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FFmpeg/libavcodec/mjpeg.c

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  1. /*

  2.  * MJPEG encoder and decoder

  3.  * Copyright (c) 2000, 2001 Gerard Lantau.

  4.  *

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

  6.  * it under the terms of the GNU General Public License as published by

  7.  * the Free Software Foundation; either version 2 of the License, or

  8.  * (at your option) any later version.

  9.  *

  10.  * This program 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

  13.  * GNU General Public License for more details.

  14.  *

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

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

  17.  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

  18.  */

  19. #include <stdlib.h>

  20. #include <stdio.h>

  21. #include "avcodec.h"

  22. #include "dsputil.h"

  23. #include "mpegvideo.h"

  24. 

  25. typedef struct MJpegContext {

  26.     UINT8 huff_size_dc_luminance[12];

  27.     UINT16 huff_code_dc_luminance[12];

  28.     UINT8 huff_size_dc_chrominance[12];

  29.     UINT16 huff_code_dc_chrominance[12];

  30. 

  31.     UINT8 huff_size_ac_luminance[256];

  32.     UINT16 huff_code_ac_luminance[256];

  33.     UINT8 huff_size_ac_chrominance[256];

  34.     UINT16 huff_code_ac_chrominance[256];

  35. } MJpegContext;

  36. 

  37. #define SOF0 0xc0

  38. #define SOI 0xd8

  39. #define EOI 0xd9

  40. #define DQT 0xdb

  41. #define DHT 0xc4

  42. #define SOS 0xda

  43. 

  44. #if 0

  45. /* These are the sample quantization tables given in JPEG spec section K.1.

  46.  * The spec says that the values given produce "good" quality, and

  47.  * when divided by 2, "very good" quality.

  48.  */

  49. static const unsigned char std_luminance_quant_tbl[64] = {

  50.     16,  11,  10,  16,  24,  40,  51,  61,

  51.     12,  12,  14,  19,  26,  58,  60,  55,

  52.     14,  13,  16,  24,  40,  57,  69,  56,

  53.     14,  17,  22,  29,  51,  87,  80,  62,

  54.     18,  22,  37,  56,  68, 109, 103,  77,

  55.     24,  35,  55,  64,  81, 104, 113,  92,

  56.     49,  64,  78,  87, 103, 121, 120, 101,

  57.     72,  92,  95,  98, 112, 100, 103,  99

  58. };

  59. static const unsigned char std_chrominance_quant_tbl[64] = {

  60.     17,  18,  24,  47,  99,  99,  99,  99,

  61.     18,  21,  26,  66,  99,  99,  99,  99,

  62.     24,  26,  56,  99,  99,  99,  99,  99,

  63.     47,  66,  99,  99,  99,  99,  99,  99,

  64.     99,  99,  99,  99,  99,  99,  99,  99,

  65.     99,  99,  99,  99,  99,  99,  99,  99,

  66.     99,  99,  99,  99,  99,  99,  99,  99,

  67.     99,  99,  99,  99,  99,  99,  99,  99

  68. };

  69. #endif

  70. 

  71. /* Set up the standard Huffman tables (cf. JPEG standard section K.3) */

  72. /* IMPORTANT: these are only valid for 8-bit data precision! */

  73. static const UINT8 bits_dc_luminance[17] =

  74. { /* 0-base */ 0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 };

  75. static const UINT8 val_dc_luminance[] =

  76. { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };

  77. 

  78. static const UINT8 bits_dc_chrominance[17] =

  79. { /* 0-base */ 0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };

  80. static const UINT8 val_dc_chrominance[] =

  81. { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };

  82. 

  83. static const UINT8 bits_ac_luminance[17] =

  84. { /* 0-base */ 0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d };

  85. static const UINT8 val_ac_luminance[] =

  86. { 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,

  87.   0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,

  88.   0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,

  89.   0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,

  90.   0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,

  91.   0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,

  92.   0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,

  93.   0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,

  94.   0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,

  95.   0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,

  96.   0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,

  97.   0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,

  98.   0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,

  99.   0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,

  100.   0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,

  101.   0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,

  102.   0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,

  103.   0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,

  104.   0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,

  105.   0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,

  106.   0xf9, 0xfa 

  107. };

  108. 

  109. static const UINT8 bits_ac_chrominance[17] =

  110. { /* 0-base */ 0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77 };

  111. 

