376 lines
12 KiB
C
376 lines
12 KiB
C
/* ***** BEGIN LICENSE BLOCK *****
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* Version: RCSL 1.0/RPSL 1.0
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*
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* Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved.
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*
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* The contents of this file, and the files included with this file, are
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* subject to the current version of the RealNetworks Public Source License
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* Version 1.0 (the "RPSL") available at
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* http://www.helixcommunity.org/content/rpsl unless you have licensed
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* the file under the RealNetworks Community Source License Version 1.0
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* (the "RCSL") available at http://www.helixcommunity.org/content/rcsl,
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* in which case the RCSL will apply. You may also obtain the license terms
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* directly from RealNetworks. You may not use this file except in
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* compliance with the RPSL or, if you have a valid RCSL with RealNetworks
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* applicable to this file, the RCSL. Please see the applicable RPSL or
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* RCSL for the rights, obligations and limitations governing use of the
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* contents of the file.
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*
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* This file is part of the Helix DNA Technology. RealNetworks is the
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* developer of the Original Code and owns the copyrights in the portions
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* it created.
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*
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* This file, and the files included with this file, is distributed and made
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* available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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* EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
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*
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* Technology Compatibility Kit Test Suite(s) Location:
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* http://www.helixcommunity.org/content/tck
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*
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* Contributor(s):
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*
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* ***** END LICENSE BLOCK ***** */
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/**************************************************************************************
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* Fixed-point MP3 decoder
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* Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com)
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* August 2003
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*
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* dqchan.c - dequantization of transform coefficients
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**************************************************************************************/
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#include "coder.h"
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#include "assembly.h"
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typedef int ARRAY3[3]; /* for short-block reordering */
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/* optional pre-emphasis for high-frequency scale factor bands */
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static const char preTab[22] = { 0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,2,2,3,3,3,2,0 };
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/* pow(2,-i/4) for i=0..3, Q31 format */
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static const int pow14[4] = {
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0x7fffffff, 0x6ba27e65, 0x5a82799a, 0x4c1bf829
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};
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/* pow(2,-i/4) * pow(j,4/3) for i=0..3 j=0..15, Q25 format */
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static const int pow43_14[4][16] = {
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{ 0x00000000, 0x10000000, 0x285145f3, 0x453a5cdb, /* Q28 */
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0x0cb2ff53, 0x111989d6, 0x15ce31c8, 0x1ac7f203,
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0x20000000, 0x257106b9, 0x2b16b4a3, 0x30ed74b4,
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0x36f23fa5, 0x3d227bd3, 0x437be656, 0x49fc823c, },
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{ 0x00000000, 0x0d744fcd, 0x21e71f26, 0x3a36abd9,
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0x0aadc084, 0x0e610e6e, 0x12560c1d, 0x168523cf,
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0x1ae89f99, 0x1f7c03a4, 0x243bae49, 0x29249c67,
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0x2e34420f, 0x33686f85, 0x38bf3dff, 0x3e370182, },
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{ 0x00000000, 0x0b504f33, 0x1c823e07, 0x30f39a55,
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0x08facd62, 0x0c176319, 0x0f6b3522, 0x12efe2ad,
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0x16a09e66, 0x1a79a317, 0x1e77e301, 0x2298d5b4,
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0x26da56fc, 0x2b3a902a, 0x2fb7e7e7, 0x3450f650, },
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{ 0x00000000, 0x09837f05, 0x17f910d7, 0x2929c7a9,
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0x078d0dfa, 0x0a2ae661, 0x0cf73154, 0x0fec91cb,
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0x1306fe0a, 0x16434a6c, 0x199ee595, 0x1d17ae3d,
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0x20abd76a, 0x2459d551, 0x28204fbb, 0x2bfe1808, },
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};
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/* pow(j,4/3) for j=16..63, Q23 format */
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static const int pow43[] = {
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0x1428a2fa, 0x15db1bd6, 0x1796302c, 0x19598d85,
