adding ffmpeg specific version

1 files changed, 995 insertions, 0 deletions

diff --git a/ffmpeg1/libavcodec/4xm.c b/ffmpeg1/libavcodec/4xm.c
new file mode 100644
index 0000000..cd22aa4
--- /dev/null
+++ b/ffmpeg1/libavcodec/4xm.c
@@ -0,0 +1,995 @@
+/*
+ * 4XM codec
+ * Copyright (c) 2003 Michael Niedermayer
+ *
+ * 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
+ * 4XM codec.
+ */
+
+#include "libavutil/frame.h"
+#include "libavutil/intreadwrite.h"
+#include "avcodec.h"
+#include "bytestream.h"
+#include "dsputil.h"
+#include "get_bits.h"
+#include "internal.h"
+
+#include "libavutil/avassert.h"
+
+#define BLOCK_TYPE_VLC_BITS 5
+#define ACDC_VLC_BITS 9
+
+#define CFRAME_BUFFER_COUNT 100
+
+static const uint8_t block_type_tab[2][4][8][2] = {
+    {
+        {    // { 8, 4, 2 } x { 8, 4, 2}
+            { 0, 1 }, { 2, 2 }, { 6, 3 }, { 14, 4 }, { 30, 5 }, { 31, 5 }, { 0, 0 }
+        }, { // { 8, 4 } x 1
+            { 0, 1 }, { 0, 0 }, { 2, 2 }, { 6, 3 }, { 14, 4 }, { 15, 4 }, { 0, 0 }
+        }, { // 1 x { 8, 4 }
+            { 0, 1 }, { 2, 2 }, { 0, 0 }, { 6, 3 }, { 14, 4 }, { 15, 4 }, { 0, 0 }
+        }, { // 1 x 2, 2 x 1
+            { 0, 1 }, { 0, 0 }, { 0, 0 }, { 2, 2 }, { 6, 3 }, { 14, 4 }, { 15, 4 }
+        }
+    }, {
+        {   // { 8, 4, 2 } x { 8, 4, 2}
+            { 1, 2 }, { 4, 3 }, { 5, 3 }, { 0, 2 }, { 6, 3 }, { 7, 3 }, { 0, 0 }
+        }, {// { 8, 4 } x 1
+            { 1, 2 }, { 0, 0 }, { 2, 2 }, { 0, 2 }, { 6, 3 }, { 7, 3 }, { 0, 0 }
+        }, {// 1 x { 8, 4 }
+            { 1, 2 }, { 2, 2 }, { 0, 0 }, { 0, 2 }, { 6, 3 }, { 7, 3 }, { 0, 0 }
+        }, {// 1 x 2, 2 x 1
+            { 1, 2 }, { 0, 0 }, { 0, 0 }, { 0, 2 }, { 2, 2 }, { 6, 3 }, { 7, 3 }
+      }
+    }
+};
+
+static const uint8_t size2index[4][4] = {
+    { -1, 3, 1, 1 },
+    {  3, 0, 0, 0 },
+    {  2, 0, 0, 0 },
+    {  2, 0, 0, 0 },
+};
+
+static const int8_t mv[256][2] = {
+    {   0,   0 }, {   0,  -1 }, {  -1,   0 }, {   1,   0 }, {   0,   1 }, {  -1,  -1 }, {   1,  -1 }, {  -1,   1 },
+    {   1,   1 }, {   0,  -2 }, {  -2,   0 }, {   2,   0 }, {   0,   2 }, {  -1,  -2 }, {   1,  -2 }, {  -2,  -1 },
+    {   2,  -1 }, {  -2,   1 }, {   2,   1 }, {  -1,   2 }, {   1,   2 }, {  -2,  -2 }, {   2,  -2 }, {  -2,   2 },
+    {   2,   2 }, {   0,  -3 }, {  -3,   0 }, {   3,   0 }, {   0,   3 }, {  -1,  -3 }, {   1,  -3 }, {  -3,  -1 },
+    {   3,  -1 }, {  -3,   1 }, {   3,   1 }, {  -1,   3 }, {   1,   3 }, {  -2,  -3 }, {   2,  -3 }, {  -3,  -2 },
+    {   3,  -2 }, {  -3,   2 }, {   3,   2 }, {  -2,   3 }, {   2,   3 }, {   0,  -4 }, {  -4,   0 }, {   4,   0 },
+    {   0,   4 }, {  -1,  -4 }, {   1,  -4 }, {  -4,  -1 }, {   4,  -1 }, {   4,   1 }, {  -1,   4 }, {   1,   4 },
+    {  -3,  -3 }, {  -3,   3 }, {   3,   3 }, {  -2,  -4 }, {  -4,  -2 }, {   4,  -2 }, {  -4,   2 }, {  -2,   4 },
+    {   2,   4 }, {  -3,  -4 }, {   3,  -4 }, {   4,  -3 }, {  -5,   0 }, {  -4,   3 }, {  -3,   4 }, {   3,   4 },
+    {  -1,  -5 }, {  -5,  -1 }, {  -5,   1 }, {  -1,   5 }, {  -2,  -5 }, {   2,  -5 }, {   5,  -2 }, {   5,   2 },
+    {  -4,  -4 }, {  -4,   4 }, {  -3,  -5 }, {  -5,  -3 }, {  -5,   3 }, {   3,   5 }, {  -6,   0 }, {   0,   6 },
+    {  -6,  -1 }, {  -6,   1 }, {   1,   6 }, {   2,  -6 }, {  -6,   2 }, {   2,   6 }, {  -5,  -4 }, {   5,   4 },
+    {   4,   5 }, {  -6,  -3 }, {   6,   3 }, {  -7,   0 }, {  -1,  -7 }, {   5,  -5 }, {  -7,   1 }, {  -1,   7 },
+    {   4,  -6 }, {   6,   4 }, {  -2,  -7 }, {  -7,   2 }, {  -3,  -7 }, {   7,  -3 }, {   3,   7 }, {   6,  -5 },
+    {   0,  -8 }, {  -1,  -8 }, {  -7,  -4 }, {  -8,   1 }, {   4,   7 }, {   2,  -8 }, {  -2,   8 }, {   6,   6 },
+    {  -8,   3 }, {   5,  -7 }, {  -5,   7 }, {   8,  -4 }, {   0,  -9 }, {  -9,  -1 }, {   1,   9 }, {   7,  -6 },
+    {  -7,   6 }, {  -5,  -8 }, {  -5,   8 }, {  -9,   3 }, {   9,  -4 }, {   7,  -7 }, {   8,  -6 }, {   6,   8 },
+    {  10,   1 }, { -10,   2 }, {   9,  -5 }, {  10,  -3 }, {  -8,  -7 }, { -10,  -4 }, {   6,  -9 }, { -11,   0 },
+    {  11,   1 }, { -11,  -2 }, {  -2,  11 }, {   7,  -9 }, {  -7,   9 }, {  10,   6 }, {  -4,  11 }, {   8,  -9 },
+    {   8,   9 }, {   5,  11 }, {   7, -10 }, {  12,  -3 }, {  11,   6 }, {  -9,  -9 }, {   8,  10 }, {   5,  12 },
