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FFmpeg/libavcodec/4xm.c

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  1. /*

  2.  * 4XM codec

  3.  * Copyright (c) 2003 Michael Niedermayer

  4.  *

  5.  * This file is part of FFmpeg.

  6.  *

  7.  * FFmpeg is free software; you can redistribute it and/or

  8.  * modify it under the terms of the GNU Lesser General Public

  9.  * License as published by the Free Software Foundation; either

  10.  * version 2.1 of the License, or (at your option) any later version.

  11.  *

  12.  * FFmpeg is distributed in the hope that it will be useful,

  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  15.  * Lesser General Public License for more details.

  16.  *

  17.  * You should have received a copy of the GNU Lesser General Public

  18.  * License along with FFmpeg; if not, write to the Free Software

  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  20.  */

  21. 

  22. /**

  23.  * @file

  24.  * 4XM codec.

  25.  */

  26. 

  27. #include "libavutil/avassert.h"

  28. #include "libavutil/frame.h"

  29. #include "libavutil/intreadwrite.h"

  30. #include "avcodec.h"

  31. #include "bytestream.h"

  32. #include "dsputil.h"

  33. #include "get_bits.h"

  34. #include "internal.h"

  35. 

  36. 

  37. #define BLOCK_TYPE_VLC_BITS 5

  38. #define ACDC_VLC_BITS 9

  39. 

  40. #define CFRAME_BUFFER_COUNT 100

  41. 

  42. static const uint8_t block_type_tab[2][4][8][2] = {

  43.     {

  44.         {    // { 8, 4, 2 } x { 8, 4, 2}

  45.             { 0, 1 }, { 2, 2 }, { 6, 3 }, { 14, 4 }, { 30, 5 }, { 31, 5 }, { 0, 0 }

  46.         }, { // { 8, 4 } x 1

  47.             { 0, 1 }, { 0, 0 }, { 2, 2 }, { 6, 3 }, { 14, 4 }, { 15, 4 }, { 0, 0 }

  48.         }, { // 1 x { 8, 4 }

  49.             { 0, 1 }, { 2, 2 }, { 0, 0 }, { 6, 3 }, { 14, 4 }, { 15, 4 }, { 0, 0 }

  50.         }, { // 1 x 2, 2 x 1

  51.             { 0, 1 }, { 0, 0 }, { 0, 0 }, { 2, 2 }, { 6, 3 }, { 14, 4 }, { 15, 4 }

  52.         }

  53.     }, {

  54.         {   // { 8, 4, 2 } x { 8, 4, 2}

  55.             { 1, 2 }, { 4, 3 }, { 5, 3 }, { 0, 2 }, { 6, 3 }, { 7, 3 }, { 0, 0 }

  56.         }, {// { 8, 4 } x 1

  57.             { 1, 2 }, { 0, 0 }, { 2, 2 }, { 0, 2 }, { 6, 3 }, { 7, 3 }, { 0, 0 }

  58.         }, {// 1 x { 8, 4 }

  59.             { 1, 2 }, { 2, 2 }, { 0, 0 }, { 0, 2 }, { 6, 3 }, { 7, 3 }, { 0, 0 }

  60.         }, {// 1 x 2, 2 x 1

  61.             { 1, 2 }, { 0, 0 }, { 0, 0 }, { 0, 2 }, { 2, 2 }, { 6, 3 }, { 7, 3 }

  62.       }

  63.     }

  64. };

  65. 

  66. static const uint8_t size2index[4][4] = {

  67.     { -1, 3, 1, 1 },

  68.     {  3, 0, 0, 0 },

  69.     {  2, 0, 0, 0 },

  70.     {  2, 0, 0, 0 },

  71. };

  72. 

  73. static const int8_t mv[256][2] = {

  74.     {   0,   0 }, {   0,  -1 }, {  -1,   0 }, {   1,   0 }, {   0,   1 }, {  -1,  -1 }, {   1,  -1 }, {  -1,   1 },

  75.     {   1,   1 }, {   0,  -2 }, {  -2,   0 }, {   2,   0 }, {   0,   2 }, {  -1,  -2 }, {   1,  -2 }, {  -2,  -1 },

  76.     {   2,  -1 }, {  -2,   1 }, {   2,   1 }, {  -1,   2 }, {   1,   2 }, {  -2,  -2 }, {   2,  -2 }, {  -2,   2 },

  77.     {   2,   2 }, {   0,  -3 }, {  -3,   0 }, {   3,   0 }, {   0,   3 }, {  -1,  -3 }, {   1,  -3 }, {  -3,  -1 },

  78.     {   3,  -1 }, {  -3,   1 }, {   3,   1 }, {  -1,   3 }, {   1,   3 }, {  -2,  -3 }, {   2,  -3 }, {  -3,  -2 },

  79.     {   3,  -2 }, {  -3,   2 }, {   3,   2 }, {  -2,   3 }, {   2,   3 }, {   0,  -4 }, {  -4,   0 }, {   4,   0 },

  80.     {   0,   4 }, {  -1,  -4 }, {   1,  -4 }, {  -4,  -1 }, {   4,  -1 }, {   4,   1 }, {  -1,   4 }, {   1,   4 },

  81.     {  -3,  -3 }, {  -3,   3 }, {   3,   3 }, {  -2,  -4 }, {  -4,  -2 }, {   4,  -2 }, {  -4,   2 }, {  -2,   4 },

  82.     {   2,   4 }, {  -3,  -4 }, {   3,  -4 }, {   4,  -3 }, {  -5,   0 }, {  -4,   3 }, {  -3,   4 }, {   3,   4 },

  83.     {  -1,  -5 }, {  -5,  -1 }, {  -5,   1 }, {  -1,   5 }, {  -2,  -5 }, {   2,  -5 }, {   5,  -2 }, {   5,   2 },

  84.     {  -4,  -4 }, {  -4,   4 }, {  -3,  -5 }, {  -5,  -3 }, {  -5,   3 }, {   3,   5 }, {  -6,   0 }, {   0,   6 },

  85.     {  -6,  -1 }, {  -6,   1 }, {   1,   6 }, {   2,  -6 }, {  -6,   2 }, {   2,   6 }, {  -5,  -4 }, {   5,   4 },

  86.     {   4,   5 }, {  -6,  -3 }, {   6,   3 }, {  -7,   0 }, {  -1,  -7 }, {   5,  -5 }, {  -7,   1 }, {  -1,   7 },

