Support arithmetic decoding in ALS.

Originally committed as revision 21799 to svn://svn.ffmpeg.org/ffmpeg/trunk

4 files changed, 733 insertions, 6 deletions

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 0b58459935..4e6f5a1af3 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -50,7 +50,7 @@ OBJS-$(CONFIG_AC3_DECODER)             += ac3dec.o ac3dec_data.o ac3.o
 OBJS-$(CONFIG_AC3_ENCODER)             += ac3enc.o ac3tab.o ac3.o
 OBJS-$(CONFIG_ALAC_DECODER)            += alac.o
 OBJS-$(CONFIG_ALAC_ENCODER)            += alacenc.o
-OBJS-$(CONFIG_ALS_DECODER)             += alsdec.o
+OBJS-$(CONFIG_ALS_DECODER)             += alsdec.o bgmc.o
 OBJS-$(CONFIG_AMV_DECODER)             += sp5xdec.o mjpegdec.o mjpeg.o
 OBJS-$(CONFIG_ANM_DECODER)             += anm.o
 OBJS-$(CONFIG_APE_DECODER)             += apedec.o
diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
index 1c6af25f21..a92c1ec8a2 100644
--- a/libavcodec/alsdec.c
+++ b/libavcodec/alsdec.c
@@ -34,6 +34,7 @@
 #include "unary.h"
 #include "mpeg4audio.h"
 #include "bytestream.h"
+#include "bgmc.h"
 
 #include <stdint.h>
 
@@ -120,6 +121,28 @@ static const int16_t mcc_weightings[] = {
 };
 
 
+/** Tail codes used in arithmetic coding using block Gilbert-Moore codes.
+ */
+static const uint8_t tail_code[16][6] = {
+    { 74, 44, 25, 13,  7, 3},
+    { 68, 42, 24, 13,  7, 3},
+    { 58, 39, 23, 13,  7, 3},
+    {126, 70, 37, 19, 10, 5},
+    {132, 70, 37, 20, 10, 5},
+    {124, 70, 38, 20, 10, 5},
+    {120, 69, 37, 20, 11, 5},
+    {116, 67, 37, 20, 11, 5},
+    {108, 66, 36, 20, 10, 5},
+    {102, 62, 36, 20, 10, 5},
+    { 88, 58, 34, 19, 10, 5},
+    {162, 89, 49, 25, 13, 7},
+    {156, 87, 49, 26, 14, 7},
+    {150, 86, 47, 26, 14, 7},
+    {142, 84, 47, 26, 14, 7},
+    {131, 79, 46, 26, 14, 7}
+};
+
+
 enum RA_Flag {
     RA_FLAG_NONE,
     RA_FLAG_FRAMES,
@@ -169,6 +192,8 @@ typedef struct {
     unsigned int frame_id;          ///< the frame ID / number of the current frame
     unsigned int js_switch;         ///< if true, joint-stereo decoding is enforced
     unsigned int num_blocks;        ///< number of blocks used in the current frame
+    uint8_t *bgmc_lut;              ///< pointer at lookup tables used for BGMC
+    unsigned int *bgmc_lut_status;  ///< pointer at lookup table status flags used for BGMC
     int ltp_lag_length;             ///< number of bits used for ltp lag value
     int *use_ltp;                   ///< contains use_ltp flags for all channels
     int *ltp_lag;                   ///< contains ltp lag values for all channels
@@ -383,7 +408,6 @@ static int check_specific_config(ALSDecContext *ctx)
     }
 
     MISSING_ERR(sconf->floating,             "Floating point decoding",     -1);
-    MISSING_ERR(sconf->bgmc,                 "BGMC entropy decoding",       -1);
     MISSING_ERR(sconf->rlslms,               "Adaptive RLS-LMS prediction", -1);
     MISSING_ERR(sconf->chan_sort,            "Channel sorting",              0);
 
@@ -554,11 +578,13 @@ static int read_var_block_data(ALSDecContext *ctx, ALSBlockData *bd)
     GetBitContext *gb        = &ctx->gb;
     unsigned int k;
     unsigned int s[8];
+    unsigned int sx[8];
     unsigned int sub_blocks, log2_sub_blocks, sb_length;
     unsigned int start      = 0;
     unsigned int opt_order;
     int          sb;
     int32_t      *quant_cof = bd->quant_cof;
+    int32_t      *current_res;
 
 
     // ensure variable block decoding by reusing this field
@@ -591,9 +617,15 @@ static int read_var_block_data(ALSDecContext *ctx, ALSBlockData *bd)
 
     sb_length = bd->block_length >> log2_sub_blocks;
 
-
     if (sconf->bgmc) {
-        // TODO: BGMC mode
+        s[0] = get_bits(gb, 8 + (sconf->resolution > 1));
+        for (k = 1; k < sub_blocks; k++)
+            s[k] = s[k - 1] + decode_rice(gb, 2);
+
+        for (k = 0; k < sub_blocks; k++) {
+            sx[k]   = s[k] & 0x0F;
+            s [k] >>= 4;
+        }
     } else {
         s[0] = get_bits(gb, 4 + (sconf->resolution > 1));
         for (k = 1; k < sub_blocks; k++)
@@ -697,9 +729,76 @@ static int read_var_block_data(ALSDecContext *ctx, ALSBlockData *bd)
 
