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FFmpeg/libavcodec/mpeg12.c

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  1. /*

  2.  * MPEG1 encoder / MPEG2 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 <string.h>

  22. #include "avcodec.h"

  23. #include "dsputil.h"

  24. #include "mpegvideo.h"

  25. 

  26. #include "mpeg12data.h"

  27. 

  28. //#define DEBUG

  29. 

  30. #ifdef DEBUG

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

  32. #else

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

  34. #endif

  35. 

  36. /* Start codes. */

  37. #define SEQ_END_CODE		0x000001b7

  38. #define SEQ_START_CODE		0x000001b3

  39. #define GOP_START_CODE		0x000001b8

  40. #define PICTURE_START_CODE	0x00000100

  41. #define SLICE_MIN_START_CODE	0x00000101

  42. #define SLICE_MAX_START_CODE	0x000001af

  43. #define EXT_START_CODE		0x000001b5

  44. #define USER_START_CODE		0x000001b2

  45. 

  46. static void mpeg1_encode_block(MpegEncContext *s, 

  47.                          DCTELEM *block, 

  48.                          int component);

  49. static void mpeg1_encode_motion(MpegEncContext *s, int val);

  50. static void mpeg1_skip_picture(MpegEncContext *s, int pict_num);

  51. static int mpeg1_decode_block(MpegEncContext *s, 

  52.                               DCTELEM *block, 

  53.                               int n);

  54. static int mpeg2_decode_block_non_intra(MpegEncContext *s, 

  55.                                         DCTELEM *block, 

  56.                                         int n);

  57. static int mpeg2_decode_block_intra(MpegEncContext *s, 

  58.                                     DCTELEM *block, 

  59.                                     int n);

  60. static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred);

  61. 

  62. static void put_header(MpegEncContext *s, int header)

  63. {

  64.     align_put_bits(&s->pb);

  65.     put_bits(&s->pb, 32, header);

  66. }

  67. 

  68. /* put sequence header if needed */

  69. static void mpeg1_encode_sequence_header(MpegEncContext *s)

  70. {

  71.         unsigned int vbv_buffer_size;

  72.         unsigned int fps, v;

  73.         int n;

  74.         UINT64 time_code;

  75.         

  76.         if ((s->picture_number % s->gop_size) == 0) {

  77.             /* mpeg1 header repeated every gop */

  78.             put_header(s, SEQ_START_CODE);

  79.             

  80.             /* search closest frame rate */

  81.             {

  82.                 int i, dmin, d;

  83.                 s->frame_rate_index = 0;

  84.                 dmin = 0x7fffffff;

  85.                 for(i=1;i<9;i++) {

  86.                     d = abs(s->frame_rate - frame_rate_tab[i]);

  87.                     if (d < dmin) {

  88.                         dmin = d;

  89.                         s->frame_rate_index = i;

  90.                     }

  91.                 }

  92.             }

  93.  

  94.             put_bits(&s->pb, 12, s->width);

  95.             put_bits(&s->pb, 12, s->height);

  96.             put_bits(&s->pb, 4, 1); /* 1/1 aspect ratio */

  97.             put_bits(&s->pb, 4, s->frame_rate_index);

  98.             v = s->bit_rate / 400;

  99.             if (v > 0x3ffff)

  100.                 v = 0x3ffff;

  101.             put_bits(&s->pb, 18, v);

  102.             put_bits(&s->pb, 1, 1); /* marker */

  103.             /* vbv buffer size: slightly greater than an I frame. We add

  104.                some margin just in case */

  105.             vbv_buffer_size = (3 * s->I_frame_bits) / (2 * 8);

  106.             put_bits(&s->pb, 10, (vbv_buffer_size + 16383) / 16384); 

  107.             put_bits(&s->pb, 1, 1); /* constrained parameter flag */

  108.             put_bits(&s->pb, 1, 0); /* no custom intra matrix */

  109.             put_bits(&s->pb, 1, 0); /* no custom non intra matrix */

  110. 

