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vdr/ac3dec/bit_allocate.c

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/*
* bit_allocate.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 <string.h>
#include "ac3.h"
#include "ac3_internal.h"
static inline int16_t logadd(int16_t a,int16_t b);
static int16_t calc_lowcomp(int16_t a,int16_t b0,int16_t b1,int16_t bin);
static inline uint16_t min(int16_t a,int16_t b);
static inline uint16_t max(int16_t a,int16_t b);
static void ba_compute_psd(int16_t start, int16_t end, int16_t exps[],
int16_t psd[], int16_t bndpsd[]);
static void ba_compute_excitation(int16_t start, int16_t end,int16_t fgain,
int16_t fastleak, int16_t slowleak, int16_t is_lfe, int16_t bndpsd[],
int16_t excite[]);
static void ba_compute_mask(int16_t start, int16_t end, uint16_t fscod,
uint16_t deltbae, uint16_t deltnseg, uint16_t deltoffst[], uint16_t deltba[],
uint16_t deltlen[], int16_t excite[], int16_t mask[]);
static void ba_compute_bap(int16_t start, int16_t end, int16_t snroffset,
int16_t psd[], int16_t mask[], int16_t bap[]);
/* Misc LUTs for bit allocation process */
static int16_t slowdec[] = { 0x0f, 0x11, 0x13, 0x15 };
static int16_t fastdec[] = { 0x3f, 0x53, 0x67, 0x7b };
static int16_t slowgain[] = { 0x540, 0x4d8, 0x478, 0x410 };
static int16_t dbpbtab[] = { 0x000, 0x700, 0x900, 0xb00 };
static uint16_t floortab[] = { 0x2f0, 0x2b0, 0x270, 0x230, 0x1f0, 0x170, 0x0f0, 0xf800 };
static int16_t fastgain[] = { 0x080, 0x100, 0x180, 0x200, 0x280, 0x300, 0x380, 0x400 };
static int16_t bndtab[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
20, 21, 22, 23, 24, 25, 26, 27, 28, 31,
34, 37, 40, 43, 46, 49, 55, 61, 67, 73,
79, 85, 97, 109, 121, 133, 157, 181, 205, 229 };
static int16_t bndsz[] = { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 3, 3,
3, 3, 3, 3, 3, 6, 6, 6, 6, 6,
6, 12, 12, 12, 12, 24, 24, 24, 24, 24 };
static int16_t masktab[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 28, 28, 29,
29, 29, 30, 30, 30, 31, 31, 31, 32, 32, 32, 33, 33, 33, 34, 34,
34, 35, 35, 35, 35, 35, 35, 36, 36, 36, 36, 36, 36, 37, 37, 37,
37, 37, 37, 38, 38, 38, 38, 38, 38, 39, 39, 39, 39, 39, 39, 40,
40, 40, 40, 40, 40, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41,
41, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 43, 43, 43,
43, 43, 43, 43, 43, 43, 43, 43, 43, 44, 44, 44, 44, 44, 44, 44,
44, 44, 44, 44, 44, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45,
45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 46, 46, 46,
46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46,
46, 46, 46, 46, 46, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47,
47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 48, 48, 48,
48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
48, 48, 48, 48, 48, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49,
49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 0, 0, 0 };
static int16_t latab[] = { 0x0040, 0x003f, 0x003e, 0x003d, 0x003c, 0x003b, 0x003a, 0x0039,
0x0038, 0x0037, 0x0036, 0x0035, 0x0034, 0x0034, 0x0033, 0x0032,
0x0031, 0x0030, 0x002f, 0x002f, 0x002e, 0x002d, 0x002c, 0x002c,
0x002b, 0x002a, 0x0029, 0x0029, 0x0028, 0x0027, 0x0026, 0x0026,
0x0025, 0x0024, 0x0024, 0x0023, 0x0023, 0x0022, 0x0021, 0x0021,
0x0020, 0x0020, 0x001f, 0x001e, 0x001e, 0x001d, 0x001d, 0x001c,
0x001c, 0x001b, 0x001b, 0x001a, 0x001a, 0x0019, 0x0019, 0x0018,
0x0018, 0x0017, 0x0017, 0x0016, 0x0016, 0x0015, 0x0015, 0x0015,