     // read all residuals
     if (sconf->bgmc) {
-        // TODO: BGMC mode
+        unsigned int delta[sub_blocks];
+        unsigned int k    [sub_blocks];
+        unsigned int b = av_clip((av_ceil_log2(bd->block_length) - 3) >> 1, 0, 5);
+        unsigned int i = start;
+
+        // read most significant bits
+        unsigned int high;
+        unsigned int low;
+        unsigned int value;
+
+        ff_bgmc_decode_init(gb, &high, &low, &value);
+
+        current_res = bd->raw_samples + start;
+
+        for (sb = 0; sb < sub_blocks; sb++, i = 0) {
+            k    [sb] = s[sb] > b ? s[sb] - b : 0;
+            delta[sb] = 5 - s[sb] + k[sb];
+
+            ff_bgmc_decode(gb, sb_length, current_res,
+                        delta[sb], sx[sb], &high, &low, &value, ctx->bgmc_lut, ctx->bgmc_lut_status);
+
+            current_res += sb_length;
+        }
+
+        ff_bgmc_decode_end(gb);
+
+
+        // read least significant bits and tails
+        i = start;
+        current_res = bd->raw_samples + start;
+
+        for (sb = 0; sb < sub_blocks; sb++, i = 0) {
+            unsigned int cur_tail_code = tail_code[sx[sb]][delta[sb]];
+            unsigned int cur_k         = k[sb];
+            unsigned int cur_s         = s[sb];
+
+            for (; i < sb_length; i++) {
+                int32_t res = *current_res;
+
+                if (res == cur_tail_code) {
+                    unsigned int max_msb =   (2 + (sx[sb] > 2) + (sx[sb] > 10))
+                                          << (5 - delta[sb]);
+
+                    res = decode_rice(gb, cur_s);
+
+                    if (res >= 0) {
+                        res += (max_msb    ) << cur_k;
+                    } else {
+                        res -= (max_msb - 1) << cur_k;
+                    }
+                } else {
+                    if (res > cur_tail_code)
+                        res--;
+
+                    if (res & 1)
+                        res = -res;
+
+                    res >>= 1;
+
+                    if (cur_k) {
+                        res <<= cur_k;
+                        res  |= get_bits_long(gb, cur_k);
+                    }
+                }
+
+            *current_res++ = res;
+            }
+        }
     } else {
-        int32_t *current_res = bd->raw_samples + start;
+        current_res = bd->raw_samples + start;
 
         for (sb = 0; sb < sub_blocks; sb++, start = 0)
             for (; start < sb_length; start++)
@@ -1348,6 +1447,8 @@ static av_cold int decode_end(AVCodecContext *avctx)
 
     av_freep(&ctx->sconf.chan_pos);
 
+    ff_bgmc_end(&ctx->bgmc_lut, &ctx->bgmc_lut_status);
+
     av_freep(&ctx->use_ltp);
     av_freep(&ctx->ltp_lag);
     av_freep(&ctx->ltp_gain);
@@ -1395,6 +1496,9 @@ static av_cold int decode_init(AVCodecContext *avctx)
         return -1;
     }
 