  111.             put_header(s, GOP_START_CODE);

  112.             put_bits(&s->pb, 1, 0); /* do drop frame */

  113.             /* time code : we must convert from the real frame rate to a

  114.                fake mpeg frame rate in case of low frame rate */

  115.             fps = frame_rate_tab[s->frame_rate_index];

  116.             time_code = s->fake_picture_number * FRAME_RATE_BASE;

  117.             s->gop_picture_number = s->fake_picture_number;

  118.             put_bits(&s->pb, 5, (time_code / (fps * 3600)) % 24);

  119.             put_bits(&s->pb, 6, (time_code / (fps * 60)) % 60);

  120.             put_bits(&s->pb, 1, 1);

  121.             put_bits(&s->pb, 6, (time_code / fps) % 60);

  122.             put_bits(&s->pb, 6, (time_code % fps) / FRAME_RATE_BASE);

  123.             put_bits(&s->pb, 1, 1); /* closed gop */

  124.             put_bits(&s->pb, 1, 0); /* broken link */

  125.         }

  126. 

  127.         if (s->frame_rate < (24 * FRAME_RATE_BASE) && s->picture_number > 0) {

  128.             /* insert empty P pictures to slow down to the desired

  129.                frame rate. Each fake pictures takes about 20 bytes */

  130.             fps = frame_rate_tab[s->frame_rate_index];

  131.             n = ((s->picture_number * fps) / s->frame_rate) - 1;

  132.             while (s->fake_picture_number < n) {

  133.                 mpeg1_skip_picture(s, s->fake_picture_number - 

  134.                                    s->gop_picture_number); 

  135.                 s->fake_picture_number++;

  136.             }

  137. 

  138.         }

  139.         s->fake_picture_number++;

  140. }

  141. 

  142. 

  143. /* insert a fake P picture */

  144. static void mpeg1_skip_picture(MpegEncContext *s, int pict_num)

  145. {

  146.     unsigned int mb_incr;

  147. 

  148.     /* mpeg1 picture header */

  149.     put_header(s, PICTURE_START_CODE);

  150.     /* temporal reference */

  151.     put_bits(&s->pb, 10, pict_num & 0x3ff); 

  152.     

  153.     put_bits(&s->pb, 3, P_TYPE);

  154.     put_bits(&s->pb, 16, 0xffff); /* non constant bit rate */

  155.     

  156.     put_bits(&s->pb, 1, 1); /* integer coordinates */

  157.     put_bits(&s->pb, 3, 1); /* forward_f_code */

  158.     

  159.     put_bits(&s->pb, 1, 0); /* extra bit picture */

  160.     

  161.     /* only one slice */

  162.     put_header(s, SLICE_MIN_START_CODE);

  163.     put_bits(&s->pb, 5, 1); /* quantizer scale */

  164.     put_bits(&s->pb, 1, 0); /* slice extra information */

  165.     

  166.     mb_incr = 1;

  167.     put_bits(&s->pb, mbAddrIncrTable[mb_incr - 1][1], 

  168.              mbAddrIncrTable[mb_incr - 1][0]);

  169.     

  170.     /* empty macroblock */

  171.     put_bits(&s->pb, 3, 1); /* motion only */

  172.     

  173.     /* zero motion x & y */

  174.     put_bits(&s->pb, 1, 1); 

  175.     put_bits(&s->pb, 1, 1); 

  176. 

  177.     /* output a number of empty slice */

  178.     mb_incr = s->mb_width * s->mb_height - 1;

  179.     while (mb_incr > 33) {

  180.         put_bits(&s->pb, 11, 0x008);

  181.         mb_incr -= 33;

  182.     }

  183.     put_bits(&s->pb, mbAddrIncrTable[mb_incr - 1][1], 

  184.              mbAddrIncrTable[mb_incr - 1][0]);

  185.     