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0x1b24e8bb, 0x1cf7fcfa, 0x1ed28af2, 0x20b4582a,
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0x229d2e6e, 0x248cdb55, 0x26832fda, 0x28800000,
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0x2a832287, 0x2c8c70a8, 0x2e9bc5d8, 0x30b0ff99,
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0x32cbfd4a, 0x34eca001, 0x3712ca62, 0x393e6088,
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0x3b6f47e0, 0x3da56717, 0x3fe0a5fc, 0x4220ed72,
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0x44662758, 0x46b03e7c, 0x48ff1e87, 0x4b52b3f3,
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0x4daaebfd, 0x5007b497, 0x5268fc62, 0x54ceb29c,
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0x5738c721, 0x59a72a59, 0x5c19cd35, 0x5e90a129,
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0x610b9821, 0x638aa47f, 0x660db90f, 0x6894c90b,
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0x6b1fc80c, 0x6daeaa0d, 0x70416360, 0x72d7e8b0,
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0x75722ef9, 0x78102b85, 0x7ab1d3ec, 0x7d571e09,
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};
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/* sqrt(0.5) in Q31 format */
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#define SQRTHALF 0x5a82799a
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/*
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* Minimax polynomial approximation to pow(x, 4/3), over the range
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* poly43lo: x = [0.5, 0.7071]
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* poly43hi: x = [0.7071, 1.0]
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*
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* Relative error < 1E-7
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* Coefs are scaled by 4, 2, 1, 0.5, 0.25
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*/
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static const int poly43lo[5] = { 0x29a0bda9, 0xb02e4828, 0x5957aa1b, 0x236c498d, 0xff581859 };
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static const int poly43hi[5] = { 0x10852163, 0xd333f6a4, 0x46e9408b, 0x27c2cef0, 0xfef577b4 };
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/* pow(2, i*4/3) as exp and frac */
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static const int pow2exp[8] = { 14, 13, 11, 10, 9, 7, 6, 5 };
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static const int pow2frac[8] = {
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0x6597fa94, 0x50a28be6, 0x7fffffff, 0x6597fa94,
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0x50a28be6, 0x7fffffff, 0x6597fa94, 0x50a28be6
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};
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/**************************************************************************************
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* Function: DequantBlock
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*
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* Description: Ken's highly-optimized, low memory dequantizer performing the operation
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* y = pow(x, 4.0/3.0) * pow(2, 25 - scale/4.0)
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*
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* Inputs: input buffer of decode Huffman codewords (signed-magnitude)
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* output buffer of same length (in-place (outbuf = inbuf) is allowed)
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* number of samples
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*
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* Outputs: dequantized samples in Q25 format
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*
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* Return: bitwise-OR of the unsigned outputs (for guard bit calculations)
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**************************************************************************************/
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static int DequantBlock(int *inbuf, int *outbuf, int num, int scale)
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{
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int tab4[4];
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int scalef, scalei, shift;
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int sx, x, y;
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int mask = 0;
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const int *tab16, *coef;
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tab16 = pow43_14[scale & 0x3];
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scalef = pow14[scale & 0x3];
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scalei = MIN(scale >> 2, 31); /* smallest input scale = -47, so smallest scalei = -12 */
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/* cache first 4 values */
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shift = MIN(scalei + 3, 31);
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shift = MAX(shift, 0);
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tab4[0] = 0;
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tab4[1] = tab16[1] >> shift;
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tab4[2] = tab16[2] >> shift;
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tab4[3] = tab16[3] >> shift;
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do {
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sx = *inbuf++;
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x = sx & 0x7fffffff; /* sx = sign|mag */
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if (x < 4) {
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y = tab4[x];
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} else if (x < 16) {
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y = tab16[x];
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y = (scalei < 0) ? y << -scalei : y >> scalei;
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} else {
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if (x < 64) {
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y = pow43[x-16];
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/* fractional scale */
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y = MULSHIFT32(y, scalef);
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shift = scalei - 3;
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} else {
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/* normalize to [0x40000000, 0x7fffffff] */
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x <<= 17;
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shift = 0;
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if (x < 0x08000000)
