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FFmpeg/libavcodec/xan.c

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  1. /*

  2.  * Wing Commander/Xan Video Decoder

  3.  * Copyright (C) 2003 the ffmpeg project

  4.  *

  5.  * This library is free software; you can redistribute it and/or

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

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

  8.  * version 2 of the License, or (at your option) any later version.

  9.  *

  10.  * This library is distributed in the hope that it will be useful,

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

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

  13.  * Lesser General Public License for more details.

  14.  *

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

  16.  * License along with this library; if not, write to the Free Software

  17.  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  18.  *

  19.  */

  20. 

  21. /**

  22.  * @file xan.c

  23.  * Xan video decoder for Wing Commander III & IV computer games

  24.  * by Mario Brito (mbrito@student.dei.uc.pt)

  25.  * and Mike Melanson (melanson@pcisys.net)

  26.  *

  27.  * The xan_wc3 decoder outputs the following colorspaces natively:

  28.  *   PAL8 (default), RGB555, RGB565, RGB24, BGR24, RGBA32, YUV444P

  29.  */

  30. 

  31. #include <stdio.h>

  32. #include <stdlib.h>

  33. #include <string.h>

  34. #include <unistd.h>

  35. 

  36. #include "common.h"

  37. #include "avcodec.h"

  38. #include "dsputil.h"

  39. 

  40. #define PALETTE_COUNT 256

  41. #define PALETTE_CONTROL_SIZE ((256 * 3) + 1)

  42. 

  43. typedef struct XanContext {

  44. 

  45.     AVCodecContext *avctx;

  46.     DSPContext dsp;

  47.     AVFrame last_frame;

  48.     AVFrame current_frame;

  49. 

  50.     unsigned char *buf;

  51.     int size;

  52. 

  53.     unsigned char palette[PALETTE_COUNT * 4];

  54. 

  55.     /* scratch space */

  56.     unsigned char *buffer1;

  57.     unsigned char *buffer2;

  58. 

  59. } XanContext;

  60. 

  61. /* RGB -> YUV conversion stuff */

  62. #define SCALEFACTOR 65536

  63. #define CENTERSAMPLE 128

  64. 

  65. #define COMPUTE_Y(r, g, b) \

  66.   (unsigned char) \

  67.   ((y_r_table[r] + y_g_table[g] + y_b_table[b]) / SCALEFACTOR)

  68. #define COMPUTE_U(r, g, b) \

  69.   (unsigned char) \

  70.   ((u_r_table[r] + u_g_table[g] + u_b_table[b]) / SCALEFACTOR + CENTERSAMPLE)

  71. #define COMPUTE_V(r, g, b) \

  72.   (unsigned char) \

  73.   ((v_r_table[r] + v_g_table[g] + v_b_table[b]) / SCALEFACTOR + CENTERSAMPLE)

  74. 

  75. #define Y_R (SCALEFACTOR *  0.29900)

  76. #define Y_G (SCALEFACTOR *  0.58700)

  77. #define Y_B (SCALEFACTOR *  0.11400)

  78. 

  79. #define U_R (SCALEFACTOR * -0.16874)

  80. #define U_G (SCALEFACTOR * -0.33126)

  81. #define U_B (SCALEFACTOR *  0.50000)

  82. 

  83. #define V_R (SCALEFACTOR *  0.50000)

  84. #define V_G (SCALEFACTOR * -0.41869)

  85. #define V_B (SCALEFACTOR * -0.08131)

  86. 

  87. /*

  88.  * Precalculate all of the YUV tables since it requires fewer than

  89.  * 10 kilobytes to store them.

  90.  */

  91. static int y_r_table[256];

  92. static int y_g_table[256];

  93. static int y_b_table[256];

  94. 

  95. static int u_r_table[256];

  96. static int u_g_table[256];

  97. static int u_b_table[256];

  98. 

  99. static int v_r_table[256];

  100. static int v_g_table[256];

  101. static int v_b_table[256];

  102. 