+    if (sconf->bgmc)
+        ff_bgmc_init(avctx, &ctx->bgmc_lut, &ctx->bgmc_lut_status);
+
     if (sconf->floating) {
         avctx->sample_fmt          = SAMPLE_FMT_FLT;
         avctx->bits_per_raw_sample = 32;
diff --git a/libavcodec/bgmc.c b/libavcodec/bgmc.c
new file mode 100644
index 0000000000..fcf02a081e
--- /dev/null
+++ b/libavcodec/bgmc.c
@@ -0,0 +1,567 @@
+/*
+ * Block Gilbert-Moore decoder
+ * Copyright (c) 2010 Thilo Borgmann <thilo.borgmann _at_ googlemail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file libavcodec/bgmc.c
+ * Block Gilbert-Moore decoder as used by MPEG-4 ALS
+ * @author Thilo Borgmann <thilo.borgmann _at_ googlemail.com>
+ */
+
+
+#include "bgmc.h"
+
+
+#define FREQ_BITS  14                      // bits used by frequency counters
+#define VALUE_BITS 18                      // bits used to represent the values
+#define TOP_VALUE  ((1 << VALUE_BITS) - 1) // maximum value
+#define FIRST_QTR  (TOP_VALUE / 4 + 1)     // first quarter of values maximum value
+#define HALF       (2 * FIRST_QTR)         // first half of values maximum value
+#define THIRD_QTR  (3 * FIRST_QTR)         // third quarter of values maximum value
+
+#define LUT_BITS   (FREQ_BITS - 8)         // number of bits used to index lookup tables
+#define LUT_SIZE   (1 << LUT_BITS)         // size of the lookup tables
+#define LUT_BUFF   4                       // number of buffered lookup tables
+
+
+/** Cumulative frequency tables for block Gilbert-Moore coding.
+ */
+static const uint16_t cf_tables_1[3][129] = {
+    {
+    16384, 16066, 15748, 15431, 15114, 14799, 14485, 14173, 13861, 13552,
+    13243, 12939, 12635, 12336, 12038, 11745, 11452, 11161, 10870, 10586,
+    10303, 10027,  9751,  9483,  9215,  8953,  8692,  8440,  8189,  7946,
+     7704,  7472,  7240,  7008,  6776,  6554,  6333,  6122,  5912,  5711,
+     5512,  5320,  5128,  4947,  4766,  4595,  4425,  4264,  4104,  3946,
+     3788,  3640,  3493,  3355,  3218,  3090,  2963,  2842,  2721,  2609,
+     2498,  2395,  2292,  2196,  2100,  2004,  1908,  1820,  1732,  1651,
+     1570,  1497,  1424,  1355,  1287,  1223,  1161,  1100,  1044,   988,
+      938,   888,   839,   790,   746,   702,   662,   623,   588,   553,
+      520,   488,   459,   431,   405,   380,   357,   334,   311,   288,
+      268,   248,   230,   213,   197,   182,   168,   154,   142,   130,
+      119,   108,    99,    90,    81,    72,    64,    56,    49,    42,
+       36,    30,    25,    20,    15,    11,     7,     3,     0
+   },
+   {
+    16384, 16080, 15776, 15473, 15170, 14868, 14567, 14268, 13970, 13674,
+    13378, 13086, 12794, 12505, 12218, 11936, 11654, 11373, 11092, 10818,
+    10544, 10276, 10008,  9749,  9490,  9236,  8982,  8737,  8492,  8256,
+     8020,  7792,  7564,  7336,  7108,  6888,  6669,  6459,  6249,  6050,
+     5852,  5660,  5468,  5286,  5104,  4931,  4760,  4598,  4436,  4275,
+     4115,  3965,  3816,  3674,  3534,  3403,  3272,  3147,  3023,  2907,
+     2792,  2684,  2577,  2476,  2375,  2274,  2173,  2079,  1986,  1897,
+     1810,  1724,  1645,  1567,  1493,  1419,  1351,  1284,  1222,  1161,
+     1105,  1050,   995,   941,   891,   842,   797,   753,   713,   673,
+      636,   599,   566,   533,   503,   473,   446,   419,   392,   365,
+      340,   316,   294,   272,   253,   234,   216,   199,   184,   169,
+      155,   142,   130,   118,   106,    95,    85,    75,    66,    57,
+       49,    41,    34,    27,    21,    15,    10,     5,     0
+   },
+   {
+    16384, 16092, 15801, 15510, 15219, 14930, 14641, 14355, 14069, 13785,
+    13501, 13219, 12938, 12661, 12384, 12112, 11841, 11571, 11301, 11037,
+    10773, 10514, 10256, 10005,  9754,  9508,  9263,  9025,  8787,  8557,
+     8327,  8103,  7879,  7655,  7431,  7215,  7000,  6792,  6585,  6387,
+     6190,  5998,  5807,  5625,  5445,  5272,  5100,  4937,  4774,  4613,
+     4452,  4301,  4150,  4007,  3865,  3731,  3597,  3469,  3341,  3218,
+     3099,  2981,  2869,  2758,  2652,  2546,  2440,  2334,  2234,  2134,
+     2041,  1949,  1864,  1779,  1699,  1620,  1547,  1474,  1407,  1340,
+     1278,  1217,  1157,  1097,  1043,   989,   940,   891,   846,   801,
+      759,   718,   680,   643,   609,   575,   543,   511,   479,   447,
+      418,   389,   363,   337,   314,   291,   270,   249,   230,   212,
+      195,   179,   164,   149,   135,   121,   108,    96,    85,    74,
+       64,    54,    45,    36,    28,    20,    13,     6,     0
+   }
+};
+
+
+static const uint16_t cf_tables_2[8][193] = {
+    {
+    16384, 16104, 15825, 15546, 15268, 14991, 14714, 14439, 14164, 13891,
+    13620, 13350, 13081, 12815, 12549, 12287, 12025, 11765, 11505, 11250,
+    10996, 10746, 10497, 10254, 10011,  9772,  9534,  9303,  9072,  8848,
+     8624,  8406,  8188,  7970,  7752,  7539,  7327,  7123,  6919,  6724,
+     6529,  6339,  6150,  5970,  5790,  5618,  5446,  5282,  5119,  4957,
+     4795,  4642,  4490,  4345,  4201,  4065,  3929,  3798,  3669,  3547,
+     3425,  3310,  3196,  3086,  2976,  2866,  2756,  2650,  2545,  2447,
+     2350,  2260,  2170,  2085,  2000,  1921,  1843,  1770,  1698,  1632,
+     1566,  1501,  1436,  1376,  1316,  1261,  1207,  1157,  1108,  1061,
