avcodec/mpegaudiodec: Hardcode tables to save space

The csa_tables (which always consist of 32 entries of four byte each,
but the type depends upon whether the decoder is fixed or
floating-point) are currently initialized once during decoder
initialization; yet it turns out that this is actually no benefit: The
code used to initialize these tables takes up 153 (fixed point) and 122
(floating point) bytes when compiled with GCC 9.3 with -O3 on x64, so it
is better to just hardcode these tables.

Essentially the same applies to the is_tables: They have a size of 128B
each and the code to initialize them occupies 149 (fixed point) resp.
140 (floating point) bytes. So hardcode them, too.

To make the origin of the tables clear, references to the code used to
create them have been added.

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

libavcodec/mips/compute_antialias_fixed.h

@@ -59,7 +59,8 @@
 static void compute_antialias_mips_fixed(MPADecodeContext *s,
                                         GranuleDef *g)
 {
-    int32_t *ptr, *csa;
+    const int32_t *csa;
+    int32_t *ptr;
     int n, i;
     int MAX_lo = 0xffffffff;
 

libavcodec/mips/compute_antialias_float.h

@@ -63,7 +63,7 @@ static void compute_antialias_mips_float(MPADecodeContext *s,
                                         GranuleDef *g)
 {
     float *ptr, *ptr_end;
-    float *csa = &csa_table[0][0];
+    const float *csa = &csa_table[0][0];
     /* temporary variables */
     float in1, in2, in3, in4, in5, in6, in7, in8;
     float out1, out2, out3, out4;

libavcodec/mpegaudiodata.h

@@ -65,9 +65,6 @@ extern uint16_t ff_scale_factor_modshift[64];
 
 extern const uint8_t ff_mpa_pretab[2][22];
 
-/* table for alias reduction (XXX: store it as integer !) */
-extern const float ff_ci_table[8];
-
 /* Initialize tables shared between the fixed and
  * floating point MPEG audio decoders. */
 void ff_mpegaudiodec_common_init_static(void);

libavcodec/mpegaudiodec_common.c

@@ -396,10 +396,6 @@ const uint8_t ff_mpa_pretab[2][22] = {
     { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 3, 3, 3, 2, 0 },
 };
 
-const float ff_ci_table[8] = {
-    -0.6, -0.535, -0.33, -0.185, -0.095, -0.041, -0.0142, -0.0037,
-};
-
 static av_cold void mpegaudiodec_common_init_static(void)
 {
     const uint8_t *huff_sym = mpa_huffsymbols, *huff_lens = mpa_hufflens;

libavcodec/mpegaudiodec_fixed.c

@@ -36,6 +36,26 @@
 #define OUT_FMT   AV_SAMPLE_FMT_S16
 #define OUT_FMT_P AV_SAMPLE_FMT_S16P
 
+/* Intensity stereo table. See commit b91d46614df189e7905538e7f5c4ed9c7ed0d274
+ * (float based mp1/mp2/mp3 decoders.) for how they were created. */
+static const int32_t is_table[2][16] = {
+    { 0x000000, 0x1B0CB1, 0x2ED9EC, 0x400000, 0x512614, 0x64F34F, 0x800000 },
+    { 0x800000, 0x64F34F, 0x512614, 0x400000, 0x2ED9EC, 0x1B0CB1, 0x000000 }
+};
+
+/* Antialiasing table. See commit ce4a29c066cddfc180979ed86396812f24337985
+ * (optimize antialias) for how they were created. */
+static const int32_t csa_table[8][4] = {
+    { 0x36E129F8, 0xDF128056, 0x15F3AA4E, 0xA831565E },
+    { 0x386E75F2, 0xE1CF24A5, 0x1A3D9A97, 0xA960AEB3 },
+    { 0x3CC6B73A, 0xEBF19FA6, 0x28B856E0, 0xAF2AE86C },
+    { 0x3EEEA054, 0xF45B88BC, 0x334A2910, 0xB56CE868 },
+    { 0x3FB6905C, 0xF9F27F18, 0x39A90F74, 0xBA3BEEBC },
+    { 0x3FF23F20, 0xFD60D1E4, 0x3D531104, 0xBD6E92C4 },
+    { 0x3FFE5932, 0xFF175EE4, 0x3F15B816, 0xBF1905B2 },
+    { 0x3FFFE34A, 0xFFC3612F, 0x3FC34479, 0xBFC37DE5 }
+};
+
 #include "mpegaudiodec_template.c"
 
 #if CONFIG_MP1_DECODER

libavcodec/mpegaudiodec_float.c

@@ -36,6 +36,39 @@
 #define OUT_FMT   AV_SAMPLE_FMT_FLT
 #define OUT_FMT_P AV_SAMPLE_FMT_FLTP
 
