Go2Meeting decoder

ELS and ePIC decoder courtesy of Maxim Poliakovski,
cleanup and integration by Diego Biurrun.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

7 files changed, 1220 insertions, 26 deletions

diff --git a/Changelog b/Changelog
index 46e5f7a292..7d4678314f 100644
--- a/Changelog
+++ b/Changelog
@@ -37,6 +37,7 @@ version <next>:
 - Hap decoder and encoder
 - DirectDraw Surface image/texture decoder
 - rewritten ASF demuxer
+- Go2Meeting decoding support
 
 
 version 11:
diff --git a/doc/general.texi b/doc/general.texi
index 0beffad370..ef9bc6a577 100644
--- a/doc/general.texi
+++ b/doc/general.texi
@@ -607,6 +607,8 @@ following image formats are supported:
     @tab Sorenson H.263 used in Flash
 @item Forward Uncompressed   @tab     @tab  X
 @item Fraps                  @tab     @tab  X
+@item Go2Meeting             @tab     @tab  X
+    @tab fourcc: G2M2, G2M3
 @item Go2Webinar             @tab     @tab  X
     @tab fourcc: G2M4
 @item H.261                  @tab  X  @tab  X
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index dcdd428792..2b6d65b60f 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -214,7 +214,7 @@ OBJS-$(CONFIG_FLIC_DECODER)            += flicvideo.o
 OBJS-$(CONFIG_FOURXM_DECODER)          += 4xm.o
 OBJS-$(CONFIG_FRAPS_DECODER)           += fraps.o
 OBJS-$(CONFIG_FRWU_DECODER)            += frwu.o
-OBJS-$(CONFIG_G2M_DECODER)             += g2meet.o
+OBJS-$(CONFIG_G2M_DECODER)             += g2meet.o elsdec.o
 OBJS-$(CONFIG_G723_1_DECODER)          += g723_1.o acelp_vectors.o \
                                           celp_filters.o
 OBJS-$(CONFIG_GIF_DECODER)             += gifdec.o lzw.o
diff --git a/libavcodec/elsdec.c b/libavcodec/elsdec.c
new file mode 100644
index 0000000000..5e89045864
--- /dev/null
+++ b/libavcodec/elsdec.c
@@ -0,0 +1,422 @@
+/*
+ * ELS (Entropy Logarithmic-Scale) decoder
+ *
+ * Copyright (c) 2013 Maxim Poliakovski
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * Entropy Logarithmic-Scale binary arithmetic decoder
+ */
+
+#include <math.h>
+#include <stdint.h>
+
+#include "libavutil/common.h"
+#include "libavutil/intreadwrite.h"
+
+#include "avcodec.h"
+#include "elsdec.h"
+
+/* ELS coder constants and structures. */
+#define ELS_JOTS_PER_BYTE   36
+#define ELS_MAX             (1 << 24)
+#define RUNG_SPACE          (64 * sizeof(ElsRungNode))
+
+/* ELS coder tables. */
+static const struct Ladder {
+    int8_t  AMps;
+    int8_t  ALps;
+    uint8_t next0;
+    uint8_t next1;
+} Ladder[174] = {
+    { -6,   -5,   2,   1 },
+    { -2,  -12,   3,   6 },
+    { -2,  -12,   4,   6 },
+    { -1,  -16,   7,   5 },
+    { -1,  -16,   8,  10 },
+    { -5,   -6,  11,   9 },
+    { -6,   -5,  10,   5 },
+    { -1,  -18,  13,  11 },
+    { -1,  -18,  12,  14 },
+    { -6,   -5,  15,  18 },
+    { -5,   -6,  14,   9 },
+    { -3,   -8,  17,  15 },
+    { -1,  -20,  20,  16 },
+    { -1,  -20,  23,  17 },
+    { -3,   -8,  16,  18 },
+    { -5,   -6,  19,  26 },
+    { -3,   -9,  22,  24 },
+    { -3,   -9,  21,  19 },
+    { -5,   -6,  24,  26 },
+    { -4,   -7,  27,  25 },
+    { -1,  -22,  34,  28 },
+    { -2,  -11,  29,  27 },
+    { -2,  -11,  28,  30 },
+    { -1,  -22,  39,  29 },
+    { -4,   -7,  30,  32 },
+    { -6,   -5,  33,  31 },
+    { -6,   -5,  32,  25 },
+    { -3,   -8,  35,  33 },
+    { -2,  -12,  36,  38 },
+    { -2,  -12,  37,  35 },
+    { -3,   -8,  38,  40 },
+    { -6,   -5,  41,  48 },
+    { -6,   -5,  40,  31 },
+    { -5,   -6,  43,  41 },
+    { -1,  -24,  94,  42 },
+    { -3,   -8,  45,  43 },
+    { -2,  -12,  42,  44 },
+    { -2,  -12,  47,  45 },
+    { -3,   -8,  44,  46 },
+    { -1,  -24, 125,  47 },
+    { -5,   -6,  46,  48 },
+    { -6,   -5,  49,  49 },
+    { -2,  -13, 152, 164 },
+    { -4,   -7,  51,  49 },
+    { -3,   -9, 164, 168 },
+    { -3,   -9,  55,  51 },
+    { -4,   -7, 168, 170 },
+    { -2,  -13,  67,  55 },
+    { -6,   -5, 170,  49 },
+    { -6,   -5,  51, 170 },
+    { -1,  -72,  50,  74 },
+    { -4,   -7,  53,  49 },
+    { -1,  -61,  50,  74 },
+    { -3,   -8,  55,  49 },
+    { -1,  -51,  52,  76 },
+    { -3,   -9,  57,  51 },
+    { -1,  -46,  54,  76 },
+    { -2,  -10,  59,  53 },
+    { -1,  -43,  56,  78 },
+    { -2,  -11,  61,  53 },
+    { -1,  -41,  58,  80 },
+    { -2,  -12,  63,  55 },
+    { -1,  -39,  60,  82 },
+    { -2,  -12,  65,  55 },
+    { -1,  -37,  62,  84 },
+    { -2,  -13,  67,  57 },
+    { -1,  -36,  64,  86 },
+    { -1,  -14,  69,  59 },
+    { -1,  -35,  66,  88 },
+    { -1,  -14,  71,  59 },
+    { -1,  -34,  68,  90 },
+    { -1,  -15,  73,  61 },
+    { -1,  -33,  70,  92 },
+    { -1,  -15,  75,  61 },
+    { -1,  -32,  72,  94 },
+    { -1,  -15,  77,  63 },
+    { -1,  -31,  74,  96 },
+    { -1,  -16,  79,  65 },
+    { -1,  -31,  76,  98 },
+    { -1,  -16,  81,  67 },
+    { -1,  -30,  78, 100 },
+    { -1,  -17,  83,  67 },
+    { -1,  -29,  80, 102 },
+    { -1,  -17,  85,  69 },
+    { -1,  -29,  82, 104 },
+    { -1,  -18,  87,  71 },
+    { -1,  -28,  84, 104 },
+    { -1,  -18,  89,  73 },
+    { -1,  -28,  86, 108 },
+    { -1,  -18,  91,  73 },
+    { -1,  -27,  88, 108 },
+    { -1,  -19,  93,  75 },
+    { -1,  -27,  90, 112 },
+    { -1,  -19,  95,  77 },
+    { -1,  -26,  92, 112 },
+    { -1,  -20,  97,  79 },
+    { -1,  -26,  94, 114 },