+     1015,   973,   931,   893,   855,   819,   783,   747,   711,   677,
+      644,   614,   584,   557,   530,   505,   480,   458,   436,   416,
+      396,   378,   360,   343,   326,   310,   295,   281,   267,   255,
+      243,   232,   221,   211,   201,   192,   183,   174,   166,   158,
+      150,   142,   134,   126,   119,   112,   106,   100,    95,    90,
+       85,    80,    76,    72,    69,    66,    63,    60,    57,    54,
+       51,    48,    46,    44,    42,    40,    38,    36,    34,    33,
+       32,    31,    30,    29,    28,    27,    26,    25,    24,    23,
+       22,    21,    20,    19,    18,    17,    16,    15,    14,    13,
+       12,    11,    10,     9,     8,     7,     6,     5,     4,     3,
+        2,     1,     0
+    },
+    {
+    16384, 16116, 15849, 15582, 15316, 15050, 14785, 14521, 14257, 13995,
+    13734, 13476, 13218, 12963, 12708, 12457, 12206, 11956, 11706, 11460,
+    11215, 10975, 10735, 10500, 10265, 10034,  9803,  9579,  9355,  9136,
+     8917,  8703,  8489,  8275,  8061,  7853,  7645,  7444,  7244,  7051,
+     6858,  6671,  6484,  6305,  6127,  5956,  5785,  5622,  5459,  5298,
+     5137,  4983,  4830,  4684,  4539,  4401,  4263,  4131,  3999,  3874,
+     3750,  3632,  3515,  3401,  3287,  3173,  3059,  2949,  2840,  2737,
+     2635,  2539,  2444,  2354,  2264,  2181,  2098,  2020,  1943,  1872,
+     1801,  1731,  1661,  1596,  1532,  1472,  1412,  1357,  1303,  1251,
+     1200,  1153,  1106,  1063,  1020,   979,   938,   897,   856,   818,
+      780,   746,   712,   681,   650,   621,   592,   566,   540,   517,
+      494,   473,   452,   431,   410,   391,   373,   356,   340,   325,
+      310,   296,   282,   270,   258,   247,   236,   225,   214,   203,
+      192,   182,   172,   162,   153,   144,   136,   128,   121,   114,
+      108,   102,    97,    92,    87,    82,    77,    73,    69,    65,
+       62,    59,    56,    53,    50,    47,    45,    43,    41,    39,
+       37,    35,    33,    31,    29,    27,    26,    25,    24,    23,
+       22,    21,    20,    19,    18,    17,    16,    15,    14,    13,
+       12,    11,    10,     9,     8,     7,     6,     5,     4,     3,
+        2,     1,     0
+    },
+    {
+    16384, 16128, 15872, 15617, 15362, 15107, 14853, 14600, 14347, 14096,
+    13846, 13597, 13350, 13105, 12860, 12618, 12376, 12135, 11894, 11657,
+    11421, 11189, 10957, 10730, 10503, 10279, 10056,  9838,  9620,  9407,
+     9195,  8987,  8779,  8571,  8363,  8159,  7955,  7758,  7561,  7371,
+     7182,  6997,  6812,  6635,  6459,  6289,  6120,  5957,  5795,  5634,
+     5473,  5319,  5165,  5018,  4871,  4732,  4593,  4458,  4324,  4197,
+     4071,  3951,  3831,  3714,  3597,  3480,  3363,  3250,  3138,  3032,
+     2927,  2828,  2729,  2635,  2541,  2453,  2366,  2284,  2202,  2126,
+     2050,  1975,  1900,  1830,  1761,  1697,  1633,  1574,  1515,  1459,
+     1403,  1351,  1300,  1252,  1205,  1160,  1115,  1070,  1025,   982,
+      939,   899,   860,   824,   789,   756,   723,   693,   663,   636,
+      609,   584,   559,   535,   511,   489,   467,   447,   427,   409,
+      391,   374,   358,   343,   328,   313,   300,   287,   274,   261,
+      248,   235,   223,   211,   200,   189,   179,   169,   160,   151,
+      143,   135,   128,   121,   115,   109,   103,    97,    92,    87,
+       82,    77,    73,    69,    65,    61,    58,    55,    52,    49,
+       46,    43,    40,    37,    35,    33,    31,    29,    27,    25,
+       23,    21,    20,    19,    18,    17,    16,    15,    14,    13,
+       12,    11,    10,     9,     8,     7,     6,     5,     4,     3,
+        2,     1,     0
+    },
+    {
+    16384, 16139, 15894, 15649, 15405, 15162, 14919, 14677, 14435, 14195,
+    13955, 13717, 13479, 13243, 13008, 12775, 12542, 12310, 12079, 11851,
+    11623, 11399, 11176, 10956, 10737, 10521, 10305, 10094,  9883,  9677,
+     9471,  9268,  9065,  8862,  8659,  8459,  8260,  8067,  7874,  7688,
+     7502,  7321,  7140,  6965,  6790,  6621,  6452,  6290,  6128,  5968,
+     5808,  5655,  5503,  5356,  5209,  5069,  4929,  4794,  4660,  4532,
+     4404,  4282,  4160,  4041,  3922,  3803,  3684,  3568,  3452,  3343,
+     3234,  3131,  3029,  2931,  2833,  2741,  2649,  2563,  2477,  2396,
+     2316,  2236,  2157,  2083,  2009,  1940,  1871,  1807,  1743,  1683,
+     1623,  1567,  1511,  1459,  1407,  1357,  1307,  1257,  1207,  1159,
+     1111,  1067,  1023,   983,   943,   905,   868,   834,   800,   769,
+      738,   709,   681,   653,   625,   600,   575,   552,   529,   508,
+      487,   466,   447,   428,   410,   392,   376,   360,   344,   328,
+      313,   298,   283,   268,   255,   242,   230,   218,   207,   196,
+      186,   176,   167,   158,   150,   142,   135,   128,   121,   114,
+      108,   102,    97,    92,    87,    82,    78,    74,    70,    66,
+       62,    58,    54,    50,    47,    44,    41,    38,    35,    32,
+       30,    28,    26,    24,    22,    20,    18,    16,    14,    13,
+       12,    11,    10,     9,     8,     7,     6,     5,     4,     3,
+        2,     1,     0
+    },
+    {
+    16384, 16149, 15915, 15681, 15447, 15214, 14981, 14749, 14517, 14286,