+    { -11,   7 }, {  13,   2 }, {   6, -12 }, {  10,   9 }, { -11,   8 }, {  -7,  12 }, {   0,  14 }, {  14,  -2 },
+    {  -9,  11 }, {  -6,  13 }, { -14,  -4 }, {  -5, -14 }, {   5,  14 }, { -15,  -1 }, { -14,  -6 }, {   3, -15 },
+    {  11, -11 }, {  -7,  14 }, {  -5,  15 }, {   8, -14 }, {  15,   6 }, {   3,  16 }, {   7, -15 }, { -16,   5 },
+    {   0,  17 }, { -16,  -6 }, { -10,  14 }, { -16,   7 }, {  12,  13 }, { -16,   8 }, { -17,   6 }, { -18,   3 },
+    {  -7,  17 }, {  15,  11 }, {  16,  10 }, {   2, -19 }, {   3, -19 }, { -11, -16 }, { -18,   8 }, { -19,  -6 },
+    {   2, -20 }, { -17, -11 }, { -10, -18 }, {   8,  19 }, { -21,  -1 }, { -20,   7 }, {  -4,  21 }, {  21,   5 },
+    {  15,  16 }, {   2, -22 }, { -10, -20 }, { -22,   5 }, {  20, -11 }, {  -7, -22 }, { -12,  20 }, {  23,  -5 },
+    {  13, -20 }, {  24,  -2 }, { -15,  19 }, { -11,  22 }, {  16,  19 }, {  23, -10 }, { -18, -18 }, {  -9, -24 },
+    {  24, -10 }, {  -3,  26 }, { -23,  13 }, { -18, -20 }, {  17,  21 }, {  -4,  27 }, {  27,   6 }, {   1, -28 },
+    { -11,  26 }, { -17, -23 }, {   7,  28 }, {  11, -27 }, {  29,   5 }, { -23, -19 }, { -28, -11 }, { -21,  22 },
+    { -30,   7 }, { -17,  26 }, { -27,  16 }, {  13,  29 }, {  19, -26 }, {  10, -31 }, { -14, -30 }, {  20, -27 },
+    { -29,  18 }, { -16, -31 }, { -28, -22 }, {  21, -30 }, { -25,  28 }, {  26, -29 }, {  25, -32 }, { -32, -32 }
+};
+
+/* This is simply the scaled down elementwise product of the standard JPEG
+ * quantizer table and the AAN premul table. */
+static const uint8_t dequant_table[64] = {
+    16, 15, 13, 19, 24, 31, 28, 17,
+    17, 23, 25, 31, 36, 63, 45, 21,
+    18, 24, 27, 37, 52, 59, 49, 20,
+    16, 28, 34, 40, 60, 80, 51, 20,
+    18, 31, 48, 66, 68, 86, 56, 21,
+    19, 38, 56, 59, 64, 64, 48, 20,
+    27, 48, 55, 55, 56, 51, 35, 15,
+    20, 35, 34, 32, 31, 22, 15,  8,
+};
+
+static VLC block_type_vlc[2][4];
+
+
+typedef struct CFrameBuffer {
+    unsigned int allocated_size;
+    unsigned int size;
+    int id;
+    uint8_t *data;
+} CFrameBuffer;
+
+typedef struct FourXContext {
+    AVCodecContext *avctx;
+    DSPContext dsp;
+    AVFrame *current_picture, *last_picture;
+    GetBitContext pre_gb;          ///< ac/dc prefix
+    GetBitContext gb;
+    GetByteContext g;
+    GetByteContext g2;
+    int mv[256];
+    VLC pre_vlc;
+    int last_dc;
+    DECLARE_ALIGNED(16, int16_t, block)[6][64];
+    void *bitstream_buffer;
+    unsigned int bitstream_buffer_size;
+    int version;
+    CFrameBuffer cfrm[CFRAME_BUFFER_COUNT];
+} FourXContext;
+
+
+#define FIX_1_082392200  70936
+#define FIX_1_414213562  92682
+#define FIX_1_847759065 121095
+#define FIX_2_613125930 171254
+
+#define MULTIPLY(var, const) (((var) * (const)) >> 16)
+
+static void idct(int16_t block[64])
+{
+    int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
+    int tmp10, tmp11, tmp12, tmp13;
+    int z5, z10, z11, z12, z13;
+    int i;
+    int temp[64];
+
+    for (i = 0; i < 8; i++) {
+        tmp10 = block[8 * 0 + i] + block[8 * 4 + i];
+        tmp11 = block[8 * 0 + i] - block[8 * 4 + i];
+
+        tmp13 = block[8 * 2 + i] + block[8 * 6 + i];
+        tmp12 = MULTIPLY(block[8 * 2 + i] - block[8 * 6 + i], FIX_1_414213562) - tmp13;
+
+        tmp0 = tmp10 + tmp13;
+        tmp3 = tmp10 - tmp13;
+        tmp1 = tmp11 + tmp12;
+        tmp2 = tmp11 - tmp12;
+
+        z13 = block[8 * 5 + i] + block[8 * 3 + i];
+        z10 = block[8 * 5 + i] - block[8 * 3 + i];
+        z11 = block[8 * 1 + i] + block[8 * 7 + i];
+        z12 = block[8 * 1 + i] - block[8 * 7 + i];
+
+        tmp7  =          z11 + z13;
+        tmp11 = MULTIPLY(z11 - z13, FIX_1_414213562);
+
+        z5    = MULTIPLY(z10 + z12, FIX_1_847759065);
+        tmp10 = MULTIPLY(z12,  FIX_1_082392200) - z5;
+        tmp12 = MULTIPLY(z10, -FIX_2_613125930) + z5;
+
+        tmp6 = tmp12 - tmp7;
+        tmp5 = tmp11 - tmp6;
+        tmp4 = tmp10 + tmp5;
+
+        temp[8 * 0 + i] = tmp0 + tmp7;
+        temp[8 * 7 + i] = tmp0 - tmp7;
+        temp[8 * 1 + i] = tmp1 + tmp6;
+        temp[8 * 6 + i] = tmp1 - tmp6;
+        temp[8 * 2 + i] = tmp2 + tmp5;
+        temp[8 * 5 + i] = tmp2 - tmp5;
