2b483958f9
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@8488 a1c6a512-1295-4272-9138-f99709370657
120 lines
3.9 KiB
C
120 lines
3.9 KiB
C
/*
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Copyright (c) 2005, The Musepack Development Team
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following
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disclaimer in the documentation and/or other materials provided
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with the distribution.
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* Neither the name of the The Musepack Development Team nor the
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names of its contributors may be used to endorse or promote
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products derived from this software without specific prior
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written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/// \file requant.c
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/// Requantization function implementations.
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/// \todo document me
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#include "musepack.h"
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#include "internal.h"
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/* C O N S T A N T S */
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// bits per sample for chosen quantizer
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const mpc_uint32_t Res_bit [18] = {
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0, 0, 0, 0, 0, 0, 0, 0, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
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};
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// coefficients for requantization
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// 65536/step bzw. 65536/(2*D+1)
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#define _(X) MAKE_MPC_SAMPLE_EX(X,14)
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const MPC_SAMPLE_FORMAT __Cc [1 + 18] = {
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_(111.285962475327f), // 32768/2/255*sqrt(3)
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_(65536.000000000000f), _(21845.333333333332f), _(13107.200000000001f), _(9362.285714285713f),
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_(7281.777777777777f), _(4369.066666666666f), _(2114.064516129032f), _(1040.253968253968f),
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_(516.031496062992f), _(257.003921568627f), _(128.250489236790f), _(64.062561094819f),
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_(32.015632633121f), _(16.003907203907f), _(8.000976681723f), _(4.000244155527f),
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_(2.000061037018f), _(1.000015259021f)
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};
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#undef _
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// offset for requantization
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// 2*D+1 = steps of quantizer
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const mpc_int32_t __Dc [1 + 18] = {
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2,
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0, 1, 2, 3, 4, 7, 15, 31, 63,
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127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767
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};
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#ifdef MPC_FIXED_POINT
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static mpc_uint32_t find_shift(double fval)
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{
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mpc_int64_t val = (mpc_int64_t)fval;
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mpc_uint32_t ptr = 0;
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if (val<0) val = -val;
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while(val) {val>>=1;ptr++;}
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return ptr > 31 ? 0 : 31 - ptr;
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}
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#endif
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/* F U N C T I O N S */
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#define SET_SCF(N,X) d->SCF[N] = MAKE_MPC_SAMPLE_EX(X,d->SCF_shift[N] = (unsigned char)find_shift(X));
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void
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mpc_decoder_scale_output(mpc_decoder *d, double factor)
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{
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mpc_int32_t n;
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double f1;
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double f2;
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#ifndef MPC_FIXED_POINT
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factor *= 1.0 / (double)(1<<(MPC_FIXED_POINT_SHIFT-1));
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#else
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factor *= 1.0 / (double)(1<<(16 - MPC_FIXED_POINT_SHIFT));
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#endif
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f1 = f2 = factor;
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// handles +1.58...-98.41 dB, where's scf[n] / scf[n-1] = 1.20050805774840750476
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SET_SCF(1,factor);
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f1 *= 0.83298066476582673961;
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f2 *= 1/0.83298066476582673961;
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for ( n = 1; n <= 128; n++ ) {
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SET_SCF((unsigned char)(1+n),f1);
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SET_SCF((unsigned char)(1-n),f2);
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f1 *= 0.83298066476582673961;
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f2 *= 1/0.83298066476582673961;
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}
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}
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void
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mpc_decoder_initialisiere_quantisierungstabellen(mpc_decoder *d, double scale_factor)
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{
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mpc_decoder_scale_output(d, scale_factor);
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}
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