  103. static int xan_decode_init(AVCodecContext *avctx)

  104. {

  105.     XanContext *s = avctx->priv_data;

  106.     int i;

  107. 

  108.     s->avctx = avctx;

  109. 

  110.     if ((avctx->codec->id == CODEC_ID_XAN_WC3) && 

  111.         (s->avctx->palctrl == NULL)) {

  112.         av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");

  113.         return -1;

  114.     }

  115. 

  116.     avctx->pix_fmt = PIX_FMT_PAL8;

  117.     avctx->has_b_frames = 0;

  118.     dsputil_init(&s->dsp, avctx);

  119. 

  120.     /* initialize the RGB -> YUV tables */

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

  122.         y_r_table[i] = Y_R * i;

  123.         y_g_table[i] = Y_G * i;

  124.         y_b_table[i] = Y_B * i;

  125. 

  126.         u_r_table[i] = U_R * i;

  127.         u_g_table[i] = U_G * i;

  128.         u_b_table[i] = U_B * i;

  129. 

  130.         v_r_table[i] = V_R * i;

  131.         v_g_table[i] = V_G * i;

  132.         v_b_table[i] = V_B * i;

  133.     }

  134. 

  135.     s->buffer1 = av_malloc(avctx->width * avctx->height);

  136.     s->buffer2 = av_malloc(avctx->width * avctx->height);

  137.     if (!s->buffer1 || !s->buffer2)

  138.         return -1;

  139. 

  140.     return 0;

  141. }

  142. 

  143. /* This function is used in lieu of memcpy(). This decoder can not use 

  144.  * memcpy because the memory locations often overlap and

  145.  * memcpy doesn't like that; it's not uncommon, for example, for

  146.  * dest = src+1, to turn byte A into  pattern AAAAAAAA.

  147.  * This was originally repz movsb in Intel x86 ASM. */

  148. static inline void bytecopy(unsigned char *dest, unsigned char *src, int count)

  149. {

  150.     int i;

  151. 

  152.     for (i = 0; i < count; i++)

  153.         dest[i] = src[i];

  154. }

  155. 

  156. static int xan_huffman_decode(unsigned char *dest, unsigned char *src)

  157. {

  158.     unsigned char byte = *src++;

  159.     unsigned char ival = byte + 0x16;

  160.     unsigned char * ptr = src + byte*2;

  161.     unsigned char val = ival;

  162.     int counter = 0;

  163. 

  164.     unsigned char bits = *ptr++;

  165. 

  166.     while ( val != 0x16 ) {

  167.         if ( (1 << counter) & bits )

  168.             val = src[byte + val - 0x17];

  169.         else

  170.             val = src[val - 0x17];

  171. 

  172.         if ( val < 0x16 ) {

  173.             *dest++ = val;

  174.             val = ival;

  175.         }

  176. 

  177.         if (counter++ == 7) {

  178.             counter = 0;

  179.             bits = *ptr++;

  180.         }

  181.     }

  182. 

  183.     return 0;

  184. }

  185. 

  186. static void xan_unpack(unsigned char *dest, unsigned char *src)

  187. {

  188.     unsigned char opcode;

  189.     int size;

  190.     int offset;

  191.     int byte1, byte2, byte3;

  192. 

  193.     for (;;) {

  194.         opcode = *src++;

  195. 

  196.         if ( (opcode & 0x80) == 0 ) {

  197. 

  198.             offset = *src++;

  199. 

  200.             size = opcode & 3;

  201.             bytecopy(dest, src, size);  dest += size;  src += size;

  202. 

  203.             size = ((opcode & 0x1c) >> 2) + 3;

  204.             bytecopy (dest, dest - (((opcode & 0x60) << 3) + offset + 1), size);

  205.             dest += size;

  206. 

  207.         } else if ( (opcode & 0x40) == 0 ) {

  208. 

  209.             byte1 = *src++;

  210.             byte2 = *src++;

  211. 

  212.             size = byte1 >> 6;

  213.             bytecopy (dest, src, size);  dest += size;  src += size;

  214. 