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x <<= 4, shift += 4;
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if (x < 0x20000000)
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x <<= 2, shift += 2;
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if (x < 0x40000000)
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x <<= 1, shift += 1;
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coef = (x < SQRTHALF) ? poly43lo : poly43hi;
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/* polynomial */
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y = coef[0];
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y = MULSHIFT32(y, x) + coef[1];
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y = MULSHIFT32(y, x) + coef[2];
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y = MULSHIFT32(y, x) + coef[3];
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y = MULSHIFT32(y, x) + coef[4];
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y = MULSHIFT32(y, pow2frac[shift]) << 3;
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/* fractional scale */
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y = MULSHIFT32(y, scalef);
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shift = scalei - pow2exp[shift];
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}
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/* integer scale */
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if (shift < 0) {
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shift = -shift;
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if (y > (0x7fffffff >> shift))
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y = 0x7fffffff; /* clip */
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else
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y <<= shift;
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} else {
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y >>= shift;
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}
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}
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/* sign and store */
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mask |= y;
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*outbuf++ = (sx < 0) ? -y : y;
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} while (--num);
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return mask;
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}
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/**************************************************************************************
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* Function: DequantChannel
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*
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* Description: dequantize one granule, one channel worth of decoded Huffman codewords
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*
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* Inputs: sample buffer (decoded Huffman codewords), length = MAX_NSAMP samples
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* work buffer for reordering short-block, length = MAX_REORDER_SAMPS
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* samples (3 * width of largest short-block critical band)
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* non-zero bound for this channel/granule
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* valid FrameHeader, SideInfoSub, ScaleFactorInfoSub, and CriticalBandInfo
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* structures for this channel/granule
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*
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* Outputs: MAX_NSAMP dequantized samples in sampleBuf
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* updated non-zero bound (indicating which samples are != 0 after DQ)
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* filled-in cbi structure indicating start and end critical bands
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*
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* Return: minimum number of guard bits in dequantized sampleBuf
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*
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* Notes: dequantized samples in Q(DQ_FRACBITS_OUT) format
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**************************************************************************************/
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int DequantChannel(int *sampleBuf, int *workBuf, int *nonZeroBound, FrameHeader *fh, SideInfoSub *sis,
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ScaleFactorInfoSub *sfis, CriticalBandInfo *cbi)
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{
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int i, j, w, cb;
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int cbStartL, cbEndL, cbStartS, cbEndS;
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int nSamps, nonZero, sfactMultiplier, gbMask;
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int globalGain, gainI;
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int cbMax[3];
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ARRAY3 *buf; /* short block reorder */
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/* set default start/end points for short/long blocks - will update with non-zero cb info */
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if (sis->blockType == 2) {
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cbStartL = 0;
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if (sis->mixedBlock) {
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cbEndL = (fh->ver == MPEG1 ? 8 : 6);
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cbStartS = 3;
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} else {
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cbEndL = 0;
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cbStartS = 0;
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}
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cbEndS = 13;
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} else {
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/* long block */
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cbStartL = 0;
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cbEndL = 22;
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cbStartS = 13;
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cbEndS = 13;
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}
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cbMax[2] = cbMax[1] = cbMax[0] = 0;
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gbMask = 0;
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i = 0;
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/* sfactScale = 0 --> quantizer step size = 2