  112. static const UINT8 val_ac_chrominance[] =

  113. { 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,

  114.   0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,

  115.   0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,

  116.   0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,

  117.   0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,

  118.   0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,

  119.   0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,

  120.   0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,

  121.   0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,

  122.   0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,

  123.   0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,

  124.   0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,

  125.   0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,

  126.   0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,

  127.   0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,

  128.   0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,

  129.   0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,

  130.   0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,

  131.   0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,

  132.   0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,

  133.   0xf9, 0xfa 

  134. };

  135. 

  136. 

  137. /* isn't this function nicer than the one in the libjpeg ? */

  138. static void build_huffman_codes(UINT8 *huff_size, UINT16 *huff_code,

  139.                                 const UINT8 *bits_table, const UINT8 *val_table)

  140. {

  141.     int i, j, k,nb, code, sym;

  142. 

  143.     code = 0;

  144.     k = 0;

  145.     for(i=1;i<=16;i++) {

  146.         nb = bits_table[i];

  147.         for(j=0;j<nb;j++) {

  148.             sym = val_table[k++];

  149.             huff_size[sym] = i;

  150.             huff_code[sym] = code;

  151.             code++;

  152.         }

  153.         code <<= 1;

  154.     }

  155. }

  156. 

  157. int mjpeg_init(MpegEncContext *s)

  158. {

  159.     MJpegContext *m;

  160.     

  161.     m = malloc(sizeof(MJpegContext));

  162.     if (!m)

  163.         return -1;

  164. 

  165.     /* build all the huffman tables */

  166.     build_huffman_codes(m->huff_size_dc_luminance,

  167.                         m->huff_code_dc_luminance,

  168.                         bits_dc_luminance,

  169.                         val_dc_luminance);

  170.     build_huffman_codes(m->huff_size_dc_chrominance,

  171.                         m->huff_code_dc_chrominance,

  172.                         bits_dc_chrominance,

  173.                         val_dc_chrominance);

  174.     build_huffman_codes(m->huff_size_ac_luminance,

  175.                         m->huff_code_ac_luminance,

  176.                         bits_ac_luminance,

  177.                         val_ac_luminance);

  178.     build_huffman_codes(m->huff_size_ac_chrominance,

  179.                         m->huff_code_ac_chrominance,

  180.                         bits_ac_chrominance,

  181.                         val_ac_chrominance);

  182.     

  183.     s->mjpeg_ctx = m;

  184.     return 0;

  185. }

  186. 

  187. void mjpeg_close(MpegEncContext *s)

  188. {

  189.     free(s->mjpeg_ctx);

  190. }

  191. 

  192. static inline void put_marker(PutBitContext *p, int code)

  193. {

  194.     put_bits(p, 8, 0xff);

  195.     put_bits(p, 8, code);

  196. }

  197. 

  198. /* table_class: 0 = DC coef, 1 = AC coefs */

  199. static int put_huffman_table(MpegEncContext *s, int table_class, int table_id,

  200.                              const UINT8 *bits_table, const UINT8 *value_table)

  201. {

  202.     PutBitContext *p = &s->pb;

  203.     int n, i;

  204. 

  205.     put_bits(p, 4, table_class);

  206.     put_bits(p, 4, table_id);

  207. 

  208.     n = 0;

  209.     for(i=1;i<=16;i++) {

  210.         n += bits_table[i];

  211.         put_bits(p, 8, bits_table[i]);

  212.     }

  213. 

  214.     for(i=0;i<n;i++)

  215.         put_bits(p, 8, value_table[i]);

  216. 

  217.     return n + 17;

  218. }

  219. 

  220. static void jpeg_table_header(MpegEncContext *s)

  221. {

  222.     PutBitContext *p = &s->pb;

  223.     int i, size;

  224.     UINT8 *ptr;

  225. 

  226.     /* quant matrixes */

  227.     put_marker(p, DQT);

  228.     put_bits(p, 16, 2 + 1 * (1 + 64));

  229.     put_bits(p, 4, 0); /* 8 bit precision */

  230.     put_bits(p, 4, 0); /* table 0 */

  231.     for(i=0;i<64;i++) {

  232.         put_bits(p, 8, s->intra_matrix[i]);

  233.     }

  234. #if 0

  235.     put_bits(p, 4, 0); /* 8 bit precision */

  236.     put_bits(p, 4, 1); /* table 1 */

  237.     for(i=0;i<64;i++) {

  238.         put_bits(p, 8, s->chroma_intra_matrix[i]);

  239.     }

  240. #endif

  241. 

  242.     /* huffman table */

  243.     put_marker(p, DHT);

  244.     flush_put_bits(p);

  245.     ptr = p->buf_ptr;

  246.     put_bits(p, 16, 0); /* patched later */

  247.     size = 2;

  248.     size += put_huffman_table(s, 0, 0, bits_dc_luminance, val_dc_luminance);

  249.     size += put_huffman_table(s, 0, 1, bits_dc_chrominance, val_dc_chrominance);

  250.     