  186.     /* empty macroblock */

  187.     put_bits(&s->pb, 3, 1); /* motion only */

  188.     

  189.     /* zero motion x & y */

  190.     put_bits(&s->pb, 1, 1); 

  191.     put_bits(&s->pb, 1, 1); 

  192. }

  193. 

  194. void mpeg1_encode_picture_header(MpegEncContext *s, int picture_number)

  195. {

  196.     static int done;

  197. 

  198.     if (!done) {

  199.         done = 1;

  200.         init_rl(&rl_mpeg1);

  201.     }

  202.     mpeg1_encode_sequence_header(s);

  203. 

  204.     /* mpeg1 picture header */

  205.     put_header(s, PICTURE_START_CODE);

  206.     /* temporal reference */

  207.     put_bits(&s->pb, 10, (s->fake_picture_number - 

  208.                           s->gop_picture_number) & 0x3ff); 

  209.     

  210.     put_bits(&s->pb, 3, s->pict_type);

  211.     put_bits(&s->pb, 16, 0xffff); /* non constant bit rate */

  212.     

  213.     if (s->pict_type == P_TYPE) {

  214.         put_bits(&s->pb, 1, 0); /* half pel coordinates */

  215.         put_bits(&s->pb, 3, s->f_code); /* forward_f_code */

  216.     }

  217.     

  218.     put_bits(&s->pb, 1, 0); /* extra bit picture */

  219.     

  220.     /* only one slice */

  221.     put_header(s, SLICE_MIN_START_CODE);

  222.     put_bits(&s->pb, 5, s->qscale); /* quantizer scale */

  223.     put_bits(&s->pb, 1, 0); /* slice extra information */

  224. }

  225. 

  226. void mpeg1_encode_mb(MpegEncContext *s,

  227.                      DCTELEM block[6][64],

  228.                      int motion_x, int motion_y)

  229. {

  230.     int mb_incr, i, cbp, mb_x, mb_y;

  231. 

  232.     mb_x = s->mb_x;

  233.     mb_y = s->mb_y;

  234. 

  235.     /* compute cbp */

  236.     cbp = 0;

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

  238.         if (s->block_last_index[i] >= 0)

  239.             cbp |= 1 << (5 - i);

  240.     }

  241. 

  242.     /* skip macroblock, except if first or last macroblock of a slice */

  243.     if ((cbp | motion_x | motion_y) == 0 &&

  244.         (!((mb_x | mb_y) == 0 ||

  245.            (mb_x == s->mb_width - 1 && mb_y == s->mb_height - 1)))) {

  246.         s->mb_incr++;

  247.     } else {

  248.         /* output mb incr */

  249.         mb_incr = s->mb_incr;

  250. 

  251.         while (mb_incr > 33) {

  252.             put_bits(&s->pb, 11, 0x008);

  253.             mb_incr -= 33;

  254.         }

  255.         put_bits(&s->pb, mbAddrIncrTable[mb_incr - 1][1], 

  256.                  mbAddrIncrTable[mb_incr - 1][0]);

  257.         

  258.         if (s->pict_type == I_TYPE) {

  259.             put_bits(&s->pb, 1, 1); /* macroblock_type : macroblock_quant = 0 */

  260.         } else {

  261.             if (s->mb_intra) {

  262.                 put_bits(&s->pb, 5, 0x03);

  263.             } else {

  264.                 if (cbp != 0) {

  265.                     if (motion_x == 0 && motion_y == 0) {

  266.                         put_bits(&s->pb, 2, 1); /* macroblock_pattern only */

  267.                         put_bits(&s->pb, mbPatTable[cbp - 1][1], mbPatTable[cbp - 1][0]);

  268.                     } else {

  269.                         put_bits(&s->pb, 1, 1); /* motion + cbp */

  270.                         mpeg1_encode_motion(s, motion_x - s->last_mv[0][0][0]); 

