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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 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.  * @file 4xm.c

  22.  * 4XM codec.

  23.  */

  24.  

  25. #include "avcodec.h"

  26. #include "dsputil.h"

  27. #include "mpegvideo.h"

  28. 

  29. //#undef NDEBUG

  30. //#include <assert.h>

  31. 

  32. #define BLOCK_TYPE_VLC_BITS 5

  33. #define ACDC_VLC_BITS 9

  34. 

  35. #define CFRAME_BUFFER_COUNT 100

  36. 

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

  38.   {   //{8,4,2}x{8,4,2}

  39.     { 0,1}, { 2,2}, { 6,3}, {14,4}, {30,5}, {31,5}, { 0,0}

  40.   },{ //{8,4}x1

  41.     { 0,1}, { 0,0}, { 2,2}, { 6,3}, {14,4}, {15,4}, { 0,0}

  42.   },{ //1x{8,4}

  43.     { 0,1}, { 2,2}, { 0,0}, { 6,3}, {14,4}, {15,4}, { 0,0}

  44.   },{ //1x2, 2x1

  45.     { 0,1}, { 0,0}, { 0,0}, { 2,2}, { 6,3}, {14,4}, {15,4}

  46.   }

  47. };

  48. 

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

  50.   {-1, 3, 1, 1},

  51.   { 3, 0, 0, 0},

  52.   { 2, 0, 0, 0},

  53.   { 2, 0, 0, 0},

  54. };

  55. 

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

  57. {  0,  0},{  0, -1},{ -1,  0},{  1,  0},{  0,  1},{ -1, -1},{  1, -1},{ -1,  1},

  58. {  1,  1},{  0, -2},{ -2,  0},{  2,  0},{  0,  2},{ -1, -2},{  1, -2},{ -2, -1},

  59. {  2, -1},{ -2,  1},{  2,  1},{ -1,  2},{  1,  2},{ -2, -2},{  2, -2},{ -2,  2},

  60. {  2,  2},{  0, -3},{ -3,  0},{  3,  0},{  0,  3},{ -1, -3},{  1, -3},{ -3, -1},

  61. {  3, -1},{ -3,  1},{  3,  1},{ -1,  3},{  1,  3},{ -2, -3},{  2, -3},{ -3, -2},

  62. {  3, -2},{ -3,  2},{  3,  2},{ -2,  3},{  2,  3},{  0, -4},{ -4,  0},{  4,  0},

  63. {  0,  4},{ -1, -4},{  1, -4},{ -4, -1},{  4, -1},{  4,  1},{ -1,  4},{  1,  4},

  64. { -3, -3},{ -3,  3},{  3,  3},{ -2, -4},{ -4, -2},{  4, -2},{ -4,  2},{ -2,  4},

  65. {  2,  4},{ -3, -4},{  3, -4},{  4, -3},{ -5,  0},{ -4,  3},{ -3,  4},{  3,  4},

  66. { -1, -5},{ -5, -1},{ -5,  1},{ -1,  5},{ -2, -5},{  2, -5},{  5, -2},{  5,  2},

  67. { -4, -4},{ -4,  4},{ -3, -5},{ -5, -3},{ -5,  3},{  3,  5},{ -6,  0},{  0,  6},

  68. { -6, -1},{ -6,  1},{  1,  6},{  2, -6},{ -6,  2},{  2,  6},{ -5, -4},{  5,  4},

  69. {  4,  5},{ -6, -3},{  6,  3},{ -7,  0},{ -1, -7},{  5, -5},{ -7,  1},{ -1,  7},

  70. {  4, -6},{  6,  4},{ -2, -7},{ -7,  2},{ -3, -7},{  7, -3},{  3,  7},{  6, -5},

  71. {  0, -8},{ -1, -8},{ -7, -4},{ -8,  1},{  4,  7},{  2, -8},{ -2,  8},{  6,  6},