  87.     {   4,  -6 }, {   6,   4 }, {  -2,  -7 }, {  -7,   2 }, {  -3,  -7 }, {   7,  -3 }, {   3,   7 }, {   6,  -5 },

  88.     {   0,  -8 }, {  -1,  -8 }, {  -7,  -4 }, {  -8,   1 }, {   4,   7 }, {   2,  -8 }, {  -2,   8 }, {   6,   6 },

  89.     {  -8,   3 }, {   5,  -7 }, {  -5,   7 }, {   8,  -4 }, {   0,  -9 }, {  -9,  -1 }, {   1,   9 }, {   7,  -6 },

  90.     {  -7,   6 }, {  -5,  -8 }, {  -5,   8 }, {  -9,   3 }, {   9,  -4 }, {   7,  -7 }, {   8,  -6 }, {   6,   8 },

  91.     {  10,   1 }, { -10,   2 }, {   9,  -5 }, {  10,  -3 }, {  -8,  -7 }, { -10,  -4 }, {   6,  -9 }, { -11,   0 },

  92.     {  11,   1 }, { -11,  -2 }, {  -2,  11 }, {   7,  -9 }, {  -7,   9 }, {  10,   6 }, {  -4,  11 }, {   8,  -9 },

  93.     {   8,   9 }, {   5,  11 }, {   7, -10 }, {  12,  -3 }, {  11,   6 }, {  -9,  -9 }, {   8,  10 }, {   5,  12 },

  94.     { -11,   7 }, {  13,   2 }, {   6, -12 }, {  10,   9 }, { -11,   8 }, {  -7,  12 }, {   0,  14 }, {  14,  -2 },

  95.     {  -9,  11 }, {  -6,  13 }, { -14,  -4 }, {  -5, -14 }, {   5,  14 }, { -15,  -1 }, { -14,  -6 }, {   3, -15 },

  96.     {  11, -11 }, {  -7,  14 }, {  -5,  15 }, {   8, -14 }, {  15,   6 }, {   3,  16 }, {   7, -15 }, { -16,   5 },

  97.     {   0,  17 }, { -16,  -6 }, { -10,  14 }, { -16,   7 }, {  12,  13 }, { -16,   8 }, { -17,   6 }, { -18,   3 },

  98.     {  -7,  17 }, {  15,  11 }, {  16,  10 }, {   2, -19 }, {   3, -19 }, { -11, -16 }, { -18,   8 }, { -19,  -6 },

  99.     {   2, -20 }, { -17, -11 }, { -10, -18 }, {   8,  19 }, { -21,  -1 }, { -20,   7 }, {  -4,  21 }, {  21,   5 },

  100.     {  15,  16 }, {   2, -22 }, { -10, -20 }, { -22,   5 }, {  20, -11 }, {  -7, -22 }, { -12,  20 }, {  23,  -5 },

  101.     {  13, -20 }, {  24,  -2 }, { -15,  19 }, { -11,  22 }, {  16,  19 }, {  23, -10 }, { -18, -18 }, {  -9, -24 },

  102.     {  24, -10 }, {  -3,  26 }, { -23,  13 }, { -18, -20 }, {  17,  21 }, {  -4,  27 }, {  27,   6 }, {   1, -28 },

  103.     { -11,  26 }, { -17, -23 }, {   7,  28 }, {  11, -27 }, {  29,   5 }, { -23, -19 }, { -28, -11 }, { -21,  22 },

  104.     { -30,   7 }, { -17,  26 }, { -27,  16 }, {  13,  29 }, {  19, -26 }, {  10, -31 }, { -14, -30 }, {  20, -27 },

  105.     { -29,  18 }, { -16, -31 }, { -28, -22 }, {  21, -30 }, { -25,  28 }, {  26, -29 }, {  25, -32 }, { -32, -32 }

  106. };

  107. 

  108. /* This is simply the scaled down elementwise product of the standard JPEG

  109.  * quantizer table and the AAN premul table. */

  110. static const uint8_t dequant_table[64] = {

  111.     16, 15, 13, 19, 24, 31, 28, 17,

  112.     17, 23, 25, 31, 36, 63, 45, 21,

  113.     18, 24, 27, 37, 52, 59, 49, 20,

  114.     16, 28, 34, 40, 60, 80, 51, 20,

  115.     18, 31, 48, 66, 68, 86, 56, 21,

  116.     19, 38, 56, 59, 64, 64, 48, 20,

  117.     27, 48, 55, 55, 56, 51, 35, 15,

  118.     20, 35, 34, 32, 31, 22, 15,  8,

  119. };

  120. 

  121. static VLC block_type_vlc[2][4];

  122. 

  123. 

  124. typedef struct CFrameBuffer {

  125.     unsigned int allocated_size;

  126.     unsigned int size;

  127.     int id;

  128.     uint8_t *data;

  129. } CFrameBuffer;

  130. 

  131. typedef struct FourXContext {

  132.     AVCodecContext *avctx;

  133.     DSPContext dsp;

  134.     AVFrame *current_picture, *last_picture;

  135.     GetBitContext pre_gb;          ///< ac/dc prefix

  136.     GetBitContext gb;

  137.     GetByteContext g;

  138.     GetByteContext g2;

  139.     int mv[256];

  140.     VLC pre_vlc;

  141.     int last_dc;

  142.     DECLARE_ALIGNED(16, int16_t, block)[6][64];

  143.     void *bitstream_buffer;

  144.     unsigned int bitstream_buffer_size;

  145.     int version;

  146.     CFrameBuffer cfrm[CFRAME_BUFFER_COUNT];

  147. } FourXContext;

  148. 

  149. 

  150. #define FIX_1_082392200  70936

  151. #define FIX_1_414213562  92682

  152. #define FIX_1_847759065 121095

  153. #define FIX_2_613125930 171254

  154. 

  155. #define MULTIPLY(var, const) (((var) * (const)) >> 16)

  156. 

  157. static void idct(int16_t block[64])

  158. {

  159.     int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;

  160.     int tmp10, tmp11, tmp12, tmp13;

  161.     int z5, z10, z11, z12, z13;

  162.     int i;

  163.     int temp[64];

  164. 

  165.     for (i = 0; i < 8; i++) {

  166.         tmp10 = block[8 * 0 + i] + block[8 * 4 + i];

  167.         tmp11 = block[8 * 0 + i] - block[8 * 4 + i];

  168. 