+    14055, 13827, 13599, 13373, 13147, 12923, 12699, 12476, 12253, 12034,
+    11815, 11599, 11383, 11171, 10959, 10750, 10541, 10337, 10133,  9933,
+     9733,  9536,  9339,  9142,  8945,  8751,  8557,  8369,  8181,  7998,
+     7816,  7638,  7460,  7288,  7116,  6950,  6785,  6625,  6465,  6306,
+     6147,  5995,  5843,  5697,  5551,  5411,  5271,  5135,  5000,  4871,
+     4742,  4618,  4495,  4374,  4253,  4132,  4011,  3893,  3775,  3663,
+     3552,  3446,  3340,  3239,  3138,  3043,  2948,  2858,  2768,  2684,
+     2600,  2516,  2433,  2355,  2278,  2205,  2133,  2065,  1997,  1932,
+     1867,  1807,  1747,  1690,  1634,  1580,  1526,  1472,  1418,  1366,
+     1314,  1266,  1218,  1174,  1130,  1088,  1047,  1009,   971,   936,
+      901,   868,   836,   804,   772,   743,   714,   685,   658,   631,
+      606,   582,   559,   536,   515,   494,   475,   456,   437,   418,
+      399,   380,   362,   344,   328,   312,   297,   283,   270,   257,
+      245,   233,   222,   211,   201,   191,   181,   172,   163,   155,
+      147,   139,   132,   125,   119,   113,   107,   101,    96,    91,
+       86,    81,    76,    71,    66,    62,    58,    54,    50,    46,
+       43,    40,    37,    34,    31,    28,    26,    24,    22,    20,
+       18,    16,    14,    12,    10,     8,     6,     5,     4,     3,
+        2,     1,     0
+    },
+    {
+    16384, 16159, 15934, 15709, 15485, 15261, 15038, 14816, 14594, 14373,
+    14152, 13933, 13714, 13497, 13280, 13065, 12850, 12636, 12422, 12211,
+    12000, 11791, 11583, 11378, 11173, 10971, 10769, 10571, 10373, 10179,
+     9985,  9793,  9601,  9409,  9217,  9029,  8842,  8658,  8475,  8297,
+     8120,  7946,  7773,  7604,  7435,  7271,  7108,  6950,  6792,  6634,
+     6477,  6326,  6175,  6029,  5883,  5742,  5602,  5466,  5330,  5199,
+     5068,  4943,  4818,  4696,  4574,  4452,  4330,  4211,  4093,  3979,
+     3866,  3759,  3652,  3549,  3446,  3348,  3250,  3157,  3065,  2977,
+     2889,  2802,  2716,  2634,  2553,  2476,  2399,  2326,  2254,  2185,
+     2117,  2052,  1987,  1926,  1866,  1808,  1750,  1692,  1634,  1578,
+     1522,  1470,  1418,  1369,  1321,  1275,  1229,  1187,  1145,  1105,
+     1066,  1027,   991,   955,   919,   883,   850,   817,   786,   756,
+      728,   700,   674,   648,   624,   600,   578,   556,   534,   512,
+      490,   468,   447,   426,   407,   388,   371,   354,   338,   322,
+      307,   293,   280,   267,   255,   243,   231,   219,   209,   199,
+      189,   179,   170,   161,   153,   145,   138,   131,   124,   117,
+      111,   105,    99,    93,    87,    81,    76,    71,    66,    61,
+       57,    53,    49,    45,    42,    39,    36,    33,    30,    27,
+       24,    21,    19,    17,    15,    13,    11,     9,     7,     5,
+        3,     1,     0
+    },
+    {
+    16384, 16169, 15954, 15739, 15524, 15310, 15096, 14883, 14670, 14458,
+    14246, 14035, 13824, 13614, 13405, 13198, 12991, 12785, 12579, 12376,
+    12173, 11972, 11772, 11574, 11377, 11182, 10987, 10795, 10603, 10414,
+    10226, 10040,  9854,  9668,  9482,  9299,  9116,  8937,  8759,  8585,
+     8411,  8241,  8071,  7906,  7741,  7580,  7419,  7263,  7107,  6952,
+     6797,  6647,  6497,  6353,  6209,  6070,  5931,  5796,  5661,  5531,
+     5401,  5275,  5150,  5027,  4904,  4781,  4658,  4538,  4419,  4304,
+     4190,  4081,  3972,  3867,  3762,  3662,  3562,  3467,  3372,  3281,
+     3191,  3101,  3012,  2928,  2844,  2764,  2684,  2608,  2533,  2460,
+     2387,  2318,  2250,  2185,  2121,  2059,  1997,  1935,  1873,  1813,
+     1754,  1698,  1642,  1588,  1535,  1483,  1433,  1384,  1338,  1292,
+     1249,  1206,  1165,  1125,  1085,  1045,  1008,   971,   937,   903,
+      871,   840,   810,   780,   752,   724,   698,   672,   647,   622,
+      597,   572,   548,   524,   502,   480,   460,   440,   421,   403,
+      386,   369,   353,   337,   323,   309,   295,   281,   268,   255,
+      243,   231,   220,   209,   199,   189,   180,   171,   163,   155,
+      147,   139,   131,   123,   116,   109,   102,    95,    89,    83,
+       77,    72,    67,    62,    57,    52,    48,    44,    40,    36,
+       32,    28,    25,    22,    19,    16,    13,    10,     8,     6,
+        4,     2,     0
+    },
+    {
+    16384, 16177, 15970, 15764, 15558, 15353, 15148, 14944, 14740, 14537,
+    14334, 14132, 13930, 13729, 13529, 13330, 13131, 12933, 12735, 12539,
+    12343, 12150, 11957, 11766, 11576, 11388, 11200, 11015, 10830, 10647,
+    10465, 10285, 10105,  9925,  9745,  9568,  9391,  9218,  9045,  8876,
+     8707,  8541,  8375,  8213,  8051,  7894,  7737,  7583,  7429,  7277,
+     7125,  6977,  6830,  6687,  6544,  6406,  6268,  6133,  5998,  5868,
+     5738,  5612,  5487,  5364,  5241,  5118,  4995,  4875,  4755,  4640,
+     4525,  4414,  4304,  4198,  4092,  3990,  3888,  3790,  3693,  3600,
+     3507,  3415,  3323,  3235,  3147,  3064,  2981,  2902,  2823,  2746,
+     2670,  2594,  2522,  2450,  2382,  2314,  2248,  2182,  2116,  2050,
+     1987,  1924,  1864,  1804,  1748,  1692,  1638,  1585,  1534,  1484,
+     1437,  1390,  1346,  1302,  1258,  1215,  1174,  1133,  1095,  1057,