+        temp[8 * 4 + i] = tmp3 + tmp4;
+        temp[8 * 3 + i] = tmp3 - tmp4;
+    }
+
+    for (i = 0; i < 8 * 8; i += 8) {
+        tmp10 = temp[0 + i] + temp[4 + i];
+        tmp11 = temp[0 + i] - temp[4 + i];
+
+        tmp13 = temp[2 + i] + temp[6 + i];
+        tmp12 = MULTIPLY(temp[2 + i] - temp[6 + i], FIX_1_414213562) - tmp13;
+
+        tmp0 = tmp10 + tmp13;
+        tmp3 = tmp10 - tmp13;
+        tmp1 = tmp11 + tmp12;
+        tmp2 = tmp11 - tmp12;
+
+        z13 = temp[5 + i] + temp[3 + i];
+        z10 = temp[5 + i] - temp[3 + i];
+        z11 = temp[1 + i] + temp[7 + i];
+        z12 = temp[1 + i] - temp[7 + i];
+
+        tmp7  = z11 + z13;
+        tmp11 = MULTIPLY(z11 - z13, FIX_1_414213562);
+
+        z5    = MULTIPLY(z10 + z12, FIX_1_847759065);
+        tmp10 = MULTIPLY(z12,  FIX_1_082392200) - z5;
+        tmp12 = MULTIPLY(z10, -FIX_2_613125930) + z5;
+
+        tmp6 = tmp12 - tmp7;
+        tmp5 = tmp11 - tmp6;
+        tmp4 = tmp10 + tmp5;
+
+        block[0 + i] = (tmp0 + tmp7) >> 6;
+        block[7 + i] = (tmp0 - tmp7) >> 6;
+        block[1 + i] = (tmp1 + tmp6) >> 6;
+        block[6 + i] = (tmp1 - tmp6) >> 6;
+        block[2 + i] = (tmp2 + tmp5) >> 6;
+        block[5 + i] = (tmp2 - tmp5) >> 6;
+        block[4 + i] = (tmp3 + tmp4) >> 6;
+        block[3 + i] = (tmp3 - tmp4) >> 6;
+    }
+}
+
+static av_cold void init_vlcs(FourXContext *f)
+{
+    static VLC_TYPE table[2][4][32][2];
+    int i, j;
+
+    for (i = 0; i < 2; i++) {
+        for (j = 0; j < 4; j++) {
+            block_type_vlc[i][j].table           = table[i][j];
+            block_type_vlc[i][j].table_allocated = 32;
+            init_vlc(&block_type_vlc[i][j], BLOCK_TYPE_VLC_BITS, 7,
+                     &block_type_tab[i][j][0][1], 2, 1,
+                     &block_type_tab[i][j][0][0], 2, 1,
+                     INIT_VLC_USE_NEW_STATIC);
+        }
+    }
+}
+
+static void init_mv(FourXContext *f, int linesize)
+{
+    int i;
+
+    for (i = 0; i < 256; i++) {
+        if (f->version > 1)
+            f->mv[i] = mv[i][0] + mv[i][1] * linesize / 2;
+        else
+            f->mv[i] = (i & 15) - 8 + ((i >> 4) - 8) * linesize / 2;
+    }
+}
+
+#if HAVE_BIGENDIAN
+#define LE_CENTRIC_MUL(dst, src, scale, dc)             \
+    {                                                   \
+        unsigned tmpval = AV_RN32(src);                 \
+        tmpval = (tmpval << 16) | (tmpval >> 16);       \
+        tmpval = tmpval * (scale) + (dc);               \
+        tmpval = (tmpval << 16) | (tmpval >> 16);       \
+        AV_WN32A(dst, tmpval);                          \
+    }
+#else
+#define LE_CENTRIC_MUL(dst, src, scale, dc)              \
+    {                                                    \
+        unsigned tmpval = AV_RN32(src) * (scale) + (dc); \
+        AV_WN32A(dst, tmpval);                           \
+    }
+#endif
+
+static inline void mcdc(uint16_t *dst, const uint16_t *src, int log2w,
+                        int h, int stride, int scale, unsigned dc)
+{
+    int i;
+    dc *= 0x10001;
+
+    switch (log2w) {
+    case 0:
+        for (i = 0; i < h; i++) {
+            dst[0] = scale * src[0] + dc;
+            if (scale)
+                src += stride;
+            dst += stride;
+        }
+        break;
+    case 1:
+        for (i = 0; i < h; i++) {
+            LE_CENTRIC_MUL(dst, src, scale, dc);
+            if (scale)
+                src += stride;
+            dst += stride;
+        }
+        break;
+    case 2:
+        for (i = 0; i < h; i++) {
+            LE_CENTRIC_MUL(dst, src, scale, dc);
+            LE_CENTRIC_MUL(dst + 2, src + 2, scale, dc);
+            if (scale)
+                src += stride;
+            dst += stride;
+        }
+        break;
+    case 3:
+        for (i = 0; i < h; i++) {
+            LE_CENTRIC_MUL(dst,     src,     scale, dc);
+            LE_CENTRIC_MUL(dst + 2, src + 2, scale, dc);
+            LE_CENTRIC_MUL(dst + 4, src + 4, scale, dc);
+            LE_CENTRIC_MUL(dst + 6, src + 6, scale, dc);
+            if (scale)
+                src += stride;
+            dst += stride;
+        }
+        break;
+    default:
+        av_assert2(0);