  215.             size = (opcode & 0x3f) + 4;

  216.             bytecopy (dest, dest - (((byte1 & 0x3f) << 8) + byte2 + 1), size);

  217.             dest += size;

  218. 

  219.         } else if ( (opcode & 0x20) == 0 ) {

  220. 

  221.             byte1 = *src++;

  222.             byte2 = *src++;

  223.             byte3 = *src++;

  224. 

  225.             size = opcode & 3;

  226.             bytecopy (dest, src, size);  dest += size;  src += size;

  227. 

  228.             size = byte3 + 5 + ((opcode & 0xc) << 6);

  229.             bytecopy (dest,

  230.                 dest - ((((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2),

  231.                 size);

  232.             dest += size;

  233.         } else {

  234.             size = ((opcode & 0x1f) << 2) + 4;

  235. 

  236.             if (size > 0x70)

  237.                 break;

  238. 

  239.             bytecopy (dest, src, size);  dest += size;  src += size;

  240.         }

  241.     }

  242. 

  243.     size = opcode & 3;

  244.     bytecopy(dest, src, size);  dest += size;  src += size;

  245. }

  246. 

  247. static void inline xan_wc3_build_palette(XanContext *s, 

  248.     unsigned int *palette_data)

  249. {

  250.     int i;

  251.     unsigned char r, g, b;

  252.     unsigned short *palette16;

  253.     unsigned int *palette32;

  254.     unsigned int pal_elem;

  255. 

  256.     /* transform the palette passed through the palette control structure

  257.      * into the necessary internal format depending on colorspace */

  258. 

  259.     switch (s->avctx->pix_fmt) {

  260. 

  261.     case PIX_FMT_RGB555:

  262.         palette16 = (unsigned short *)s->palette;

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

  264.             pal_elem = palette_data[i];

  265.             r = (pal_elem >> 16) & 0xff;

  266.             g = (pal_elem >> 8) & 0xff;

  267.             b = pal_elem & 0xff;

  268.             palette16[i] = 

  269.                 ((r >> 3) << 10) |

  270.                 ((g >> 3) <<  5) |

  271.                 ((b >> 3) <<  0);

  272.         }

  273.         break;

  274. 

  275.     case PIX_FMT_RGB565:

  276.         palette16 = (unsigned short *)s->palette;

  277.         for (i = 0; i < PALETTE_COUNT; i++) {

  278.             pal_elem = palette_data[i];

  279.             r = (pal_elem >> 16) & 0xff;

  280.             g = (pal_elem >> 8) & 0xff;

  281.             b = pal_elem & 0xff;

  282.             palette16[i] = 

  283.                 ((r >> 3) << 11) |

  284.                 ((g >> 2) <<  5) |

  285.                 ((b >> 3) <<  0);

  286.         }

  287.         break;

  288. 

  289.     case PIX_FMT_RGB24:

  290.         for (i = 0; i < PALETTE_COUNT; i++) {

  291.             pal_elem = palette_data[i];

  292.             r = (pal_elem >> 16) & 0xff;

  293.             g = (pal_elem >> 8) & 0xff;

  294.             b = pal_elem & 0xff;

  295.             s->palette[i * 4 + 0] = r;

  296.             s->palette[i * 4 + 1] = g;

  297.             s->palette[i * 4 + 2] = b;

  298.         }

  299.         break;

  300. 

  301.     case PIX_FMT_BGR24:

  302.         for (i = 0; i < PALETTE_COUNT; i++) {

  303.             pal_elem = palette_data[i];

  304.             r = (pal_elem >> 16) & 0xff;

  305.             g = (pal_elem >> 8) & 0xff;

  306.             b = pal_elem & 0xff;

  307.             s->palette[i * 4 + 0] = b;

  308.             s->palette[i * 4 + 1] = g;

  309.             s->palette[i * 4 + 2] = r;

  310.         }

  311.         break;

  312. 

