[FFmpeg-soc] [soc]: r2215 - in eac3: ac3dec_data.c ac3dec_data.h eac3dec.c

[jbr]

Author: jbr
Date: Mon May 26 23:35:51 2008
New Revision: 2215

Log:
split GAQ remapping table to reduce redundancy

Modified:
   eac3/ac3dec_data.c
   eac3/ac3dec_data.h
   eac3/eac3dec.c

Modified: eac3/ac3dec_data.c
==============================================================================
--- eac3/ac3dec_data.c	(original)
+++ eac3/ac3dec_data.c	Mon May 26 23:35:51 2008
@@ -43,35 +43,46 @@ const uint8_t ff_eac3_bits_vs_hebap[20] 
 };
 
 /**
- * Table E3.6
- * Large mantissa inverse quantization (remapping) constants
- * ff_eac3_gaq_remap[hebap+8][x<0,x>=0][Gk=1,2,4][a,b]
+ * Table E3.6, Gk=1
+ * No gain (Gk=1) inverse quantization, remapping scale factors
+ * ff_eac3_gaq_remap[hebap+8]
  */
-const int16_t ff_eac3_gaq_remap[12][2][3][2] = {
-{{{   4681,       0}, { -10923,   16384}, {  -4681,    8192}},
- {{   4681,       0}, { -10923,   -5461}, {  -4681,   -1170}}},
-{{{   2185,       0}, { -14043,   16384}, {  -6554,    8192}},
- {{   2185,       0}, { -14043,  -11703}, {  -6554,   -4915}}},
-{{{   1057,       0}, { -15292,   16384}, {  -7399,    8192}},
- {{   1057,       0}, { -15292,  -14199}, {  -7399,   -6606}}},
-{{{    520,       0}, { -15855,   16384}, {  -7802,    8192}},
- {{    520,       0}, { -15855,  -15327}, {  -7802,   -7412}}},
-{{{    258,       0}, { -16124,   16384}, {  -7998,    8192}},
- {{    258,       0}, { -16124,  -15864}, {  -7998,   -7805}}},
-{{{    129,       0}, { -16255,   16384}, {  -8096,    8192}},
- {{    129,       0}, { -16255,  -16126}, {  -8096,   -7999}}},
-{{{     64,       0}, { -16320,   16384}, {  -8144,    8192}},
- {{     64,       0}, { -16320,  -16255}, {  -8144,   -8096}}},
-{{{     32,       0}, { -16352,   16384}, {  -8168,    8192}},
- {{     32,       0}, { -16352,  -16320}, {  -8168,   -8144}}},
-{{{     16,       0}, { -16368,   16384}, {  -8180,    8192}},
- {{     16,       0}, { -16368,  -16352}, {  -8180,   -8168}}},
-{{{      8,       0}, {      0,       0}, {      0,       0}},
- {{      8,       0}, {      0,       0}, {      0,       0}}},
-{{{      2,       0}, {      0,       0}, {      0,       0}},
- {{      2,       0}, {      0,       0}, {      0,       0}}},
-{{{      0,       0}, {      0,       0}, {      0,       0}},
- {{      0,       0}, {      0,       0}, {      0,       0}}},
+const int16_t ff_eac3_gaq_remap_1[12] = {
+    4681, 2185, 1057, 520, 258, 129, 64, 32, 16, 8, 2, 0
+};
+
+/**
+ * Table E3.6, Gk=2 & Gk=4, A
+ * Large mantissa inverse quantization, remapping scale factors
+ * ff_eac3_gaq_remap_2_4_a[hebap-8][Gk=2,4]
+ */
+const int16_t ff_eac3_gaq_remap_2_4_a[9][2] = {
+    { -10923, -4681 },
+    { -14043, -6554 },
+    { -15292, -7399 },
+    { -15855, -7802 },
+    { -16124, -7998 },
+    { -16255, -8096 },
+    { -16320, -8144 },
+    { -16352, -8168 },
+    { -16368, -8180 }
+};
+
+/**
+ * Table E3.6, Gk=2 & Gk=4, B
+ * Large mantissa inverse quantization, negative mantissa remapping offsets
+ * ff_eac3_gaq_remap_3_4_b[hebap-8][Gk=2,4]
+ */
+const int16_t ff_eac3_gaq_remap_2_4_b[9][2] = {
+    {  -5461, -1170},
+    { -11703, -4915},
+    { -14199, -6606},
+    { -15327, -7412},
+    { -15864, -7805},
+    { -16126, -7999},
+    { -16255, -8096},
+    { -16320, -8144},
+    { -16352, -8168}
 };
 
 /**

Modified: eac3/ac3dec_data.h
==============================================================================
--- eac3/ac3dec_data.h	(original)
+++ eac3/ac3dec_data.h	Mon May 26 23:35:51 2008
@@ -26,7 +26,9 @@
 
 extern const uint8_t  ff_eac3_hebap_tab[64];
 extern const uint8_t ff_eac3_bits_vs_hebap[20];
-extern const int16_t ff_eac3_gaq_remap[12][2][3][2];
+extern const int16_t ff_eac3_gaq_remap_1[12];
+extern const int16_t ff_eac3_gaq_remap_2_4_a[9][2];
+extern const int16_t ff_eac3_gaq_remap_2_4_b[9][2];
 extern const uint8_t ff_eac3_gaq_gk[4][3];
 
 extern const int16_t (*ff_eac3_vq_hebap[8])[6];

Modified: eac3/eac3dec.c
==============================================================================
--- eac3/eac3dec.c	(original)
+++ eac3/eac3dec.c	Mon May 26 23:35:51 2008
@@ -230,17 +230,23 @@ void ff_eac3_get_transform_coeffs_aht_ch
                 int pre_mantissa = get_sbits(gbc, gbits);
                 if (pre_mantissa == -(1 << (gbits-1))) {
                     // large mantissa
+                    int64_t a, b;
                     mant = get_sbits(gbc, bits-2+log_gain) << (26-log_gain-bits);
-                    remap = 1;
+                    /* remap mantissa value to correct for asymmetric quantization */
+                    a = ff_eac3_gaq_remap_2_4_a[hebap-8][log_gain-1] + 32768;
+                    if(mant >= 0)
+                        b = 32768 >> log_gain;
+                    else
+                        b = ff_eac3_gaq_remap_2_4_b[hebap-8][log_gain-1];
+                    mant = (a * mant + b) >> 15;
                 } else {
+                    /* small mantissa, no GAQ, or Gk=1 */
                     mant = pre_mantissa << (24 - bits);
-                    remap = !log_gain;
-                }
-
-                if (remap) {
-                    int64_t a = ff_eac3_gaq_remap[hebap-8][0][log_gain][0] + 32768;
-                    int64_t b = ff_eac3_gaq_remap[hebap-8][mant<0][log_gain][1];
-                    mant = (a * mant + b) >> 15;
+                    if(!log_gain) {
+                        /* remap mantissa value for no GAQ or Gk=1 */
+                        int64_t a = ff_eac3_gaq_remap_1[hebap-8] + 32768;
+                        mant = (a * mant) >> 15;
+                    }
                 }
                 s->pre_mantissa[blk][ch][bin] = mant;
             }