mirror of
https://github.com/alsa-project/alsa-tools.git
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353 lines
7.8 KiB
C
353 lines
7.8 KiB
C
/*
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* coeff.c
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*
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* Copyright (C) Aaron Holtzman - May 1999
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*
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* This file is part of ac3dec, a free Dolby AC-3 stream decoder.
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*
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* ac3dec is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* ac3dec is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU Make; see the file COPYING. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include "ac3.h"
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#include "ac3_internal.h"
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#include "decode.h"
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#include "bitstream.h"
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#include "dither.h"
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#include "coeff.h"
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//
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//Lookup tables of 0.15 two's complement quantization values
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//
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static const uint_16 q_1[3] =
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{
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( -2 << 15)/3, 0,( 2 << 15)/3
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};
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static const uint_16 q_2[5] =
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{
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( -4 << 15)/5,( -2 << 15)/5, 0,
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( 2 << 15)/5,( 4 << 15)/5
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};
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static const uint_16 q_3[7] =
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{
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( -6 << 15)/7,( -4 << 15)/7,( -2 << 15)/7, 0,
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( 2 << 15)/7,( 4 << 15)/7,( 6 << 15)/7
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};
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static const uint_16 q_4[11] =
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{
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(-10 << 15)/11,(-8 << 15)/11,(-6 << 15)/11, ( -4 << 15)/11,(-2 << 15)/11, 0,
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( 2 << 15)/11,( 4 << 15)/11,( 6 << 15)/11, ( 8 << 15)/11,(10 << 15)/11
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};
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static const uint_16 q_5[15] =
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{
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(-14 << 15)/15,(-12 << 15)/15,(-10 << 15)/15,
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( -8 << 15)/15,( -6 << 15)/15,( -4 << 15)/15,
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( -2 << 15)/15, 0 ,( 2 << 15)/15,
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( 4 << 15)/15,( 6 << 15)/15,( 8 << 15)/15,
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( 10 << 15)/15,( 12 << 15)/15,( 14 << 15)/15
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};
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//
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// Scale factors for convert_to_float
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//
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static const uint_32 u32_scale_factors[25] =
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{
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0x38000000, //2 ^ -(0 + 15)
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0x37800000, //2 ^ -(1 + 15)
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0x37000000, //2 ^ -(2 + 15)
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0x36800000, //2 ^ -(3 + 15)
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0x36000000, //2 ^ -(4 + 15)
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0x35800000, //2 ^ -(5 + 15)
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0x35000000, //2 ^ -(6 + 15)
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0x34800000, //2 ^ -(7 + 15)
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0x34000000, //2 ^ -(8 + 15)
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0x33800000, //2 ^ -(9 + 15)
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0x33000000, //2 ^ -(10 + 15)
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0x32800000, //2 ^ -(11 + 15)
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0x32000000, //2 ^ -(12 + 15)
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0x31800000, //2 ^ -(13 + 15)
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0x31000000, //2 ^ -(14 + 15)
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0x30800000, //2 ^ -(15 + 15)
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0x30000000, //2 ^ -(16 + 15)
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0x2f800000, //2 ^ -(17 + 15)
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0x2f000000, //2 ^ -(18 + 15)
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0x2e800000, //2 ^ -(19 + 15)
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0x2e000000, //2 ^ -(20 + 15)
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0x2d800000, //2 ^ -(21 + 15)
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0x2d000000, //2 ^ -(22 + 15)
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0x2c800000, //2 ^ -(23 + 15)
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0x2c000000 //2 ^ -(24 + 15)
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};
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static float *scale_factor = (float*)u32_scale_factors;
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//These store the persistent state of the packed mantissas
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static uint_16 m_1[3];
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static uint_16 m_2[3];
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static uint_16 m_4[2];
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static uint_16 m_1_pointer;
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static uint_16 m_2_pointer;
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static uint_16 m_4_pointer;
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//Conversion from bap to number of bits in the mantissas
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//zeros account for cases 0,1,2,4 which are special cased
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static uint_16 qnttztab[16] = { 0, 0, 0, 3, 0 , 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16};
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static void coeff_reset(void);
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static sint_16 coeff_get_mantissa(uint_16 bap, uint_16 dithflag);
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static void coeff_uncouple_ch(float samples[],bsi_t *bsi,audblk_t *audblk,uint_32 ch);
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//
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// Convert a 0.15 fixed point number into IEEE single
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// precision floating point and scale by 2^-exp
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//
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static inline float
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convert_to_float(uint_16 exp, sint_16 mantissa)
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{
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float x;
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//the scale by 2^-15 is built into the scale factor table
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x = mantissa * scale_factor[exp];
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return x;
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}
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void
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coeff_unpack(bsi_t *bsi, audblk_t *audblk, stream_samples_t samples)
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{
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uint_16 i,j;
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uint_32 done_cpl = 0;
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sint_16 mantissa;
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coeff_reset();
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for(i=0; i< bsi->nfchans; i++)
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{
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for(j=0; j < audblk->endmant[i]; j++)
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{
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mantissa = coeff_get_mantissa(audblk->fbw_bap[i][j],audblk->dithflag[i]);
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samples[i][j] = convert_to_float(audblk->fbw_exp[i][j],mantissa);
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}
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if(audblk->cplinu && audblk->chincpl[i] && !(done_cpl))
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{
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// ncplmant is equal to 12 * ncplsubnd
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// Don't dither coupling channel until channel separation so that
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// interchannel noise is uncorrelated
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for(j=audblk->cplstrtmant; j < audblk->cplendmant; j++)
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audblk->cplmant[j] = coeff_get_mantissa(audblk->cpl_bap[j],0);
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done_cpl = 1;
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}
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}
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//uncouple the channel if necessary
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if(audblk->cplinu)
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{
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for(i=0; i< bsi->nfchans; i++)
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{
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if(audblk->chincpl[i])
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coeff_uncouple_ch(samples[i],bsi,audblk,i);