  313.     case PIX_FMT_PAL8:

  314.     case PIX_FMT_RGBA32:

  315.         palette32 = (unsigned int *)s->palette;

  316.         memcpy (palette32, palette_data, PALETTE_COUNT * sizeof(unsigned int));

  317.         break;

  318. 

  319.     case PIX_FMT_YUV444P:

  320.         for (i = 0; i < PALETTE_COUNT; i++) {

  321.             pal_elem = palette_data[i];

  322.             r = (pal_elem >> 16) & 0xff;

  323.             g = (pal_elem >> 8) & 0xff;

  324.             b = pal_elem & 0xff;

  325.             s->palette[i * 4 + 0] = COMPUTE_Y(r, g, b);

  326.             s->palette[i * 4 + 1] = COMPUTE_U(r, g, b);

  327.             s->palette[i * 4 + 2] = COMPUTE_V(r, g, b);

  328.         }

  329.         break;

  330. 

  331.     default:

  332.         av_log(s->avctx, AV_LOG_ERROR, " Xan WC3: Unhandled colorspace\n");

  333.         break;

  334.     }

  335. }

  336. 

  337. /* advance current_x variable; reset accounting variables if current_x

  338.  * moves beyond width */

  339. #define ADVANCE_CURRENT_X() \

  340.     current_x++; \

  341.     if (current_x >= width) { \

  342.         index += line_inc; \

  343.         current_x = 0; \

  344.     }

  345. 

  346. static void inline xan_wc3_output_pixel_run(XanContext *s, 

  347.     unsigned char *pixel_buffer, int x, int y, int pixel_count)

  348. {

  349.     int stride;

  350.     int line_inc;

  351.     int index;

  352.     int current_x;

  353.     int width = s->avctx->width;

  354.     unsigned char pix;

  355.     unsigned char *palette_plane;

  356.     unsigned char *y_plane;

  357.     unsigned char *u_plane;

  358.     unsigned char *v_plane;

  359.     unsigned char *rgb_plane;

  360.     unsigned short *rgb16_plane;

  361.     unsigned short *palette16;

  362.     unsigned int *rgb32_plane;

  363.     unsigned int *palette32;

  364. 

  365.     switch (s->avctx->pix_fmt) {

  366. 

  367.     case PIX_FMT_PAL8:

  368.         palette_plane = s->current_frame.data[0];

  369.         stride = s->current_frame.linesize[0];

  370.         line_inc = stride - width;

  371.         index = y * stride + x;

  372.         current_x = x;

  373.         while(pixel_count--) {

  374. 

  375.             /* don't do a memcpy() here; keyframes generally copy an entire

  376.              * frame of data and the stride needs to be accounted for */

  377.             palette_plane[index++] = *pixel_buffer++;

  378. 

  379.             ADVANCE_CURRENT_X();

  380.         }

  381.         break;

  382. 

  383.     case PIX_FMT_RGB555:

  384.     case PIX_FMT_RGB565:

  385.         rgb16_plane = (unsigned short *)s->current_frame.data[0];

  386.         palette16 = (unsigned short *)s->palette;

  387.         stride = s->current_frame.linesize[0] / 2;

  388.         line_inc = stride - width;

  389.         index = y * stride + x;

  390.         current_x = x;

  391.         while(pixel_count--) {

  392. 

  393.             rgb16_plane[index++] = palette16[*pixel_buffer++];

  394. 

  395.             ADVANCE_CURRENT_X();

  396.         }

  397.         break;

  398. 

  399.     case PIX_FMT_RGB24:

  400.     case PIX_FMT_BGR24:

  401.         rgb_plane = s->current_frame.data[0];

  402.         stride = s->current_frame.linesize[0];

  403.         line_inc = stride - width * 3;

  404.         index = y * stride + x * 3;

  405.         current_x = x;

  406.         while(pixel_count--) {

  407.             pix = *pixel_buffer++;

  408. 

  409.             rgb_plane[index++] = s->palette[pix * 4 + 0];

  410.             rgb_plane[index++] = s->palette[pix * 4 + 1];

  411.             rgb_plane[index++] = s->palette[pix * 4 + 2];

  412. 