0x0014, 0x0014, 0x0013, 0x0013, 0x0013, 0x0012, 0x0012, 0x0012,
0x0011, 0x0011, 0x0011, 0x0010, 0x0010, 0x0010, 0x000f, 0x000f,
0x000f, 0x000e, 0x000e, 0x000e, 0x000d, 0x000d, 0x000d, 0x000d,
0x000c, 0x000c, 0x000c, 0x000c, 0x000b, 0x000b, 0x000b, 0x000b,
0x000a, 0x000a, 0x000a, 0x000a, 0x000a, 0x0009, 0x0009, 0x0009,
0x0009, 0x0009, 0x0008, 0x0008, 0x0008, 0x0008, 0x0008, 0x0008,
0x0007, 0x0007, 0x0007, 0x0007, 0x0007, 0x0007, 0x0006, 0x0006,
0x0006, 0x0006, 0x0006, 0x0006, 0x0006, 0x0006, 0x0005, 0x0005,
0x0005, 0x0005, 0x0005, 0x0005, 0x0005, 0x0005, 0x0004, 0x0004,
0x0004, 0x0004, 0x0004, 0x0004, 0x0004, 0x0004, 0x0004, 0x0004,
0x0004, 0x0003, 0x0003, 0x0003, 0x0003, 0x0003, 0x0003, 0x0003,
0x0003, 0x0003, 0x0003, 0x0003, 0x0003, 0x0003, 0x0003, 0x0002,
0x0002, 0x0002, 0x0002, 0x0002, 0x0002, 0x0002, 0x0002, 0x0002,
0x0002, 0x0002, 0x0002, 0x0002, 0x0002, 0x0002, 0x0002, 0x0002,
0x0002, 0x0002, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001,
0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001,
0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001,
0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001,
0x0001, 0x0001, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
0x0000, 0x0000, 0x0000, 0x0000};
static int16_t hth[][50] = {{ 0x04d0, 0x04d0, 0x0440, 0x0400, 0x03e0, 0x03c0, 0x03b0, 0x03b0,
0x03a0, 0x03a0, 0x03a0, 0x03a0, 0x03a0, 0x0390, 0x0390, 0x0390,
0x0380, 0x0380, 0x0370, 0x0370, 0x0360, 0x0360, 0x0350, 0x0350,
0x0340, 0x0340, 0x0330, 0x0320, 0x0310, 0x0300, 0x02f0, 0x02f0,
0x02f0, 0x02f0, 0x0300, 0x0310, 0x0340, 0x0390, 0x03e0, 0x0420,
0x0460, 0x0490, 0x04a0, 0x0460, 0x0440, 0x0440, 0x0520, 0x0800,
0x0840, 0x0840 },
{ 0x04f0, 0x04f0, 0x0460, 0x0410, 0x03e0, 0x03d0, 0x03c0, 0x03b0,
0x03b0, 0x03a0, 0x03a0, 0x03a0, 0x03a0, 0x03a0, 0x0390, 0x0390,
0x0390, 0x0380, 0x0380, 0x0380, 0x0370, 0x0370, 0x0360, 0x0360,
0x0350, 0x0350, 0x0340, 0x0340, 0x0320, 0x0310, 0x0300, 0x02f0,
0x02f0, 0x02f0, 0x02f0, 0x0300, 0x0320, 0x0350, 0x0390, 0x03e0,
0x0420, 0x0450, 0x04a0, 0x0490, 0x0460, 0x0440, 0x0480, 0x0630,
0x0840, 0x0840 },
{ 0x0580, 0x0580, 0x04b0, 0x0450, 0x0420, 0x03f0, 0x03e0, 0x03d0,
0x03c0, 0x03b0, 0x03b0, 0x03b0, 0x03a0, 0x03a0, 0x03a0, 0x03a0,
0x03a0, 0x03a0, 0x03a0, 0x03a0, 0x0390, 0x0390, 0x0390, 0x0390,
0x0380, 0x0380, 0x0380, 0x0370, 0x0360, 0x0350, 0x0340, 0x0330,
0x0320, 0x0310, 0x0300, 0x02f0, 0x02f0, 0x02f0, 0x0300, 0x0310,
0x0330, 0x0350, 0x03c0, 0x0410, 0x0470, 0x04a0, 0x0460, 0x0440,
0x0450, 0x04e0 }};
static int16_t baptab[] = { 0, 1, 1, 1, 1, 1, 2, 2, 3, 3, 3, 4, 4, 5, 5, 6,
6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10,
10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14,
14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15, 15 };
static int16_t sdecay;
static int16_t fdecay;
static int16_t sgain;
static int16_t dbknee;
static int16_t floor;
static int16_t psd[256];
static int16_t bndpsd[256];
static int16_t excite[256];
static int16_t mask[256];
/**
*
**/
static inline uint16_t max(int16_t a,int16_t b)
{
return (a > b ? a : b);
}
/**
*
**/
static inline uint16_t min(int16_t a,int16_t b)
{
return (a < b ? a : b);
}
/**
*
**/
static inline int16_t logadd(int16_t a,int16_t b)
{
int16_t c;
int16_t address;
c = a - b;
address = min((abs(c) >> 1), 255);
if (c >= 0)
return(a + latab[address]);
else
return(b + latab[address]);
}
/**
*
**/
void bit_allocate(uint16_t fscod, bsi_t *bsi, audblk_t *audblk)
{
uint16_t i;