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* sfactScale = 1 --> quantizer step size = sqrt(2)
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* so sfactMultiplier = 2 or 4 (jump through globalGain by powers of 2 or sqrt(2))
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*/
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sfactMultiplier = 2 * (sis->sfactScale + 1);
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/* offset globalGain by -2 if midSide enabled, for 1/sqrt(2) used in MidSideProc()
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* (DequantBlock() does 0.25 * gainI so knocking it down by two is the same as
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* dividing every sample by sqrt(2) = multiplying by 2^-.5)
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*/
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globalGain = sis->globalGain;
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if (fh->modeExt >> 1)
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globalGain -= 2;
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globalGain += IMDCT_SCALE; /* scale everything by sqrt(2), for fast IMDCT36 */
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/* long blocks */
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for (cb = 0; cb < cbEndL; cb++) {
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nonZero = 0;
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nSamps = fh->sfBand->l[cb + 1] - fh->sfBand->l[cb];
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gainI = 210 - globalGain + sfactMultiplier * (sfis->l[cb] + (sis->preFlag ? (int)preTab[cb] : 0));
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nonZero |= DequantBlock(sampleBuf + i, sampleBuf + i, nSamps, gainI);
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i += nSamps;
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/* update highest non-zero critical band */
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if (nonZero)
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cbMax[0] = cb;
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gbMask |= nonZero;
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if (i >= *nonZeroBound)
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break;
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}
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/* set cbi (Type, EndS[], EndSMax will be overwritten if we proceed to do short blocks) */
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cbi->cbType = 0; /* long only */
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cbi->cbEndL = cbMax[0];
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cbi->cbEndS[0] = cbi->cbEndS[1] = cbi->cbEndS[2] = 0;
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cbi->cbEndSMax = 0;
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/* early exit if no short blocks */
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if (cbStartS >= 12)
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return CLZ(gbMask) - 1;
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/* short blocks */
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cbMax[2] = cbMax[1] = cbMax[0] = cbStartS;
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for (cb = cbStartS; cb < cbEndS; cb++) {
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nSamps = fh->sfBand->s[cb + 1] - fh->sfBand->s[cb];
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for (w = 0; w < 3; w++) {
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nonZero = 0;
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gainI = 210 - globalGain + 8*sis->subBlockGain[w] + sfactMultiplier*(sfis->s[cb][w]);
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nonZero |= DequantBlock(sampleBuf + i + nSamps*w, workBuf + nSamps*w, nSamps, gainI);
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/* update highest non-zero critical band */
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if (nonZero)
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cbMax[w] = cb;
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gbMask |= nonZero;
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}
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/* reorder blocks */
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buf = (ARRAY3 *)(sampleBuf + i);
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i += 3*nSamps;
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for (j = 0; j < nSamps; j++) {
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buf[j][0] = workBuf[0*nSamps + j];
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buf[j][1] = workBuf[1*nSamps + j];
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buf[j][2] = workBuf[2*nSamps + j];
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}
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ASSERT(3*nSamps <= MAX_REORDER_SAMPS);
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if (i >= *nonZeroBound)
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break;
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}
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/* i = last non-zero INPUT sample processed, which corresponds to highest possible non-zero
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* OUTPUT sample (after reorder)
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* however, the original nzb is no longer necessarily true
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* for each cb, buf[][] is updated with 3*nSamps samples (i increases 3*nSamps each time)
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* (buf[j + 1][0] = 3 (input) samples ahead of buf[j][0])
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* so update nonZeroBound to i
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*/
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*nonZeroBound = i;
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ASSERT(*nonZeroBound <= MAX_NSAMP);
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cbi->cbType = (sis->mixedBlock ? 2 : 1); /* 2 = mixed short/long, 1 = short only */
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cbi->cbEndS[0] = cbMax[0];
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cbi->cbEndS[1] = cbMax[1];
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cbi->cbEndS[2] = cbMax[2];
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cbi->cbEndSMax = cbMax[0];
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cbi->cbEndSMax = MAX(cbi->cbEndSMax, cbMax[1]);
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cbi->cbEndSMax = MAX(cbi->cbEndSMax, cbMax[2]);
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return CLZ(gbMask) - 1;
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}
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