  413.             ADVANCE_CURRENT_X();

  414.         }

  415.         break;

  416. 

  417.     case PIX_FMT_RGBA32:

  418.         rgb32_plane = (unsigned int *)s->current_frame.data[0];

  419.         palette32 = (unsigned int *)s->palette;

  420.         stride = s->current_frame.linesize[0] / 4;

  421.         line_inc = stride - width;

  422.         index = y * stride + x;

  423.         current_x = x;

  424.         while(pixel_count--) {

  425. 

  426.             rgb32_plane[index++] = palette32[*pixel_buffer++];

  427. 

  428.             ADVANCE_CURRENT_X();

  429.         }

  430.         break;

  431. 

  432.     case PIX_FMT_YUV444P:

  433.         y_plane = s->current_frame.data[0];

  434.         u_plane = s->current_frame.data[1];

  435.         v_plane = s->current_frame.data[2];

  436.         stride = s->current_frame.linesize[0];

  437.         line_inc = stride - width;

  438.         index = y * stride + x;

  439.         current_x = x;

  440.         while(pixel_count--) {

  441.             pix = *pixel_buffer++;

  442. 

  443.             y_plane[index] = s->palette[pix * 4 + 0];

  444.             u_plane[index] = s->palette[pix * 4 + 1];

  445.             v_plane[index] = s->palette[pix * 4 + 2];

  446. 

  447.             index++;

  448.             ADVANCE_CURRENT_X();

  449.         }

  450.         break;

  451. 

  452.     default:

  453.         av_log(s->avctx, AV_LOG_ERROR, " Xan WC3: Unhandled colorspace\n");

  454.         break;

  455.     }

  456. }

  457. 

  458. #define ADVANCE_CURFRAME_X() \

  459.     curframe_x++; \

  460.     if (curframe_x >= width) { \

  461.         curframe_index += line_inc; \

  462.         curframe_x = 0; \

  463.     }

  464. 

  465. #define ADVANCE_PREVFRAME_X() \

  466.     prevframe_x++; \

  467.     if (prevframe_x >= width) { \

  468.         prevframe_index += line_inc; \

  469.         prevframe_x = 0; \

  470.     }

  471. 

  472. static void inline xan_wc3_copy_pixel_run(XanContext *s, 

  473.     int x, int y, int pixel_count, int motion_x, int motion_y)

  474. {

  475.     int stride;

  476.     int line_inc;

  477.     int curframe_index, prevframe_index;

  478.     int curframe_x, prevframe_x;

  479.     int width = s->avctx->width;

  480.     unsigned char *palette_plane, *prev_palette_plane;

  481.     unsigned char *y_plane, *u_plane, *v_plane;

  482.     unsigned char *prev_y_plane, *prev_u_plane, *prev_v_plane;

  483.     unsigned char *rgb_plane, *prev_rgb_plane;

  484.     unsigned short *rgb16_plane, *prev_rgb16_plane;

  485.     unsigned int *rgb32_plane, *prev_rgb32_plane;

  486. 

  487.     switch (s->avctx->pix_fmt) {

  488. 

  489.     case PIX_FMT_PAL8:

  490.         palette_plane = s->current_frame.data[0];

  491.         prev_palette_plane = s->last_frame.data[0];

  492.         stride = s->current_frame.linesize[0];

  493.         line_inc = stride - width;

  494.         curframe_index = y * stride + x;

  495.         curframe_x = x;

  496.         prevframe_index = (y + motion_y) * stride + x + motion_x;

  497.         prevframe_x = x + motion_x;

  498.         while(pixel_count--) {

  499. 

  500.             palette_plane[curframe_index++] = 

  501.                 prev_palette_plane[prevframe_index++];

  502. 

  503.             ADVANCE_CURFRAME_X();

  504.             ADVANCE_PREVFRAME_X();

  505.         }

  506.         break;

  507. 