  251.     size += put_huffman_table(s, 1, 0, bits_ac_luminance, val_ac_luminance);

  252.     size += put_huffman_table(s, 1, 1, bits_ac_chrominance, val_ac_chrominance);

  253.     ptr[0] = size >> 8;

  254.     ptr[1] = size;

  255. }

  256. 

  257. void mjpeg_picture_header(MpegEncContext *s)

  258. {

  259.     put_marker(&s->pb, SOI);

  260. 

  261.     jpeg_table_header(s);

  262. 

  263.     put_marker(&s->pb, SOF0);

  264. 

  265.     put_bits(&s->pb, 16, 17);

  266.     put_bits(&s->pb, 8, 8); /* 8 bits/component */

  267.     put_bits(&s->pb, 16, s->height);

  268.     put_bits(&s->pb, 16, s->width);

  269.     put_bits(&s->pb, 8, 3); /* 3 components */

  270.     

  271.     /* Y component */

  272.     put_bits(&s->pb, 8, 1); /* component number */

  273.     put_bits(&s->pb, 4, 2); /* H factor */

  274.     put_bits(&s->pb, 4, 2); /* V factor */

  275.     put_bits(&s->pb, 8, 0); /* select matrix */

  276.     

  277.     /* Cb component */

  278.     put_bits(&s->pb, 8, 2); /* component number */

  279.     put_bits(&s->pb, 4, 1); /* H factor */

  280.     put_bits(&s->pb, 4, 1); /* V factor */

  281.     put_bits(&s->pb, 8, 0); /* select matrix */

  282. 

  283.     /* Cr component */

  284.     put_bits(&s->pb, 8, 3); /* component number */

  285.     put_bits(&s->pb, 4, 1); /* H factor */

  286.     put_bits(&s->pb, 4, 1); /* V factor */

  287.     put_bits(&s->pb, 8, 0); /* select matrix */

  288. 

  289.     /* scan header */

  290.     put_marker(&s->pb, SOS);

  291.     put_bits(&s->pb, 16, 12); /* length */

  292.     put_bits(&s->pb, 8, 3); /* 3 components */

  293.     

  294.     /* Y component */

  295.     put_bits(&s->pb, 8, 1); /* index */

  296.     put_bits(&s->pb, 4, 0); /* DC huffman table index */

  297.     put_bits(&s->pb, 4, 0); /* AC huffman table index */

  298.     

  299.     /* Cb component */

  300.     put_bits(&s->pb, 8, 2); /* index */

  301.     put_bits(&s->pb, 4, 1); /* DC huffman table index */

  302.     put_bits(&s->pb, 4, 1); /* AC huffman table index */

  303.     

  304.     /* Cr component */

  305.     put_bits(&s->pb, 8, 3); /* index */

  306.     put_bits(&s->pb, 4, 1); /* DC huffman table index */

  307.     put_bits(&s->pb, 4, 1); /* AC huffman table index */

  308. 

  309.     put_bits(&s->pb, 8, 0); /* Ss (not used) */

  310.     put_bits(&s->pb, 8, 63); /* Se (not used) */

  311.     put_bits(&s->pb, 8, 0); /* (not used) */

  312. }

  313. 

  314. void mjpeg_picture_trailer(MpegEncContext *s)

  315. {

  316.     jflush_put_bits(&s->pb);

  317.     put_marker(&s->pb, EOI);

  318. }

  319. 

  320. static inline void encode_dc(MpegEncContext *s, int val, 

  321.                              UINT8 *huff_size, UINT16 *huff_code)

  322. {

  323.     int mant, nbits;

  324. 

  325.     if (val == 0) {

  326.         jput_bits(&s->pb, huff_size[0], huff_code[0]);

  327.     } else {

  328.         mant = val;

  329.         if (val < 0) {

  330.             val = -val;

  331.             mant--;

  332.         }

  333.         

  334.         /* compute the log (XXX: optimize) */

  335.         nbits = 0;

  336.         while (val != 0) {

  337.             val = val >> 1;

  338.             nbits++;

  339.         }

  340.             

  341.         jput_bits(&s->pb, huff_size[nbits], huff_code[nbits]);

  342.         

  343.         jput_bits(&s->pb, nbits, mant & ((1 << nbits) - 1));

  344.     }

  345. }

  346. 