  72. { -8,  3},{  5, -7},{ -5,  7},{  8, -4},{  0, -9},{ -9, -1},{  1,  9},{  7, -6},

  73. { -7,  6},{ -5, -8},{ -5,  8},{ -9,  3},{  9, -4},{  7, -7},{  8, -6},{  6,  8},

  74. { 10,  1},{-10,  2},{  9, -5},{ 10, -3},{ -8, -7},{-10, -4},{  6, -9},{-11,  0},

  75. { 11,  1},{-11, -2},{ -2, 11},{  7, -9},{ -7,  9},{ 10,  6},{ -4, 11},{  8, -9},

  76. {  8,  9},{  5, 11},{  7,-10},{ 12, -3},{ 11,  6},{ -9, -9},{  8, 10},{  5, 12},

  77. {-11,  7},{ 13,  2},{  6,-12},{ 10,  9},{-11,  8},{ -7, 12},{  0, 14},{ 14, -2},

  78. { -9, 11},{ -6, 13},{-14, -4},{ -5,-14},{  5, 14},{-15, -1},{-14, -6},{  3,-15},

  79. { 11,-11},{ -7, 14},{ -5, 15},{  8,-14},{ 15,  6},{  3, 16},{  7,-15},{-16,  5},

  80. {  0, 17},{-16, -6},{-10, 14},{-16,  7},{ 12, 13},{-16,  8},{-17,  6},{-18,  3},

  81. { -7, 17},{ 15, 11},{ 16, 10},{  2,-19},{  3,-19},{-11,-16},{-18,  8},{-19, -6},

  82. {  2,-20},{-17,-11},{-10,-18},{  8, 19},{-21, -1},{-20,  7},{ -4, 21},{ 21,  5},

  83. { 15, 16},{  2,-22},{-10,-20},{-22,  5},{ 20,-11},{ -7,-22},{-12, 20},{ 23, -5},

  84. { 13,-20},{ 24, -2},{-15, 19},{-11, 22},{ 16, 19},{ 23,-10},{-18,-18},{ -9,-24},

  85. { 24,-10},{ -3, 26},{-23, 13},{-18,-20},{ 17, 21},{ -4, 27},{ 27,  6},{  1,-28},

  86. {-11, 26},{-17,-23},{  7, 28},{ 11,-27},{ 29,  5},{-23,-19},{-28,-11},{-21, 22},

  87. {-30,  7},{-17, 26},{-27, 16},{ 13, 29},{ 19,-26},{ 10,-31},{-14,-30},{ 20,-27},

  88. {-29, 18},{-16,-31},{-28,-22},{ 21,-30},{-25, 28},{ 26,-29},{ 25,-32},{-32,-32}

  89. };

  90. 

  91. // this is simply the scaled down elementwise product of the standard jpeg quantizer table and the AAN premul table

  92. static const uint8_t dequant_table[64]={

  93.  16, 15, 13, 19, 24, 31, 28, 17,

  94.  17, 23, 25, 31, 36, 63, 45, 21,

  95.  18, 24, 27, 37, 52, 59, 49, 20,

  96.  16, 28, 34, 40, 60, 80, 51, 20,

  97.  18, 31, 48, 66, 68, 86, 56, 21,

  98.  19, 38, 56, 59, 64, 64, 48, 20,

  99.  27, 48, 55, 55, 56, 51, 35, 15,

  100.  20, 35, 34, 32, 31, 22, 15,  8,

  101. };

  102. 

  103. static VLC block_type_vlc[4];

  104. 

  105. 

  106. typedef struct CFrameBuffer{

  107.     int allocated_size;

  108.     int size;

  109.     int id;

  110.     uint8_t *data;

  111. }CFrameBuffer;

  112. 

