add support for spectral extension

Originally committed as revision 15812 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 46 insertions, 0 deletions

diff --git a/libavcodec/ac3dec_data.c b/libavcodec/ac3dec_data.c
index a70c8fca45..fb21888c78 100644
--- a/libavcodec/ac3dec_data.c
+++ b/libavcodec/ac3dec_data.c
@@ -1127,6 +1127,52 @@ const uint8_t ff_eac3_frm_expstr[32][6] = {
 const uint8_t ff_eac3_default_cpl_band_struct[18] =
 { 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1 };
 
+ /**
+ * Table E2.15 Default Spectral Extension Banding Structure
+ */
+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 };
+
+/**
+ * Table E.25: Spectral Extension Attenuation Table
+ * 24-bit fixed-point version of the floating-point table in the specification.
+ * ff_eac3_spx_atten_tab[code][bin]=lrint(pow(1<<(bin+1),(code+1)/-15.0)*(1<<23));
+ */
+const int32_t ff_eac3_spx_atten_tab[32][3] = {
+    { 8009792, 7648083, 7302707 },
+    { 7648083, 6972929, 6357376 },
+    { 7302707, 6357376, 5534417 },
+    { 6972929, 5796163, 4817990 },
+    { 6658043, 5284492, 4194304 },
+    { 6357376, 4817990, 3651354 },
+    { 6070287, 4392670, 3178688 },
+    { 5796163, 4004896, 2767209 },
+    { 5534417, 3651354, 2408995 },
+    { 5284492, 3329021, 2097152 },
+    { 5045853, 3035144, 1825677 },
+    { 4817990, 2767209, 1589344 },
+    { 4600417, 2522926, 1383604 },
+    { 4392670, 2300209, 1204498 },
+    { 4194304, 2097152, 1048576 },
+    { 4004896, 1912021,  912838 },
+    { 3824041, 1743232,  794672 },
+    { 3651354, 1589344,  691802 },
+    { 3486464, 1449041,  602249 },
+    { 3329021, 1321123,  524288 },
+    { 3178688, 1204498,  456419 },
+    { 3035144, 1098167,  397336 },
+    { 2898081, 1001224,  345901 },
+    { 2767209,  912838,  301124 },
+    { 2642246,  832255,  262144 },
+    { 2522926,  758786,  228210 },
+    { 2408995,  691802,  198668 },
+    { 2300209,  630732,  172951 },
+    { 2196335,  575052,  150562 },
+    { 2097152,  524288,  131072 },
+    { 2002448,  478005,  114105 },
+    { 1912021,  435808,   99334 }
+};
+
 /**
  * Table of bin locations for rematrixing bands
  * reference: Section 7.5.2 Rematrixing : Frequency Band Definitions