  169.         tmp13 = block[8 * 2 + i] + block[8 * 6 + i];

  170.         tmp12 = MULTIPLY(block[8 * 2 + i] - block[8 * 6 + i], FIX_1_414213562) - tmp13;

  171. 

  172.         tmp0 = tmp10 + tmp13;

  173.         tmp3 = tmp10 - tmp13;

  174.         tmp1 = tmp11 + tmp12;

  175.         tmp2 = tmp11 - tmp12;

  176. 

  177.         z13 = block[8 * 5 + i] + block[8 * 3 + i];

  178.         z10 = block[8 * 5 + i] - block[8 * 3 + i];

  179.         z11 = block[8 * 1 + i] + block[8 * 7 + i];

  180.         z12 = block[8 * 1 + i] - block[8 * 7 + i];

  181. 

  182.         tmp7  =          z11 + z13;

  183.         tmp11 = MULTIPLY(z11 - z13, FIX_1_414213562);

  184. 

  185.         z5    = MULTIPLY(z10 + z12, FIX_1_847759065);

  186.         tmp10 = MULTIPLY(z12,  FIX_1_082392200) - z5;

  187.         tmp12 = MULTIPLY(z10, -FIX_2_613125930) + z5;

  188. 

  189.         tmp6 = tmp12 - tmp7;

  190.         tmp5 = tmp11 - tmp6;

  191.         tmp4 = tmp10 + tmp5;

  192. 

  193.         temp[8 * 0 + i] = tmp0 + tmp7;

  194.         temp[8 * 7 + i] = tmp0 - tmp7;

  195.         temp[8 * 1 + i] = tmp1 + tmp6;

  196.         temp[8 * 6 + i] = tmp1 - tmp6;

  197.         temp[8 * 2 + i] = tmp2 + tmp5;

  198.         temp[8 * 5 + i] = tmp2 - tmp5;

  199.         temp[8 * 4 + i] = tmp3 + tmp4;

  200.         temp[8 * 3 + i] = tmp3 - tmp4;

  201.     }

  202. 

  203.     for (i = 0; i < 8 * 8; i += 8) {

  204.         tmp10 = temp[0 + i] + temp[4 + i];

  205.         tmp11 = temp[0 + i] - temp[4 + i];

  206. 

  207.         tmp13 = temp[2 + i] + temp[6 + i];

  208.         tmp12 = MULTIPLY(temp[2 + i] - temp[6 + i], FIX_1_414213562) - tmp13;

  209. 

  210.         tmp0 = tmp10 + tmp13;

  211.         tmp3 = tmp10 - tmp13;

  212.         tmp1 = tmp11 + tmp12;

  213.         tmp2 = tmp11 - tmp12;

  214. 

  215.         z13 = temp[5 + i] + temp[3 + i];

  216.         z10 = temp[5 + i] - temp[3 + i];

  217.         z11 = temp[1 + i] + temp[7 + i];

  218.         z12 = temp[1 + i] - temp[7 + i];

  219. 

  220.         tmp7  = z11 + z13;

  221.         tmp11 = MULTIPLY(z11 - z13, FIX_1_414213562);

  222. 

  223.         z5    = MULTIPLY(z10 + z12, FIX_1_847759065);

  224.         tmp10 = MULTIPLY(z12,  FIX_1_082392200) - z5;

  225.         tmp12 = MULTIPLY(z10, -FIX_2_613125930) + z5;

  226. 

  227.         tmp6 = tmp12 - tmp7;

  228.         tmp5 = tmp11 - tmp6;

  229.         tmp4 = tmp10 + tmp5;

  230. 

  231.         block[0 + i] = (tmp0 + tmp7) >> 6;

  232.         block[7 + i] = (tmp0 - tmp7) >> 6;

  233.         block[1 + i] = (tmp1 + tmp6) >> 6;

  234.         block[6 + i] = (tmp1 - tmp6) >> 6;

  235.         block[2 + i] = (tmp2 + tmp5) >> 6;

  236.         block[5 + i] = (tmp2 - tmp5) >> 6;

  237.         block[4 + i] = (tmp3 + tmp4) >> 6;

  238.         block[3 + i] = (tmp3 - tmp4) >> 6;

  239.     }

  240. }

  241. 

  242. static av_cold void init_vlcs(FourXContext *f)

  243. {

  244.     static VLC_TYPE table[2][4][32][2];

  245.     int i, j;

  246. 

  247.     for (i = 0; i < 2; i++) {

  248.         for (j = 0; j < 4; j++) {

  249.             block_type_vlc[i][j].table           = table[i][j];

  250.             block_type_vlc[i][j].table_allocated = 32;

  251.             init_vlc(&block_type_vlc[i][j], BLOCK_TYPE_VLC_BITS, 7,

  252.                      &block_type_tab[i][j][0][1], 2, 1,

  253.                      &block_type_tab[i][j][0][0], 2, 1,

  254.                      INIT_VLC_USE_NEW_STATIC);

  255.         }

  256.     }

  257. }

  258. 

  259. static void init_mv(FourXContext *f, int linesize)

  260. {

  261.     int i;

  262. 

  263.     for (i = 0; i < 256; i++) {

  264.         if (f->version > 1)

  265.             f->mv[i] = mv[i][0] + mv[i][1] * linesize / 2;

  266.         else

  267.             f->mv[i] = (i & 15) - 8 + ((i >> 4) - 8) * linesize / 2;

  268.     }

  269. }

  270. 

  271. #if HAVE_BIGENDIAN

  272. #define LE_CENTRIC_MUL(dst, src, scale, dc)             \

  273.     {                                                   \

  274.         unsigned tmpval = AV_RN32(src);                 \

  275.         tmpval = (tmpval << 16) | (tmpval >> 16);       \

  276.         tmpval = tmpval * (scale) + (dc);               \

  277.         tmpval = (tmpval << 16) | (tmpval >> 16);       \

  278.         AV_WN32A(dst, tmpval);                          \

  279.     }

  280. #else

  281. #define LE_CENTRIC_MUL(dst, src, scale, dc)              \

  282.     {                                                    \

  283.         unsigned tmpval = AV_RN32(src) * (scale) + (dc); \

  284.         AV_WN32A(dst, tmpval);                           \

  285.     }

  286. #endif

  287. 

  288. static inline void mcdc(uint16_t *dst, const uint16_t *src, int log2w,

  289.                         int h, int stride, int scale, unsigned dc)

  290. {

  291.     int i;

  292.     dc *= 0x10001;

  293. 