+    }
+}
+
+static void decode_p_block(FourXContext *f, uint16_t *dst, uint16_t *src,
+                           int log2w, int log2h, int stride)
+{
+    const int index = size2index[log2h][log2w];
+    const int h     = 1 << log2h;
+    int code        = get_vlc2(&f->gb,
+                               block_type_vlc[1 - (f->version > 1)][index].table,
+                               BLOCK_TYPE_VLC_BITS, 1);
+    uint16_t *start = (uint16_t *)f->last_picture->data[0];
+    uint16_t *end   = start + stride * (f->avctx->height - h + 1) - (1 << log2w);
+
+    av_assert2(code >= 0 && code <= 6);
+
+    if (code == 0) {
+        if (bytestream2_get_bytes_left(&f->g) < 1) {
+            av_log(f->avctx, AV_LOG_ERROR, "bytestream overread\n");
+            return;
+        }
+        src += f->mv[bytestream2_get_byteu(&f->g)];
+        if (start > src || src > end) {
+            av_log(f->avctx, AV_LOG_ERROR, "mv out of pic\n");
+            return;
+        }
+        mcdc(dst, src, log2w, h, stride, 1, 0);
+    } else if (code == 1) {
+        log2h--;
+        decode_p_block(f, dst, src, log2w, log2h, stride);
+        decode_p_block(f, dst + (stride << log2h),
+                          src + (stride << log2h), log2w, log2h, stride);
+    } else if (code == 2) {
+        log2w--;
+        decode_p_block(f, dst , src, log2w, log2h, stride);
+        decode_p_block(f, dst + (1 << log2w),
+                          src + (1 << log2w), log2w, log2h, stride);
+    } else if (code == 3 && f->version < 2) {
+        mcdc(dst, src, log2w, h, stride, 1, 0);
+    } else if (code == 4) {
+        if (bytestream2_get_bytes_left(&f->g) < 1) {
+            av_log(f->avctx, AV_LOG_ERROR, "bytestream overread\n");
+            return;
+        }
+        src += f->mv[bytestream2_get_byteu(&f->g)];
+        if (start > src || src > end) {
+            av_log(f->avctx, AV_LOG_ERROR, "mv out of pic\n");
+            return;
+        }
+        if (bytestream2_get_bytes_left(&f->g2) < 2){
+            av_log(f->avctx, AV_LOG_ERROR, "wordstream overread\n");
+            return;
+        }
+        mcdc(dst, src, log2w, h, stride, 1, bytestream2_get_le16u(&f->g2));
+    } else if (code == 5) {
+        if (bytestream2_get_bytes_left(&f->g2) < 2) {
+            av_log(f->avctx, AV_LOG_ERROR, "wordstream overread\n");
+            return;
+        }
+        mcdc(dst, src, log2w, h, stride, 0, bytestream2_get_le16u(&f->g2));
+    } else if (code == 6) {
+        if (bytestream2_get_bytes_left(&f->g2) < 4) {
+            av_log(f->avctx, AV_LOG_ERROR, "wordstream overread\n");
+            return;
+        }
+        if (log2w) {
+            dst[0]      = bytestream2_get_le16u(&f->g2);
+            dst[1]      = bytestream2_get_le16u(&f->g2);
+        } else {
+            dst[0]      = bytestream2_get_le16u(&f->g2);
+            dst[stride] = bytestream2_get_le16u(&f->g2);
+        }
+    }
+}
+
+static int decode_p_frame(FourXContext *f, AVFrame *frame,
+                          const uint8_t *buf, int length)
+{
+    int x, y;
+    const int width  = f->avctx->width;
+    const int height = f->avctx->height;
+    uint16_t *src    = (uint16_t *)f->last_picture->data[0];
+    uint16_t *dst    = (uint16_t *)frame->data[0];
+    const int stride =             frame->linesize[0] >> 1;
+    unsigned int bitstream_size, bytestream_size, wordstream_size, extra,
+                 bytestream_offset, wordstream_offset;
+
+    if (f->version > 1) {
+        extra           = 20;
+        if (length < extra)
+            return -1;
+        bitstream_size  = AV_RL32(buf + 8);
+        wordstream_size = AV_RL32(buf + 12);
+        bytestream_size = AV_RL32(buf + 16);
+    } else {
+        extra           = 0;
+        bitstream_size  = AV_RL16(buf - 4);
+        wordstream_size = AV_RL16(buf - 2);
+        bytestream_size = FFMAX(length - bitstream_size - wordstream_size, 0);
+    }
+
+    if (bitstream_size > length || bitstream_size >= INT_MAX/8 ||
+        bytestream_size > length - bitstream_size ||
+        wordstream_size > length - bytestream_size - bitstream_size ||
+        extra > length - bytestream_size - bitstream_size - wordstream_size) {