+    { -1,  -20,  99,  81 },
+    { -1,  -25,  96, 116 },
+    { -1,  -20, 101,  83 },
+    { -1,  -25,  98, 118 },
+    { -1,  -21, 103,  83 },
+    { -1,  -24, 100, 120 },
+    { -1,  -21, 105,  85 },
+    { -1,  -24, 102, 122 },
+    { -1,  -22, 107,  87 },
+    { -1,  -23, 104, 124 },
+    { -1,  -22, 109,  89 },
+    { -1,  -23, 106, 126 },
+    { -1,  -22, 111,  91 },
+    { -1,  -22, 108, 128 },
+    { -1,  -23, 113,  93 },
+    { -1,  -22, 110, 130 },
+    { -1,  -23, 115,  95 },
+    { -1,  -22, 112, 132 },
+    { -1,  -24, 117,  97 },
+    { -1,  -21, 114, 134 },
+    { -1,  -24, 119,  99 },
+    { -1,  -21, 116, 136 },
+    { -1,  -25, 121, 101 },
+    { -1,  -20, 118, 136 },
+    { -1,  -25, 123, 103 },
+    { -1,  -20, 120, 138 },
+    { -1,  -26, 125, 105 },
+    { -1,  -20, 122, 140 },
+    { -1,  -26, 127, 107 },
+    { -1,  -19, 124, 142 },
+    { -1,  -27, 129, 107 },
+    { -1,  -19, 126, 144 },
+    { -1,  -27, 131, 111 },
+    { -1,  -18, 128, 146 },
+    { -1,  -28, 133, 111 },
+    { -1,  -18, 130, 146 },
+    { -1,  -28, 135, 115 },
+    { -1,  -18, 132, 148 },
+    { -1,  -29, 137, 115 },
+    { -1,  -17, 134, 150 },
+    { -1,  -29, 139, 117 },
+    { -1,  -17, 136, 152 },
+    { -1,  -30, 141, 119 },
+    { -1,  -16, 138, 152 },
+    { -1,  -31, 143, 121 },
+    { -1,  -16, 140, 154 },
+    { -1,  -31, 145, 123 },
+    { -1,  -15, 142, 156 },
+    { -1,  -32, 147, 125 },
+    { -1,  -15, 144, 158 },
+    { -1,  -33, 149, 127 },
+    { -1,  -15, 146, 158 },
+    { -1,  -34, 151, 129 },
+    { -1,  -14, 148, 160 },
+    { -1,  -35, 153, 131 },
+    { -1,  -14, 150, 160 },
+    { -1,  -36, 155, 133 },
+    { -2,  -13, 152, 162 },
+    { -1,  -37, 157, 135 },
+    { -2,  -12, 154, 164 },
+    { -1,  -39, 159, 137 },
+    { -2,  -12, 156, 164 },
+    { -1,  -41, 161, 139 },
+    { -2,  -11, 158, 166 },
+    { -1,  -43, 163, 141 },
+    { -2,  -10, 160, 166 },
+    { -1,  -46, 165, 143 },
+    { -3,   -9, 162, 168 },
+    { -1,  -51, 167, 143 },
+    { -3,   -8, 164, 170 },
+    { -1,  -61, 169, 145 },
+    { -4,   -7, 166, 170 },
+    { -1,  -72, 169, 145 },
+    { -6,   -5, 168,  49 },
+    {  0, -108, 171, 171 },
+    {  0, -108, 172, 172 },
+    { -6,   -5, 173, 173 },
+};
+
+static const uint32_t els_exp_tab[ELS_JOTS_PER_BYTE * 4 + 1] = {
+           0,        0,       0,       0,       0,       0,         0,        0,
+           0,        0,       0,       0,       0,       0,         0,        0,
+           0,        0,       0,       0,       0,       0,         0,        0,
+           0,        0,       0,       0,       0,       0,         0,        0,
+           0,        0,       0,       0,       1,       1,         1,        1,
+           1,        2,       2,       2,       3,       4,         4,        5,
+           6,        7,       8,      10,      11,      13,        16,       18,
+          21,       25,      29,      34,      40,      47,        54,       64,
+          74,       87,     101,     118,     138,      161,      188,      219,
+         256,      298,     348,     406,     474,      552,      645,      752,
+         877,     1024,    1194,    1393,    1625,     1896,     2211,     2580,
+        3010,     3511,    4096,    4778,    5573,     6501,     7584,     8847,
+       10321,    12040,   14045,   16384,   19112,    22295,    26007,    30339,
+       35391,    41285,   48160,   56180,   65536,    76288,    89088,   103936,
+      121344,   141312,  165120,  192512,  224512,   262144,   305664,   356608,
+      416000,   485376,  566016,  660480,  770560,   898816,  1048576,  1223168,
+     1426688,  1664256, 1941504, 2264832, 2642176,  3082240,  3595520,  4194304,
+     4892672,  5707520, 6657792, 7766784, 9060096, 10568960, 12328960, 14382080,
+    16777216,
+};
+
+void ff_els_decoder_init(ElsDecCtx *ctx, const uint8_t *in, size_t data_size)
+{
+    int nbytes;
+
+    /* consume up to 3 bytes from the input data */
+    if (data_size >= 3) {
+        ctx->x = AV_RB24(in);
+        nbytes = 3;
+    } else if (data_size == 2) {
+        ctx->x = AV_RB16(in);
+        nbytes = 2;
+    } else {
+        ctx->x = *in;
+        nbytes = 1;
+    }
+
+    ctx->in_buf    = in + nbytes;
+    ctx->data_size = data_size - nbytes;
+    ctx->err       = 0;
+    ctx->j         = ELS_JOTS_PER_BYTE;
+    ctx->t         = ELS_MAX;
+    ctx->diff      = FFMIN(ELS_MAX - ctx->x,
+                           ELS_MAX - els_exp_tab[ELS_JOTS_PER_BYTE * 4 - 1]);
+}
+
+void ff_els_decoder_uninit(ElsUnsignedRung *rung)
+{
+    av_free(rung->rem_rung_list);
+}
+
+static int els_import_byte(ElsDecCtx *ctx)
+{
+    if (!ctx->data_size) {
+        ctx->err = AVERROR_EOF;
+        return AVERROR_EOF;
+    }
+    ctx->x   = (ctx->x << 8) | *ctx->in_buf++;
+    ctx->data_size--;
+    ctx->j  += ELS_JOTS_PER_BYTE;
+    ctx->t <<= 8;
+
+    return 0;
+}
+
+int ff_els_decode_bit(ElsDecCtx *ctx, uint8_t *rung)
+{
+    int z, bit, ret;
+    const uint32_t *pAllowable = &els_exp_tab[ELS_JOTS_PER_BYTE * 3];
+
+    if (ctx->err)
+        return 0;
+
+    z          = pAllowable[ctx->j + Ladder[*rung].ALps];
+    ctx->t    -= z;
+    ctx->diff -= z;
+    if (ctx->diff > 0)
+        return *rung & 1;   /* shortcut for x < t > pAllowable[j - 1] */
+
+    if (ctx->t > ctx->x) {  /* decode most probable symbol (MPS) */