  508.     case PIX_FMT_RGB555:

  509.     case PIX_FMT_RGB565:

  510.         rgb16_plane = (unsigned short *)s->current_frame.data[0];

  511.         prev_rgb16_plane = (unsigned short *)s->last_frame.data[0];

  512.         stride = s->current_frame.linesize[0] / 2;

  513.         line_inc = stride - width;

  514.         curframe_index = y * stride + x;

  515.         curframe_x = x;

  516.         prevframe_index = (y + motion_y) * stride + x + motion_x;

  517.         prevframe_x = x + motion_x;

  518.         while(pixel_count--) {

  519. 

  520.             rgb16_plane[curframe_index++] = 

  521.                 prev_rgb16_plane[prevframe_index++];

  522. 

  523.             ADVANCE_CURFRAME_X();

  524.             ADVANCE_PREVFRAME_X();

  525.         }

  526.         break;

  527. 

  528.     case PIX_FMT_RGB24:

  529.     case PIX_FMT_BGR24:

  530.         rgb_plane = s->current_frame.data[0];

  531.         prev_rgb_plane = s->last_frame.data[0];

  532.         stride = s->current_frame.linesize[0];

  533.         line_inc = stride - width * 3;

  534.         curframe_index = y * stride + x * 3;

  535.         curframe_x = x;

  536.         prevframe_index = (y + motion_y) * stride + 

  537.             (3 * (x + motion_x));

  538.         prevframe_x = x + motion_x;

  539.         while(pixel_count--) {

  540. 

  541.             rgb_plane[curframe_index++] = prev_rgb_plane[prevframe_index++];

  542.             rgb_plane[curframe_index++] = prev_rgb_plane[prevframe_index++];

  543.             rgb_plane[curframe_index++] = prev_rgb_plane[prevframe_index++];

  544. 

  545.             ADVANCE_CURFRAME_X();

  546.             ADVANCE_PREVFRAME_X();

  547.         }

  548.         break;

  549. 

  550.     case PIX_FMT_RGBA32:

  551.         rgb32_plane = (unsigned int *)s->current_frame.data[0];

  552.         prev_rgb32_plane = (unsigned int *)s->last_frame.data[0];

  553.         stride = s->current_frame.linesize[0] / 4;

  554.         line_inc = stride - width;

  555.         curframe_index = y * stride + x;

  556.         curframe_x = x;

  557.         prevframe_index = (y + motion_y) * stride + x + motion_x;

  558.         prevframe_x = x + motion_x;

  559.         while(pixel_count--) {

  560. 

  561.             rgb32_plane[curframe_index++] = 

  562.                 prev_rgb32_plane[prevframe_index++];

  563. 

  564.             ADVANCE_CURFRAME_X();

  565.             ADVANCE_PREVFRAME_X();

  566.         }

  567.         break;

  568. 

  569.     case PIX_FMT_YUV444P:

  570.         y_plane = s->current_frame.data[0];

  571.         u_plane = s->current_frame.data[1];

  572.         v_plane = s->current_frame.data[2];

  573.         prev_y_plane = s->last_frame.data[0];

  574.         prev_u_plane = s->last_frame.data[1];

  575.         prev_v_plane = s->last_frame.data[2];

  576.         stride = s->current_frame.linesize[0];

  577.         line_inc = stride - width;

  578.         curframe_index = y * stride + x;

  579.         curframe_x = x;

  580.         prevframe_index = (y + motion_y) * stride + x + motion_x;

  581.         prevframe_x = x + motion_x;

  582.         while(pixel_count--) {

  583. 

  584.             y_plane[curframe_index] = prev_y_plane[prevframe_index];

  585.             u_plane[curframe_index] = prev_u_plane[prevframe_index];

  586.             v_plane[curframe_index] = prev_v_plane[prevframe_index];

  587. 

  588.             curframe_index++;

  589.             ADVANCE_CURFRAME_X();

  590.             prevframe_index++;

  591.             ADVANCE_PREVFRAME_X();

  592.         }

  593.         break;

  594. 