+        av_log(f->avctx, AV_LOG_ERROR, "lengths %d %d %d %d\n", bitstream_size, bytestream_size, wordstream_size,
+        bitstream_size+ bytestream_size+ wordstream_size - length);
+        return AVERROR_INVALIDDATA;
+    }
+
+    av_fast_malloc(&f->bitstream_buffer, &f->bitstream_buffer_size,
+                   bitstream_size + FF_INPUT_BUFFER_PADDING_SIZE);
+    if (!f->bitstream_buffer)
+        return AVERROR(ENOMEM);
+    f->dsp.bswap_buf(f->bitstream_buffer, (const uint32_t*)(buf + extra),
+                     bitstream_size / 4);
+    memset((uint8_t*)f->bitstream_buffer + bitstream_size,
+           0, FF_INPUT_BUFFER_PADDING_SIZE);
+    init_get_bits(&f->gb, f->bitstream_buffer, 8 * bitstream_size);
+
+    wordstream_offset = extra + bitstream_size;
+    bytestream_offset = extra + bitstream_size + wordstream_size;
+    bytestream2_init(&f->g2, buf + wordstream_offset,
+                     length - wordstream_offset);
+    bytestream2_init(&f->g, buf + bytestream_offset,
+                     length - bytestream_offset);
+
+    init_mv(f, frame->linesize[0]);
+
+    for (y = 0; y < height; y += 8) {
+        for (x = 0; x < width; x += 8)
+            decode_p_block(f, dst + x, src + x, 3, 3, stride);
+        src += 8 * stride;
+        dst += 8 * stride;
+    }
+
+    return 0;
+}
+
+/**
+ * decode block and dequantize.
+ * Note this is almost identical to MJPEG.
+ */
+static int decode_i_block(FourXContext *f, int16_t *block)
+{
+    int code, i, j, level, val;
+
+    if (get_bits_left(&f->gb) < 2){
+        av_log(f->avctx, AV_LOG_ERROR, "%d bits left before decode_i_block()\n", get_bits_left(&f->gb));
+        return -1;
+    }
+
+    /* DC coef */
+    val = get_vlc2(&f->pre_gb, f->pre_vlc.table, ACDC_VLC_BITS, 3);
+    if (val >> 4)
+        av_log(f->avctx, AV_LOG_ERROR, "error dc run != 0\n");
+
+    if (val)
+        val = get_xbits(&f->gb, val);
+
+    val        = val * dequant_table[0] + f->last_dc;
+    f->last_dc = block[0] = val;
+    /* AC coefs */
+    i = 1;
+    for (;;) {
+        code = get_vlc2(&f->pre_gb, f->pre_vlc.table, ACDC_VLC_BITS, 3);
+
+        /* EOB */
+        if (code == 0)
+            break;
+        if (code == 0xf0) {
+            i += 16;
+        } else {
+            level = get_xbits(&f->gb, code & 0xf);
+            i    += code >> 4;
+            if (i >= 64) {
+                av_log(f->avctx, AV_LOG_ERROR, "run %d oveflow\n", i);
+                return 0;
+            }
+
+            j = ff_zigzag_direct[i];
+            block[j] = level * dequant_table[j];
+            i++;
+            if (i >= 64)
+                break;
+        }
+    }
+
+    return 0;
+}
+
+static inline void idct_put(FourXContext *f, AVFrame *frame, int x, int y)
+{
+    int16_t (*block)[64] = f->block;
+    int stride           = frame->linesize[0] >> 1;
+    int i;
+    uint16_t *dst = ((uint16_t*)frame->data[0]) + y * stride + x;
+
+    for (i = 0; i < 4; i++) {
+        block[i][0] += 0x80 * 8 * 8;
+        idct(block[i]);
+    }
+
+    if (!(f->avctx->flags & CODEC_FLAG_GRAY)) {
+        for (i = 4; i < 6; i++)
+            idct(block[i]);
+    }
+
+    /* Note transform is:
+     * y  = ( 1b + 4g + 2r) / 14
+     * cb = ( 3b - 2g - 1r) / 14
+     * cr = (-1b - 4g + 5r) / 14 */
+    for (y = 0; y < 8; y++) {
+        for (x = 0; x < 8; x++) {
+            int16_t *temp = block[(x >> 2) + 2 * (y >> 2)] +
+                            2 * (x & 3) + 2 * 8 * (y & 3); // FIXME optimize
+            int cb = block[4][x + 8 * y];
+            int cr = block[5][x + 8 * y];
+            int cg = (cb + cr) >> 1;
+            int y;
+
+            cb += cb;
+
+            y               = temp[0];
+            dst[0]          = ((y + cb) >> 3) + (((y - cg) & 0xFC) << 3) + (((y + cr) & 0xF8) << 8);
+            y               = temp[1];
+            dst[1]          = ((y + cb) >> 3) + (((y - cg) & 0xFC) << 3) + (((y + cr) & 0xF8) << 8);
+            y               = temp[8];
+            dst[stride]     = ((y + cb) >> 3) + (((y - cg) & 0xFC) << 3) + (((y + cr) & 0xF8) << 8);
+            y               = temp[9];
+            dst[1 + stride] = ((y + cb) >> 3) + (((y - cg) & 0xFC) << 3) + (((y + cr) & 0xF8) << 8);