  113. typedef struct FourXContext{

  114.     AVCodecContext *avctx;

  115.     DSPContext dsp;

  116.     AVFrame current_picture, last_picture;

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

  118.     GetBitContext gb;

  119.     uint8_t *bytestream;

  120.     uint16_t *wordstream;

  121.     int mv[256];

  122.     VLC pre_vlc;

  123.     int last_dc;

  124.     DCTELEM __align8 block[6][64];

  125.     uint8_t *bitstream_buffer;

  126.     int bitstream_buffer_size;

  127.     CFrameBuffer cfrm[CFRAME_BUFFER_COUNT];

  128. } FourXContext;

  129. 

  130. 

  131. #define FIX_1_082392200  70936

  132. #define FIX_1_414213562  92682

  133. #define FIX_1_847759065 121095

  134. #define FIX_2_613125930 171254

  135. 

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

  137. 

  138. static void idct(DCTELEM block[64]){

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

  140.     int tmp10, tmp11, tmp12, tmp13;

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

  142.     int i;

  143.     int temp[64];

  144.     

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

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

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

  148. 

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

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

  151. 

  152.         tmp0 = tmp10 + tmp13;

  153.         tmp3 = tmp10 - tmp13;

  154.         tmp1 = tmp11 + tmp12;

  155.         tmp2 = tmp11 - tmp12;

  156.         

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

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

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

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

  161. 

  162.         tmp7  =          z11 + z13;

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

  164. 

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

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

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

  168. 

  169.         tmp6 = tmp12 - tmp7;

  170.         tmp5 = tmp11 - tmp6;

  171.         tmp4 = tmp10 + tmp5;

  172. 

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

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

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

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

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

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

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

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

  181.     }

  182.   

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

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

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

  186. 

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

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

  189. 

  190.         tmp0 = tmp10 + tmp13;

  191.         tmp3 = tmp10 - tmp13;

  192.         tmp1 = tmp11 + tmp12;

  193.         tmp2 = tmp11 - tmp12;

  194. 

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

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

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

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

  199. 

  200.         tmp7 = z11 + z13;

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

  202. 

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

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

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

  206. 

  207.         tmp6 = tmp12 - tmp7;

  208.         tmp5 = tmp11 - tmp6;

  209.         tmp4 = tmp10 + tmp5;

  210. 

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

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

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

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

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

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

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

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

  219.     }

  220. }

  221. 

  222. static void init_vlcs(FourXContext *f){

  223.     static int done = 0;

  224.     int i;

  225. 

  226.     if (!done) {

  227.         done = 1;

  228. 

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

  230.             init_vlc(&block_type_vlc[i], BLOCK_TYPE_VLC_BITS, 7, 

  231.                      &block_type_tab[i][0][1], 2, 1,

  232.                      &block_type_tab[i][0][0], 2, 1);

  233.         }

  234.     }

  235. }

  236. 

  237. static void init_mv(FourXContext *f){

  238.     int i;

  239. 

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

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

  242.     }

  243. }

  244. 

  245. static inline void mcdc(uint16_t *dst, uint16_t *src, int log2w, int h, int stride, int scale, int dc){

  246.    int i;

  247.    dc*= 0x10001;

  248. 

  249.    switch(log2w){

  250.    case 0:

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

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

  253.             if(scale) src += stride;

  254.             dst += stride;

  255.         }

  256.         break;

  257.     case 1:

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

  259.             ((uint32_t*)dst)[0] = scale*((uint32_t*)src)[0] + dc;

  260.             if(scale) src += stride;

  261.             dst += stride;

  262.         }

  263.         break;

  264.     case 2:

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

  266.             ((uint32_t*)dst)[0] = scale*((uint32_t*)src)[0] + dc;

  267.             ((uint32_t*)dst)[1] = scale*((uint32_t*)src)[1] + dc;

  268.             if(scale) src += stride;

  269.             dst += stride;

  270.         }

  271.         break;

  272.     case 3:

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

  274.             ((uint32_t*)dst)[0] = scale*((uint32_t*)src)[0] + dc;

  275.             ((uint32_t*)dst)[1] = scale*((uint32_t*)src)[1] + dc;

  276.             ((uint32_t*)dst)[2] = scale*((uint32_t*)src)[2] + dc;

  277.             ((uint32_t*)dst)[3] = scale*((uint32_t*)src)[3] + dc;

  278.             if(scale) src += stride;

  279.             dst += stride;

  280.         }

  281.         break;

  282.     default: assert(0);

  283.     }

  284. }

  285. 