  595.     default:

  596.         av_log(s->avctx, AV_LOG_ERROR, " Xan WC3: Unhandled colorspace\n");

  597.         break;

  598.     }

  599. }

  600. 

  601. static void xan_wc3_decode_frame(XanContext *s) {

  602. 

  603.     int width = s->avctx->width;

  604.     int height = s->avctx->height;

  605.     int total_pixels = width * height;

  606.     unsigned char opcode;

  607.     unsigned char flag = 0;

  608.     int size = 0;

  609.     int motion_x, motion_y;

  610.     int x, y;

  611. 

  612.     unsigned char *opcode_buffer = s->buffer1;

  613.     unsigned char *imagedata_buffer = s->buffer2;

  614. 

  615.     /* pointers to segments inside the compressed chunk */

  616.     unsigned char *huffman_segment;

  617.     unsigned char *size_segment;

  618.     unsigned char *vector_segment;

  619.     unsigned char *imagedata_segment;

  620. 

  621.     huffman_segment =   s->buf + LE_16(&s->buf[0]);

  622.     size_segment =      s->buf + LE_16(&s->buf[2]);

  623.     vector_segment =    s->buf + LE_16(&s->buf[4]);

  624.     imagedata_segment = s->buf + LE_16(&s->buf[6]);

  625. 

  626.     xan_huffman_decode(opcode_buffer, huffman_segment);

  627. 

  628.     if (imagedata_segment[0] == 2)

  629.         xan_unpack(imagedata_buffer, &imagedata_segment[1]);

  630.     else

  631.         imagedata_buffer = &imagedata_segment[1];

  632. 

  633.     /* use the decoded data segments to build the frame */

  634.     x = y = 0;

  635.     while (total_pixels) {

  636. 

  637.         opcode = *opcode_buffer++;

  638.         size = 0;

  639. 

  640.         switch (opcode) {

  641. 

  642.         case 0:

  643.             flag ^= 1;

  644.             continue;

  645. 

  646.         case 1:

  647.         case 2:

  648.         case 3:

  649.         case 4:

  650.         case 5:

  651.         case 6:

  652.         case 7:

  653.         case 8:

  654.             size = opcode;

  655.             break;

  656. 

  657.         case 12:

  658.         case 13:

  659.         case 14:

  660.         case 15:

  661.         case 16:

  662.         case 17:

  663.         case 18:

  664.             size += (opcode - 10);

  665.             break;

  666. 

  667.         case 9:

  668.         case 19:

  669.             size = *size_segment++;

  670.             break;

  671. 

  672.         case 10:

  673.         case 20:

  674.             size = BE_16(&size_segment[0]);

  675.             size_segment += 2;

  676.             break;

  677. 

  678.         case 11:

  679.         case 21:

  680.             size = (size_segment[0] << 16) | (size_segment[1] << 8) |

  681.                 size_segment[2];

  682.             size_segment += 3;

  683.             break;

  684.         }

  685. 

  686.         if (opcode < 12) {

  687.             flag ^= 1;

  688.             if (flag) {

  689.                 /* run of (size) pixels is unchanged from last frame */

  690.                 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);

  691.             } else {

  692.                 /* output a run of pixels from imagedata_buffer */

  693.                 xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);

  694.                 imagedata_buffer += size;

  695.             }

  696.         } else {

  697.             /* run-based motion compensation from last frame */

  698.             motion_x = (*vector_segment >> 4) & 0xF;

  699.             motion_y = *vector_segment & 0xF;

  700.             vector_segment++;

  701. 

  702.             /* sign extension */

  703.             if (motion_x & 0x8)

  704.                 motion_x |= 0xFFFFFFF0;

  705.             if (motion_y & 0x8)

  706.                 motion_y |= 0xFFFFFFF0;

  707. 

  708.             /* copy a run of pixels from the previous frame */

  709.             xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);

  710. 

  711.             flag = 0;

  712.         }

  713. 