+        ctx->j += Ladder[*rung].AMps;
+        while (ctx->t > pAllowable[ctx->j])
+            ctx->j++;
+
+        if (ctx->j <= 0) { /* MPS: import one byte from bytestream. */
+            ret = els_import_byte(ctx);
+            if (ret < 0)
+                return ret;
+        }
+
+        z     = ctx->t;
+        bit   = *rung & 1;
+        *rung = Ladder[*rung].next0;
+    } else { /* decode less probable symbol (LPS) */
+        ctx->x -= ctx->t;
+        ctx->t  = z;
+
+        ctx->j += Ladder[*rung].ALps;
+        if (ctx->j <= 0) {
+            /* LPS: import one byte from bytestream. */
+            z <<= 8;
+            ret = els_import_byte(ctx);
+            if (ret < 0)
+                return ret;
+            if (ctx->j <= 0) {
+                /* LPS: import second byte from bytestream. */
+                z <<= 8;
+                ret = els_import_byte(ctx);
+                if (ret < 0)
+                    return ret;
+                while (pAllowable[ctx->j - 1] >= z)
+                    ctx->j--;
+            }
+        }
+
+        bit   = !(*rung & 1);
+        *rung = Ladder[*rung].next1;
+    }
+
+    ctx->diff = FFMIN(z - ctx->x, z - pAllowable[ctx->j - 1]);
+
+    return bit;
+}
+
+unsigned ff_els_decode_unsigned(ElsDecCtx *ctx, ElsUnsignedRung *ur)
+{
+    int i, n, r, bit;
+    ElsRungNode *rung_node;
+
+    if (ctx->err)
+        return 0;
+
+    /* decode unary prefix */
+    for (n = 0; n < ELS_EXPGOLOMB_LEN + 1; n++)
+        if (ff_els_decode_bit(ctx, &ur->prefix_rung[n]))
+            break;
+
+    /* handle the error/overflow case */
+    if (ctx->err || n >= ELS_EXPGOLOMB_LEN) {
+        ctx->err = AVERROR(EOVERFLOW);
+        return 0;
+    }
+
+    /* handle the zero case */
+    if (!n)
+        return 0;
+
+    /* initialize probability tree */
+    if (!ur->rem_rung_list) {
+        ur->rem_rung_list = av_realloc(NULL, RUNG_SPACE);
+        if (!ur->rem_rung_list) {
+            ctx->err = AVERROR(ENOMEM);
+            return 0;
+        }
+        memset(ur->rem_rung_list, 0, RUNG_SPACE);
+        ur->rung_list_size = RUNG_SPACE;
+        ur->avail_index    = ELS_EXPGOLOMB_LEN;
+    }
+
+    /* decode the remainder */
+    for (i = 0, r = 0, bit = 0; i < n; i++) {
+        if (!i)
+            rung_node = &ur->rem_rung_list[n];
+        else {
+            if (!rung_node->next_index) {
+                if (ur->rung_list_size <= (ur->avail_index + 2) * sizeof(ElsRungNode)) {
+                    // remember rung_node position
+                    ptrdiff_t pos     = rung_node - ur->rem_rung_list;
+                    ur->rem_rung_list = av_realloc(ur->rem_rung_list,
+                                                   ur->rung_list_size +
+                                                   RUNG_SPACE);
+                    if (!ur->rem_rung_list) {
+                        av_free(ur->rem_rung_list);
+                        ctx->err = AVERROR(ENOMEM);
+                        return 0;
+                    }
+                    memset((uint8_t *) ur->rem_rung_list + ur->rung_list_size, 0,
+                           RUNG_SPACE);
+                    ur->rung_list_size += RUNG_SPACE;
+                    // restore rung_node position in the new list
+                    rung_node = &ur->rem_rung_list[pos];
+                }
+                rung_node->next_index = ur->avail_index;
+                ur->avail_index      += 2;
+            }
+            rung_node = &ur->rem_rung_list[rung_node->next_index + bit];
+        }
+
+        bit = ff_els_decode_bit(ctx, &rung_node->rung);
+        if (ctx->err)
+            return bit;
+
+        r = (r << 1) + bit;
+    }
+
+    return (1 << n) - 1 + r; /* make value from exp golomb code */
+}
diff --git a/libavcodec/elsdec.h b/libavcodec/elsdec.h
new file mode 100644
index 0000000000..515b49aa71
--- /dev/null
+++ b/libavcodec/elsdec.h
@@ -0,0 +1,60 @@
+/*
+ * ELS (Entropy Logarithmic-Scale) decoder
+ *
+ * Copyright (c) 2013 Maxim Poliakovski
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * Entropy Logarithmic-Scale binary arithmetic coder
+ */
+
+#ifndef AVCODEC_ELSDEC_H
+#define AVCODEC_ELSDEC_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#define ELS_EXPGOLOMB_LEN   10
+
+typedef struct ElsDecCtx {
+    const uint8_t *in_buf;
+    unsigned x;
+    size_t data_size;
+    int j, t, diff, err;
+} ElsDecCtx;
+
+typedef struct ElsRungNode {
+    uint8_t  rung;
+    uint16_t next_index;
+} ElsRungNode;
+
+typedef struct ElsUnsignedRung {
+    uint8_t      prefix_rung[ELS_EXPGOLOMB_LEN + 1];
+    ElsRungNode  *rem_rung_list;
+    size_t       rung_list_size;
+    uint16_t     avail_index;
+} ElsUnsignedRung;
+
+void ff_els_decoder_init(ElsDecCtx *ctx, const uint8_t *in, size_t data_size);
+void ff_els_decoder_uninit(ElsUnsignedRung *rung);
+int  ff_els_decode_bit(ElsDecCtx *ctx, unsigned char *rung);
+unsigned ff_els_decode_unsigned(ElsDecCtx *ctx, ElsUnsignedRung *ur);
+
+#endif /* AVCODEC_ELSDEC_H */
diff --git a/libavcodec/g2meet.c b/libavcodec/g2meet.c
index b3d2bc4aba..d0b36f0ea8 100644
--- a/libavcodec/g2meet.c
+++ b/libavcodec/g2meet.c
@@ -1,6 +1,7 @@
 /*
- * Go2Webinar decoder
+ * Go2Webinar / Go2Meeting decoder
  * Copyright (c) 2012 Konstantin Shishkov
+ * Copyright (c) 2013 Maxim Poliakovski
  *
  * This file is part of Libav.
  *
@@ -21,7 +22,7 @@
 