  271.                         mpeg1_encode_motion(s, motion_y - s->last_mv[0][0][1]); 

  272.                         put_bits(&s->pb, mbPatTable[cbp - 1][1], mbPatTable[cbp - 1][0]);

  273.                     }

  274.                 } else {

  275.                     put_bits(&s->pb, 3, 1); /* motion only */

  276.                     mpeg1_encode_motion(s, motion_x - s->last_mv[0][0][0]); 

  277.                     mpeg1_encode_motion(s, motion_y - s->last_mv[0][0][1]); 

  278.                 }

  279.             }

  280.         }

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

  282.             if (cbp & (1 << (5 - i))) {

  283.                 mpeg1_encode_block(s, block[i], i);

  284.             }

  285.         }

  286.         s->mb_incr = 1;

  287.     }

  288.     s->last_mv[0][0][0] = motion_x;

  289.     s->last_mv[0][0][1] = motion_y;

  290. }

  291. 

  292. static void mpeg1_encode_motion(MpegEncContext *s, int val)

  293. {

  294.     int code, bit_size, l, m, bits, range, sign;

  295. 

  296.     if (val == 0) {

  297.         /* zero vector */

  298.         code = 0;

  299.         put_bits(&s->pb,

  300.                  mbMotionVectorTable[0][1], 

  301.                  mbMotionVectorTable[0][0]); 

  302.     } else {

  303.         bit_size = s->f_code - 1;

  304.         range = 1 << bit_size;

  305.         /* modulo encoding */

  306.         l = 16 * range;

  307.         m = 2 * l;

  308.         if (val < -l) {

  309.             val += m;

  310.         } else if (val >= l) {

  311.             val -= m;

  312.         }

  313. 

  314.         if (val >= 0) {

  315.             val--;

  316.             code = (val >> bit_size) + 1;

  317.             bits = val & (range - 1);

  318.             sign = 0;

  319.         } else {

  320.             val = -val;

  321.             val--;

  322.             code = (val >> bit_size) + 1;

  323.             bits = val & (range - 1);

  324.             sign = 1;

  325.         }

  326.         put_bits(&s->pb,

  327.                  mbMotionVectorTable[code][1], 

  328.                  mbMotionVectorTable[code][0]); 

  329.         put_bits(&s->pb, 1, sign);

  330.         if (bit_size > 0) {

  331.             put_bits(&s->pb, bit_size, bits);

  332.         }

  333.     }

  334. }

  335. 

  336. static inline void encode_dc(MpegEncContext *s, int diff, int component)

  337. {

  338.     int adiff, index;

  339. 

  340.     adiff = abs(diff);

  341.     index = vlc_dc_table[adiff];

  342.     if (component == 0) {

  343.         put_bits(&s->pb, vlc_dc_lum_bits[index], vlc_dc_lum_code[index]);

  344.     } else {

  345.         put_bits(&s->pb, vlc_dc_chroma_bits[index], vlc_dc_chroma_code[index]);

  346.     }

  347.     if (diff > 0) {

  348.         put_bits(&s->pb, index, (diff & ((1 << index) - 1)));

  349.     } else if (diff < 0) {

  350.         put_bits(&s->pb, index, ((diff - 1) & ((1 << index) - 1)));

  351.     }

  352. }

  353. 

  354. static void mpeg1_encode_block(MpegEncContext *s, 

  355.                                DCTELEM *block, 

  356.                                int n)

  357. {

  358.     int alevel, level, last_non_zero, dc, diff, i, j, run, last_index, sign;

  359.     int code, component;

  360.     RLTable *rl = &rl_mpeg1;

  361. 

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

  363. 