  347. static void encode_block(MpegEncContext *s, DCTELEM *block, int n)

  348. {

  349.     int mant, nbits, code, i, j;

  350.     int component, dc, run, last_index, val;

  351.     MJpegContext *m = s->mjpeg_ctx;

  352.     UINT8 *huff_size_ac;

  353.     UINT16 *huff_code_ac;

  354.     

  355.     /* DC coef */

  356.     component = (n <= 3 ? 0 : n - 4 + 1);

  357.     dc = block[0]; /* overflow is impossible */

  358.     val = dc - s->last_dc[component];

  359.     if (n < 4) {

  360.         encode_dc(s, val, m->huff_size_dc_luminance, m->huff_code_dc_luminance);

  361.         huff_size_ac = m->huff_size_ac_luminance;

  362.         huff_code_ac = m->huff_code_ac_luminance;

  363.     } else {

  364.         encode_dc(s, val, m->huff_size_dc_chrominance, m->huff_code_dc_chrominance);

  365.         huff_size_ac = m->huff_size_ac_chrominance;

  366.         huff_code_ac = m->huff_code_ac_chrominance;

  367.     }

  368.     s->last_dc[component] = dc;

  369.     

  370.     /* AC coefs */

  371.     

  372.     run = 0;

  373.     last_index = s->block_last_index[n];

  374.     for(i=1;i<=last_index;i++) {

  375.         j = zigzag_direct[i];

  376.         val = block[j];

  377.         if (val == 0) {

  378.             run++;

  379.         } else {

  380.             while (run >= 16) {

  381.                 jput_bits(&s->pb, huff_size_ac[0xf0], huff_code_ac[0xf0]);

  382.                 run -= 16;

  383.             }

  384.             mant = val;

  385.             if (val < 0) {

  386.                 val = -val;

  387.                 mant--;

  388.             }

  389.             

  390.             /* compute the log (XXX: optimize) */

  391.             nbits = 0;

  392.             while (val != 0) {

  393.                 val = val >> 1;

  394.                 nbits++;

  395.             }

  396.             code = (run << 4) | nbits;

  397. 

  398.             jput_bits(&s->pb, huff_size_ac[code], huff_code_ac[code]);

  399.         

  400.             jput_bits(&s->pb, nbits, mant & ((1 << nbits) - 1));

  401.             run = 0;

  402.         }

  403.     }

  404. 

  405.     /* output EOB only if not already 64 values */

  406.     if (last_index < 63 || run != 0)

  407.         jput_bits(&s->pb, huff_size_ac[0], huff_code_ac[0]);

  408. }

  409. 

  410. void mjpeg_encode_mb(MpegEncContext *s, 

  411.                      DCTELEM block[6][64])

  412. {

  413.     int i;

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

  415.         encode_block(s, block[i], i);

  416.     }

  417. }

  418. 

  419. /******************************************/

  420. /* decoding */

  421. 

  422. //#define DEBUG

  423. 

  424. #ifdef DEBUG

  425. #define dprintf(fmt,args...) printf(fmt, ## args)

  426. #else

  427. #define dprintf(fmt,args...)

  428. #endif

  429. 

  430. /* compressed picture size */

  431. #define PICTURE_BUFFER_SIZE 100000

  432. 

  433. #define MAX_COMPONENTS 4

  434. 

  435. typedef struct MJpegDecodeContext {

  436.     GetBitContext gb;

  437.     UINT32 header_state;

  438.     int start_code; /* current start code */

  439.     UINT8 *buf_ptr;

  440.     int buffer_size;

  441.     int mpeg_enc_ctx_allocated; /* true if decoding context allocated */

  442.     INT16 quant_matrixes[4][64];

  443.     VLC vlcs[2][4];

  444.     int width, height;

  445.     int h_count[MAX_COMPONENTS]; /* horizontal and vertical count for each component */

  446.     int v_count[MAX_COMPONENTS];

  447.     int h_max, v_max; /* maximum h and v counts */

  448.     int quant_index[4];   /* quant table index for each component */

  449.     int last_dc[MAX_COMPONENTS]; /* last DEQUANTIZED dc (XXX: am I right to do that ?) */

  450.     UINT8 *current_picture[MAX_COMPONENTS]; /* picture structure */

  451.     int linesize[MAX_COMPONENTS];

  452.     DCTELEM block[64] __align8;

  453.     UINT8 buffer[PICTURE_BUFFER_SIZE]; 

  454. } MJpegDecodeContext;

  455. 

  456. static int mjpeg_decode_init(AVCodecContext *avctx)

  457. {

  458.     MJpegDecodeContext *s = avctx->priv_data;

  459. 