  294.     switch (log2w) {

  295.     case 0:

  296.         for (i = 0; i < h; i++) {

  297.             dst[0] = scale * src[0] + dc;

  298.             if (scale)

  299.                 src += stride;

  300.             dst += stride;

  301.         }

  302.         break;

  303.     case 1:

  304.         for (i = 0; i < h; i++) {

  305.             LE_CENTRIC_MUL(dst, src, scale, dc);

  306.             if (scale)

  307.                 src += stride;

  308.             dst += stride;

  309.         }

  310.         break;

  311.     case 2:

  312.         for (i = 0; i < h; i++) {

  313.             LE_CENTRIC_MUL(dst, src, scale, dc);

  314.             LE_CENTRIC_MUL(dst + 2, src + 2, scale, dc);

  315.             if (scale)

  316.                 src += stride;

  317.             dst += stride;

  318.         }

  319.         break;

  320.     case 3:

  321.         for (i = 0; i < h; i++) {

  322.             LE_CENTRIC_MUL(dst,     src,     scale, dc);

  323.             LE_CENTRIC_MUL(dst + 2, src + 2, scale, dc);

  324.             LE_CENTRIC_MUL(dst + 4, src + 4, scale, dc);

  325.             LE_CENTRIC_MUL(dst + 6, src + 6, scale, dc);

  326.             if (scale)

  327.                 src += stride;

  328.             dst += stride;

  329.         }

  330.         break;

  331.     default:

  332.         av_assert2(0);

  333.     }

  334. }

  335. 

  336. static void decode_p_block(FourXContext *f, uint16_t *dst, uint16_t *src,

  337.                            int log2w, int log2h, int stride)

  338. {

  339.     const int index = size2index[log2h][log2w];

  340.     const int h     = 1 << log2h;

  341.     int code        = get_vlc2(&f->gb,

  342.                                block_type_vlc[1 - (f->version > 1)][index].table,

  343.                                BLOCK_TYPE_VLC_BITS, 1);

  344.     uint16_t *start = (uint16_t *)f->last_picture->data[0];

  345.     uint16_t *end   = start + stride * (f->avctx->height - h + 1) - (1 << log2w);

  346. 

  347.     av_assert2(code >= 0 && code <= 6);

  348. 

  349.     if (code == 0) {

  350.         if (bytestream2_get_bytes_left(&f->g) < 1) {

  351.             av_log(f->avctx, AV_LOG_ERROR, "bytestream overread\n");

  352.             return;

  353.         }

  354.         src += f->mv[bytestream2_get_byteu(&f->g)];

  355.         if (start > src || src > end) {

  356.             av_log(f->avctx, AV_LOG_ERROR, "mv out of pic\n");

  357.             return;

  358.         }

  359.         mcdc(dst, src, log2w, h, stride, 1, 0);

  360.     } else if (code == 1) {

  361.         log2h--;

  362.         decode_p_block(f, dst, src, log2w, log2h, stride);

  363.         decode_p_block(f, dst + (stride << log2h),

  364.                           src + (stride << log2h), log2w, log2h, stride);

  365.     } else if (code == 2) {

  366.         log2w--;

  367.         decode_p_block(f, dst , src, log2w, log2h, stride);

  368.         decode_p_block(f, dst + (1 << log2w),

  369.                           src + (1 << log2w), log2w, log2h, stride);

  370.     } else if (code == 3 && f->version < 2) {

  371.         mcdc(dst, src, log2w, h, stride, 1, 0);

  372.     } else if (code == 4) {

  373.         if (bytestream2_get_bytes_left(&f->g) < 1) {

  374.             av_log(f->avctx, AV_LOG_ERROR, "bytestream overread\n");

  375.             return;

  376.         }

  377.         src += f->mv[bytestream2_get_byteu(&f->g)];

  378.         if (start > src || src > end) {

  379.             av_log(f->avctx, AV_LOG_ERROR, "mv out of pic\n");

  380.             return;

  381.         }

  382.         if (bytestream2_get_bytes_left(&f->g2) < 2){

  383.             av_log(f->avctx, AV_LOG_ERROR, "wordstream overread\n");

  384.             return;

  385.         }

  386.         mcdc(dst, src, log2w, h, stride, 1, bytestream2_get_le16u(&f->g2));

  387.     } else if (code == 5) {

  388.         if (bytestream2_get_bytes_left(&f->g2) < 2) {

  389.             av_log(f->avctx, AV_LOG_ERROR, "wordstream overread\n");

  390.             return;

  391.         }

  392.         mcdc(dst, src, log2w, h, stride, 0, bytestream2_get_le16u(&f->g2));

  393.     } else if (code == 6) {

  394.         if (bytestream2_get_bytes_left(&f->g2) < 4) {

  395.             av_log(f->avctx, AV_LOG_ERROR, "wordstream overread\n");

  396.             return;

  397.         }

  398.         if (log2w) {

  399.             dst[0]      = bytestream2_get_le16u(&f->g2);

  400.             dst[1]      = bytestream2_get_le16u(&f->g2);

  401.         } else {

  402.             dst[0]      = bytestream2_get_le16u(&f->g2);

  403.             dst[stride] = bytestream2_get_le16u(&f->g2);

  404.         }

  405.     }

  406. }

  407. 

  408. static int decode_p_frame(FourXContext *f, AVFrame *frame,

  409.                           const uint8_t *buf, int length)

  410. {

  411.     int x, y;

  412.     const int width  = f->avctx->width;

  413.     const int height = f->avctx->height;

  414.     uint16_t *src    = (uint16_t *)f->last_picture->data[0];

  415.     uint16_t *dst    = (uint16_t *)frame->data[0];

  416.     const int stride =             frame->linesize[0] >> 1;

  417.     unsigned int bitstream_size, bytestream_size, wordstream_size, extra,

  418.                  bytestream_offset, wordstream_offset;

  419. 

  420.     if (f->version > 1) {

  421.         extra           = 20;

  422.         if (length < extra)

  423.             return -1;

  424.         bitstream_size  = AV_RL32(buf + 8);

  425.         wordstream_size = AV_RL32(buf + 12);

  426.         bytestream_size = AV_RL32(buf + 16);

  427.     } else {

  428.         extra           = 0;

  429.         bitstream_size  = AV_RL16(buf - 4);

  430.         wordstream_size = AV_RL16(buf - 2);

  431.         bytestream_size = FFMAX(length - bitstream_size - wordstream_size, 0);

  432.     }

  433. 