+     1021,   986,   952,   918,   887,   856,   827,   798,   770,   742,
+      714,   686,   659,   632,   607,   582,   559,   536,   514,   492,
+      472,   452,   433,   415,   398,   381,   364,   348,   333,   318,
+      304,   290,   277,   264,   252,   240,   229,   218,   208,   198,
+      188,   178,   168,   158,   149,   140,   132,   124,   116,   108,
+      101,    94,    87,    81,    75,    69,    64,    59,    54,    49,
+       44,    39,    35,    31,    27,    23,    19,    15,    12,     9,
+        6,     3,     0
+    }
+};
+
+
+static const uint16_t cf_tables_3[5][257] = {
+    {
+    16384, 16187, 15990, 15793, 15597, 15401, 15205, 15009, 14813, 14618,
+    14423, 14230, 14037, 13845, 13653, 13463, 13273, 13083, 12894, 12706,
+    12518, 12332, 12146, 11962, 11778, 11597, 11416, 11237, 11059, 10882,
+    10706, 10532, 10358, 10184, 10010,  9838,  9666,  9497,  9328,  9163,
+     8999,  8837,  8675,  8517,  8359,  8205,  8051,  7901,  7751,  7602,
+     7453,  7308,  7163,  7022,  6882,  6745,  6609,  6476,  6343,  6214,
+     6085,  5960,  5835,  5712,  5589,  5466,  5343,  5223,  5103,  4987,
+     4872,  4761,  4650,  4542,  4435,  4332,  4229,  4130,  4031,  3936,
+     3841,  3747,  3653,  3563,  3473,  3387,  3302,  3220,  3138,  3059,
+     2980,  2905,  2830,  2759,  2688,  2619,  2550,  2481,  2412,  2345,
+     2278,  2215,  2152,  2092,  2032,  1974,  1917,  1863,  1809,  1758,
+     1707,  1659,  1611,  1564,  1517,  1473,  1429,  1387,  1346,  1307,
+     1268,  1230,  1193,  1158,  1123,  1090,  1058,  1026,   994,   962,
+      930,   899,   869,   841,   813,   786,   760,   735,   710,   687,
+      664,   643,   622,   602,   582,   562,   543,   525,   507,   490,
+      473,   457,   442,   427,   412,   398,   385,   373,   361,   349,
+      337,   325,   313,   301,   290,   279,   269,   259,   249,   240,
+      231,   222,   214,   206,   199,   192,   185,   178,   171,   165,
+      159,   153,   148,   143,   138,   133,   128,   123,   119,   115,
+      111,   107,   103,    99,    95,    91,    87,    83,    80,    77,
+       74,    71,    68,    65,    63,    61,    59,    57,    55,    53,
+       51,    49,    47,    45,    43,    41,    40,    39,    38,    37,
+       36,    35,    34,    33,    32,    31,    30,    29,    28,    27,
+       26,    25,    24,    23,    22,    21,    20,    19,    18,    17,
+       16,    15,    14,    13,    12,    11,    10,     9,     8,     7,
+        6,     5,     4,     3,     2,     1,     0
+    },
+    {
+    16384, 16195, 16006, 15817, 15629, 15441, 15253, 15065, 14878, 14692,
+    14506, 14321, 14136, 13952, 13768, 13585, 13402, 13219, 13037, 12857,
+    12677, 12499, 12321, 12144, 11967, 11792, 11617, 11444, 11271, 11100,
+    10930, 10762, 10594, 10426, 10258, 10091,  9925,  9761,  9598,  9438,
+     9278,  9120,  8963,  8809,  8655,  8504,  8354,  8207,  8060,  7914,
+     7769,  7627,  7485,  7347,  7209,  7074,  6939,  6807,  6676,  6548,
+     6420,  6296,  6172,  6050,  5928,  5806,  5684,  5564,  5444,  5328,
+     5212,  5100,  4988,  4879,  4771,  4667,  4563,  4462,  4362,  4265,
+     4169,  4073,  3978,  3886,  3795,  3707,  3619,  3535,  3451,  3369,
+     3288,  3210,  3133,  3059,  2985,  2913,  2841,  2769,  2697,  2627,
+     2557,  2490,  2424,  2360,  2297,  2237,  2177,  2119,  2062,  2007,
+     1953,  1901,  1849,  1798,  1748,  1700,  1652,  1607,  1562,  1519,
+     1476,  1435,  1394,  1355,  1317,  1281,  1245,  1210,  1175,  1140,
+     1105,  1071,  1037,  1005,   973,   943,   913,   885,   857,   830,
+      804,   779,   754,   731,   708,   685,   663,   642,   621,   601,
+      581,   563,   545,   528,   511,   495,   479,   463,   448,   433,
+      419,   405,   391,   377,   364,   351,   338,   326,   314,   302,
+      291,   280,   270,   260,   251,   242,   234,   226,   218,   210,
+      202,   195,   188,   181,   174,   168,   162,   156,   150,   144,
+      139,   134,   129,   124,   119,   114,   109,   104,   100,    96,
+       92,    88,    84,    80,    77,    74,    71,    68,    65,    62,
+       59,    56,    54,    52,    50,    48,    46,    44,    42,    40,
+       38,    36,    34,    33,    32,    31,    30,    29,    28,    27,
+       26,    25,    24,    23,    22,    21,    20,    19,    18,    17,
+       16,    15,    14,    13,    12,    11,    10,     9,     8,     7,
+        6,     5,     4,     3,     2,     1,     0
+    },
+    {
+    16384, 16203, 16022, 15842, 15662, 15482, 15302, 15122, 14942, 14763,
+    14584, 14406, 14228, 14051, 13874, 13698, 13522, 13347, 13172, 12998,
+    12824, 12652, 12480, 12310, 12140, 11971, 11803, 11637, 11471, 11307,
+    11143, 10980, 10817, 10654, 10491, 10330, 10169, 10011,  9853,  9697,
+     9542,  9389,  9236,  9086,  8936,  8789,  8642,  8498,  8355,  8212,
+     8070,  7931,  7792,  7656,  7520,  7388,  7256,  7126,  6996,  6870,
+     6744,  6621,  6498,  6377,  6256,  6135,  6014,  5895,  5776,  5660,
+     5545,  5433,  5321,  5212,  5104,  4999,  4895,  4793,  4692,  4594,
+     4496,  4400,  4304,  4211,  4118,  4028,  3939,  3853,  3767,  3684,
+     3601,  3521,  3441,  3364,  3287,  3212,  3137,  3062,  2987,  2915,