+            dst            += 2;
+        }
+        dst += 2 * stride - 2 * 8;
+    }
+}
+
+static int decode_i_mb(FourXContext *f)
+{
+    int ret;
+    int i;
+
+    f->dsp.clear_blocks(f->block[0]);
+
+    for (i = 0; i < 6; i++)
+        if ((ret = decode_i_block(f, f->block[i])) < 0)
+            return ret;
+
+    return 0;
+}
+
+static const uint8_t *read_huffman_tables(FourXContext *f,
+                                          const uint8_t * const buf, int buf_size)
+{
+    int frequency[512] = { 0 };
+    uint8_t flag[512];
+    int up[512];
+    uint8_t len_tab[257];
+    int bits_tab[257];
+    int start, end;
+    const uint8_t *ptr = buf;
+    const uint8_t *ptr_end = buf + buf_size;
+    int j;
+
+    memset(up, -1, sizeof(up));
+
+    start = *ptr++;
+    end   = *ptr++;
+    for (;;) {
+        int i;
+
+        if (ptr_end - ptr < FFMAX(end - start + 1, 0) + 1) {
+            av_log(f->avctx, AV_LOG_ERROR, "invalid data in read_huffman_tables\n");
+            return NULL;
+        }
+        for (i = start; i <= end; i++)
+            frequency[i] = *ptr++;
+        start = *ptr++;
+        if (start == 0)
+            break;
+
+        end = *ptr++;
+    }
+    frequency[256] = 1;
+
+    while ((ptr - buf) & 3)
+        ptr++; // 4byte align
+
+    if (ptr > ptr_end) {
+        av_log(f->avctx, AV_LOG_ERROR, "ptr overflow in read_huffman_tables\n");
+        return NULL;
+    }
+
+    for (j = 257; j < 512; j++) {
+        int min_freq[2] = { 256 * 256, 256 * 256 };
+        int smallest[2] = { 0, 0 };
+        int i;
+        for (i = 0; i < j; i++) {
+            if (frequency[i] == 0)
+                continue;
+            if (frequency[i] < min_freq[1]) {
+                if (frequency[i] < min_freq[0]) {
+                    min_freq[1] = min_freq[0];
+                    smallest[1] = smallest[0];
+                    min_freq[0] = frequency[i];
+                    smallest[0] = i;
+                } else {
+                    min_freq[1] = frequency[i];
+                    smallest[1] = i;
+                }
+            }
+        }
+        if (min_freq[1] == 256 * 256)
+            break;
+
+        frequency[j]           = min_freq[0] + min_freq[1];
+        flag[smallest[0]]      = 0;
+        flag[smallest[1]]      = 1;
+        up[smallest[0]]        =
+        up[smallest[1]]        = j;
+        frequency[smallest[0]] = frequency[smallest[1]] = 0;
+    }
+
+    for (j = 0; j < 257; j++) {
+        int node, len = 0, bits = 0;
+
+        for (node = j; up[node] != -1; node = up[node]) {
+            bits += flag[node] << len;
+            len++;
+            if (len > 31)
+                // can this happen at all ?
+                av_log(f->avctx, AV_LOG_ERROR,
+                       "vlc length overflow\n");
+        }
+
+        bits_tab[j] = bits;
+        len_tab[j]  = len;
+    }
+
+    if (init_vlc(&f->pre_vlc, ACDC_VLC_BITS, 257, len_tab, 1, 1,
+                 bits_tab, 4, 4, 0))
+        return NULL;
+
+    return ptr;
+}
+
+static int mix(int c0, int c1)
+{
+    int blue  =  2 * (c0 & 0x001F) + (c1 & 0x001F);
+    int green = (2 * (c0 & 0x03E0) + (c1 & 0x03E0)) >> 5;
+    int red   =  2 * (c0 >> 10)    + (c1 >> 10);
+    return red / 3 * 1024 + green / 3 * 32 + blue / 3;
+}
+
+static int decode_i2_frame(FourXContext *f, AVFrame *frame, const uint8_t *buf, int length)
+{
+    int x, y, x2, y2;
+    const int width  = f->avctx->width;
+    const int height = f->avctx->height;
+    const int mbs    = (FFALIGN(width, 16) >> 4) * (FFALIGN(height, 16) >> 4);
+    uint16_t *dst    = (uint16_t*)frame->data[0];
+    const int stride =            frame->linesize[0]>>1;
+    const uint8_t *buf_end = buf + length;
+    GetByteContext g3;
+
+    if (length < mbs * 8) {
+        av_log(f->avctx, AV_LOG_ERROR, "packet size too small\n");
+        return AVERROR_INVALIDDATA;
+    }
+    bytestream2_init(&g3, buf, length);
+
+    for (y = 0; y < height; y += 16) {
+        for (x = 0; x < width; x += 16) {
+            unsigned int color[4] = { 0 }, bits;
+            if (buf_end - buf < 8)
+                return -1;
+            // warning following is purely guessed ...
