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avcodec/ac3{dec,enc}: Deduplicate gain levels table

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(I don't know why the encoder only uses eight of the nine values.)

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-05-24 18:58:24 +02:00
parent 11723b3526
commit dbd2ca3580
4 changed files with 32 additions and 28 deletions
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36
libavcodec/ac3dec.c
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@@ -61,18 +61,6 @@ static float dynamic_range_tab[256];
float ff_ac3_heavy_dynamic_range_tab[256];
#endif
/** Adjustments in dB gain */
static const float gain_levels[9] = {
LEVEL_PLUS_3DB,
LEVEL_PLUS_1POINT5DB,
LEVEL_ONE,
LEVEL_MINUS_1POINT5DB,
LEVEL_MINUS_3DB,
LEVEL_MINUS_4POINT5DB,
LEVEL_MINUS_6DB,
LEVEL_ZERO,
LEVEL_MINUS_9DB
};
/** Adjustments in dB gain (LFE, +10 to -21 dB) */
static const float gain_levels_lfe[32] = {
@@ -346,8 +334,8 @@ static int parse_frame_header(AC3DecodeContext *s)
static int set_downmix_coeffs(AC3DecodeContext *s)
{
int i;
float cmix = gain_levels[s-> center_mix_level];
float smix = gain_levels[s->surround_mix_level];
float cmix = ff_ac3_gain_levels[s-> center_mix_level];
float smix = ff_ac3_gain_levels[s->surround_mix_level];
float norm0, norm1;
float downmix_coeffs[2][AC3_MAX_CHANNELS];
@@ -360,8 +348,8 @@ static int set_downmix_coeffs(AC3DecodeContext *s)
}
for (i = 0; i < s->fbw_channels; i++) {
downmix_coeffs[0][i] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
downmix_coeffs[1][i] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
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]];
}
if (s->channel_mode > 1 && s->channel_mode & 1) {
downmix_coeffs[0][1] = downmix_coeffs[1][1] = cmix;
@@ -1562,10 +1550,10 @@ dependent_frame:
s->output_mode = AC3_CHMODE_STEREO;
}
s->loro_center_mix_level = gain_levels[s-> center_mix_level];
s->loro_surround_mix_level = gain_levels[s->surround_mix_level];
s->ltrt_center_mix_level = gain_levels[s-> center_mix_level_ltrt];
s->ltrt_surround_mix_level = gain_levels[s->surround_mix_level_ltrt];
s->loro_center_mix_level = ff_ac3_gain_levels[s-> center_mix_level];
s->loro_surround_mix_level = ff_ac3_gain_levels[s->surround_mix_level];
s->ltrt_center_mix_level = ff_ac3_gain_levels[s-> center_mix_level_ltrt];
s->ltrt_surround_mix_level = ff_ac3_gain_levels[s->surround_mix_level_ltrt];
switch (s->preferred_downmix) {
case AC3_DMIXMOD_LTRT:
s->preferred_stereo_downmix = AV_DOWNMIX_TYPE_LTRT;
@@ -1804,10 +1792,10 @@ skip:
downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_UNKNOWN;
break;
}
downmix_info->center_mix_level = gain_levels[s-> center_mix_level];
downmix_info->center_mix_level_ltrt = gain_levels[s-> center_mix_level_ltrt];
downmix_info->surround_mix_level = gain_levels[s-> surround_mix_level];
downmix_info->surround_mix_level_ltrt = gain_levels[s->surround_mix_level_ltrt];
downmix_info->center_mix_level = ff_ac3_gain_levels[s-> center_mix_level];
downmix_info->center_mix_level_ltrt = ff_ac3_gain_levels[s-> center_mix_level_ltrt];
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];
else

5
libavcodec/ac3enc.c
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@@ -71,10 +71,7 @@ static const float surmixlev_options[SURMIXLEV_NUM_OPTIONS] = {
};
#define EXTMIXLEV_NUM_OPTIONS 8
static const float extmixlev_options[EXTMIXLEV_NUM_OPTIONS] = {
LEVEL_PLUS_3DB, LEVEL_PLUS_1POINT5DB, LEVEL_ONE, LEVEL_MINUS_1POINT5DB,
LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB, LEVEL_MINUS_6DB, LEVEL_ZERO
};
#define extmixlev_options ff_ac3_gain_levels
/* The first two options apply only to the AC-3 encoders;
* the rest is also valid for EAC-3. When modifying it,

14
libavcodec/ac3tab.c
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@@ -25,6 +25,7 @@
*/
#include "libavutil/channel_layout.h"
#include "libavutil/mathematics.h"
#include "ac3tab.h"
@@ -147,6 +148,19 @@ const uint16_t ff_ac3_fast_gain_tab[8]= {
0x080, 0x100, 0x180, 0x200, 0x280, 0x300, 0x380, 0x400,
};
/** Adjustments in dB gain */
const float ff_ac3_gain_levels[9] = {
LEVEL_PLUS_3DB,
LEVEL_PLUS_1POINT5DB,
LEVEL_ONE,
LEVEL_MINUS_1POINT5DB,
LEVEL_MINUS_3DB,
LEVEL_MINUS_4POINT5DB,
LEVEL_MINUS_6DB,
LEVEL_ZERO,
LEVEL_MINUS_9DB
};
const uint64_t ff_eac3_custom_channel_map_locations[16][2] = {
{ 1, AV_CH_FRONT_LEFT },
{ 1, AV_CH_FRONT_CENTER },

5
libavcodec/ac3tab.h
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@@ -26,6 +26,9 @@
#include "ac3defs.h"
#include "libavutil/attributes_internal.h"
FF_VISIBILITY_PUSH_HIDDEN
extern const uint16_t ff_ac3_frame_size_tab[38][3];
extern const uint8_t ff_ac3_channels_tab[8];
extern const uint16_t ff_ac3_channel_layout_tab[8];
@@ -43,7 +46,9 @@ extern const int16_t ff_ac3_floor_tab[8];
extern const uint16_t ff_ac3_fast_gain_tab[8];
extern const uint8_t ff_ac3_band_start_tab[AC3_CRITICAL_BANDS+1];
extern const uint8_t ff_ac3_bin_to_band_tab[253];
extern const float ff_ac3_gain_levels[9];
extern const uint64_t ff_eac3_custom_channel_map_locations[16][2];
FF_VISIBILITY_POP_HIDDEN
#define COMMON_CHANNEL_MAP \
{ { 0, 1, }, { 0, 1, 2, } },\