  286. static void decode_p_block(FourXContext *f, uint16_t *dst, uint16_t *src, int log2w, int log2h, int stride){

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

  288.     const int h= 1<<log2h;

  289.     int code= get_vlc2(&f->gb, block_type_vlc[index].table, BLOCK_TYPE_VLC_BITS, 1);

  290.     

  291.     assert(code>=0 && code<=6);

  292. 

  293.     if(code == 0){

  294.         src += f->mv[ *f->bytestream++ ];

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

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

  297.         log2h--;

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

  299.         decode_p_block(f, dst + (stride<<log2h), src + (stride<<log2h), log2w, log2h, stride);

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

  301.         log2w--;

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

  303.         decode_p_block(f, dst + (1<<log2w), src + (1<<log2w), log2w, log2h, stride);

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

  305.         src += f->mv[ *f->bytestream++ ];

  306.         mcdc(dst, src, log2w, h, stride, 1, le2me_16(*f->wordstream++));

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

  308.         mcdc(dst, src, log2w, h, stride, 0, le2me_16(*f->wordstream++));

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

  310.         if(log2w){

  311.             dst[0] = le2me_16(*f->wordstream++);

  312.             dst[1] = le2me_16(*f->wordstream++);

  313.         }else{

  314.             dst[0     ] = le2me_16(*f->wordstream++);

  315.             dst[stride] = le2me_16(*f->wordstream++);

  316.         }

  317.     }

  318. }

  319. 

  320. static int get32(void *p){

  321.     return le2me_32(*(uint32_t*)p);

  322. }

  323. 

  324. static int decode_p_frame(FourXContext *f, uint8_t *buf, int length){

  325.     int x, y;

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

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

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

  329.     uint16_t *dst= (uint16_t*)f->current_picture.data[0];

  330.     const int stride= f->current_picture.linesize[0]>>1;

  331.     const int bitstream_size= get32(buf+8);

  332.     const int bytestream_size= get32(buf+16);

  333.     const int wordstream_size= get32(buf+12);

  334.     

  335.     if(bitstream_size+ bytestream_size+ wordstream_size + 20 != length)

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

  337.         bitstream_size+ bytestream_size+ wordstream_size - length);

  338.     

  339.     f->bitstream_buffer= av_fast_realloc(f->bitstream_buffer, &f->bitstream_buffer_size, bitstream_size + FF_INPUT_BUFFER_PADDING_SIZE);

  340.     f->dsp.bswap_buf((uint32_t*)f->bitstream_buffer, (uint32_t*)(buf + 20), bitstream_size/4);

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

  342. 

  343.     f->wordstream= (uint16_t*)(buf + 20 + bitstream_size);

  344.     f->bytestream= buf + 20 + bitstream_size + wordstream_size;

  345.     

  346.     init_mv(f);

  347.     

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

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

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

  351.         }

  352.         src += 8*stride; 

  353.         dst += 8*stride; 

  354.     }

  355.     

  356.     if(bitstream_size != (get_bits_count(&f->gb)+31)/32*4)

  357.         av_log(f->avctx, AV_LOG_ERROR, " %d %d %d bytes left\n", 

  358.             bitstream_size - (get_bits_count(&f->gb)+31)/32*4, 

  359.             bytestream_size - (f->bytestream - (buf + 20 + bitstream_size + wordstream_size)),

  360.             wordstream_size - (((uint8_t*)f->wordstream) - (buf + 20 + bitstream_size))

  361.         );

  362.     

  363.     return 0;

  364. }

  365. 

  366. /**

  367.  * decode block and dequantize.