+            color[0] = bytestream2_get_le16u(&g3);
+            color[1] = bytestream2_get_le16u(&g3);
+
+            if (color[0] & 0x8000)
+                av_log(NULL, AV_LOG_ERROR, "unk bit 1\n");
+            if (color[1] & 0x8000)
+                av_log(NULL, AV_LOG_ERROR, "unk bit 2\n");
+
+            color[2] = mix(color[0], color[1]);
+            color[3] = mix(color[1], color[0]);
+
+            bits = bytestream2_get_le32u(&g3);
+            for (y2 = 0; y2 < 16; y2++) {
+                for (x2 = 0; x2 < 16; x2++) {
+                    int index = 2 * (x2 >> 2) + 8 * (y2 >> 2);
+                    dst[y2 * stride + x2] = color[(bits >> index) & 3];
+                }
+            }
+            dst += 16;
+        }
+        dst += 16 * stride - x;
+    }
+
+    return 0;
+}
+
+static int decode_i_frame(FourXContext *f, AVFrame *frame, const uint8_t *buf, int length)
+{
+    int x, y, ret;
+    const int width  = f->avctx->width;
+    const int height = f->avctx->height;
+    const unsigned int bitstream_size = AV_RL32(buf);
+    unsigned int prestream_size;
+    const uint8_t *prestream;
+
+    if (bitstream_size > (1<<26) || length < bitstream_size + 12) {
+        av_log(f->avctx, AV_LOG_ERROR, "packet size too small\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    prestream_size = 4 * AV_RL32(buf + bitstream_size + 4);
+    prestream      =             buf + bitstream_size + 12;
+
+    if (prestream_size + bitstream_size + 12 != length
+        || bitstream_size > (1 << 26)
+        || prestream_size > (1 << 26)) {
+        av_log(f->avctx, AV_LOG_ERROR, "size mismatch %d %d %d\n",
+               prestream_size, bitstream_size, length);
+        return AVERROR_INVALIDDATA;
+    }
+
+    prestream = read_huffman_tables(f, prestream, buf + length - prestream);
+    if (!prestream) {
+        av_log(f->avctx, AV_LOG_ERROR, "Error reading Huffman tables.\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    av_assert0(prestream <= buf + length);
+
+    init_get_bits(&f->gb, buf + 4, 8 * bitstream_size);
+
+    prestream_size = length + buf - prestream;
+
+    av_fast_malloc(&f->bitstream_buffer, &f->bitstream_buffer_size,
+                   prestream_size + FF_INPUT_BUFFER_PADDING_SIZE);
+    if (!f->bitstream_buffer)
+        return AVERROR(ENOMEM);
+    f->dsp.bswap_buf(f->bitstream_buffer, (const uint32_t*)prestream,
+                     prestream_size / 4);
+    memset((uint8_t*)f->bitstream_buffer + prestream_size,
+           0, FF_INPUT_BUFFER_PADDING_SIZE);
+    init_get_bits(&f->pre_gb, f->bitstream_buffer, 8 * prestream_size);
+
+    f->last_dc = 0 * 128 * 8 * 8;
+
+    for (y = 0; y < height; y += 16) {
+        for (x = 0; x < width; x += 16) {
+            if ((ret = decode_i_mb(f)) < 0)
+                return ret;
+
+            idct_put(f, frame, x, y);
+        }
+    }
+
+    if (get_vlc2(&f->pre_gb, f->pre_vlc.table, ACDC_VLC_BITS, 3) != 256)
+        av_log(f->avctx, AV_LOG_ERROR, "end mismatch\n");
+
+    return 0;
+}
+
+static int decode_frame(AVCodecContext *avctx, void *data,
+                        int *got_frame, AVPacket *avpkt)
+{
+    const uint8_t *buf    = avpkt->data;
+    int buf_size          = avpkt->size;
+    FourXContext *const f = avctx->priv_data;
+    AVFrame *picture      = data;
+    int i, frame_4cc, frame_size, ret;
+
+    if (buf_size < 12)
+        return AVERROR_INVALIDDATA;
+    frame_4cc = AV_RL32(buf);
+    if (buf_size != AV_RL32(buf + 4) + 8 || buf_size < 20)
+        av_log(f->avctx, AV_LOG_ERROR, "size mismatch %d %d\n",
+               buf_size, AV_RL32(buf + 4));
+
+    if (frame_4cc == AV_RL32("cfrm")) {
+        int free_index       = -1;
+        const int data_size  = buf_size - 20;
+        const int id         = AV_RL32(buf + 12);
+        const int whole_size = AV_RL32(buf + 16);
+        CFrameBuffer *cfrm;
+
+        if (data_size < 0 || whole_size < 0) {
+            av_log(f->avctx, AV_LOG_ERROR, "sizes invalid\n");
+            return AVERROR_INVALIDDATA;
+        }
+
+        if (f->version <= 1) {
+            av_log(f->avctx, AV_LOG_ERROR, "cfrm in version %d\n", f->version);
+            return AVERROR_INVALIDDATA;
+        }
+
+        for (i = 0; i < CFRAME_BUFFER_COUNT; i++)
+            if (f->cfrm[i].id && f->cfrm[i].id < avctx->frame_number)
+                av_log(f->avctx, AV_LOG_ERROR, "lost c frame %d\n",
+                       f->cfrm[i].id);
+
+        for (i = 0; i < CFRAME_BUFFER_COUNT; i++) {
+            if (f->cfrm[i].id == id)
+                break;
+            if (f->cfrm[i].size == 0)
+                free_index = i;
+        }
+
+        if (i >= CFRAME_BUFFER_COUNT) {
+            i             = free_index;
+            f->cfrm[i].id = id;
+        }
+        cfrm = &f->cfrm[i];
+
+        if (data_size > UINT_MAX -  cfrm->size - FF_INPUT_BUFFER_PADDING_SIZE)