  460.     s->header_state = 0;

  461.     s->mpeg_enc_ctx_allocated = 0;

  462.     s->buffer_size = PICTURE_BUFFER_SIZE - 1; /* minus 1 to take into

  463.                                                  account FF 00 case */

  464.     s->start_code = -1;

  465.     s->buf_ptr = s->buffer;

  466.     return 0;

  467. }

  468. 

  469. /* quantize tables */

  470. static int mjpeg_decode_dqt(MJpegDecodeContext *s,

  471.                             UINT8 *buf, int buf_size)

  472. {

  473.     int len, index, i;

  474.     init_get_bits(&s->gb, buf, buf_size);

  475. 

  476.     len = get_bits(&s->gb, 16);

  477.     len -= 2;

  478. 

  479.     while (len >= 65) {

  480.         /* only 8 bit precision handled */

  481.         if (get_bits(&s->gb, 4) != 0)

  482.             return -1;

  483.         index = get_bits(&s->gb, 4);

  484.         if (index >= 4)

  485.             return -1;

  486.         dprintf("index=%d\n", index);

  487.         /* read quant table */

  488.         for(i=0;i<64;i++)

  489.             s->quant_matrixes[index][i] = get_bits(&s->gb, 8);

  490.         len -= 65;

  491.     }

  492.     return 0;

  493. }

  494. 

  495. /* decode huffman tables and build VLC decoders */

  496. static int mjpeg_decode_dht(MJpegDecodeContext *s,

  497.                             UINT8 *buf, int buf_size)

  498. {

  499.     int len, index, i, class, n, v, code_max;

  500.     UINT8 bits_table[17];

  501.     UINT8 val_table[256];

  502.     UINT8 huff_size[256];

  503.     UINT16 huff_code[256];

  504.     

  505.     init_get_bits(&s->gb, buf, buf_size);

  506. 

  507.     len = get_bits(&s->gb, 16);

  508.     len -= 2;

  509. 

  510.     while (len > 0) {

  511.         if (len < 17)

  512.             return -1;

  513.         class = get_bits(&s->gb, 4);

  514.         if (class >= 2)

  515.             return -1;

  516.         index = get_bits(&s->gb, 4);

  517.         if (index >= 4)

  518.             return -1;

  519.         n = 0;

  520.         for(i=1;i<=16;i++) {

  521.             bits_table[i] = get_bits(&s->gb, 8);

  522.             n += bits_table[i];

  523.         }

  524.         len -= 17;

  525.         if (len < n || n > 256)

  526.             return -1;

  527. 

  528.         code_max = 0;

  529.         for(i=0;i<n;i++) {

  530.             v = get_bits(&s->gb, 8);

  531.             if (v > code_max)

  532.                 code_max = v;

  533.             val_table[i] = v;

  534.         }

  535.         len -= n;

  536. 

  537.         /* now build size/code table */

  538.         memset(huff_size, 0, sizeof(huff_size));

  539.         build_huffman_codes(huff_size, huff_code, bits_table, val_table);

  540.         

  541.         /* build VLC and flush previous vlc if present */

  542.         free_vlc(&s->vlcs[class][index]);

  543.         dprintf("class=%d index=%d nb_codes=%d\n",

  544.                class, index, code_max + 1);

  545.         init_vlc(&s->vlcs[class][index], 9, code_max + 1,

  546.                  huff_size, 1, 1,

  547.                  huff_code, 2, 2);

  548.     }

  549.     return 0;

  550. }

  551. 

  552. static int mjpeg_decode_sof0(MJpegDecodeContext *s,

  553.                              UINT8 *buf, int buf_size)

  554. {

  555.     int len, nb_components, i, index, width, height;

  556. 

  557.     init_get_bits(&s->gb, buf, buf_size);

  558. 

  559.     /* XXX: verify len field validity */

  560.     len = get_bits(&s->gb, 16);

  561.     /* only 8 bits/component accepted */

  562.     if (get_bits(&s->gb, 8) != 8)

  563.         return -1;

  564.     height = get_bits(&s->gb, 16);

  565.     width = get_bits(&s->gb, 16);

  566. 

  567.     nb_components = get_bits(&s->gb, 8);

  568.     if (nb_components <= 0 ||

  569.         nb_components > MAX_COMPONENTS)

  570.         return -1;

  571.     s->h_max = 1;

  572.     s->v_max = 1;

  573.     for(i=0;i<nb_components;i++) {

  574.         /* component id */

  575.         index = get_bits(&s->gb, 8) - 1;

  576.         /* XXX: avoid this limitation */

  577.         if (index < 0 || index >= MAX_COMPONENTS)

  578.             return -1;

  579.         s->h_count[i] = get_bits(&s->gb, 4);

  580.         s->v_count[i] = get_bits(&s->gb, 4);

  581.         /* compute hmax and vmax (only used in interleaved case) */

  582.         if (s->h_count[i] > s->h_max)

  583.             s->h_max = s->h_count[i];

  584.         if (s->v_count[i] > s->v_max)

  585.             s->v_max = s->v_count[i];

  586. 