 /**
  * @file
- * Go2Webinar decoder
+ * Go2Webinar / Go2Meeting decoder
  */
 
 #include <inttypes.h>
@@ -32,12 +33,16 @@
 #include "avcodec.h"
 #include "blockdsp.h"
 #include "bytestream.h"
+#include "elsdec.h"
 #include "get_bits.h"
 #include "idctdsp.h"
 #include "internal.h"
 #include "jpegtables.h"
 #include "mjpeg.h"
 
+#define EPIC_PIX_STACK_SIZE 1024
+#define EPIC_PIX_STACK_MAX  (EPIC_PIX_STACK_SIZE - 1)
+
 enum ChunkType {
     DISPLAY_INFO = 0xC8,
     TILE_DATA,
@@ -74,6 +79,42 @@ static const uint8_t chroma_quant[64] = {
     50, 50, 50, 50, 50, 50, 50, 50,
 };
 
+typedef struct ePICPixListElem {
+    struct ePICPixListElem *next;
+    uint32_t               pixel;
+    uint8_t                rung;
+} ePICPixListElem;
+
+typedef struct ePICPixHashElem {
+    uint32_t                pix_id;
+    struct ePICPixListElem  *list;
+} ePICPixHashElem;
+
+#define EPIC_HASH_SIZE 256
+typedef struct ePICPixHash {
+    ePICPixHashElem *bucket[EPIC_HASH_SIZE];
+    int              bucket_size[EPIC_HASH_SIZE];
+    int              bucket_fill[EPIC_HASH_SIZE];
+} ePICPixHash;
+
+typedef struct ePICContext {
+    ElsDecCtx        els_ctx;
+    int              next_run_pos;
+    ElsUnsignedRung  unsigned_rung;
+    uint8_t          W_flag_rung;
+    uint8_t          N_flag_rung;
+    uint8_t          W_ctx_rung[256];
+    uint8_t          N_ctx_rung[512];
+    uint8_t          nw_pred_rung[256];
+    uint8_t          ne_pred_rung[256];
+    uint8_t          prev_row_rung[14];
+    uint8_t          runlen_zeroes[14];
+    uint8_t          runlen_one;
+    int              stack_pos;
+    uint32_t         stack[EPIC_PIX_STACK_SIZE];
+    ePICPixHash      hash;
+} ePICContext;
+
 typedef struct JPGContext {
     BlockDSPContext bdsp;
     IDCTDSPContext idsp;
@@ -87,7 +128,9 @@ typedef struct JPGContext {
 } JPGContext;
 
 typedef struct G2MContext {
+    ePICContext ec;
     JPGContext jc;
+
     int        version;
 
     int        compression;
@@ -101,8 +144,9 @@ typedef struct G2MContext {
     uint8_t    *framebuf;
     int        framebuf_stride, old_width, old_height;
 
-    uint8_t    *synth_tile, *jpeg_tile;
-    int        tile_stride, old_tile_w, old_tile_h;
+    uint8_t    *synth_tile, *jpeg_tile, *epic_buf, *epic_buf_base;
+    int        tile_stride, epic_buf_stride, old_tile_w, old_tile_h;
+    int        swapuv;
 
     uint8_t    *kempf_buf, *kempf_flags;
 
@@ -229,11 +273,11 @@ static int jpg_decode_block(JPGContext *c, GetBitContext *gb,
     return 0;
 }
 
-static inline void yuv2rgb(uint8_t *out, int Y, int U, int V)
+static inline void yuv2rgb(uint8_t *out, int ridx, int Y, int U, int V)
 {
-    out[0] = av_clip_uint8(Y + (             91881 * V + 32768 >> 16));
-    out[1] = av_clip_uint8(Y + (-22554 * U - 46802 * V + 32768 >> 16));
-    out[2] = av_clip_uint8(Y + (116130 * U             + 32768 >> 16));
+    out[ridx]     = av_clip_uint8(Y +              (91881 * V + 32768 >> 16));
+    out[1]        = av_clip_uint8(Y + (-22554 * U - 46802 * V + 32768 >> 16));
+    out[2 - ridx] = av_clip_uint8(Y + (116130 * U             + 32768 >> 16));
 }
 
 static int jpg_decode_data(JPGContext *c, int width, int height,
@@ -247,6 +291,7 @@ static int jpg_decode_data(JPGContext *c, int width, int height,
     int bx, by;
     int unesc_size;
     int ret;
+    const int ridx = swapuv ? 2 : 0;
 
     if ((ret = av_reallocp(&c->buf,
                            src_size + FF_INPUT_BUFFER_PADDING_SIZE)) < 0)
@@ -298,9 +343,9 @@ static int jpg_decode_data(JPGContext *c, int width, int height,
                     int Y, U, V;
 
                     Y = c->block[(j >> 3) * 2 + (i >> 3)][(i & 7) + (j & 7) * 8];
-                    U = c->block[4 ^ swapuv][(i >> 1) + (j >> 1) * 8] - 128;
-                    V = c->block[5 ^ swapuv][(i >> 1) + (j >> 1) * 8] - 128;
-                    yuv2rgb(out + i * 3, Y, U, V);
+                    U = c->block[4][(i >> 1) + (j >> 1) * 8] - 128;
+                    V = c->block[5][(i >> 1) + (j >> 1) * 8] - 128;
+                    yuv2rgb(out + i * 3, ridx, Y, U, V);
                 }
             }
 
@@ -317,6 +362,659 @@ static int jpg_decode_data(JPGContext *c, int width, int height,
     return 0;
 }
 