  368.  * Note this is allmost identical to mjpeg

  369.  */

  370. static int decode_i_block(FourXContext *f, DCTELEM *block){

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

  372. 

  373.     /* DC coef */

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

  375.     if (val>>4){

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

  377.     }

  378. 

  379.     if(val)

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

  381. 

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

  383.     f->last_dc =

  384.     block[0] = val;

  385.     /* AC coefs */

  386.     i = 1;

  387.     for(;;) {

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

  389.         

  390.         /* EOB */

  391.         if (code == 0)

  392.             break;

  393.         if (code == 0xf0) {

  394.             i += 16;

  395.         } else {

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

  397.             i += code >> 4;

  398.             if (i >= 64) {

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

  400.                 return 0;

  401.             }

  402. 

  403.             j= ff_zigzag_direct[i];

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

  405.             i++;

  406.             if (i >= 64)

  407.                 break;

  408.         }

  409.     }

  410. 

  411.     return 0;

  412. }

  413. 

  414. static inline void idct_put(FourXContext *f, int x, int y){

  415.     DCTELEM (*block)[64]= f->block;

  416.     int stride= f->current_picture.linesize[0]>>1;

  417.     int i;

  418.     uint16_t *dst = ((uint16_t*)f->current_picture.data[0]) + y * stride + x;

  419.     

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

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

  422.         idct(block[i]);

  423.     }

  424. 

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

  426.         for(i=4; i<6; i++) idct(block[i]);

  427.     }

  428. 

  429. /* Note transform is:

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

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

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

  433. */ 

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

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

  436.             DCTELEM *temp= block[(x>>2) + 2*(y>>2)] + 2*(x&3) + 2*8*(y&3); //FIXME optimize

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

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

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

  440.             int y;

  441.             

  442.             cb+=cb;

  443.             

  444.             y = temp[0];

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

  446.             y = temp[1];

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

  448.             y = temp[8];

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

  450.             y = temp[9];

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

  452.             dst += 2;

  453.         }

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

  455.     }

  456. }

  457. 

  458. static int decode_i_mb(FourXContext *f){

  459.     int i;

  460.     

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

  462.     

  463.     for(i=0; i<6; i++){

  464.         if(decode_i_block(f, f->block[i]) < 0)

  465.             return -1;

  466.     }

  467.     

  468.     return 0;

  469. }

  470. 

  471. static uint8_t *read_huffman_tables(FourXContext *f, uint8_t * const buf){

  472.     int frequency[512];

  473.     uint8_t flag[512];

  474.     int up[512];

  475.     uint8_t len_tab[257];

  476.     int bits_tab[257];

  477.     int start, end;

  478.     uint8_t *ptr= buf;

  479.     int j;

  480.     

  481.     memset(frequency, 0, sizeof(frequency));

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

  483. 

  484.     start= *ptr++;

  485.     end= *ptr++;

  486.     for(;;){

  487.         int i;

  488.         

  489.         for(i=start; i<=end; i++){

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

  491. //            printf("%d %d %d\n", start, end, frequency[i]);

  492.         }

  493.         start= *ptr++;

  494.         if(start==0) break;

  495.         

  496.         end= *ptr++;

  497.     }

  498.     frequency[256]=1;

  499. 

  500.     while((ptr - buf)&3) ptr++; // 4byte align 

  501. 

  502. //    for(j=0; j<16; j++)

  503. //        printf("%2X", ptr[j]);

  504.     

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

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

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

  508.         int i;

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

  510.             if(frequency[i] == 0) continue;

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

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

  513.                     min_freq[1]= min_freq[0]; smallest[1]= smallest[0];

  514.                     min_freq[0]= frequency[i];smallest[0]= i;

  515.                 }else{

  516.                     min_freq[1]= frequency[i];smallest[1]= i;

  517.                 }

  518.             }

  519.         }

  520.         if(min_freq[1] == 256*256) break;

  521.         

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

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

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

  525.         up[ smallest[0] ]= 

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

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

  528.     }

  529. 