  587.         /* XXX: only 420 is accepted */

  588.         if ((i == 0 && (s->h_count[i] != 2 || s->v_count[i] != 2)) ||

  589.             (i != 0 && (s->h_count[i] != 1 || s->v_count[i] != 1)))

  590.             return -1;

  591.         s->quant_index[i] = get_bits(&s->gb, 8);

  592.         if (s->quant_index[i] >= 4)

  593.             return -1;

  594.         dprintf("component %d %d:%d\n", i, s->h_count[i], s->v_count[i]);

  595.     }

  596. 

  597.     /* if different size, realloc/alloc picture */

  598.     /* XXX: also check h_count and v_count */

  599.     if (width != s->width || height != s->height) {

  600.         for(i=0;i<MAX_COMPONENTS;i++) {

  601.             free(s->current_picture[i]);

  602.             s->current_picture[i] = NULL;

  603.         }

  604.         s->width = width;

  605.         s->height = height;

  606.         for(i=0;i<nb_components;i++) {

  607.             int w, h, hh, vv;

  608.             hh = s->h_max / s->h_count[i];

  609.             vv = s->v_max / s->v_count[i];

  610.             w = (s->width + 8 * hh - 1) / (8 * hh);

  611.             h = (s->height + 8 * vv - 1) / (8 * vv);

  612.             w = w * 8;

  613.             h = h * 8;

  614.             s->linesize[i] = w;

  615.             /* memory test is done in mjpeg_decode_sos() */

  616.             s->current_picture[i] = av_mallocz(w * h);

  617.         }

  618.     }

  619. 

  620.     return 0;

  621. }

  622. 

  623. static inline int decode_dc(MJpegDecodeContext *s, int dc_index)

  624. {

  625.     VLC *dc_vlc;

  626.     int code, diff;

  627. 

  628.     dc_vlc = &s->vlcs[0][dc_index];

  629.     code = get_vlc(&s->gb, dc_vlc);

  630.     if (code < 0)

  631.         return 0xffff;

  632.     if (code == 0) {

  633.         diff = 0;

  634.     } else {

  635.         diff = get_bits(&s->gb, code);

  636.         if ((diff & (1 << (code - 1))) == 0) 

  637.             diff = (-1 << code) | (diff + 1);

  638.     }

  639.     return diff;

  640. }

  641. 

  642. /* decode block and dequantize */

  643. static int decode_block(MJpegDecodeContext *s, DCTELEM *block, 

  644.                         int component, int dc_index, int ac_index, int quant_index)

  645. {

  646.     int nbits, code, i, j, level;

  647.     int run, val;

  648.     VLC *ac_vlc;

  649.     INT16 *quant_matrix;

  650. 

  651.     quant_matrix = s->quant_matrixes[quant_index];

  652.     /* DC coef */

  653.     val = decode_dc(s, dc_index);

  654.     if (val == 0xffff) {

  655.         dprintf("error dc\n");

  656.         return -1;

  657.     }

  658.     val = val * quant_matrix[0] + s->last_dc[component];

  659.     s->last_dc[component] = val;

  660.     block[0] = val;

  661. 

  662.     /* AC coefs */

  663.     ac_vlc = &s->vlcs[1][ac_index];

  664.     i = 1;

  665.     for(;;) {

  666.         code = get_vlc(&s->gb, ac_vlc);

  667.         if (code < 0) {

  668.             dprintf("error ac\n");

  669.             return -1;

  670.         }

  671.         /* EOB */

  672.         if (code == 0)

  673.             break;

  674.         if (code == 0xf0) {

  675.             i += 16;

  676.         } else {

  677.             run = code >> 4;

  678.             nbits = code & 0xf;

  679.             level = get_bits(&s->gb, nbits);

  680.             if ((level & (1 << (nbits - 1))) == 0) 

  681.                 level = (-1 << nbits) | (level + 1);

  682.             i += run;

  683.             if (i >= 64) {

  684.                 dprintf("error count: %d\n", i);

  685.                 return -1;

  686.             }

  687.             j = zigzag_direct[i];

  688.             block[j] = level * quant_matrix[j];

  689.             i++;

  690.         }

  691.     }

  692.     return 0;

  693. }

  694. 