  434.     if (bitstream_size > length || bitstream_size >= INT_MAX/8 ||

  435.         bytestream_size > length - bitstream_size ||

  436.         wordstream_size > length - bytestream_size - bitstream_size ||

  437.         extra > length - bytestream_size - bitstream_size - wordstream_size) {

  438.         av_log(f->avctx, AV_LOG_ERROR, "lengths %d %d %d %d\n", bitstream_size, bytestream_size, wordstream_size,

  439.         bitstream_size+ bytestream_size+ wordstream_size - length);

  440.         return AVERROR_INVALIDDATA;

  441.     }

  442. 

  443.     av_fast_malloc(&f->bitstream_buffer, &f->bitstream_buffer_size,

  444.                    bitstream_size + FF_INPUT_BUFFER_PADDING_SIZE);

  445.     if (!f->bitstream_buffer)

  446.         return AVERROR(ENOMEM);

  447.     f->dsp.bswap_buf(f->bitstream_buffer, (const uint32_t*)(buf + extra),

  448.                      bitstream_size / 4);

  449.     memset((uint8_t*)f->bitstream_buffer + bitstream_size,

  450.            0, FF_INPUT_BUFFER_PADDING_SIZE);

  451.     init_get_bits(&f->gb, f->bitstream_buffer, 8 * bitstream_size);

  452. 

  453.     wordstream_offset = extra + bitstream_size;

  454.     bytestream_offset = extra + bitstream_size + wordstream_size;

  455.     bytestream2_init(&f->g2, buf + wordstream_offset,

  456.                      length - wordstream_offset);

  457.     bytestream2_init(&f->g, buf + bytestream_offset,

  458.                      length - bytestream_offset);

  459. 

  460.     init_mv(f, frame->linesize[0]);

  461. 

  462.     for (y = 0; y < height; y += 8) {

  463.         for (x = 0; x < width; x += 8)

  464.             decode_p_block(f, dst + x, src + x, 3, 3, stride);

  465.         src += 8 * stride;

  466.         dst += 8 * stride;

  467.     }

  468. 

  469.     return 0;

  470. }

  471. 

  472. /**

  473.  * decode block and dequantize.

  474.  * Note this is almost identical to MJPEG.

  475.  */

  476. static int decode_i_block(FourXContext *f, int16_t *block)

  477. {

  478.     int code, i, j, level, val;

  479. 

  480.     if (get_bits_left(&f->gb) < 2){

  481.         av_log(f->avctx, AV_LOG_ERROR, "%d bits left before decode_i_block()\n", get_bits_left(&f->gb));

  482.         return -1;

  483.     }

  484. 

  485.     /* DC coef */

  486.     val = get_vlc2(&f->pre_gb, f->pre_vlc.table, ACDC_VLC_BITS, 3);

  487.     if (val >> 4)

  488.         av_log(f->avctx, AV_LOG_ERROR, "error dc run != 0\n");

  489. 

  490.     if (val)

  491.         val = get_xbits(&f->gb, val);

  492. 

  493.     val        = val * dequant_table[0] + f->last_dc;

  494.     f->last_dc = block[0] = val;

  495.     /* AC coefs */

  496.     i = 1;

  497.     for (;;) {

  498.         code = get_vlc2(&f->pre_gb, f->pre_vlc.table, ACDC_VLC_BITS, 3);

  499. 

  500.         /* EOB */

  501.         if (code == 0)

  502.             break;

  503.         if (code == 0xf0) {

  504.             i += 16;

  505.         } else {

  506.             level = get_xbits(&f->gb, code & 0xf);

  507.             i    += code >> 4;

  508.             if (i >= 64) {

  509.                 av_log(f->avctx, AV_LOG_ERROR, "run %d oveflow\n", i);

  510.                 return 0;

  511.             }

  512. 

  513.             j = ff_zigzag_direct[i];

  514.             block[j] = level * dequant_table[j];

  515.             i++;

  516.             if (i >= 64)

  517.                 break;

  518.         }

  519.     }

  520. 

  521.     return 0;

  522. }

  523. 

  524. static inline void idct_put(FourXContext *f, AVFrame *frame, int x, int y)

  525. {

  526.     int16_t (*block)[64] = f->block;

  527.     int stride           = frame->linesize[0] >> 1;

  528.     int i;

  529.     uint16_t *dst = ((uint16_t*)frame->data[0]) + y * stride + x;

  530. 

  531.     for (i = 0; i < 4; i++) {

  532.         block[i][0] += 0x80 * 8 * 8;

  533.         idct(block[i]);

  534.     }

  535. 

  536.     if (!(f->avctx->flags & CODEC_FLAG_GRAY)) {

  537.         for (i = 4; i < 6; i++)

  538.             idct(block[i]);

  539.     }

  540. 

  541.     /* Note transform is:

  542.      * y  = ( 1b + 4g + 2r) / 14

  543.      * cb = ( 3b - 2g - 1r) / 14

  544.      * cr = (-1b - 4g + 5r) / 14 */

  545.     for (y = 0; y < 8; y++) {

  546.         for (x = 0; x < 8; x++) {

  547.             int16_t *temp = block[(x >> 2) + 2 * (y >> 2)] +

  548.                             2 * (x & 3) + 2 * 8 * (y & 3); // FIXME optimize

  549.             int cb = block[4][x + 8 * y];

  550.             int cr = block[5][x + 8 * y];

  551.             int cg = (cb + cr) >> 1;

  552.             int y;

  553. 

  554.             cb += cb;

  555. 

  556.             y               = temp[0];

  557.             dst[0]          = ((y + cb) >> 3) + (((y - cg) & 0xFC) << 3) + (((y + cr) & 0xF8) << 8);

  558.             y               = temp[1];

  559.             dst[1]          = ((y + cb) >> 3) + (((y - cg) & 0xFC) << 3) + (((y + cr) & 0xF8) << 8);

  560.             y               = temp[8];

  561.             dst[stride]     = ((y + cb) >> 3) + (((y - cg) & 0xFC) << 3) + (((y + cr) & 0xF8) << 8);

  562.             y               = temp[9];

  563.             dst[1 + stride] = ((y + cb) >> 3) + (((y - cg) & 0xFC) << 3) + (((y + cr) & 0xF8) << 8);

  564.             dst            += 2;

  565.         }

  566.         dst += 2 * stride - 2 * 8;

  567.     }

  568. }

  569. 