  364.     /* DC coef */

  365.     if (s->mb_intra) {

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

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

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

  369.         encode_dc(s, diff, component);

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

  371.         i = 1;

  372.     } else {

  373.         /* encode the first coefficient : needs to be done here because

  374.            it is handled slightly differently */

  375.         level = block[0];

  376.         if (abs(level) == 1) {

  377.                 code = ((UINT32)level >> 31); /* the sign bit */

  378.                 put_bits(&s->pb, 2, code | 0x02);

  379.                 i = 1;

  380.         } else {

  381.             i = 0;

  382.             last_non_zero = -1;

  383.             goto next_coef;

  384.         }

  385.     }

  386. 

  387.     /* now quantify & encode AC coefs */

  388.     last_non_zero = i - 1;

  389.     for(;i<=last_index;i++) {

  390.         j = zigzag_direct[i];

  391.         level = block[j];

  392.     next_coef:

  393. #if 0

  394.         if (level != 0)

  395.             dprintf("level[%d]=%d\n", i, level);

  396. #endif            

  397.         /* encode using VLC */

  398.         if (level != 0) {

  399.             run = i - last_non_zero - 1;

  400.             sign = 0;

  401.             alevel = level;

  402.             if (alevel < 0) {

  403. 		sign = 1;

  404.                 alevel = -alevel;

  405. 	    }

  406.             code = get_rl_index(rl, 0, run, alevel);

  407.             put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);

  408.             if (code != rl->n) {

  409.                 put_bits(&s->pb, 1, sign);

  410.             } else {

  411.                 /* escape: only clip in this case */

  412.                 put_bits(&s->pb, 6, run);

  413.                 if (alevel < 128) {

  414.                     put_bits(&s->pb, 8, level & 0xff);

  415.                 } else {

  416.                     if (level < 0) {

  417.                         put_bits(&s->pb, 16, 0x8001 + level + 255);

  418.                     } else {

  419.                         put_bits(&s->pb, 16, level & 0xffff);

  420.                     }

  421.                 }

  422.             }

  423.             last_non_zero = i;

  424.         }

  425.     }

  426.     /* end of block */

  427.     put_bits(&s->pb, 2, 0x2);

  428. }

  429. 

  430. /******************************************/

  431. /* decoding */

  432. 

  433. static VLC dc_lum_vlc;

  434. static VLC dc_chroma_vlc;

  435. static VLC mv_vlc;

  436. static VLC mbincr_vlc;

  437. static VLC mb_ptype_vlc;

  438. static VLC mb_btype_vlc;

  439. static VLC mb_pat_vlc;

  440. 

  441. void mpeg1_init_vlc(MpegEncContext *s)

  442. {

  443.     static int done = 0;

  444. 

  445.     if (!done) {

  446. 

  447.         init_vlc(&dc_lum_vlc, 9, 12, 

  448.                  vlc_dc_lum_bits, 1, 1,

  449.                  vlc_dc_lum_code, 2, 2);

  450.         init_vlc(&dc_chroma_vlc, 9, 12, 

  451.                  vlc_dc_chroma_bits, 1, 1,

  452.                  vlc_dc_chroma_code, 2, 2);

  453.         init_vlc(&mv_vlc, 9, 17, 

  454.                  &mbMotionVectorTable[0][1], 2, 1,

  455.                  &mbMotionVectorTable[0][0], 2, 1);

  456.         init_vlc(&mbincr_vlc, 9, 34, 

  457.                  &mbAddrIncrTable[0][1], 2, 1,

  458.                  &mbAddrIncrTable[0][0], 2, 1);

  459.         init_vlc(&mb_pat_vlc, 9, 63, 

  460.                  &mbPatTable[0][1], 2, 1,

  461.                  &mbPatTable[0][0], 2, 1);

  462.         

