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use floating-point mantissa dequantization tables

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Originally committed as revision 9888 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Justin Ruggles 18 years ago
parent 04ac5cada1
commit 5aefe3ebef
1 changed files with 80 additions and 121 deletions
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  1. 201
      libavcodec/ac3dec.c

201
libavcodec/ac3dec.c
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@ -52,22 +52,22 @@ static float scale_factors[25];
/** table for grouping exponents */
static uint8_t exp_ungroup_tbl[128][3];
static int16_t l3_quantizers_1[32];
static int16_t l3_quantizers_2[32];
static int16_t l3_quantizers_3[32];
static int16_t l5_quantizers_1[128];
static int16_t l5_quantizers_2[128];
static int16_t l5_quantizers_3[128];
/** tables for ungrouping mantissas */
static float b1_mantissas[32][3];
static float b2_mantissas[128][3];
static float b3_mantissas[8];
static float b4_mantissas[128][2];
static float b5_mantissas[16];
static int16_t l7_quantizers[7];
static int16_t l11_quantizers_1[128];
static int16_t l11_quantizers_2[128];
static int16_t l15_quantizers[15];
static const uint8_t qntztab[16] = { 0, 5, 7, 3, 7, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16 };
/**
* Quantization table: levels for symmetric. bits for asymmetric.
* reference: Table 7.18 Mapping of bap to Quantizer
*/
static const uint8_t qntztab[16] = {
0, 3, 5, 7, 11, 15,
5, 6, 7, 8, 9, 10, 11, 12, 14, 16
};
/* Adjustmens in dB gain */
#define LEVEL_MINUS_3DB 0.7071067811865476
@ -193,58 +193,10 @@ static void ac3_window_init(float *window)
window[i] = sqrt(local_window[i] / sum);
}
/*
* Generate quantizer tables.
*/
static void generate_quantizers_table(int16_t quantizers[], int level, int length)
static inline float
symmetric_dequant(int code, int levels)
{
int i;
for (i = 0; i < length; i++)
quantizers[i] = ((2 * i - level + 1) << 15) / level;
}
static void generate_quantizers_table_1(int16_t quantizers[], int level, int length1, int length2, int size)
{
int i, j;
int16_t v;
for (i = 0; i < length1; i++) {
v = ((2 * i - level + 1) << 15) / level;
for (j = 0; j < length2; j++)
quantizers[i * length2 + j] = v;
}
for (i = length1 * length2; i < size; i++)
quantizers[i] = 0;
}
static void generate_quantizers_table_2(int16_t quantizers[], int level, int length1, int length2, int size)
{
int i, j;
int16_t v;
for (i = 0; i < length1; i++) {
v = ((2 * (i % level) - level + 1) << 15) / level;
for (j = 0; j < length2; j++)
quantizers[i * length2 + j] = v;
}
for (i = length1 * length2; i < size; i++)
quantizers[i] = 0;
}
static void generate_quantizers_table_3(int16_t quantizers[], int level, int length1, int length2, int size)
{
int i, j;
for (i = 0; i < length1; i++)
for (j = 0; j < length2; j++)
quantizers[i * length2 + j] = ((2 * (j % level) - level + 1) << 15) / level;
for (i = length1 * length2; i < size; i++)
quantizers[i] = 0;
return (code - (levels >> 1)) * (2.0f / levels);