  570. static int decode_i_mb(FourXContext *f)

  571. {

  572.     int ret;

  573.     int i;

  574. 

  575.     f->dsp.clear_blocks(f->block[0]);

  576. 

  577.     for (i = 0; i < 6; i++)

  578.         if ((ret = decode_i_block(f, f->block[i])) < 0)

  579.             return ret;

  580. 

  581.     return 0;

  582. }

  583. 

  584. static const uint8_t *read_huffman_tables(FourXContext *f,

  585.                                           const uint8_t * const buf, int buf_size)

  586. {

  587.     int frequency[512] = { 0 };

  588.     uint8_t flag[512];

  589.     int up[512];

  590.     uint8_t len_tab[257];

  591.     int bits_tab[257];

  592.     int start, end;

  593.     const uint8_t *ptr = buf;

  594.     const uint8_t *ptr_end = buf + buf_size;

  595.     int j;

  596. 

  597.     memset(up, -1, sizeof(up));

  598. 

  599.     start = *ptr++;

  600.     end   = *ptr++;

  601.     for (;;) {

  602.         int i;

  603. 

  604.         if (ptr_end - ptr < FFMAX(end - start + 1, 0) + 1) {

  605.             av_log(f->avctx, AV_LOG_ERROR, "invalid data in read_huffman_tables\n");

  606.             return NULL;

  607.         }

  608.         for (i = start; i <= end; i++)

  609.             frequency[i] = *ptr++;

  610.         start = *ptr++;

  611.         if (start == 0)

  612.             break;

  613. 

  614.         end = *ptr++;

  615.     }

  616.     frequency[256] = 1;

  617. 

  618.     while ((ptr - buf) & 3)

  619.         ptr++; // 4byte align

  620. 

  621.     if (ptr > ptr_end) {

  622.         av_log(f->avctx, AV_LOG_ERROR, "ptr overflow in read_huffman_tables\n");

  623.         return NULL;

  624.     }

  625. 

  626.     for (j = 257; j < 512; j++) {

  627.         int min_freq[2] = { 256 * 256, 256 * 256 };

  628.         int smallest[2] = { 0, 0 };

  629.         int i;

  630.         for (i = 0; i < j; i++) {

  631.             if (frequency[i] == 0)

  632.                 continue;

  633.             if (frequency[i] < min_freq[1]) {

  634.                 if (frequency[i] < min_freq[0]) {

  635.                     min_freq[1] = min_freq[0];

  636.                     smallest[1] = smallest[0];

  637.                     min_freq[0] = frequency[i];

  638.                     smallest[0] = i;

  639.                 } else {

  640.                     min_freq[1] = frequency[i];

  641.                     smallest[1] = i;

  642.                 }

  643.             }

  644.         }

  645.         if (min_freq[1] == 256 * 256)

  646.             break;

  647. 

  648.         frequency[j]           = min_freq[0] + min_freq[1];

  649.         flag[smallest[0]]      = 0;

  650.         flag[smallest[1]]      = 1;

  651.         up[smallest[0]]        =

  652.         up[smallest[1]]        = j;

  653.         frequency[smallest[0]] = frequency[smallest[1]] = 0;

  654.     }

  655. 

  656.     for (j = 0; j < 257; j++) {

  657.         int node, len = 0, bits = 0;

  658. 

  659.         for (node = j; up[node] != -1; node = up[node]) {

  660.             bits += flag[node] << len;

  661.             len++;

  662.             if (len > 31)

  663.                 // can this happen at all ?

  664.                 av_log(f->avctx, AV_LOG_ERROR,

  665.                        "vlc length overflow\n");

  666.         }

  667. 

  668.         bits_tab[j] = bits;

  669.         len_tab[j]  = len;

  670.     }

  671. 

  672.     if (init_vlc(&f->pre_vlc, ACDC_VLC_BITS, 257, len_tab, 1, 1,

  673.                  bits_tab, 4, 4, 0))

  674.         return NULL;

  675. 

  676.     return ptr;

  677. }

  678. 

  679. static int mix(int c0, int c1)

  680. {

  681.     int blue  =  2 * (c0 & 0x001F) + (c1 & 0x001F);

  682.     int green = (2 * (c0 & 0x03E0) + (c1 & 0x03E0)) >> 5;

  683.     int red   =  2 * (c0 >> 10)    + (c1 >> 10);

  684.     return red / 3 * 1024 + green / 3 * 32 + blue / 3;

  685. }

  686. 

  687. static int decode_i2_frame(FourXContext *f, AVFrame *frame, const uint8_t *buf, int length)

  688. {

  689.     int x, y, x2, y2;

  690.     const int width  = f->avctx->width;

  691.     const int height = f->avctx->height;

  692.     const int mbs    = (FFALIGN(width, 16) >> 4) * (FFALIGN(height, 16) >> 4);

  693.     uint16_t *dst    = (uint16_t*)frame->data[0];

  694.     const int stride =            frame->linesize[0]>>1;

  695.     const uint8_t *buf_end = buf + length;

  696.     GetByteContext g3;

  697. 

  698.     if (length < mbs * 8) {

  699.         av_log(f->avctx, AV_LOG_ERROR, "packet size too small\n");

  700.         return AVERROR_INVALIDDATA;

  701.     }

  702.     bytestream2_init(&g3, buf, length);

  703. 

  704.     for (y = 0; y < height; y += 16) {

  705.         for (x = 0; x < width; x += 16) {

  706.             unsigned int color[4] = { 0 }, bits;

  707.             if (buf_end - buf < 8)

  708.                 return -1;

  709.             // warning following is purely guessed ...

  710.             color[0] = bytestream2_get_le16u(&g3);

  711.             color[1] = bytestream2_get_le16u(&g3);

  712. 

  713.             if (color[0] & 0x8000)

  714.                 av_log(NULL, AV_LOG_ERROR, "unk bit 1\n");

  715.             if (color[1] & 0x8000)

  716.                 av_log(NULL, AV_LOG_ERROR, "unk bit 2\n");

  717. 

  718.             color[2] = mix(color[0], color[1]);

  719.             color[3] = mix(color[1], color[0]);

  720. 