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}
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}
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if(bsi->lfeon)
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{
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// There are always 7 mantissas for lfe, no dither for lfe
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for(j=0; j < 7 ; j++)
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{
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mantissa = coeff_get_mantissa(audblk->lfe_bap[j],0);
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samples[5][j] = convert_to_float(audblk->lfe_exp[j],mantissa);
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}
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}
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}
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//
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//Fetch a mantissa from the bitstream
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//
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//The mantissa returned is a signed 0.15 fixed point number
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//
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static sint_16
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coeff_get_mantissa(uint_16 bap, uint_16 dithflag)
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{
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uint_16 mantissa;
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uint_16 group_code;
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//If the bap is 0-5 then we have special cases to take care of
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switch(bap)
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{
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case 0:
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if(dithflag)
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mantissa = dither_gen();
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else
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mantissa = 0;
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break;
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case 1:
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if(m_1_pointer > 2)
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{
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group_code = bitstream_get(5);
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if(group_code > 26)
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goto error;
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m_1[0] = group_code / 9;
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m_1[1] = (group_code % 9) / 3;
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m_1[2] = (group_code % 9) % 3;
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m_1_pointer = 0;
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}
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mantissa = m_1[m_1_pointer++];
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mantissa = q_1[mantissa];
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break;
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case 2:
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if(m_2_pointer > 2)
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{
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group_code = bitstream_get(7);
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if(group_code > 124)
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goto error;
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m_2[0] = group_code / 25;
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m_2[1] = (group_code % 25) / 5 ;
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m_2[2] = (group_code % 25) % 5 ;
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m_2_pointer = 0;
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}
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mantissa = m_2[m_2_pointer++];
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mantissa = q_2[mantissa];
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break;
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case 3:
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mantissa = bitstream_get(3);
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if(mantissa > 6)
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goto error;
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mantissa = q_3[mantissa];
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break;
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case 4:
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if(m_4_pointer > 1)
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{
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group_code = bitstream_get(7);
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if(group_code > 120)
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goto error;
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m_4[0] = group_code / 11;
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m_4[1] = group_code % 11;
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m_4_pointer = 0;
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}
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mantissa = m_4[m_4_pointer++];
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mantissa = q_4[mantissa];
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break;
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case 5:
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mantissa = bitstream_get(4);
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if(mantissa > 14)
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goto error;
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mantissa = q_5[mantissa];
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break;
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default:
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mantissa = bitstream_get(qnttztab[bap]);
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mantissa <<= 16 - qnttztab[bap];
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}
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return mantissa;
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error:
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if(!error_flag)
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fprintf(stderr,"** Invalid mantissa - skipping frame **\n");
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error_flag = 1;
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return 0;
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}
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//
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// Reset the mantissa state
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//
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static void
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coeff_reset(void)
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{
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m_1[2] = m_1[1] = m_1[0] = 0;
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m_2[2] = m_2[1] = m_2[0] = 0;
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m_4[1] = m_4[0] = 0;
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m_1_pointer = m_2_pointer = m_4_pointer = 3;
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}
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//
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// Uncouple the coupling channel into a fbw channel
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//
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static void
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coeff_uncouple_ch(float samples[],bsi_t *bsi,audblk_t *audblk,uint_32 ch)
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{
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uint_32 bnd = 0;
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uint_32 sub_bnd = 0;
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uint_32 i,j;
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float cpl_coord = 1.0;
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uint_32 cpl_exp_tmp;
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uint_32 cpl_mant_tmp;
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sint_16 mantissa;
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for(i=audblk->cplstrtmant;i<audblk->cplendmant;)
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{
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if(!audblk->cplbndstrc[sub_bnd++])
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{
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cpl_exp_tmp = audblk->cplcoexp[ch][bnd] + 3 * audblk->mstrcplco[ch];
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if(audblk->cplcoexp[ch][bnd] == 15)
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cpl_mant_tmp = (audblk->cplcomant[ch][bnd]) << 11;
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else
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cpl_mant_tmp = ((0x10) | audblk->cplcomant[ch][bnd]) << 10;
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cpl_coord = convert_to_float(cpl_exp_tmp,cpl_mant_tmp) * 8.0f;
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//Invert the phase for the right channel if necessary
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if(bsi->acmod == 0x2 && audblk->phsflginu && ch == 1 && audblk->phsflg[bnd])
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cpl_coord *= -1;
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bnd++;
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}
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for(j=0;j < 12; j++)
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{
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//Get new dither values for each channel if necessary, so
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//the channels are uncorrelated
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if(audblk->dithflag[ch] && audblk->cpl_bap[i] == 0)
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mantissa = dither_gen();
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else
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mantissa = audblk->cplmant[i];
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samples[i] = cpl_coord * convert_to_float(audblk->cpl_exp[i],mantissa);
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i++;
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}
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}
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}
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