would have). + * Equivalently, we can think of the dequantized coefficients as + * Q(DQ_FRACBITS_OUT - 15) with no implicit bias. + **************************************************************************************/ +int Dequantize(MP3DecInfo *mp3DecInfo, int gr) +{ + int i, ch, nSamps, mOut[2]; + FrameHeader *fh; + SideInfo *si; + ScaleFactorInfo *sfi; + HuffmanInfo *hi; + DequantInfo *di; + CriticalBandInfo *cbi; + + /* validate pointers */ + if (!mp3DecInfo || !mp3DecInfo->FrameHeaderPS || !mp3DecInfo->SideInfoPS || !mp3DecInfo->ScaleFactorInfoPS || + !mp3DecInfo->HuffmanInfoPS || !mp3DecInfo->DequantInfoPS) + return -1; + + fh = (FrameHeader *)(mp3DecInfo->FrameHeaderPS); + + /* si is an array of up to 4 structs, stored as gr0ch0, gr0ch1, gr1ch0, gr1ch1 */ + si = (SideInfo *)(mp3DecInfo->SideInfoPS); + sfi = (ScaleFactorInfo *)(mp3DecInfo->ScaleFactorInfoPS); + hi = (HuffmanInfo *)mp3DecInfo->HuffmanInfoPS; + di = (DequantInfo *)mp3DecInfo->DequantInfoPS; + cbi = di->cbi; + mOut[0] = mOut[1] = 0; + + /* dequantize all the samples in each channel */ + for (ch = 0; ch < mp3DecInfo->nChans; ch++) { + hi->gb[ch] = DequantChannel(hi->huffDecBuf[ch], di->workBuf, &hi->nonZeroBound[ch], fh, + &si->sis[gr][ch], &sfi->sfis[gr][ch], &cbi[ch]); + } + + /* joint stereo processing assumes one guard bit in input samples + * it's extremely rare not to have at least one gb, so if this is the case + * just make a pass over the data and clip to [-2^30+1, 2^30-1] + * in practice this may never happen + */ + if (fh->modeExt && (hi->gb[0] < 1 || hi->gb[1] < 1)) { + for (i = 0; i < hi->nonZeroBound[0]; i++) { + if (hi->huffDecBuf[0][i] < -0x3fffffff) hi->huffDecBuf[0][i] = -0x3fffffff; + if (hi->huffDecBuf[0][i] > 0x3fffffff) hi->huffDecBuf[0][i] = 0x3fffffff; + } + for (i = 0; i < hi->nonZeroBound[1]; i++) { + if (hi->huffDecBuf[1][i] < -0x3fffffff) hi->huffDecBuf[1][i] = -0x3fffffff; + if (hi->huffDecBuf[1][i] > 0x3fffffff) hi->huffDecBuf[1][i] = 0x3fffffff; + } + } + + /* do mid-side stereo processing, if enabled */ + if (fh->modeExt >> 1) { + if (fh->modeExt & 0x01) { + /* intensity stereo enabled - run mid-side up to start of right zero region */ + if (cbi[1].cbType == 0) + nSamps = fh->sfBand->l[cbi[1].cbEndL + 1]; + else + nSamps = 3 * fh->sfBand->s[cbi[1].cbEndSMax + 1]; + } else { + /* intensity stereo disabled - run mid-side on whole spectrum */ + nSamps = MAX(hi->nonZeroBound[0], hi->nonZeroBound[1]); + } + MidSideProc(hi->huffDecBuf, nSamps, mOut); + } + + /* do intensity stereo processing, if enabled */ + if (fh->modeExt & 0x01) { + nSamps = hi->nonZeroBound[0]; + if (fh->ver == MPEG1) { + IntensityProcMPEG1(hi->huffDecBuf, nSamps, fh, &sfi->sfis[gr][1], di->cbi, + fh->modeExt >> 1, si->sis[gr][1].mixedBlock, mOut); + } else { + IntensityProcMPEG2(hi->huffDecBuf, nSamps, fh, &sfi->sfis[gr][1], di->cbi, &sfi->sfjs, + fh->modeExt >> 1, si->sis[gr][1].mixedBlock, mOut); + } + } + + /* adjust guard bit count and nonZeroBound if we did any stereo processing */ + if (fh->modeExt) { + hi->gb[0] = CLZ(mOut[0]) - 1; + hi->gb[1] = CLZ(mOut[1]) - 1; + nSamps = MAX(hi->nonZeroBound[0], hi->nonZeroBound[1]); + hi->nonZeroBound[0] = nSamps; + hi->nonZeroBound[1] = nSamps; + } + + /* output format Q(DQ_FRACBITS_OUT) */ + return 0; +} |