  695. static int mjpeg_decode_sos(MJpegDecodeContext *s,

  696.                             UINT8 *buf, int buf_size)

  697. {

  698.     int len, nb_components, i, j, n, h, v;

  699.     int mb_width, mb_height, mb_x, mb_y, vmax, hmax, index;

  700.     int comp_index[4];

  701.     int dc_index[4];

  702.     int ac_index[4];

  703.     int nb_blocks[4];

  704.     int h_count[4];

  705.     int v_count[4];

  706.     

  707.     init_get_bits(&s->gb, buf, buf_size);

  708.     /* XXX: verify len field validity */

  709.     len = get_bits(&s->gb, 16);

  710.     nb_components = get_bits(&s->gb, 8);

  711.     /* XXX: only interleaved scan accepted */

  712.     if (nb_components != 3)

  713.         return -1;

  714.     vmax = 0;

  715.     hmax = 0;

  716.     for(i=0;i<nb_components;i++) {

  717.         index = get_bits(&s->gb, 8) - 1;

  718.         /* XXX: this limitation is not OK */

  719.         if (index < 0 || index >= 4) 

  720.             return -1;

  721.         comp_index[i] = index;

  722.         

  723.         nb_blocks[i] = s->h_count[index] * s->v_count[index];

  724.         h_count[i] = s->h_count[index];

  725.         v_count[i] = s->v_count[index];

  726.         

  727.         dc_index[i] = get_bits(&s->gb, 4);

  728.         if (dc_index[i] >= 4)

  729.             return -1;

  730.         ac_index[i] = get_bits(&s->gb, 4);

  731.         if (ac_index[i] >= 4)

  732.             return -1;

  733.     }

  734.     get_bits(&s->gb, 8); /* Ss */

  735.     get_bits(&s->gb, 8); /* Se */

  736.     get_bits(&s->gb, 8); /* not used */

  737. 

  738.     for(i=0;i<nb_components;i++) 

  739.         s->last_dc[i] = 1024;

  740. 

  741.     if (nb_components > 1) {

  742.         /* interleaved stream */

  743.         mb_width = (s->width + s->h_max * 8 - 1) / (s->h_max * 8);

  744.         mb_height = (s->height + s->v_max * 8 - 1) / (s->v_max * 8);

  745.     } else {

  746.         h = s->h_max / s->h_count[comp_index[0]];

  747.         v = s->v_max / s->v_count[comp_index[0]];

  748.         mb_width = (s->width + h * 8 - 1) / (h * 8);

  749.         mb_height = (s->height + v * 8 - 1) / (v * 8);

  750.         nb_blocks[0] = 1;

  751.         h_count[0] = 1;

  752.         v_count[0] = 1;

  753.     }

  754. 

  755.     for(mb_y = 0; mb_y < mb_height; mb_y++) {

  756.         for(mb_x = 0; mb_x < mb_width; mb_x++) {

  757.             for(i=0;i<nb_components;i++) {

  758.                 UINT8 *ptr;

  759.                 int x, y, c;

  760.                 n = nb_blocks[i];

  761.                 c = comp_index[i];

  762.                 h = h_count[i];

  763.                 v = v_count[i];

  764.                 x = 0;

  765.                 y = 0;

  766.                 for(j=0;j<n;j++) {

  767.                     memset(s->block, 0, sizeof(s->block));

  768.                     if (decode_block(s, s->block, i, 

  769.                                      dc_index[i], ac_index[i], 

  770.                                      s->quant_index[c]) < 0) {

  771.                         dprintf("error %d %d\n", mb_y, mb_x);

  772.                         return -1;

  773.                     }

  774.                     ff_idct (s->block);

  775.                     ptr = s->current_picture[c] + 

  776.                         (s->linesize[c] * (v * mb_y + y) * 8) + 

  777.                         (h * mb_x + x) * 8;

  778.                     put_pixels_clamped(s->block, ptr, s->linesize[c]);

  779.                     if (++x == h) {

  780.                         x = 0;

  781.                         y++;

  782.                     }

  783.                 }

  784.             }

  785.         }

  786.     }

  787.     return 0;

  788. }

  789. 

  790. /* return the 8 bit start code value and update the search

  791.    state. Return -1 if no start code found */

  792. static int find_marker(UINT8 **pbuf_ptr, UINT8 *buf_end, 

  793.                        UINT32 *header_state)

  794. {

  795.     UINT8 *buf_ptr;

  796.     unsigned int state, v;

  797.     int val;

  798. 