+#define LOAD_NEIGHBOURS(x)      \
+    W   = curr_row[(x)   - 1];  \
+    N   = above_row[(x)];       \
+    WW  = curr_row[(x)   - 2];  \
+    NW  = above_row[(x)  - 1];  \
+    NE  = above_row[(x)  + 1];  \
+    NN  = above2_row[(x)];      \
+    NNW = above2_row[(x) - 1];  \
+    NWW = above_row[(x)  - 2];  \
+    NNE = above2_row[(x) + 1]
+
+#define UPDATE_NEIGHBOURS(x)    \
+    NNW = NN;                   \
+    NN  = NNE;                  \
+    NWW = NW;                   \
+    NW  = N;                    \
+    N   = NE;                   \
+    NE  = above_row[(x)  + 1];  \
+    NNE = above2_row[(x) + 1]
+
+#define R_shift 16
+#define G_shift  8
+#define B_shift  0
+
+static inline int log2_ceil(uint32_t x)
+{
+    int c = 0;
+
+    for (--x; x > 0; x >>= 1)
+        c++;
+
+    return c;
+}
+
+/* improved djb2 hash from http://www.cse.yorku.ca/~oz/hash.html */
+static int djb2_hash(uint32_t key)
+{
+    int h = 5381;
+
+    h = (h * 33) ^ ((key >> 24) & 0xFF); // xxx: probably not needed at all
+    h = (h * 33) ^ ((key >> 16) & 0xFF);
+    h = (h * 33) ^ ((key >>  8) & 0xFF);
+    h = (h * 33) ^  (key        & 0xFF);
+
+    return h & (EPIC_HASH_SIZE - 1);
+}
+
+static void epic_hash_init(ePICPixHash *hash)
+{
+    memset(hash, 0, sizeof(*hash));
+}
+
+static ePICPixHashElem *epic_hash_find(const ePICPixHash *hash, uint32_t key)
+{
+    int i, idx = djb2_hash(key);
+    ePICPixHashElem *bucket = hash->bucket[idx];
+
+    for (i = 0; i < hash->bucket_fill[idx]; i++)
+        if (bucket[i].pix_id == key)
+            return &bucket[i];
+
+    return NULL;
+}
+
+static ePICPixHashElem *epic_hash_add(ePICPixHash *hash, uint32_t key)
+{
+    ePICPixHashElem *bucket, *ret;
+    int idx = djb2_hash(key);
+
+    if (hash->bucket_size[idx] > INT_MAX / sizeof(**hash->bucket))
+        return NULL;
+
+    if (!(hash->bucket_fill[idx] < hash->bucket_size[idx])) {
+        int new_size = hash->bucket_size[idx] + 16;
+        bucket = av_realloc(hash->bucket[idx], new_size * sizeof(*bucket));
+        if (!bucket)
+            return NULL;
+        hash->bucket[idx]      = bucket;
+        hash->bucket_size[idx] = new_size;
+    }
+
+    ret = &hash->bucket[idx][hash->bucket_fill[idx]++];
+    memset(ret, 0, sizeof(*ret));
+    ret->pix_id = key;
+    return ret;
+}
+
+static int epic_add_pixel_to_cache(ePICPixHash *hash, uint32_t key, uint32_t pix)
+{
+    ePICPixListElem *new_elem;
+    ePICPixHashElem *hash_elem = epic_hash_find(hash, key);
+
+    if (!hash_elem) {
+        if (!(hash_elem = epic_hash_add(hash, key)))
+            return AVERROR(ENOMEM);
+    }
+
+    new_elem = av_mallocz(sizeof(*new_elem));
+    if (!new_elem)
+        return AVERROR(ENOMEM);
+
+    new_elem->pixel = pix;
+    new_elem->next  = hash_elem->list;
+    hash_elem->list = new_elem;
+
+    return 0;
+}
+
+static inline int epic_cache_entries_for_pixel(const ePICPixHash *hash,
+                                               uint32_t pix)
+{
+    ePICPixHashElem *hash_elem = epic_hash_find(hash, pix);
+
+    if (hash_elem != NULL && hash_elem->list != NULL)
+        return 1;
+
+    return 0;
+}
+
+static void epic_free_pixel_cache(ePICPixHash *hash)
+{
+    int i, j;
+
+    for (i = 0; i < EPIC_HASH_SIZE; i++) {
+        for (j = 0; j < hash->bucket_fill[i]; j++) {
+            ePICPixListElem *list_elem = hash->bucket[i][j].list;
+            while (list_elem) {
+                ePICPixListElem *tmp = list_elem->next;
+                av_free(list_elem);
+                list_elem = tmp;
+            }
+        }
+        av_freep(&hash->bucket[i]);
+        hash->bucket_size[i] =
+        hash->bucket_fill[i] = 0;
+    }
+}
+
+static inline int is_pixel_on_stack(const ePICContext *dc, uint32_t pix)
+{
+    int i;
+
+    for (i = 0; i < dc->stack_pos; i++)
+        if (dc->stack[i] == pix)
+            break;
+
+    return i != dc->stack_pos;
+}
+
+#define TOSIGNED(val) (((val) >> 1) ^ -((val) & 1))
+
+static inline int epic_decode_component_pred(ePICContext *dc,
+                                             int N, int W, int NW)
+{
+    unsigned delta = ff_els_decode_unsigned(&dc->els_ctx, &dc->unsigned_rung);
+    return mid_pred(N, N + W - NW, W) - TOSIGNED(delta);
+}
+
+static uint32_t epic_decode_pixel_pred(ePICContext *dc, int x, int y,
+                                       const uint32_t *curr_row,
+                                       const uint32_t *above_row)
+{
+    uint32_t N, W, NW, pred;
+    unsigned delta;
+    int GN, GW, GNW, R, G, B;
+
+    if (x && y) {
+        W  = curr_row[x  - 1];
+        N  = above_row[x];
+        NW = above_row[x - 1];
+
+        GN  = (N  >> G_shift) & 0xFF;
+        GW  = (W  >> G_shift) & 0xFF;
+        GNW = (NW >> G_shift) & 0xFF;
+
+        G = epic_decode_component_pred(dc, GN, GW, GNW);
+
+        R = G + epic_decode_component_pred(dc,
+                                           ((N  >> R_shift) & 0xFF) - GN,
+                                           ((W  >> R_shift) & 0xFF) - GW,
+                                           ((NW >> R_shift) & 0xFF) - GNW);
+
+        B = G + epic_decode_component_pred(dc,
+                                           ((N  >> B_shift) & 0xFF) - GN,
+                                           ((W  >> B_shift) & 0xFF) - GW,
+                                           ((NW >> B_shift) & 0xFF) - GNW);
+    } else {
+        if (x)
+            pred = curr_row[x - 1];
+        else
+            pred = above_row[x];
+
+        delta = ff_els_decode_unsigned(&dc->els_ctx, &dc->unsigned_rung);
+        R     = ((pred >> R_shift) & 0xFF) - TOSIGNED(delta);
+
+        delta = ff_els_decode_unsigned(&dc->els_ctx, &dc->unsigned_rung);
+        G     = ((pred >> G_shift) & 0xFF) - TOSIGNED(delta);
+
+        delta = ff_els_decode_unsigned(&dc->els_ctx, &dc->unsigned_rung);
+        B     = ((pred >> B_shift) & 0xFF) - TOSIGNED(delta);
+    }
+
+    return (R << R_shift) | (G << G_shift) | (B << B_shift);
+}
+
+static int epic_predict_pixel(ePICContext *dc, uint8_t *rung,
+                              uint32_t *pPix, uint32_t pix)
+{
+    if (!ff_els_decode_bit(&dc->els_ctx, rung)) {
+        *pPix = pix;
+        return 1;
+    }
+    dc->stack[dc->stack_pos++ & EPIC_PIX_STACK_MAX] = pix;
+    return 0;
+}
+
+static int epic_handle_edges(ePICContext *dc, int x, int y,
+                             const uint32_t *curr_row,
+                             const uint32_t *above_row, uint32_t *pPix)
+{
+    uint32_t pix;
+
+    if (!x && !y) { /* special case: top-left pixel */
+        /* the top-left pixel is coded independently with 3 unsigned numbers */
+        *pPix = (ff_els_decode_unsigned(&dc->els_ctx, &dc->unsigned_rung) << R_shift) |
+                (ff_els_decode_unsigned(&dc->els_ctx, &dc->unsigned_rung) << G_shift) |
+                (ff_els_decode_unsigned(&dc->els_ctx, &dc->unsigned_rung) << B_shift);
+        return 1;
+    }
+
+    if (x) { /* predict from W first */
+        pix = curr_row[x - 1];
+        if (epic_predict_pixel(dc, &dc->W_flag_rung, pPix, pix))
+            return 1;
+    }
+
+    if (y) { /* then try to predict from N */
+        pix = above_row[x];
+        if (!dc->stack_pos || dc->stack[0] != pix) {
+            if (epic_predict_pixel(dc, &dc->N_flag_rung, pPix, pix))
+                return 1;
+        }
+    }
+
+    return 0;
+}
+
+static int epic_decode_run_length(ePICContext *dc, int x, int y, int tile_width,
+                                  const uint32_t *curr_row,