+     2843,  2773,  2704,  2638,  2572,  2508,  2445,  2384,  2324,  2266,
+     2208,  2153,  2098,  2044,  1990,  1939,  1888,  1839,  1791,  1745,
+     1699,  1655,  1611,  1569,  1527,  1487,  1448,  1409,  1370,  1331,
+     1292,  1255,  1218,  1183,  1148,  1115,  1082,  1051,  1020,   990,
+      960,   932,   904,   878,   852,   826,   801,   777,   753,   731,
+      709,   687,   666,   645,   625,   605,   586,   567,   550,   533,
+      516,   499,   482,   465,   449,   433,   418,   403,   389,   375,
+      362,   349,   337,   325,   314,   303,   293,   283,   273,   263,
+      254,   245,   236,   227,   219,   211,   204,   197,   190,   183,
+      177,   171,   165,   159,   153,   147,   141,   135,   130,   125,
+      120,   115,   110,   105,   101,    97,    93,    89,    85,    81,
+       77,    74,    71,    68,    65,    62,    59,    56,    53,    51,
+       49,    47,    45,    43,    41,    39,    37,    35,    33,    31,
+       29,    27,    25,    23,    22,    21,    20,    19,    18,    17,
+       16,    15,    14,    13,    12,    11,    10,     9,     8,     7,
+        6,     5,     4,     3,     2,     1,     0
+    },
+    {
+    16384, 16210, 16036, 15863, 15690, 15517, 15344, 15172, 15000, 14828,
+    14656, 14485, 14314, 14145, 13976, 13808, 13640, 13472, 13304, 13137,
+    12970, 12804, 12639, 12475, 12312, 12149, 11987, 11827, 11667, 11508,
+    11349, 11192, 11035, 10878, 10721, 10565, 10410, 10257, 10104,  9953,
+     9802,  9654,  9506,  9359,  9213,  9070,  8927,  8787,  8647,  8508,
+     8369,  8233,  8097,  7964,  7831,  7700,  7570,  7442,  7315,  7190,
+     7065,  6943,  6821,  6701,  6581,  6461,  6341,  6223,  6105,  5990,
+     5876,  5764,  5653,  5545,  5437,  5331,  5226,  5124,  5022,  4924,
+     4826,  4729,  4632,  4538,  4444,  4353,  4262,  4174,  4087,  4002,
+     3917,  3835,  3753,  3674,  3595,  3518,  3441,  3364,  3287,  3212,
+     3138,  3066,  2995,  2926,  2858,  2792,  2726,  2662,  2599,  2538,
+     2478,  2420,  2362,  2305,  2249,  2195,  2141,  2089,  2037,  1988,
+     1939,  1891,  1844,  1799,  1754,  1711,  1668,  1626,  1584,  1542,
+     1500,  1459,  1418,  1380,  1342,  1305,  1269,  1234,  1199,  1166,
+     1133,  1102,  1071,  1041,  1012,   983,   954,   926,   899,   872,
+      847,   822,   798,   774,   751,   728,   707,   686,   666,   646,
+      627,   608,   589,   570,   552,   534,   517,   500,   484,   468,
+      453,   438,   424,   410,   397,   384,   372,   360,   348,   336,
+      325,   314,   303,   293,   283,   273,   264,   255,   246,   237,
+      229,   221,   213,   205,   197,   189,   181,   174,   167,   160,
+      154,   148,   142,   136,   131,   126,   121,   116,   111,   106,
+      101,    97,    93,    89,    85,    81,    77,    73,    70,    67,
+       64,    61,    58,    55,    52,    49,    46,    43,    40,    37,
+       35,    33,    31,    29,    27,    25,    23,    21,    19,    17,
+       16,    15,    14,    13,    12,    11,    10,     9,     8,     7,
+        6,     5,     4,     3,     2,     1,     0
+    },
+    {
+    16384, 16218, 16052, 15886, 15720, 15554, 15389, 15224, 15059, 14895,
+    14731, 14567, 14403, 14240, 14077, 13915, 13753, 13591, 13429, 13269,
+    13109, 12950, 12791, 12633, 12476, 12320, 12164, 12009, 11854, 11701,
+    11548, 11396, 11244, 11092, 10940, 10790, 10640, 10492, 10344, 10198,
+    10052,  9908,  9764,  9622,  9481,  9342,  9203,  9066,  8929,  8793,
+     8657,  8524,  8391,  8261,  8131,  8003,  7875,  7749,  7624,  7502,
+     7380,  7260,  7140,  7022,  6904,  6786,  6668,  6551,  6435,  6322,
+     6209,  6099,  5989,  5881,  5773,  5668,  5563,  5461,  5359,  5260,
+     5161,  5063,  4965,  4871,  4777,  4686,  4595,  4506,  4417,  4331,
+     4245,  4162,  4079,  3999,  3919,  3841,  3763,  3685,  3607,  3530,
+     3454,  3380,  3307,  3236,  3166,  3097,  3029,  2963,  2897,  2834,
+     2771,  2710,  2650,  2591,  2532,  2475,  2418,  2363,  2309,  2257,
+     2205,  2155,  2105,  2057,  2009,  1963,  1918,  1873,  1828,  1783,
+     1738,  1694,  1650,  1607,  1565,  1524,  1484,  1445,  1407,  1369,
+     1333,  1297,  1263,  1229,  1197,  1165,  1134,  1103,  1073,  1043,
+     1015,   987,   960,   933,   907,   882,   858,   834,   811,   788,
+      766,   744,   722,   700,   679,   658,   638,   618,   599,   581,
+      563,   545,   528,   511,   495,   480,   465,   451,   437,   423,
+      410,   397,   384,   372,   360,   348,   337,   326,   315,   305,
+      295,   285,   275,   265,   255,   245,   236,   227,   219,   211,
+      203,   195,   188,   181,   174,   167,   161,   155,   149,   143,
+      137,   131,   126,   121,   116,   111,   106,   101,    97,    93,
+       89,    85,    81,    77,    73,    69,    65,    61,    58,    55,
+       52,    49,    46,    43,    40,    37,    34,    32,    30,    28,
+       26,    24,    22,    20,    18,    16,    14,    12,    10,     8,
+        6,     5,     4,     3,     2,     1,     0
+    }
+};
+
+
+static const uint16_t * const cf_table[16] = {
+    cf_tables_1[0], cf_tables_1[1], cf_tables_1[2], cf_tables_2[0],
+    cf_tables_2[1], cf_tables_2[2], cf_tables_2[3], cf_tables_2[4],