+            return AVERROR_INVALIDDATA;
+
+        cfrm->data = av_fast_realloc(cfrm->data, &cfrm->allocated_size,
+                                     cfrm->size + data_size + FF_INPUT_BUFFER_PADDING_SIZE);
+        // explicit check needed as memcpy below might not catch a NULL
+        if (!cfrm->data) {
+            av_log(f->avctx, AV_LOG_ERROR, "realloc failure\n");
+            return AVERROR(ENOMEM);
+        }
+
+        memcpy(cfrm->data + cfrm->size, buf + 20, data_size);
+        cfrm->size += data_size;
+
+        if (cfrm->size >= whole_size) {
+            buf        = cfrm->data;
+            frame_size = cfrm->size;
+
+            if (id != avctx->frame_number)
+                av_log(f->avctx, AV_LOG_ERROR, "cframe id mismatch %d %d\n",
+                       id, avctx->frame_number);
+
+            cfrm->size = cfrm->id = 0;
+            frame_4cc  = AV_RL32("pfrm");
+        } else
+            return buf_size;
+    } else {
+        buf        = buf      + 12;
+        frame_size = buf_size - 12;
+    }
+
+    FFSWAP(AVFrame*, f->current_picture, f->last_picture);
+
+    // alternatively we would have to use our own buffer management
+    avctx->flags |= CODEC_FLAG_EMU_EDGE;
+
+    if ((ret = ff_reget_buffer(avctx, f->current_picture)) < 0)
+        return ret;
+
+    if (frame_4cc == AV_RL32("ifr2")) {
+        f->current_picture->pict_type = AV_PICTURE_TYPE_I;
+        if ((ret = decode_i2_frame(f, f->current_picture, buf - 4, frame_size + 4)) < 0) {
+            av_log(f->avctx, AV_LOG_ERROR, "decode i2 frame failed\n");
+            return ret;
+        }
+    } else if (frame_4cc == AV_RL32("ifrm")) {
+        f->current_picture->pict_type = AV_PICTURE_TYPE_I;
+        if ((ret = decode_i_frame(f, f->current_picture, buf, frame_size)) < 0) {
+            av_log(f->avctx, AV_LOG_ERROR, "decode i frame failed\n");
+            return ret;
+        }
+    } else if (frame_4cc == AV_RL32("pfrm") || frame_4cc == AV_RL32("pfr2")) {
+        if (!f->last_picture->data[0]) {
+            if ((ret = ff_get_buffer(avctx, f->last_picture,
+                                     AV_GET_BUFFER_FLAG_REF)) < 0)
+                return ret;
+            for (i=0; i<avctx->height; i++)
+                memset(f->last_picture->data[0] + i*f->last_picture->linesize[0], 0, 2*avctx->width);
+        }
+
+        f->current_picture->pict_type = AV_PICTURE_TYPE_P;
+        if ((ret = decode_p_frame(f, f->current_picture, buf, frame_size)) < 0) {
+            av_log(f->avctx, AV_LOG_ERROR, "decode p frame failed\n");
+            return ret;
+        }
+    } else if (frame_4cc == AV_RL32("snd_")) {
+        av_log(avctx, AV_LOG_ERROR, "ignoring snd_ chunk length:%d\n",
+               buf_size);
+    } else {
+        av_log(avctx, AV_LOG_ERROR, "ignoring unknown chunk length:%d\n",
+               buf_size);
+    }
+
+    f->current_picture->key_frame = f->current_picture->pict_type == AV_PICTURE_TYPE_I;
+
+    if ((ret = av_frame_ref(picture, f->current_picture)) < 0)
+        return ret;
+    *got_frame = 1;
+
+    emms_c();
+
+    return buf_size;
+}
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+    FourXContext * const f = avctx->priv_data;
+
+    if (avctx->extradata_size != 4 || !avctx->extradata) {
+        av_log(avctx, AV_LOG_ERROR, "extradata wrong or missing\n");
+        return AVERROR_INVALIDDATA;
+    }
+    if((avctx->width % 16) || (avctx->height % 16)) {
+        av_log(avctx, AV_LOG_ERROR, "unsupported width/height\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    f->version = AV_RL32(avctx->extradata) >> 16;
+    ff_dsputil_init(&f->dsp, avctx);
+    f->avctx = avctx;
+    init_vlcs(f);
+
+    if (f->version > 2)
+        avctx->pix_fmt = AV_PIX_FMT_RGB565;
+    else
+        avctx->pix_fmt = AV_PIX_FMT_BGR555;
+
+    f->current_picture = av_frame_alloc();
+    f->last_picture    = av_frame_alloc();
+    if (!f->current_picture  || !f->last_picture)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+
+static av_cold int decode_end(AVCodecContext *avctx)
+{
+    FourXContext * const f = avctx->priv_data;
+    int i;
+
+    av_freep(&f->bitstream_buffer);
+    f->bitstream_buffer_size = 0;
+    for (i = 0; i < CFRAME_BUFFER_COUNT; i++) {
+        av_freep(&f->cfrm[i].data);
+        f->cfrm[i].allocated_size = 0;
+    }
+    ff_free_vlc(&f->pre_vlc);
+    av_frame_free(&f->current_picture);
+    av_frame_free(&f->last_picture);
+
+    return 0;
+}
+
+AVCodec ff_fourxm_decoder = {
+    .name           = "4xm",
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_4XM,
+    .priv_data_size = sizeof(FourXContext),
+    .init           = decode_init,
+    .close          = decode_end,
+    .decode         = decode_frame,
+    .capabilities   = CODEC_CAP_DR1,
+    .long_name      = NULL_IF_CONFIG_SMALL("4X Movie"),
+};