+                                  const uint32_t *above_row,
+                                  const uint32_t *above2_row,
+                                  uint32_t *pPix, int *pRun)
+{
+    int idx, got_pixel = 0, WWneW, old_WWneW = 0;
+    uint32_t W, WW, N, NN, NW, NE, NWW, NNW, NNE;
+
+    *pRun = 0;
+
+    LOAD_NEIGHBOURS(x);
+
+    if (dc->next_run_pos == x) {
+        /* can't reuse W for the new pixel in this case */
+        WWneW = 1;
+    } else {
+        idx = (WW  != W)  << 7 |
+              (NW  != W)  << 6 |
+              (N   != NE) << 5 |
+              (NW  != N)  << 4 |
+              (NWW != NW) << 3 |
+              (NNE != NE) << 2 |
+              (NN  != N)  << 1 |
+              (NNW != NW);
+        WWneW = ff_els_decode_bit(&dc->els_ctx, &dc->W_ctx_rung[idx]);
+    }
+
+    if (WWneW)
+        dc->stack[dc->stack_pos++ & EPIC_PIX_STACK_MAX] = W;
+    else {
+        *pPix     = W;
+        got_pixel = 1;
+    }
+
+    do {
+        int NWneW = 1;
+        if (got_pixel) // pixel value already known (derived from either W or N)
+            NWneW = *pPix != N;
+        else { // pixel value is unknown and will be decoded later
+            NWneW = *pRun ? NWneW : NW != W;
+
+            /* TODO: RFC this mess! */
+            switch (((NW != N) << 2) | (NWneW << 1) | WWneW) {
+            case 0:
+                break; // do nothing here
+            case 3:
+            case 5:
+            case 6:
+            case 7:
+                if (!is_pixel_on_stack(dc, N)) {
+                    idx = WWneW       << 8 |
+                          (*pRun ? old_WWneW : WW != W) << 7 |
+                          NWneW       << 6 |
+                          (N   != NE) << 5 |
+                          (NW  != N)  << 4 |
+                          (NWW != NW) << 3 |
+                          (NNE != NE) << 2 |
+                          (NN  != N)  << 1 |
+                          (NNW != NW);
+                    if (!ff_els_decode_bit(&dc->els_ctx, &dc->N_ctx_rung[idx])) {
+                        NWneW = 0;
+                        *pPix = N;
+                        got_pixel = 1;
+                        break;
+                    }
+                }
+                /* fall through */
+            default:
+                NWneW = 1;
+                old_WWneW = WWneW;
+                if (!is_pixel_on_stack(dc, N))
+                    dc->stack[dc->stack_pos++ & EPIC_PIX_STACK_MAX] = N;
+            }
+        }
+
+        (*pRun)++;
+        if (x + *pRun >= tile_width - 1)
+            break;
+
+        UPDATE_NEIGHBOURS(x + *pRun);
+
+        if (!NWneW && NW == N && N == NE) {
+            int pos, run, rle;
+            int start_pos = x + *pRun;
+
+            /* scan for a run of pix in the line above */
+            uint32_t pix = above_row[start_pos + 1];
+            for (pos = start_pos + 2; pos < tile_width; pos++)
+                if (!(above_row[pos] == pix))
+                    break;
+            run = pos - start_pos - 1;
+            idx = log2_ceil(run);
+            if (ff_els_decode_bit(&dc->els_ctx, &dc->prev_row_rung[idx]))
+                *pRun += run;
+            else {
+                int flag;
+                /* run-length is coded as plain binary number of idx - 1 bits */
+                for (pos = idx - 1, rle = 0, flag = 0; pos >= 0; pos--) {
+                    if ((1 << pos) + rle < run &&
+                        ff_els_decode_bit(&dc->els_ctx,
+                                          flag ? &dc->runlen_one
+                                               : &dc->runlen_zeroes[pos])) {
+                        flag = 1;
+                        rle |= 1 << pos;
+                    }
+                }
+                *pRun += rle;
+                break; // return immediately
+            }
+            if (x + *pRun >= tile_width - 1)
+                break;
+
+            LOAD_NEIGHBOURS(x + *pRun);
+            WWneW = 0;
+            NWneW = 0;
+        }
+
+        idx = WWneW       << 7 |
+              NWneW       << 6 |
+              (N   != NE) << 5 |
+              (NW  != N)  << 4 |
+              (NWW != NW) << 3 |
+              (NNE != NE) << 2 |
+              (NN  != N)  << 1 |
+              (NNW != NW);
+        WWneW = ff_els_decode_bit(&dc->els_ctx, &dc->W_ctx_rung[idx]);
+    } while (!WWneW);
+
+    dc->next_run_pos = x + *pRun;
+    return got_pixel;
+}
+
+static int epic_predict_pixel2(ePICContext *dc, uint8_t *rung,
+                               uint32_t *pPix, uint32_t pix)
+{
+    if (ff_els_decode_bit(&dc->els_ctx, rung)) {
+        *pPix = pix;
+        return 1;
+    }
+    dc->stack[dc->stack_pos++ & EPIC_PIX_STACK_MAX] = pix;
+    return 0;
+}
+
+static int epic_predict_from_NW_NE(ePICContext *dc, int x, int y, int run,
+                                   int tile_width, const uint32_t *curr_row,
+                                   const uint32_t *above_row, uint32_t *pPix)
+{
+    int pos;
+
+    /* try to reuse the NW pixel first */
+    if (x && y) {
+        uint32_t NW = above_row[x - 1];
+        if (NW != curr_row[x - 1] && NW != above_row[x] && !is_pixel_on_stack(dc, NW)) {
+            if (epic_predict_pixel2(dc, &dc->nw_pred_rung[NW & 0xFF], pPix, NW))
+                return 1;
+        }
+    }
+
+    /* try to reuse the NE[x + run, y] pixel */
+    pos = x + run - 1;
+    if (pos < tile_width - 1 && y) {
+        uint32_t NE = above_row[pos + 1];
+        if (NE != above_row[pos] && !is_pixel_on_stack(dc, NE)) {
+            if (epic_predict_pixel2(dc, &dc->ne_pred_rung[NE & 0xFF], pPix, NE))
+                return 1;
+        }
+    }
+
+    return 0;
+}
+
+static int epic_decode_from_cache(ePICContext *dc, uint32_t W, uint32_t *pPix)
+{
+    ePICPixListElem *list, *prev = NULL;
+    ePICPixHashElem *hash_elem = epic_hash_find(&dc->hash, W);
+
+    if (!hash_elem || !hash_elem->list)
+        return 0;
+
+    list = hash_elem->list;
+    while (list) {
+        if (!is_pixel_on_stack(dc, list->pixel)) {
+            if (ff_els_decode_bit(&dc->els_ctx, &list->rung)) {
+                *pPix = list->pixel;
+                if (list != hash_elem->list) {
+                    prev->next      = list->next;
+                    list->next      = hash_elem->list;
+                    hash_elem->list = list;
+                }
+                return 1;
+            }
+            dc->stack[dc->stack_pos++ & EPIC_PIX_STACK_MAX] = list->pixel;
+        }
+        prev = list;
+        list = list->next;
+    }
+
+    return 0;
+}
+
+static int epic_decode_tile(ePICContext *dc, uint8_t *out, int tile_height,
+                            int tile_width, int stride)
+{
+    int x, y;
+    uint32_t pix;
+    uint32_t *curr_row = NULL, *above_row = NULL, *above2_row;
+
+    for (y = 0; y < tile_height; y++, out += stride) {
+        above2_row = above_row;
+        above_row  = curr_row;
+        curr_row   = (uint32_t *) out;
+
+        for (x = 0, dc->next_run_pos = 0; x < tile_width;) {
+            if (dc->els_ctx.err)
+                return AVERROR_INVALIDDATA; // bail out in the case of ELS overflow
+
+            pix = curr_row[x - 1]; // get W pixel
+
+            if (y >= 1 && x >= 2 &&
+                pix != curr_row[x - 2]  && pix != above_row[x - 1] &&
+                pix != above_row[x - 2] && pix != above_row[x] &&
+                !epic_cache_entries_for_pixel(&dc->hash, pix)) {
+                curr_row[x] = epic_decode_pixel_pred(dc, x, y, curr_row, above_row);