  721.             bits = bytestream2_get_le32u(&g3);

  722.             for (y2 = 0; y2 < 16; y2++) {

  723.                 for (x2 = 0; x2 < 16; x2++) {

  724.                     int index = 2 * (x2 >> 2) + 8 * (y2 >> 2);

  725.                     dst[y2 * stride + x2] = color[(bits >> index) & 3];

  726.                 }

  727.             }

  728.             dst += 16;

  729.         }

  730.         dst += 16 * stride - x;

  731.     }

  732. 

  733.     return 0;

  734. }

  735. 

  736. static int decode_i_frame(FourXContext *f, AVFrame *frame, const uint8_t *buf, int length)

  737. {

  738.     int x, y, ret;

  739.     const int width  = f->avctx->width;

  740.     const int height = f->avctx->height;

  741.     const unsigned int bitstream_size = AV_RL32(buf);

  742.     unsigned int prestream_size;

  743.     const uint8_t *prestream;

  744. 

  745.     if (bitstream_size > (1<<26) || length < bitstream_size + 12) {

  746.         av_log(f->avctx, AV_LOG_ERROR, "packet size too small\n");

  747.         return AVERROR_INVALIDDATA;

  748.     }

  749. 

  750.     prestream_size = 4 * AV_RL32(buf + bitstream_size + 4);

  751.     prestream      =             buf + bitstream_size + 12;

  752. 

  753.     if (prestream_size + bitstream_size + 12 != length

  754.         || bitstream_size > (1 << 26)

  755.         || prestream_size > (1 << 26)) {

  756.         av_log(f->avctx, AV_LOG_ERROR, "size mismatch %d %d %d\n",

  757.                prestream_size, bitstream_size, length);

  758.         return AVERROR_INVALIDDATA;

  759.     }

  760. 

  761.     prestream = read_huffman_tables(f, prestream, buf + length - prestream);

  762.     if (!prestream) {

  763.         av_log(f->avctx, AV_LOG_ERROR, "Error reading Huffman tables.\n");

  764.         return AVERROR_INVALIDDATA;

  765.     }

  766. 

  767.     av_assert0(prestream <= buf + length);

  768. 

  769.     init_get_bits(&f->gb, buf + 4, 8 * bitstream_size);

  770. 

  771.     prestream_size = length + buf - prestream;

  772. 

  773.     av_fast_malloc(&f->bitstream_buffer, &f->bitstream_buffer_size,

  774.                    prestream_size + FF_INPUT_BUFFER_PADDING_SIZE);

  775.     if (!f->bitstream_buffer)

  776.         return AVERROR(ENOMEM);

  777.     f->dsp.bswap_buf(f->bitstream_buffer, (const uint32_t*)prestream,

  778.                      prestream_size / 4);

  779.     memset((uint8_t*)f->bitstream_buffer + prestream_size,

  780.            0, FF_INPUT_BUFFER_PADDING_SIZE);

  781.     init_get_bits(&f->pre_gb, f->bitstream_buffer, 8 * prestream_size);

  782. 

  783.     f->last_dc = 0 * 128 * 8 * 8;

  784. 

  785.     for (y = 0; y < height; y += 16) {

  786.         for (x = 0; x < width; x += 16) {

  787.             if ((ret = decode_i_mb(f)) < 0)

  788.                 return ret;

  789. 

  790.             idct_put(f, frame, x, y);

  791.         }

  792.     }

  793. 

  794.     if (get_vlc2(&f->pre_gb, f->pre_vlc.table, ACDC_VLC_BITS, 3) != 256)

  795.         av_log(f->avctx, AV_LOG_ERROR, "end mismatch\n");

  796. 

  797.     return 0;

  798. }

  799. 

  800. static int decode_frame(AVCodecContext *avctx, void *data,

  801.                         int *got_frame, AVPacket *avpkt)

  802. {

  803.     const uint8_t *buf    = avpkt->data;

  804.     int buf_size          = avpkt->size;

  805.     FourXContext *const f = avctx->priv_data;

  806.     AVFrame *picture      = data;

  807.     int i, frame_4cc, frame_size, ret;

  808. 

  809.     if (buf_size < 12)

  810.         return AVERROR_INVALIDDATA;

  811.     frame_4cc = AV_RL32(buf);

  812.     if (buf_size != AV_RL32(buf + 4) + 8 || buf_size < 20)

  813.         av_log(f->avctx, AV_LOG_ERROR, "size mismatch %d %d\n",

  814.                buf_size, AV_RL32(buf + 4));

  815. 

  816.     if (frame_4cc == AV_RL32("cfrm")) {

  817.         int free_index       = -1;

  818.         const int data_size  = buf_size - 20;

  819.         const int id         = AV_RL32(buf + 12);

  820.         const int whole_size = AV_RL32(buf + 16);

  821.         CFrameBuffer *cfrm;

  822. 

  823.         if (data_size < 0 || whole_size < 0) {

  824.             av_log(f->avctx, AV_LOG_ERROR, "sizes invalid\n");

  825.             return AVERROR_INVALIDDATA;

  826.         }

  827. 

  828.         if (f->version <= 1) {

  829.             av_log(f->avctx, AV_LOG_ERROR, "cfrm in version %d\n", f->version);

  830.             return AVERROR_INVALIDDATA;

  831.         }

  832. 

  833.         for (i = 0; i < CFRAME_BUFFER_COUNT; i++)

  834.             if (f->cfrm[i].id && f->cfrm[i].id < avctx->frame_number)

  835.                 av_log(f->avctx, AV_LOG_ERROR, "lost c frame %d\n",

  836.                        f->cfrm[i].id);

  837. 

  838.         for (i = 0; i < CFRAME_BUFFER_COUNT; i++) {

  839.             if (f->cfrm[i].id == id)

  840.                 break;

  841.             if (f->cfrm[i].size == 0)

  842.                 free_index = i;

  843.         }

  844. 

  845.         if (i >= CFRAME_BUFFER_COUNT) {

  846.             i             = free_index;

  847.             f->cfrm[i].id = id;

  848.         }

  849.         cfrm = &f->cfrm[i];

  850. 

  851.         if (data_size > UINT_MAX -  cfrm->size - FF_INPUT_BUFFER_PADDING_SIZE)

  852.             return AVERROR_INVALIDDATA;

  853. 

  854.         cfrm->data = av_fast_realloc(cfrm->data, &cfrm->allocated_size,

  855.                                      cfrm->size + data_size + FF_INPUT_BUFFER_PADDING_SIZE);

  856.         // explicit check needed as memcpy below might not catch a NULL

  857.         if (!cfrm->data) {

  858.             av_log(f->avctx, AV_LOG_ERROR, "realloc failure\n");

  859.             return AVERROR(ENOMEM);

  860.         }

  861. 