}
/*
@ -254,31 +206,38 @@ static void ac3_tables_init(void)
{
int i;
/* Quantizer ungrouping tables. */
// for level-3 quantizers
generate_quantizers_table_1(l3_quantizers_1, 3, 3, 9, 32);
generate_quantizers_table_2(l3_quantizers_2, 3, 9, 3, 32);
generate_quantizers_table_3(l3_quantizers_3, 3, 9, 3, 32);
//for level-5 quantizers
generate_quantizers_table_1(l5_quantizers_1, 5, 5, 25, 128);
generate_quantizers_table_2(l5_quantizers_2, 5, 25, 5, 128);
generate_quantizers_table_3(l5_quantizers_3, 5, 25, 5, 128);
//for level-7 quantizers
generate_quantizers_table(l7_quantizers, 7, 7);
//for level-4 quantizers
generate_quantizers_table_2(l11_quantizers_1, 11, 11, 11, 128);
generate_quantizers_table_3(l11_quantizers_2, 11, 11, 11, 128);
//for level-15 quantizers
generate_quantizers_table(l15_quantizers, 15, 15);
/* End Quantizer ungrouping tables. */
/* generate grouped mantissa tables
reference: Section 7.3.5 Ungrouping of Mantissas */
for(i=0; i<32; i++) {
/* bap=1 mantissas */
b1_mantissas[i][0] = symmetric_dequant( i / 9 , 3);
b1_mantissas[i][1] = symmetric_dequant((i % 9) / 3, 3);
b1_mantissas[i][2] = symmetric_dequant((i % 9) % 3, 3);
}
for(i=0; i<128; i++) {
/* bap=2 mantissas */
b2_mantissas[i][0] = symmetric_dequant( i / 25 , 5);
b2_mantissas[i][1] = symmetric_dequant((i % 25) / 5, 5);
b2_mantissas[i][2] = symmetric_dequant((i % 25) % 5, 5);
/* bap=4 mantissas */
b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
}
/* generate ungrouped mantissa tables
reference: Tables 7.21 and 7.23 */
for(i=0; i<7; i++) {
/* bap=3 mantissas */
b3_mantissas[i] = symmetric_dequant(i, 7);
}
for(i=0; i<15; i++) {
/* bap=5 mantissas */
b5_mantissas[i] = symmetric_dequant(i, 15);
}
//generate scale factors
for (i = 0; i < 25; i++)
scale_factors[i] = pow(2.0, -(i + 15));
scale_factors[i] = pow(2.0, -i);
/* generate exponent tables
reference: Section 7.1.3 Exponent Decoding */
@ -440,7 +399,7 @@ static void uncouple_channels(AC3DecodeContext *ctx)
for(j=0; j<12; j++) {
for(ch=1; ch<=ctx->nfchans; ch++) {
if(ctx->chincpl[ch-1])
ctx->transform_coeffs[ch][i] = ctx->transform_coeffs_cpl[i] * ctx->cplco[ch-1][bnd];
ctx->transform_coeffs[ch][i] = ctx->transform_coeffs_cpl[i] * ctx->cplco[ch-1][bnd] * 8.0f;
}
i++;
}
@ -449,12 +408,12 @@ static void uncouple_channels(AC3DecodeContext *ctx)
}
typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantization */
int16_t l3_quantizers[3];
int16_t l5_quantizers[3];
int16_t l11_quantizers[2];
int l3ptr;
int l5ptr;
int l11ptr;
float b1_mant[3];
float b2_mant[3];
float b4_mant[2];
int b1ptr;
int b2ptr;
int b4ptr;
} mant_groups;
/* Get the transform coefficients for particular channel */
@ -491,51 +450,51 @@ static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_gro
tbap = bap[i];
switch (tbap) {
case 0:
coeffs[i] = (av_random(&ctx->dith_state) & 0xFFFF) * LEVEL_MINUS_3DB;
coeffs[i] = ((av_random(&ctx->dith_state) & 0xFFFF) * LEVEL_MINUS_3DB) / 32768.0f;
break;
case 1:
if (m->l3ptr > 2) {
if(m->b1ptr > 2) {
gcode = get_bits(gb, 5);
m->l3_quantizers[0] = l3_quantizers_1[gcode];