+    cf_tables_2[5], cf_tables_2[6], cf_tables_2[7], cf_tables_3[0],
+    cf_tables_3[1], cf_tables_3[2], cf_tables_3[3], cf_tables_3[4]
+};
+
+
+/** Initializes a given lookup table using a given delta
+ */
+static void bgmc_lut_fillp(uint8_t *lut, unsigned int *lut_status,
+                           unsigned int delta)
+{
+    unsigned int sx, i;
+
+    for (sx = 0; sx < 16; sx++)
+        for (i = 0; i < LUT_SIZE; i++) {
+            unsigned int target = (i + 1) << (FREQ_BITS - LUT_BITS);
+            unsigned int symbol = 1 << delta;
+
+            while (cf_table[sx][symbol] > target)
+                symbol += 1 << delta;
+
+            *lut++ = symbol >> delta;
+        }
+
+    *lut_status = delta;
+}
+
+
+/** Retunes the index of a suitable lookup table for a given delta
+ */
+static uint8_t* bgmc_lut_getp(uint8_t *lut, unsigned int *lut_status,
+                              unsigned int delta)
+{
+    unsigned int i = av_clip(delta, 0, LUT_BUFF - 1);
+
+    lut += (i * LUT_SIZE) << 4;
+
+    if (lut_status[i] != delta)
+        bgmc_lut_fillp(lut, &lut_status[i], delta);
+
+    return lut;
+}
+
+
+/** Initializes the lookup table arrays
+ */
+int ff_bgmc_init(AVCodecContext *avctx, uint8_t **cf_lut, unsigned int **cf_lut_status)
+{
+    *cf_lut        = av_malloc(sizeof(*cf_lut       ) * LUT_BUFF * 16 * LUT_SIZE);
+    *cf_lut_status = av_malloc(sizeof(*cf_lut_status) * LUT_BUFF);
+
+    if (!cf_lut || !cf_lut_status) {
+        ff_bgmc_end(cf_lut, cf_lut_status);
+        av_log(avctx, AV_LOG_ERROR, "Allocating buffer memory failed.\n");
+        return AVERROR(ENOMEM);
+    }
+
+    return 0;
+}
+
+
+/** Releases the lookup table arrays
+ */
+void ff_bgmc_end(uint8_t **cf_lut, unsigned int **cf_lut_status)
+{
+    av_freep(cf_lut);
+    av_freep(cf_lut_status);
+}
+
+
+/** Initializes decoding and reads the first value
+ */
+void ff_bgmc_decode_init(GetBitContext *gb,
+                      unsigned int *h, unsigned int *l, unsigned int *v)
+{
+    *h = TOP_VALUE;
+    *l = 0;
+    *v = get_bits_long(gb, VALUE_BITS);
+}
+
+
+/** Finish decoding
+ */
+void ff_bgmc_decode_end(GetBitContext *gb)
+{
+    skip_bits_long(gb, -(VALUE_BITS - 2));
+}
+
+
+/** Reads and decodes a block Gilbert-Moore coded symbol
+ */
+void ff_bgmc_decode(GetBitContext *gb, unsigned int num, int32_t *dst,
+                 unsigned int delta, unsigned int sx,
+                 unsigned int *h, unsigned int *l, unsigned int *v,
+                 uint8_t *cf_lut, unsigned int *cf_lut_status)
+{
+    unsigned int i;
+    uint8_t *lut = bgmc_lut_getp(cf_lut, cf_lut_status, delta);
+
+    // read current state
+    unsigned int high   = *h;
+    unsigned int low    = *l;
+    unsigned int value  = *v;
+
+    lut += sx * LUT_SIZE;
+
+    // decode num samples
+    for (i = 0; i < num; i++) {
+        unsigned int range  = high - low + 1;
+        unsigned int target = (((value - low + 1) << FREQ_BITS) - 1) / range;
+        unsigned int symbol = lut[target >> (FREQ_BITS - LUT_BITS)] << delta;
+
+        while (cf_table[sx][symbol] > target)
+            symbol += 1 << delta;
+
+        symbol = (symbol >> delta) - 1;
+
+        high = low + ((range * cf_table[sx][(symbol    ) << delta] - (1 << FREQ_BITS)) >> FREQ_BITS);
+        low  = low + ((range * cf_table[sx][(symbol + 1) << delta]                   ) >> FREQ_BITS);
+
+        while (1) {
+            if (high >= HALF) {
+                if        (low >= HALF) {
+                    value -= HALF;
+                    low   -= HALF;
+                    high  -= HALF;
+                } else if (low >= FIRST_QTR && high < THIRD_QTR) {
+                    value -= FIRST_QTR;
+                    low   -= FIRST_QTR;
+                    high  -= FIRST_QTR;
+                } else break;
+            }
+
+            low   *= 2;
+            high   = 2 * high  + 1;
+            value  = 2 * value + get_bits1(gb);
+        }
+
+        *dst++ = symbol;
+    }
+
+    // save current state
+    *h = high;
+    *l = low;
+    *v = value;
+}
+
diff --git a/libavcodec/bgmc.h b/libavcodec/bgmc.h
new file mode 100644
index 0000000000..bae4f3b9a0
--- /dev/null
+++ b/libavcodec/bgmc.h
@@ -0,0 +1,56 @@
+/*
+ * Block Gilbert-Moore decoder
+ * Copyright (c) 2010 Thilo Borgmann <thilo.borgmann _at_ googlemail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file libavcodec/bgmc.h
+ * Block Gilbert-Moore decoder header
+ * @author Thilo Borgmann <thilo.borgmann _at_ googlemail.com>
+ */
+
+
+#ifndef AVCODEC_BGMC_H
+#define AVCODEC_BGMC_H
+
+
+#include "avcodec.h"
+#include "get_bits.h"
+
+
+int ff_bgmc_init(AVCodecContext *avctx, uint8_t **cf_lut, unsigned int **cf_lut_status);
+
+
+void ff_bgmc_end(uint8_t **cf_lut, unsigned int **cf_lut_status);
+
+
+void ff_bgmc_decode_init(GetBitContext *gb,
+                      unsigned int *h, unsigned int *l, unsigned int *v);
+
+
+void ff_bgmc_decode_end(GetBitContext *gb);
+
+
+void ff_bgmc_decode(GetBitContext *gb, unsigned int num, int32_t *dst,
+                 unsigned int delta, unsigned int sx,
+                 unsigned int *h, unsigned int *l, unsigned int *v,
+                 uint8_t *cf_lut, unsigned int *cf_lut_status);
+
+
+#endif /* AVCODEC_BGMC_H */