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vdr/ac3dec/coeff.c
2001-08-03 14:18:08 +02:00

354 lines
7.8 KiB
C

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