  799.     state = *header_state;

  800.     buf_ptr = *pbuf_ptr;

  801.     if (state) {

  802.         /* get marker */

  803.     found:

  804.         if (buf_ptr < buf_end) {

  805.             val = *buf_ptr++;

  806.             state = 0;

  807.         } else {

  808.             val = -1;

  809.         }

  810.     } else {

  811.         while (buf_ptr < buf_end) {

  812.             v = *buf_ptr++;

  813.             if (v == 0xff) {

  814.                 state = 1;

  815.                 goto found;

  816.             }

  817.         }

  818.         val = -1;

  819.     }

  820.     *pbuf_ptr = buf_ptr;

  821.     *header_state = state;

  822.     return val;

  823. }

  824. 

  825. static int mjpeg_decode_frame(AVCodecContext *avctx, 

  826.                               void *data, int *data_size,

  827.                               UINT8 *buf, int buf_size)

  828. {

  829.     MJpegDecodeContext *s = avctx->priv_data;

  830.     UINT8 *buf_end, *buf_ptr, *buf_start;

  831.     int len, code, start_code, input_size, i;

  832.     AVPicture *picture = data;

  833. 

  834.     /* no supplementary picture */

  835.     if (buf_size == 0) {

  836.         *data_size = 0;

  837.         return 0;

  838.     }

  839. 

  840.     buf_ptr = buf;

  841.     buf_end = buf + buf_size;

  842.     while (buf_ptr < buf_end) {

  843.         buf_start = buf_ptr;

  844.         /* find start next marker */

  845.         code = find_marker(&buf_ptr, buf_end, &s->header_state);

  846.         /* copy to buffer */

  847.         len = buf_ptr - buf_start;

  848.         if (len + (s->buf_ptr - s->buffer) > s->buffer_size) {

  849.             /* data too big : flush */

  850.             s->buf_ptr = s->buffer;

  851.             if (code > 0)

  852.                 s->start_code = code;

  853.         } else {

  854.             memcpy(s->buf_ptr, buf_start, len);

  855.             s->buf_ptr += len;

  856.             /* if we got FF 00, we copy FF to the stream to unescape FF 00 */

  857.             if (code == 0) {

  858.                 s->buf_ptr--;

  859.             } else if (code > 0) {

  860.                 /* prepare data for next start code */

  861.                 input_size = s->buf_ptr - s->buffer;

  862.                 start_code = s->start_code;

  863.                 s->buf_ptr = s->buffer;

  864.                 s->start_code = code;

  865.                 switch(start_code) {

  866.                 case SOI:

  867.                     /* nothing to do on SOI */

  868.                     break;

  869.                 case DQT:

  870.                     mjpeg_decode_dqt(s, s->buffer, input_size);

  871.                     break;

  872.                 case DHT:

  873.                     mjpeg_decode_dht(s, s->buffer, input_size);

  874.                     break;

  875.                 case SOF0:

  876.                     mjpeg_decode_sof0(s, s->buffer, input_size);

  877.                     break;

  878.                 case SOS:

  879.                     mjpeg_decode_sos(s, s->buffer, input_size);

  880.                     if (s->start_code == EOI) {

  881.                         /* XXX: YUV420 hardcoded */

  882.                         for(i=0;i<3;i++) {

  883.                             picture->data[i] = s->current_picture[i];

  884.                             picture->linesize[i] = s->linesize[i];

  885.                         }

  886.                         *data_size = sizeof(AVPicture);

  887.                         avctx->height = s->height;

  888.                         avctx->width = s->width;

  889.                         avctx->pix_fmt = PIX_FMT_YUV420P;

  890.                         goto the_end;

  891.                     }

  892.                     break;

  893.                 }

  894.             }

  895.         }

  896.     }

  897.  the_end:

  898.     return buf_ptr - buf;

  899. }

  900. 

  901. static int mjpeg_decode_end(AVCodecContext *avctx)

  902. {

  903.     MJpegDecodeContext *s = avctx->priv_data;

  904.     int i, j;

  905. 

  906.     for(i=0;i<MAX_COMPONENTS;i++)

  907.         free(s->current_picture[i]);

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

  909.         for(j=0;j<4;j++)

  910.             free_vlc(&s->vlcs[i][j]);

  911.     }

  912.     return 0;

  913. }

  914. 

  915. AVCodec mjpeg_decoder = {

  916.     "mjpeg",

  917.     CODEC_TYPE_VIDEO,

  918.     CODEC_ID_MJPEG,

  919.     sizeof(MJpegDecodeContext),

  920.     mjpeg_decode_init,

  921.     NULL,

  922.     mjpeg_decode_end,

  923.     mjpeg_decode_frame,

  924. };