  714.         /* coordinate accounting */

  715.         total_pixels -= size;

  716.         while (size) {

  717.             if (x + size >= width) {

  718.                 y++;

  719.                 size -= (width - x);

  720.                 x = 0;

  721.             } else {

  722.                 x += size;

  723.                 size = 0;

  724.             }

  725.         }

  726.     }

  727. 

  728.     /* for PAL8, make the palette available on the way out */

  729.     if (s->avctx->pix_fmt == PIX_FMT_PAL8) {

  730.         memcpy(s->current_frame.data[1], s->palette, PALETTE_COUNT * 4);

  731.         s->current_frame.palette_has_changed = 1;

  732.         s->avctx->palctrl->palette_changed = 0;

  733.     }

  734. }

  735. 

  736. static void xan_wc4_decode_frame(XanContext *s) {

  737. }

  738. 

  739. static int xan_decode_frame(AVCodecContext *avctx,

  740.                             void *data, int *data_size,

  741.                             uint8_t *buf, int buf_size)

  742. {

  743.     XanContext *s = avctx->priv_data;

  744.     AVPaletteControl *palette_control = avctx->palctrl;

  745.     int keyframe = 0;

  746. 

  747.     if (palette_control->palette_changed) {

  748.         /* load the new palette and reset the palette control */

  749.         xan_wc3_build_palette(s, palette_control->palette);

  750.         /* If pal8 we clear flag when we copy palette */

  751.         if (s->avctx->pix_fmt != PIX_FMT_PAL8)

  752.             palette_control->palette_changed = 0;

  753.         keyframe = 1;

  754.     }

  755. 

  756.     if (avctx->get_buffer(avctx, &s->current_frame)) {

  757.         av_log(s->avctx, AV_LOG_ERROR, "  Xan Video: get_buffer() failed\n");

  758.         return -1;

  759.     }

  760.     s->current_frame.reference = 3;

  761. 

  762.     s->buf = buf;

  763.     s->size = buf_size;

  764. 

  765.     if (avctx->codec->id == CODEC_ID_XAN_WC3)

  766.         xan_wc3_decode_frame(s);

  767.     else if (avctx->codec->id == CODEC_ID_XAN_WC4)

  768.         xan_wc4_decode_frame(s);

  769. 

  770.     /* release the last frame if it is allocated */

  771.     if (s->last_frame.data[0])

  772.         avctx->release_buffer(avctx, &s->last_frame);

  773. 

  774.     /* shuffle frames */

  775.     s->last_frame = s->current_frame;

  776. 

  777.     *data_size = sizeof(AVFrame);

  778.     *(AVFrame*)data = s->current_frame;

  779. 

  780.     /* always report that the buffer was completely consumed */

  781.     return buf_size;

  782. }

  783. 

  784. static int xan_decode_end(AVCodecContext *avctx)

  785. {

  786.     XanContext *s = avctx->priv_data;

  787. 

  788.     /* release the last frame */

  789.     avctx->release_buffer(avctx, &s->last_frame);

  790. 

  791.     av_free(s->buffer1);

  792.     av_free(s->buffer2);

  793. 

  794.     return 0;

  795. }

  796. 

  797. AVCodec xan_wc3_decoder = {

  798.     "xan_wc3",

  799.     CODEC_TYPE_VIDEO,

  800.     CODEC_ID_XAN_WC3,

  801.     sizeof(XanContext),

  802.     xan_decode_init,

  803.     NULL,

  804.     xan_decode_end,

  805.     xan_decode_frame,

  806.     CODEC_CAP_DR1,

  807. };

  808. 

  809. /*

  810. AVCodec xan_wc4_decoder = {

  811.     "xan_wc4",

  812.     CODEC_TYPE_VIDEO,

  813.     CODEC_ID_XAN_WC4,

  814.     sizeof(XanContext),

  815.     xan_decode_init,

  816.     NULL,

  817.     xan_decode_end,

  818.     xan_decode_frame,

  819.     CODEC_CAP_DR1,

  820. };

  821. */