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

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

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/ac3dec.c

@@ -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 cmix = ff_ac3_gain_levels[s->  center_mix_level];
-    float smix = gain_levels[s->surround_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[0][i] = ff_ac3_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[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_center_mix_level   = ff_ac3_gain_levels[s->  center_mix_level];
-        s->loro_surround_mix_level = gain_levels[s->surround_mix_level];
+        s->loro_surround_mix_level = ff_ac3_gain_levels[s->surround_mix_level];
-        s->ltrt_center_mix_level   = gain_levels[s->  center_mix_level_ltrt];
+        s->ltrt_center_mix_level   = ff_ac3_gain_levels[s->  center_mix_level_ltrt];
-        s->ltrt_surround_mix_level = gain_levels[s->surround_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        = ff_ac3_gain_levels[s->       center_mix_level];
-        downmix_info->center_mix_level_ltrt   = gain_levels[s->  center_mix_level_ltrt];
+        downmix_info->center_mix_level_ltrt   = ff_ac3_gain_levels[s->  center_mix_level_ltrt];
-        downmix_info->surround_mix_level      = gain_levels[s->     surround_mix_level];
+        downmix_info->surround_mix_level      = ff_ac3_gain_levels[s->     surround_mix_level];
-        downmix_info->surround_mix_level_ltrt = gain_levels[s->surround_mix_level_ltrt];
+        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

libavcodec/ac3enc.c

@@ -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] = {
+#define extmixlev_options ff_ac3_gain_levels
-    LEVEL_PLUS_3DB,  LEVEL_PLUS_1POINT5DB,  LEVEL_ONE,       LEVEL_MINUS_1POINT5DB,
-    LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB, LEVEL_MINUS_6DB, LEVEL_ZERO
-};
 
 /* The first two options apply only to the AC-3 encoders;
  * the rest is also valid for EAC-3. When modifying it,

libavcodec/ac3tab.c

@@ -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 },

libavcodec/ac3tab.h

@@ -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,         } },\