[FFmpeg-cvslog] r9888 - trunk/libavcodec/ac3dec.c
jbr
subversion
Sat Aug 4 05:21:17 CEST 2007
Author: jbr
Date: Sat Aug 4 05:21:17 2007
New Revision: 9888
Log:
use floating-point mantissa dequantization tables
Modified:
trunk/libavcodec/ac3dec.c
Modified: trunk/libavcodec/ac3dec.c
==============================================================================
--- trunk/libavcodec/ac3dec.c (original)
+++ trunk/libavcodec/ac3dec.c Sat Aug 4 05:21:17 2007
@@ -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];
-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];
+/** 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 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 *windo
window[i] = sqrt(local_window[i] / sum);
}
-/*
- * Generate quantizer tables.
- */
-static void generate_quantizers_table(int16_t quantizers[], int level, int length)
-{
- 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)
+static inline float
+symmetric_dequant(int code, int levels)
{
- 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);
+ /* 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);
- //for level-15 quantizers
- generate_quantizers_table(l15_quantizers, 15, 15);
- /* End Quantizer ungrouping tables. */
+ /* 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(AC3DecodeC
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(AC3DecodeC
}
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(AC3De
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(AC3Decod
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(AC3Deco
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(AC3Deco
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(AC3Deco
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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