  862.         memcpy(cfrm->data + cfrm->size, buf + 20, data_size);

  863.         cfrm->size += data_size;

  864. 

  865.         if (cfrm->size >= whole_size) {

  866.             buf        = cfrm->data;

  867.             frame_size = cfrm->size;

  868. 

  869.             if (id != avctx->frame_number)

  870.                 av_log(f->avctx, AV_LOG_ERROR, "cframe id mismatch %d %d\n",

  871.                        id, avctx->frame_number);

  872. 

  873.             cfrm->size = cfrm->id = 0;

  874.             frame_4cc  = AV_RL32("pfrm");

  875.         } else

  876.             return buf_size;

  877.     } else {

  878.         buf        = buf      + 12;

  879.         frame_size = buf_size - 12;

  880.     }

  881. 

  882.     FFSWAP(AVFrame*, f->current_picture, f->last_picture);

  883. 

  884.     // alternatively we would have to use our own buffer management

  885.     avctx->flags |= CODEC_FLAG_EMU_EDGE;

  886. 

  887.     if ((ret = ff_reget_buffer(avctx, f->current_picture)) < 0)

  888.         return ret;

  889. 

  890.     if (frame_4cc == AV_RL32("ifr2")) {

  891.         f->current_picture->pict_type = AV_PICTURE_TYPE_I;

  892.         if ((ret = decode_i2_frame(f, f->current_picture, buf - 4, frame_size + 4)) < 0) {

  893.             av_log(f->avctx, AV_LOG_ERROR, "decode i2 frame failed\n");

  894.             return ret;

  895.         }

  896.     } else if (frame_4cc == AV_RL32("ifrm")) {

  897.         f->current_picture->pict_type = AV_PICTURE_TYPE_I;

  898.         if ((ret = decode_i_frame(f, f->current_picture, buf, frame_size)) < 0) {

  899.             av_log(f->avctx, AV_LOG_ERROR, "decode i frame failed\n");

  900.             return ret;

  901.         }

  902.     } else if (frame_4cc == AV_RL32("pfrm") || frame_4cc == AV_RL32("pfr2")) {

  903.         if (!f->last_picture->data[0]) {

  904.             if ((ret = ff_get_buffer(avctx, f->last_picture,

  905.                                      AV_GET_BUFFER_FLAG_REF)) < 0)

  906.                 return ret;

  907.             for (i=0; i<avctx->height; i++)

  908.                 memset(f->last_picture->data[0] + i*f->last_picture->linesize[0], 0, 2*avctx->width);

  909.         }

  910. 

  911.         f->current_picture->pict_type = AV_PICTURE_TYPE_P;

  912.         if ((ret = decode_p_frame(f, f->current_picture, buf, frame_size)) < 0) {

  913.             av_log(f->avctx, AV_LOG_ERROR, "decode p frame failed\n");

  914.             return ret;

  915.         }

  916.     } else if (frame_4cc == AV_RL32("snd_")) {

  917.         av_log(avctx, AV_LOG_ERROR, "ignoring snd_ chunk length:%d\n",

  918.                buf_size);

  919.     } else {

  920.         av_log(avctx, AV_LOG_ERROR, "ignoring unknown chunk length:%d\n",

  921.                buf_size);

  922.     }

  923. 

  924.     f->current_picture->key_frame = f->current_picture->pict_type == AV_PICTURE_TYPE_I;

  925. 

  926.     if ((ret = av_frame_ref(picture, f->current_picture)) < 0)

  927.         return ret;

  928.     *got_frame = 1;

  929. 

  930.     emms_c();

  931. 

  932.     return buf_size;

  933. }

  934. 

  935. static av_cold int decode_init(AVCodecContext *avctx)

  936. {

  937.     FourXContext * const f = avctx->priv_data;

  938. 

  939.     if (avctx->extradata_size != 4 || !avctx->extradata) {

  940.         av_log(avctx, AV_LOG_ERROR, "extradata wrong or missing\n");

  941.         return AVERROR_INVALIDDATA;

  942.     }

  943.     if((avctx->width % 16) || (avctx->height % 16)) {

  944.         av_log(avctx, AV_LOG_ERROR, "unsupported width/height\n");

  945.         return AVERROR_INVALIDDATA;

  946.     }

  947. 

  948.     f->version = AV_RL32(avctx->extradata) >> 16;

  949.     ff_dsputil_init(&f->dsp, avctx);

  950.     f->avctx = avctx;

  951.     init_vlcs(f);

  952. 

  953.     if (f->version > 2)

  954.         avctx->pix_fmt = AV_PIX_FMT_RGB565;

  955.     else

  956.         avctx->pix_fmt = AV_PIX_FMT_BGR555;

  957. 

  958.     f->current_picture = av_frame_alloc();

  959.     f->last_picture    = av_frame_alloc();

  960.     if (!f->current_picture  || !f->last_picture)

  961.         return AVERROR(ENOMEM);

  962. 

  963.     return 0;

  964. }

  965. 

  966. 

  967. static av_cold int decode_end(AVCodecContext *avctx)

  968. {

  969.     FourXContext * const f = avctx->priv_data;

  970.     int i;

  971. 

  972.     av_freep(&f->bitstream_buffer);

  973.     f->bitstream_buffer_size = 0;

  974.     for (i = 0; i < CFRAME_BUFFER_COUNT; i++) {

  975.         av_freep(&f->cfrm[i].data);

  976.         f->cfrm[i].allocated_size = 0;

  977.     }

  978.     ff_free_vlc(&f->pre_vlc);

  979.     av_frame_free(&f->current_picture);

  980.     av_frame_free(&f->last_picture);

  981. 

  982.     return 0;

  983. }

  984. 

  985. AVCodec ff_fourxm_decoder = {

  986.     .name           = "4xm",

  987.     .type           = AVMEDIA_TYPE_VIDEO,

  988.     .id             = AV_CODEC_ID_4XM,

  989.     .priv_data_size = sizeof(FourXContext),

  990.     .init           = decode_init,

  991.     .close          = decode_end,

  992.     .decode         = decode_frame,

  993.     .capabilities   = CODEC_CAP_DR1,

  994.     .long_name      = NULL_IF_CONFIG_SMALL("4X Movie"),

  995. };