+                x++;
+            } else {
+                int got_pixel, run;
+                dc->stack_pos = 0; // empty stack
+
+                if (y < 2 || x < 2 || x == tile_width - 1) {
+                    run       = 1;
+                    got_pixel = epic_handle_edges(dc, x, y, curr_row, above_row, &pix);
+                } else
+                    got_pixel = epic_decode_run_length(dc, x, y, tile_width,
+                                                       curr_row, above_row,
+                                                       above2_row, &pix, &run);
+
+                if (!got_pixel && !epic_predict_from_NW_NE(dc, x, y, run,
+                                                           tile_width, curr_row,
+                                                           above_row, &pix)) {
+                    uint32_t ref_pix = curr_row[x - 1];
+                    if (!x || !epic_decode_from_cache(dc, ref_pix, &pix)) {
+                        pix = epic_decode_pixel_pred(dc, x, y, curr_row, above_row);
+                        if (x) {
+                            int ret = epic_add_pixel_to_cache(&dc->hash,
+                                                              ref_pix,
+                                                              pix);
+                            if (ret)
+                                return ret;
+                        }
+                    }
+                }
+                for (; run > 0; x++, run--)
+                    curr_row[x] = pix;
+            }
+        }
+    }
+
+    return 0;
+}
+
+static int epic_jb_decode_tile(G2MContext *c, int tile_x, int tile_y,
+                               const uint8_t *src, size_t src_size,
+                               AVCodecContext *avctx)
+{
+    uint8_t prefix, mask = 0x80;
+    int extrabytes, tile_width, tile_height, awidth, aheight;
+    size_t els_dsize;
+    uint8_t *dst;
+
+    if (!src_size)
+        return 0;
+
+    /* get data size of the ELS partition as unsigned variable-length integer */
+    prefix = *src++;
+    src_size--;
+    for (extrabytes = 0; (prefix & mask) && (extrabytes < 7); extrabytes++)
+        mask >>= 1;
+    if (extrabytes > 3 || src_size < extrabytes) {
+        av_log(avctx, AV_LOG_ERROR, "ePIC: invalid data size VLI\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    els_dsize = prefix & ((0x80 >> extrabytes) - 1); // mask out the length prefix
+    while (extrabytes-- > 0) {
+        els_dsize = (els_dsize << 8) | *src++;
+        src_size--;
+    }
+
+    if (src_size < els_dsize) {
+        av_log(avctx, AV_LOG_ERROR, "ePIC: data too short, needed %zu, got %zu\n",
+               els_dsize, src_size);
+        return AVERROR_INVALIDDATA;
+    }
+
+    tile_width  = FFMIN(c->width  - tile_x * c->tile_width,  c->tile_width);
+    tile_height = FFMIN(c->height - tile_y * c->tile_height, c->tile_height);
+    awidth      = FFALIGN(tile_width,  16);
+    aheight     = FFALIGN(tile_height, 16);
+
+    if (els_dsize) {
+        int ret, i, j, k;
+        uint8_t tr_r, tr_g, tr_b, *buf;
+        uint32_t *in;
+        /* ELS decoder initializations */
+        memset(&c->ec, 0, sizeof(c->ec));
+        ff_els_decoder_init(&c->ec.els_ctx, src, els_dsize);
+        epic_hash_init(&c->ec.hash);
+
+        /* decode transparent pixel value */
+        tr_r = ff_els_decode_unsigned(&c->ec.els_ctx, &c->ec.unsigned_rung);
+        tr_g = ff_els_decode_unsigned(&c->ec.els_ctx, &c->ec.unsigned_rung);
+        tr_b = ff_els_decode_unsigned(&c->ec.els_ctx, &c->ec.unsigned_rung);
+        if (c->ec.els_ctx.err != 0) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "ePIC: couldn't decode transparency pixel!\n");
+            return AVERROR_INVALIDDATA;
+        }
+
+        ret = epic_decode_tile(&c->ec, c->epic_buf, tile_height, tile_width,
+                               c->epic_buf_stride);
+
+        epic_free_pixel_cache(&c->ec.hash);
+        ff_els_decoder_uninit(&c->ec.unsigned_rung);
+
+        if (ret) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "ePIC: tile decoding failed, frame=%d, tile_x=%d, tile_y=%d\n",
+                   avctx->frame_number, tile_x, tile_y);
+            return AVERROR_INVALIDDATA;
+        }
+
+        buf = c->epic_buf;
+        dst = c->framebuf + tile_x * c->tile_width * 3 +
+              tile_y * c->tile_height * c->framebuf_stride;
+
+        for (j = 0; j < tile_height; j++) {
+            uint8_t *out = dst;
+            in  = (uint32_t *) buf;
+            for (i = 0; i < tile_width; i++) {
+                out[0] = (in[i] >> R_shift) & 0xFF;
+                out[1] = (in[i] >> G_shift) & 0xFF;
+                out[2] = (in[i] >> B_shift) & 0xFF;
+                out   += 3;
+            }
+            buf += c->epic_buf_stride;
+            dst += c->framebuf_stride;
+        }
+
+        if (src_size > els_dsize) {
+            uint8_t *jpg;
+            uint32_t tr;
+            int bstride = FFALIGN(tile_width, 16) >> 3;
+            int nblocks = 0;
+            int estride = c->epic_buf_stride >> 2;
+
+            src      += els_dsize;
+            src_size -= els_dsize;
+
+            in = (uint32_t *) c->epic_buf;
+            tr = (tr_r << R_shift) | (tr_g << G_shift) | (tr_b << B_shift);
+
+            memset(c->kempf_flags, 0,
+                   (aheight >> 3) * bstride * sizeof(*c->kempf_flags));
+            for (j = 0; j < tile_height; j += 8) {
+                for (i = 0; i < tile_width; i += 8) {
+                    c->kempf_flags[(i >> 3) + (j >> 3) * bstride] = 0;
+                    for (k = 0; k < 8 * 8; k++) {
+                        if (in[i + (k & 7) + (k >> 3) * estride] == tr) {
+                            c->kempf_flags[(i >> 3) + (j >> 3) * bstride] = 1;
+                            nblocks++;
+                            break;
+                        }
+                    }
+                }
+                in += 8 * estride;
+            }
+
+            memset(c->jpeg_tile, 0, c->tile_stride * aheight);
+            jpg_decode_data(&c->jc, awidth, aheight, src, src_size,
+                            c->jpeg_tile, c->tile_stride,
+                            c->kempf_flags, bstride, nblocks, c->swapuv);
+
+            in  = (uint32_t *) c->epic_buf;
+            dst = c->framebuf + tile_x * c->tile_width * 3 +
+                  tile_y * c->tile_height * c->framebuf_stride;
+            jpg = c->jpeg_tile;
+            for (j = 0; j < tile_height; j++) {
+                for (i = 0; i < tile_width; i++)
+                    if (in[i] == tr)
+                        memcpy(dst + i * 3, jpg + i * 3, 3);
+                in  += c->epic_buf_stride >> 2;
+                dst += c->framebuf_stride;
+                jpg += c->tile_stride;
+            }
+        }
+    } else {
+        dst = c->framebuf + tile_x * c->tile_width * 3 +
+              tile_y * c->tile_height * c->framebuf_stride;
+        return jpg_decode_data(&c->jc, tile_width, tile_height, src, src_size,
+                               dst, c->framebuf_stride, NULL, 0, 0, c->swapuv);
+    }
+
+    return 0;
+}
+
 static void kempf_restore_buf(const uint8_t *src, int len,
                               uint8_t *dst, int stride,
                               const uint8_t *jpeg_tile, int tile_stride,
@@ -325,6 +1023,7 @@ static void kempf_restore_buf(const uint8_t *src, int len,
 {
     GetBitContext gb;
     int i, j, nb, col;
+    int align_width = FFALIGN(width, 16);
 