m->l3_quantizers[1] = l3_quantizers_2[gcode];
m->l3_quantizers[2] = l3_quantizers_3[gcode];
m->l3ptr = 0;
m->b1_mant[0] = b1_mantissas[gcode][0];
m->b1_mant[1] = b1_mantissas[gcode][1];
m->b1_mant[2] = b1_mantissas[gcode][2];
m->b1ptr = 0;
}
coeffs[i] = m->l3_quantizers[m->l3ptr++];
coeffs[i] = m->b1_mant[m->b1ptr++];
break;
case 2:
if (m->l5ptr > 2) {
if(m->b2ptr > 2) {
gcode = get_bits(gb, 7);
m->l5_quantizers[0] = l5_quantizers_1[gcode];
m->l5_quantizers[1] = l5_quantizers_2[gcode];
m->l5_quantizers[2] = l5_quantizers_3[gcode];
m->l5ptr = 0;
m->b2_mant[0] = b2_mantissas[gcode][0];
m->b2_mant[1] = b2_mantissas[gcode][1];
m->b2_mant[2] = b2_mantissas[gcode][2];
m->b2ptr = 0;
}
coeffs[i] = m->l5_quantizers[m->l5ptr++];
coeffs[i] = m->b2_mant[m->b2ptr++];
break;
case 3:
coeffs[i] = l7_quantizers[get_bits(gb, 3)];
coeffs[i] = b3_mantissas[get_bits(gb, 3)];
break;
case 4:
if (m->l11ptr > 1) {
if(m->b4ptr > 1) {
gcode = get_bits(gb, 7);
m->l11_quantizers[0] = l11_quantizers_1[gcode];
m->l11_quantizers[1] = l11_quantizers_2[gcode];
m->l11ptr = 0;
m->b4_mant[0] = b4_mantissas[gcode][0];
m->b4_mant[1] = b4_mantissas[gcode][1];
m->b4ptr = 0;
}
coeffs[i] = m->l11_quantizers[m->l11ptr++];
coeffs[i] = m->b4_mant[m->b4ptr++];
break;
case 5:
coeffs[i] = l15_quantizers[get_bits(gb, 4)];
coeffs[i] = b5_mantissas[get_bits(gb, 4)];
break;
default:
coeffs[i] = get_sbits(gb, qntztab[tbap]) << (16 - qntztab[tbap]);
coeffs[i] = get_sbits(gb, qntztab[tbap]) * scale_factors[qntztab[tbap]-1];
break;
}
coeffs[i] *= scale_factors[exps[i]];
@ -587,7 +546,7 @@ static int get_transform_coeffs(AC3DecodeContext * ctx)
int got_cplchan = 0;
mant_groups m;
m.l3ptr = m.l5ptr = m.l11ptr = 3;
m.b1ptr = m.b2ptr = m.b4ptr = 3;
for (i = 0; i < ctx->nfchans; i++) {
/* transform coefficients for individual channel */
@ -747,7 +706,7 @@ static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
if (get_bits1(gb)) { /* dynamic range */
dynrng = get_sbits(gb, 8);
ctx->dynrng = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
ctx->dynrng = (((dynrng & 0x1f) | 0x20) << 13) * pow(2.0, -(18 - (dynrng >> 5)));
} else if(blk == 0) {
ctx->dynrng = 1.0;
}
@ -755,7 +714,7 @@ static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
if(acmod == AC3_ACMOD_DUALMONO) { /* dynamic range 1+1 mode */
if(get_bits1(gb)) {
dynrng = get_sbits(gb, 8);
ctx->dynrng2 = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
ctx->dynrng2 = (((dynrng & 0x1f) | 0x20) << 13) * pow(2.0, -(18 - (dynrng >> 5)));
} else if(blk == 0) {
ctx->dynrng2 = 1.0;
}
@ -807,10 +766,10 @@ static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
cplcoexp = get_bits(gb, 4);
cplcomant = get_bits(gb, 4);
if (cplcoexp == 15)
cplcomant <<= 14;
ctx->cplco[i][bnd] = cplcomant / 16.0f;
else
cplcomant = (cplcomant | 0x10) << 13;
ctx->cplco[i][bnd] = cplcomant * scale_factors[cplcoexp + mstrcplco];
ctx->cplco[i][bnd] = (cplcomant + 16.0f) / 32.0f;
ctx->cplco[i][bnd] *= scale_factors[cplcoexp + mstrcplco];
}
}

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