int16_t fgain;
int16_t snroffset;
int16_t start;
int16_t end;
int16_t fastleak;
int16_t slowleak;
/* Only perform bit_allocation if the exponents have changed or we
* have new sideband information */
if (audblk->chexpstr[0] == 0 && audblk->chexpstr[1] == 0 &&
audblk->chexpstr[2] == 0 && audblk->chexpstr[3] == 0 &&
audblk->chexpstr[4] == 0 && audblk->cplexpstr == 0 &&
audblk->lfeexpstr == 0 && audblk->baie == 0 &&
audblk->snroffste == 0 && audblk->deltbaie == 0)
return;
/* Do some setup before we do the bit alloc */
sdecay = slowdec[audblk->sdcycod];
fdecay = fastdec[audblk->fdcycod];
sgain = slowgain[audblk->sgaincod];
dbknee = dbpbtab[audblk->dbpbcod];
floor = floortab[audblk->floorcod];
/* if all the SNR offset constants are zero then the whole block is zero */
if(!audblk->csnroffst && !audblk->fsnroffst[0] &&
!audblk->fsnroffst[1] && !audblk->fsnroffst[2] &&
!audblk->fsnroffst[3] && !audblk->fsnroffst[4] &&
!audblk->cplfsnroffst && !audblk->lfefsnroffst) {
memset(audblk->fbw_bap,0,sizeof(uint16_t) * 256 * 5);
memset(audblk->cpl_bap,0,sizeof(uint16_t) * 256);
memset(audblk->lfe_bap,0,sizeof(uint16_t) * 7);
return;
}
for(i = 0; i < bsi->nfchans; i++)
{
start = 0;
end = audblk->endmant[i] ;
fgain = fastgain[audblk->fgaincod[i]];
snroffset = (((audblk->csnroffst - 15) << 4) + audblk->fsnroffst[i]) << 2 ;
fastleak = 0;
slowleak = 0;
ba_compute_psd(start, end, audblk->fbw_exp[i], psd, bndpsd);
ba_compute_excitation(start, end , fgain, fastleak, slowleak, 0, bndpsd, excite);
ba_compute_mask(start, end, fscod, audblk->deltbae[i], audblk->deltnseg[i],
audblk->deltoffst[i], audblk->deltba[i], audblk->deltlen[i], excite, mask);
ba_compute_bap(start, end, snroffset, psd, mask, audblk->fbw_bap[i]);
}
if(audblk->cplinu) {
start = audblk->cplstrtmant;
end = audblk->cplendmant;
fgain = fastgain[audblk->cplfgaincod];
snroffset = (((audblk->csnroffst - 15) << 4) + audblk->cplfsnroffst) << 2 ;
fastleak = (audblk->cplfleak << 8) + 768;
slowleak = (audblk->cplsleak << 8) + 768;
ba_compute_psd(start, end, audblk->cpl_exp, psd, bndpsd);
ba_compute_excitation(start, end , fgain, fastleak, slowleak, 0, bndpsd, excite);
ba_compute_mask(start, end, fscod, audblk->cpldeltbae, audblk->cpldeltnseg,
audblk->cpldeltoffst, audblk->cpldeltba, audblk->cpldeltlen, excite, mask);
ba_compute_bap(start, end, snroffset, psd, mask, audblk->cpl_bap);
}
if(bsi->lfeon) {
start = 0;
end = 7;
fgain = fastgain[audblk->lfefgaincod];
snroffset = (((audblk->csnroffst - 15) << 4) + audblk->lfefsnroffst) << 2 ;
fastleak = 0;
slowleak = 0;
ba_compute_psd(start, end, audblk->lfe_exp, psd, bndpsd);
ba_compute_excitation(start, end , fgain, fastleak, slowleak, 1, bndpsd, excite);
/* Perform no delta bit allocation for lfe */
ba_compute_mask(start, end, fscod, 2, 0, 0, 0, 0, excite, mask);
ba_compute_bap(start, end, snroffset, psd, mask, audblk->lfe_bap);
}
}
/**
*
**/
static void ba_compute_psd(int16_t start, int16_t end, int16_t exps[],
int16_t psd[], int16_t bndpsd[])
{
int bin,i,j,k;
int16_t lastbin = 0;
/* Map the exponents into dBs */
for (bin=start; bin<end; bin++) {
psd[bin] = (3072 - (exps[bin] << 7));
}
/* Integrate the psd function over each bit allocation band */
j = start;
k = masktab[start];
do {
lastbin = min(bndtab[k] + bndsz[k], end);
bndpsd[k] = psd[j];
j++;
for (i = j; i < lastbin; i++) {
bndpsd[k] = logadd(bndpsd[k], psd[j]);
j++;
}
k++;
} while (end > lastbin);
}
/**
*
**/
static void ba_compute_excitation(int16_t start, int16_t end,int16_t fgain,