     init_get_bits(&gb, src, len * 8);
 
@@ -343,6 +1042,7 @@ static void kempf_restore_buf(const uint8_t *src, int len,
             else
                 memcpy(dst + i * 3, jpeg_tile + i * 3, 3);
         }
+        skip_bits_long(&gb, nb * (align_width - width));
     }
 }
 
@@ -466,22 +1166,31 @@ static int g2m_init_buffers(G2MContext *c)
             return AVERROR(ENOMEM);
     }
     if (!c->synth_tile || !c->jpeg_tile ||
+        (c->compression == 2 && !c->epic_buf_base) ||
         c->old_tile_w < c->tile_width ||
         c->old_tile_h < c->tile_height) {
-        c->tile_stride = FFALIGN(c->tile_width * 3, 16);
-        aligned_height = FFALIGN(c->tile_height,    16);
+        c->tile_stride     = FFALIGN(c->tile_width * 3, 16);
+        c->epic_buf_stride = FFALIGN(c->tile_width * 4, 16);
+        aligned_height     = FFALIGN(c->tile_height,    16);
         av_free(c->synth_tile);
         av_free(c->jpeg_tile);
         av_free(c->kempf_buf);
         av_free(c->kempf_flags);
+        av_free(c->epic_buf_base);
         c->synth_tile  = av_mallocz(c->tile_stride      * aligned_height);
         c->jpeg_tile   = av_mallocz(c->tile_stride      * aligned_height);
-        c->kempf_buf   = av_mallocz((c->tile_width + 1) * aligned_height
-                                    + FF_INPUT_BUFFER_PADDING_SIZE);
-        c->kempf_flags = av_mallocz( c->tile_width      * aligned_height);
+        c->kempf_buf   = av_mallocz((c->tile_width + 1) * aligned_height +
+                                    FF_INPUT_BUFFER_PADDING_SIZE);
+        c->kempf_flags = av_mallocz(c->tile_width       * aligned_height);
         if (!c->synth_tile || !c->jpeg_tile ||
             !c->kempf_buf || !c->kempf_flags)
             return AVERROR(ENOMEM);
+        if (c->compression == 2) {
+            c->epic_buf_base = av_mallocz(c->epic_buf_stride * aligned_height + 4);
+            if (!c->epic_buf_base)
+                return AVERROR(ENOMEM);
+            c->epic_buf = c->epic_buf_base + 4;
+        }
     }
 
     return 0;
@@ -690,10 +1399,7 @@ static int g2m_decode_frame(AVCodecContext *avctx, void *data,
         return AVERROR_INVALIDDATA;
     }
 
-    if ((magic & 0xF) < 4) {
-        av_log(avctx, AV_LOG_ERROR, "G2M2 and G2M3 are not yet supported\n");
-        return AVERROR(ENOSYS);
-    }
+    c->swapuv = magic == MKBETAG('G', '2', 'M', '2');
 
     while (bytestream2_get_bytes_left(&bc) > 5) {
         chunk_size  = bytestream2_get_le32(&bc) - 1;
@@ -795,9 +1501,10 @@ static int g2m_decode_frame(AVCodecContext *avctx, void *data,
             ret = 0;
             switch (c->compression) {
             case COMPR_EPIC_J_B:
-                av_log(avctx, AV_LOG_ERROR,
-                       "ePIC j-b compression is not implemented yet\n");
-                return AVERROR(ENOSYS);
+                ret = epic_jb_decode_tile(c, c->tile_x, c->tile_y,
+                                          buf + bytestream2_tell(&bc),
+                                          chunk_size - 2, avctx);
+                break;
             case COMPR_KEMPF_J_B:
                 ret = kempf_decode_tile(c, c->tile_x, c->tile_y,
                                         buf + bytestream2_tell(&bc),
@@ -895,6 +1602,7 @@ static av_cold int g2m_decode_end(AVCodecContext *avctx)
 
     jpg_free_context(&c->jc);
 
+    av_freep(&c->epic_buf_base);
     av_freep(&c->kempf_buf);
     av_freep(&c->kempf_flags);
     av_freep(&c->synth_tile);
@@ -915,4 +1623,5 @@ AVCodec ff_g2m_decoder = {
     .close          = g2m_decode_end,
     .decode         = g2m_decode_frame,
     .capabilities   = CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };
diff --git a/libavcodec/version.h b/libavcodec/version.h
index b0643cc922..850f465797 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -29,8 +29,8 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR 56
-#define LIBAVCODEC_VERSION_MINOR 29
-#define LIBAVCODEC_VERSION_MICRO  1
+#define LIBAVCODEC_VERSION_MINOR 31
+#define LIBAVCODEC_VERSION_MICRO  0
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
                                                LIBAVCODEC_VERSION_MINOR, \