+/* Intensity stereo table. See commit b91d46614df189e7905538e7f5c4ed9c7ed0d274
+ * (float based mp1/mp2/mp3 decoders.) for how they were created. */
+static const float is_table[2][16] = {
+    { 0.000000000000000000e+00, 2.113248705863952637e-01, 3.660253882408142090e-01,
+      5.000000000000000000e-01, 6.339746117591857910e-01, 7.886751294136047363e-01,
+      1.000000000000000000e+00 },
+    { 1.000000000000000000e+00, 7.886751294136047363e-01, 6.339746117591857910e-01,
+      5.000000000000000000e-01, 3.660253882408142090e-01, 2.113248705863952637e-01,
+      0.000000000000000000e+00 }
+};
+
+/* Antialiasing table. See commit 6f1ec38ce2193d3d4cacd87edb452c6d7ba751ec
+ * (mpegaudio: clean up compute_antialias() definition) for how they were
+ * created. */
+static const float csa_table[8][4] = {
+    { 8.574929237365722656e-01, -5.144957900047302246e-01,
+      3.429971337318420410e-01, -1.371988654136657715e+00 },
+    { 8.817420005798339844e-01, -4.717319905757904053e-01,
+      4.100100100040435791e-01, -1.353474020957946777e+00 },
+    { 9.496286511421203613e-01, -3.133774697780609131e-01,
+      6.362511515617370605e-01, -1.263006091117858887e+00 },
+    { 9.833145737648010254e-01, -1.819131970405578613e-01,
+      8.014013767242431641e-01, -1.165227770805358887e+00 },
+    { 9.955177903175354004e-01, -9.457419067621231079e-02,
+      9.009436368942260742e-01, -1.090092062950134277e+00 },
+    { 9.991605877876281738e-01, -4.096558317542076111e-02,
+      9.581949710845947266e-01, -1.040126085281372070e+00 },
+    { 9.998992085456848145e-01, -1.419856864959001541e-02,
+      9.857006072998046875e-01, -1.014097809791564941e+00 },
+    { 9.999931454658508301e-01, -3.699974622577428818e-03,
+      9.962931871414184570e-01, -1.003693103790283203e+00 }
+};
+
 #include "mpegaudiodec_template.c"
 
 #if CONFIG_MP1FLOAT_DECODER

libavcodec/mpegaudiodec_template.c

@@ -99,9 +99,7 @@ typedef struct MPADecodeContext {
 
 #include "mpegaudio_tablegen.h"
 /* intensity stereo coef table */
-static INTFLOAT is_table[2][16];
 static INTFLOAT is_table_lsf[2][2][16];
-static INTFLOAT csa_table[8][4];
 
 /* [i][j]:  2^(-j/3) * FRAC_ONE * 2^(i+2) / (2^(i+2) - 1) */
 static int32_t scale_factor_mult[15][3];
@@ -258,22 +256,6 @@ static av_cold void decode_init_static(void)
 
     mpegaudio_tableinit();
 
-    for (i = 0; i < 7; i++) {
-        float f;
-        INTFLOAT v;
-        if (i != 6) {
-            f = tan((double)i * M_PI / 12.0);
-            v = FIXR(f / (1.0 + f));
-        } else {
-            v = FIXR(1.0);
-        }
-        is_table[0][    i] = v;
-        is_table[1][6 - i] = v;
-    }
-    /* invalid values */
-    for (i = 7; i < 16; i++)
-        is_table[0][i] = is_table[1][i] = 0.0;
-
     for (i = 0; i < 16; i++) {
         double f;
         int e, k;
@@ -289,24 +271,6 @@ static av_cold void decode_init_static(void)
                     (float) is_table_lsf[j][1][i]);
         }
     }
-
-    for (i = 0; i < 8; i++) {
-        double ci, cs, ca;
-        ci = ff_ci_table[i];
-        cs = 1.0 / sqrt(1.0 + ci * ci);
-        ca = cs * ci;
-#if !USE_FLOATS
-        csa_table[i][0] = FIXHR(cs/4);
-        csa_table[i][1] = FIXHR(ca/4);
-        csa_table[i][2] = FIXHR(ca/4) + FIXHR(cs/4);
-        csa_table[i][3] = FIXHR(ca/4) - FIXHR(cs/4);
-#else
-        csa_table[i][0] = cs;
-        csa_table[i][1] = ca;
-        csa_table[i][2] = ca + cs;
-        csa_table[i][3] = ca - cs;
-#endif
-    }
     RENAME(ff_mpa_synth_init)();
     ff_mpegaudiodec_common_init_static();
 }
@@ -970,7 +934,8 @@ static void compute_stereo(MPADecodeContext *s, GranuleDef *g0, GranuleDef *g1)
 {
     int i, j, k, l;
     int sf_max, sf, len, non_zero_found;
-    INTFLOAT (*is_tab)[16], *tab0, *tab1, v1, v2;
+    INTFLOAT *tab0, *tab1, v1, v2;
+    const INTFLOAT (*is_tab)[16];
     SUINTFLOAT tmp0, tmp1;
     int non_zero_found_short[3];