int16_t fastleak, int16_t slowleak, int16_t is_lfe, int16_t bndpsd[],
int16_t excite[])
{
int bin;
int16_t bndstrt;
int16_t bndend;
int16_t lowcomp = 0;
int16_t begin = 0;
/* Compute excitation function */
bndstrt = masktab[start];
bndend = masktab[end - 1] + 1;
if (bndstrt == 0) { /* For fbw and lfe channels */
lowcomp = calc_lowcomp(lowcomp, bndpsd[0], bndpsd[1], 0);
excite[0] = bndpsd[0] - fgain - lowcomp;
lowcomp = calc_lowcomp(lowcomp, bndpsd[1], bndpsd[2], 1);
excite[1] = bndpsd[1] - fgain - lowcomp;
begin = 7 ;
// Note: Do not call calc_lowcomp() for the last band of the lfe channel,(bin=6)
for (bin = 2; bin < 7; bin++) {
if (!(is_lfe && (bin == 6)))
lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin+1], bin);
fastleak = bndpsd[bin] - fgain;
slowleak = bndpsd[bin] - sgain;
excite[bin] = fastleak - lowcomp;
if (!(is_lfe && (bin == 6))) {
if (bndpsd[bin] <= bndpsd[bin+1]) {
begin = bin + 1 ;
break;
}
}
}
for (bin = begin; bin < min(bndend, 22); bin++) {
if (!(is_lfe && (bin == 6)))
lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin+1], bin);
fastleak -= fdecay ;
fastleak = max(fastleak, bndpsd[bin] - fgain);
slowleak -= sdecay ;
slowleak = max(slowleak, bndpsd[bin] - sgain);
excite[bin] = max(fastleak - lowcomp, slowleak);
}
begin = 22;
}
else /* For coupling channel */
begin = bndstrt;
for (bin = begin; bin < bndend; bin++) {
fastleak -= fdecay;
fastleak = max(fastleak, bndpsd[bin] - fgain);
slowleak -= sdecay;
slowleak = max(slowleak, bndpsd[bin] - sgain);
excite[bin] = max(fastleak, slowleak) ;
}
}
/**
*
**/
static void ba_compute_mask(int16_t start, int16_t end, uint16_t fscod,
uint16_t deltbae, uint16_t deltnseg, uint16_t deltoffst[], uint16_t deltba[],
uint16_t deltlen[], int16_t excite[], int16_t mask[])
{
int bin,k;
int16_t bndstrt;
int16_t bndend;
int16_t delta;
bndstrt = masktab[start];
bndend = masktab[end - 1] + 1;
/* Compute the masking curve */
for (bin = bndstrt; bin < bndend; bin++) {
if (bndpsd[bin] < dbknee) {
excite[bin] += ((dbknee - bndpsd[bin]) >> 2);
}
mask[bin] = max(excite[bin], hth[fscod][bin]);
}
/* Perform delta bit modulation if necessary */
if ((deltbae == DELTA_BIT_REUSE) || (deltbae == DELTA_BIT_NEW)) {
int16_t band = 0;
int16_t seg = 0;
for (seg = 0; seg < deltnseg+1; seg++) {
band += deltoffst[seg];
if (deltba[seg] >= 4) {
delta = (deltba[seg] - 3) << 7;
} else {
delta = (deltba[seg] - 4) << 7;
}
for (k = 0; k < deltlen[seg]; k++) {
mask[band] += delta;
band++;
}
}
}
}
/**
*
**/
static void ba_compute_bap(int16_t start, int16_t end, int16_t snroffset,
int16_t psd[], int16_t mask[], int16_t bap[])
{
int i,j,k;
int16_t lastbin = 0;
int16_t address = 0;
/* Compute the bit allocation pointer for each bin */
i = start;
j = masktab[start];
do {
lastbin = min(bndtab[j] + bndsz[j], end);
mask[j] -= snroffset;
mask[j] -= floor;
if (mask[j] < 0)
mask[j] = 0;
mask[j] &= 0x1fe0;
mask[j] += floor;
for (k = i; k < lastbin; k++) {
address = (psd[i] - mask[j]) >> 5;
address = min(63, max(0, address));
bap[i] = baptab[address];
i++;
}
j++;
} while (end > lastbin);
}
/**
*
**/
static int16_t calc_lowcomp (int16_t a, int16_t b0, int16_t b1, int16_t bin)
{
if (bin < 7) {
if ((b0 + 256) == b1)
a = 384;
else if (b0 > b1)
a = max(0, a - 64);
} else if (bin < 20) {
if ((b0 + 256) == b1)
a = 320;
else if (b0 > b1)
a = max(0, a - 64) ;
} else
a = max(0, a - 128);
return(a);
}
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