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avcodec/ac3dec: Deduplicate tables

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Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-05-30 00:20:15 +02:00
parent dbd2ca3580
commit 2d5f5e8726
3 changed files with 42 additions and 40 deletions
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44
libavcodec/ac3dec.c
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@ -46,47 +46,11 @@
#include "decode.h"
#include "kbdwin.h"
/**
* Quantization table: levels for symmetric. bits for asymmetric.
* reference: Table 7.18 Mapping of bap to Quantizer
*/
static const uint8_t quantization_tab[16] = {
0, 3, 5, 7, 11, 15,
5, 6, 7, 8, 9, 10, 11, 12, 14, 16
};
#if (!USE_FIXED)
/** dynamic range table. converts codes to scale factors. */
static float dynamic_range_tab[256];
float ff_ac3_heavy_dynamic_range_tab[256];
#endif
/** Adjustments in dB gain (LFE, +10 to -21 dB) */
static const float gain_levels_lfe[32] = {
3.162275, 2.818382, 2.511886, 2.238719, 1.995261, 1.778278, 1.584893,
1.412536, 1.258924, 1.122018, 1.000000, 0.891251, 0.794328, 0.707946,
0.630957, 0.562341, 0.501187, 0.446683, 0.398107, 0.354813, 0.316227,
0.281838, 0.251188, 0.223872, 0.199526, 0.177828, 0.158489, 0.141253,
0.125892, 0.112201, 0.100000, 0.089125
};
/**
* Table for default stereo downmixing coefficients
* reference: Section 7.8.2 Downmixing Into Two Channels
*/
static const uint8_t ac3_default_coeffs[8][5][2] = {
{ { 2, 7 }, { 7, 2 }, },
{ { 4, 4 }, },
{ { 2, 7 }, { 7, 2 }, },
{ { 2, 7 }, { 5, 5 }, { 7, 2 }, },
{ { 2, 7 }, { 7, 2 }, { 6, 6 }, },
{ { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
{ { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
{ { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
};
#if (!USE_FIXED)
/*
* Initialize tables at runtime.
*/
@ -348,8 +312,8 @@ static int set_downmix_coeffs(AC3DecodeContext *s)
}
for (i = 0; i < s->fbw_channels; i++) {
downmix_coeffs[0][i] = ff_ac3_gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
downmix_coeffs[1][i] = ff_ac3_gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
downmix_coeffs[0][i] = ff_ac3_gain_levels[ff_ac3_default_coeffs[s->channel_mode][i][0]];
downmix_coeffs[1][i] = ff_ac3_gain_levels[ff_ac3_default_coeffs[s->channel_mode][i][1]];
}
if (s->channel_mode > 1 && s->channel_mode & 1) {
downmix_coeffs[0][1] = downmix_coeffs[1][1] = cmix;
@ -547,7 +511,7 @@ static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, ma
av_log(s->avctx, AV_LOG_ERROR, "bap %d is invalid in plain AC-3\n", bap);
bap = 15;
}
mantissa = (unsigned)get_sbits(gbc, quantization_tab[bap]) << (24 - quantization_tab[bap]);
mantissa = (unsigned)get_sbits(gbc, ff_ac3_quantization_tab[bap]) << (24 - ff_ac3_quantization_tab[bap]);
break;
}
coeffs[freq] = mantissa >> exps[freq];
@ -1797,7 +1761,7 @@ skip:
downmix_info->surround_mix_level = ff_ac3_gain_levels[s-> surround_mix_level];
downmix_info->surround_mix_level_ltrt = ff_ac3_gain_levels[s->surround_mix_level_ltrt];
if (s->lfe_mix_level_exists)
downmix_info->lfe_mix_level = gain_levels_lfe[s->lfe_mix_level];
downmix_info->lfe_mix_level = ff_eac3_gain_levels_lfe[s->lfe_mix_level];
else
downmix_info->lfe_mix_level = 0.0; // -inf dB
}

33
libavcodec/ac3dec_data.c
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@ -137,6 +137,30 @@ av_cold void ff_ac3_init_static(void)
ff_thread_once(&ac3_init_static_once, ac3_init_static);
}
/**
* Quantization table: levels for symmetric. bits for asymmetric.
* reference: Table 7.18 Mapping of bap to Quantizer
*/
const uint8_t ff_ac3_quantization_tab[16] = {
0, 3, 5, 7, 11, 15,
5, 6, 7, 8, 9, 10, 11, 12, 14, 16
};
/**
* Table for default stereo downmixing coefficients
* reference: Section 7.8.2 Downmixing Into Two Channels
*/
const uint8_t ff_ac3_default_coeffs[8][5][2] = {
{ { 2, 7 }, { 7, 2 }, },
{ { 4, 4 }, },
{ { 2, 7 }, { 7, 2 }, },
{ { 2, 7 }, { 5, 5 }, { 7, 2 }, },
{ { 2, 7 }, { 7, 2 }, { 6, 6 }, },
{ { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
{ { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
{ { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
};
const uint8_t ff_eac3_hebap_tab[64] = {
0, 1, 2, 3, 4, 5, 6, 7, 8, 8,
8, 8, 9, 9, 9, 10, 10, 10, 10, 11,
@ -152,3 +176,12 @@ const uint8_t ff_eac3_hebap_tab[64] = {
*/
const uint8_t ff_eac3_default_spx_band_struct[17] =
{ 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1 };
/** Adjustments in dB gain (LFE, +10 to -21 dB) */
const float ff_eac3_gain_levels_lfe[32] = {
3.162275, 2.818382, 2.511886, 2.238719, 1.995261, 1.778278, 1.584893,
1.412536, 1.258924, 1.122018, 1.000000, 0.891251, 0.794328, 0.707946,
0.630957, 0.562341, 0.501187, 0.446683, 0.398107, 0.354813, 0.316227,
0.281838, 0.251188, 0.223872, 0.199526, 0.177828, 0.158489, 0.141253,
0.125892, 0.112201, 0.100000, 0.089125
};

5
libavcodec/ac3dec_data.h
View File

@ -39,8 +39,13 @@ extern int ff_ac3_bap1_mantissas[32][3];
extern int ff_ac3_bap2_mantissas[128][3];
extern int ff_ac3_bap4_mantissas[128][2];
extern const uint8_t ff_ac3_quantization_tab[16];
extern const uint8_t ff_ac3_default_coeffs[8][5][2];
extern const uint8_t ff_eac3_hebap_tab[64];
extern const uint8_t ff_eac3_default_spx_band_struct[17];
extern const float ff_eac3_gain_levels_lfe[32];
void ff_ac3_init_static(void);