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

  531.         int node;

  532.         int len=0;

  533.         int bits=0;

  534. 

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

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

  537.             len++;

  538.             if(len > 31) av_log(f->avctx, AV_LOG_ERROR, "vlc length overflow\n"); //can this happen at all ?

  539.         }

  540.         

  541.         bits_tab[j]= bits;

  542.         len_tab[j]= len;

  543.     }

  544.     

  545.     init_vlc(&f->pre_vlc, ACDC_VLC_BITS, 257, 

  546.              len_tab , 1, 1,

  547.              bits_tab, 4, 4);

  548.              

  549.     return ptr;

  550. }

  551. 

  552. static int decode_i_frame(FourXContext *f, uint8_t *buf, int length){

  553.     int x, y;

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

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

  556.     uint16_t *dst= (uint16_t*)f->current_picture.data[0];

  557.     const int stride= f->current_picture.linesize[0]>>1;

  558.     const int bitstream_size= get32(buf);

  559.     const int token_count __attribute__((unused)) = get32(buf + bitstream_size + 8);

  560.     int prestream_size= 4*get32(buf + bitstream_size + 4);

  561.     uint8_t *prestream= buf + bitstream_size + 12;

  562.     

  563.     if(prestream_size + bitstream_size + 12 != length)

  564.         av_log(f->avctx, AV_LOG_ERROR, "size missmatch %d %d %d\n", prestream_size, bitstream_size, length);

  565.    

  566.     prestream= read_huffman_tables(f, prestream);

  567. 

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

  569. 

  570.     prestream_size= length + buf - prestream;

  571. 

  572.     f->bitstream_buffer= av_fast_realloc(f->bitstream_buffer, &f->bitstream_buffer_size, prestream_size + FF_INPUT_BUFFER_PADDING_SIZE);

  573.     f->dsp.bswap_buf((uint32_t*)f->bitstream_buffer, (uint32_t*)prestream, prestream_size/4);

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

  575. 

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

  577.     

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

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

  580.             if(decode_i_mb(f) < 0)

  581.                 return -1;

  582. 

  583.             idct_put(f, x, y);

  584.         }

  585.         dst += 16*stride; 

  586.     }

  587. 

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

  589.         av_log(f->avctx, AV_LOG_ERROR, "end missmatch\n");

  590.     

  591.     return 0;

  592. }

  593. 

  594. static int decode_frame(AVCodecContext *avctx, 

  595.                         void *data, int *data_size,

  596.                         uint8_t *buf, int buf_size)

  597. {

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

  599.     AVFrame *picture = data;

  600.     AVFrame *p, temp;

  601.     int i, frame_4cc, frame_size;

  602. 

  603.     *data_size = 0;

  604. 

  605.     /* special case for last picture */

  606.     if (buf_size == 0) {

  607.         return 0;

  608.     }

  609. 

  610.     frame_4cc= get32(buf);

  611.     if(buf_size != get32(buf+4)+8){

  612.         av_log(f->avctx, AV_LOG_ERROR, "size missmatch %d %d\n", buf_size, get32(buf+4));

  613.     }

  614. 

  615.     if(frame_4cc == ff_get_fourcc("cfrm")){

  616.         int free_index=-1;

  617.         const int data_size= buf_size - 20;

  618.         const int id= get32(buf+12);

  619.         const int whole_size= get32(buf+16);

  620.         CFrameBuffer *cfrm;

  621. 

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

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

  624.                 av_log(f->avctx, AV_LOG_ERROR, "lost c frame %d\n", f->cfrm[i].id);

  625.         }

  626.         

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

  628.             if(f->cfrm[i].id   == id) break;

  629.             if(f->cfrm[i].size == 0 ) free_index= i;

  630.         }

  631. 

  632.         if(i>=CFRAME_BUFFER_COUNT){

  633.             i= free_index;

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

  635.         }

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

  637.         

  638.         cfrm->data= av_fast_realloc(cfrm->data, &cfrm->allocated_size, cfrm->size + data_size + FF_INPUT_BUFFER_PADDING_SIZE);

  639.         

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

  641.         cfrm->size += data_size;

  642.         

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

  644.             buf= cfrm->data;

  645.             frame_size= cfrm->size;

  646.             

  647.             if(id != avctx->frame_number){

  648.                 av_log(f->avctx, AV_LOG_ERROR, "cframe id missmatch %d %d\n", id, avctx->frame_number);

  649.             }

  650.             

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

  652.             frame_4cc= ff_get_fourcc("pfrm");

  653.         }else

  654.             return buf_size;

  655.     }else{

  656.         buf= buf + 12;

  657.         frame_size= buf_size - 12;

  658.     }    

  659. 

  660.     temp= f->current_picture;

  661.     f->current_picture= f->last_picture;

  662.     f->last_picture= temp;

  663. 

  664.     p= &f->current_picture;

  665.     avctx->coded_frame= p;

  666. 

  667.     avctx->flags |= CODEC_FLAG_EMU_EDGE; // alternatively we would have to use our own buffer management

  668. 

  669.     if(p->data[0])

  670.         avctx->release_buffer(avctx, p);

  671. 

  672.     p->reference= 1;

  673.     if(avctx->get_buffer(avctx, p) < 0){

  674.         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

  675.         return -1;

  676.     }

  677. 

  678.     if(frame_4cc == ff_get_fourcc("ifrm")){

  679.         p->pict_type= I_TYPE;

  680.         if(decode_i_frame(f, buf, frame_size) < 0)

  681.             return -1;

  682.     }else if(frame_4cc == ff_get_fourcc("pfrm")){

  683.         p->pict_type= P_TYPE;

  684.         if(decode_p_frame(f, buf, frame_size) < 0)

  685.             return -1;

  686.     }else if(frame_4cc == ff_get_fourcc("snd_")){

  687.         av_log(avctx, AV_LOG_ERROR, "ignoring snd_ chunk length:%d\n", buf_size);

  688.     }else{

  689.         av_log(avctx, AV_LOG_ERROR, "ignoring unknown chunk length:%d\n", buf_size);

  690.     }

  691. 

  692. #if 0

  693. for(i=0; i<20; i++){

  694.     printf("%2X %c ", buf[i], clip(buf[i],16,126));

  695. }

  696. #endif

  697. 

  698.     p->key_frame= p->pict_type == I_TYPE;

  699. 

  700.     *picture= *p;

  701.     *data_size = sizeof(AVPicture);

  702. 

  703.     emms_c();

  704.     

  705.     return buf_size;

  706. }

  707. 

  708. 

  709. static void common_init(AVCodecContext *avctx){

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

  711. 

  712.     dsputil_init(&f->dsp, avctx);

  713. 

  714.     f->avctx= avctx;

  715. }

  716. 

  717. static int decode_init(AVCodecContext *avctx){

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

  719.  

  720.     common_init(avctx);

  721.     init_vlcs(f);

  722. 

  723.     avctx->pix_fmt= PIX_FMT_RGB565;

  724. 

  725.     return 0;

  726. }

  727. 

  728. 

  729. static int decode_end(AVCodecContext *avctx){

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

  731.     int i;

  732. 

  733.     av_freep(&f->bitstream_buffer);

  734.     f->bitstream_buffer_size=0;

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

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

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

  738.     }

  739.     free_vlc(&f->pre_vlc);

  740.     

  741.     avcodec_default_free_buffers(avctx);

  742. 

  743.     return 0;

  744. }

  745. 

  746. AVCodec fourxm_decoder = {

  747.     "4xm",

  748.     CODEC_TYPE_VIDEO,

  749.     CODEC_ID_4XM,

  750.     sizeof(FourXContext),

  751.     decode_init,

  752.     NULL,

  753.     decode_end,

  754.     decode_frame,

  755.     /*CODEC_CAP_DR1,*/

  756. };