  463.         init_vlc(&mb_ptype_vlc, 6, 32, 

  464.                  &table_mb_ptype[0][1], 2, 1,

  465.                  &table_mb_ptype[0][0], 2, 1);

  466.         init_vlc(&mb_btype_vlc, 6, 32, 

  467.                  &table_mb_btype[0][1], 2, 1,

  468.                  &table_mb_btype[0][0], 2, 1);

  469.         init_rl(&rl_mpeg1);

  470.         init_rl(&rl_mpeg2);

  471.         /* cannot use generic init because we must add the EOB code */

  472.         init_vlc(&rl_mpeg1.vlc, 9, rl_mpeg1.n + 2, 

  473.                  &rl_mpeg1.table_vlc[0][1], 4, 2,

  474.                  &rl_mpeg1.table_vlc[0][0], 4, 2);

  475.         init_vlc(&rl_mpeg2.vlc, 9, rl_mpeg2.n + 2, 

  476.                  &rl_mpeg2.table_vlc[0][1], 4, 2,

  477.                  &rl_mpeg2.table_vlc[0][0], 4, 2);

  478.     }

  479. }

  480. 

  481. static inline int get_dmv(MpegEncContext *s)

  482. {

  483.     if(get_bits(&s->gb, 1)) 

  484.         return 1 - (get_bits(&s->gb, 1) << 1);

  485.     else

  486.         return 0;

  487. }

  488. 

  489. /* motion type (for mpeg2) */

  490. #define MT_FIELD 1

  491. #define MT_FRAME 2

  492. #define MT_16X8  2

  493. #define MT_DMV   3

  494. 

  495. static int mpeg_decode_mb(MpegEncContext *s,

  496.                           DCTELEM block[6][64])

  497. {

  498.     int i, j, k, cbp, val, code, mb_type, motion_type;

  499.     

  500.     /* skip mb handling */

  501.     if (s->mb_incr == 0) {

  502.         /* read again increment */

  503.         s->mb_incr = 1;

  504.         for(;;) {

  505.             code = get_vlc(&s->gb, &mbincr_vlc);

  506.             if (code < 0)

  507.                 return 1; /* error = end of slice */

  508.             if (code >= 33) {

  509.                 if (code == 33) {

  510.                     s->mb_incr += 33;

  511.                 }

  512.                 /* otherwise, stuffing, nothing to do */

  513.             } else {

  514.                 s->mb_incr += code;

  515.                 break;

  516.             }

  517.         }

  518.     }

  519.     if (++s->mb_x >= s->mb_width) {

  520.         s->mb_x = 0;

  521.         if (s->mb_y >= (s->mb_height - 1))

  522.             return -1;

  523.         s->mb_y++;

  524.     }

  525.     dprintf("decode_mb: x=%d y=%d\n", s->mb_x, s->mb_y);

  526. 

  527.     if (--s->mb_incr != 0) {

  528.         /* skip mb */

  529.         s->mb_intra = 0;

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

  531.             s->block_last_index[i] = -1;

  532.         s->mv_type = MV_TYPE_16X16;

  533.         if (s->pict_type == P_TYPE) {

  534.             /* if P type, zero motion vector is implied */

  535.             s->mv_dir = MV_DIR_FORWARD;

  536.             s->mv[0][0][0] = s->mv[0][0][1] = 0;

  537.             s->last_mv[0][0][0] = s->last_mv[0][0][1] = 0;

  538.         } else {

  539.             /* if B type, reuse previous vectors and directions */

  540.             s->mv[0][0][0] = s->last_mv[0][0][0];

  541.             s->mv[0][0][1] = s->last_mv[0][0][1];

  542.             s->mv[1][0][0] = s->last_mv[1][0][0];

  543.             s->mv[1][0][1] = s->last_mv[1][0][1];

  544.         }

  545.         s->mb_skiped = 1;

  546.         return 0;

  547.     }

  548. 

  549.     switch(s->pict_type) {

  550.     default:

  551.     case I_TYPE:

  552.         if (get_bits(&s->gb, 1) == 0) {

  553.             if (get_bits(&s->gb, 1) == 0)

  554.                 return -1;

  555.             mb_type = MB_QUANT | MB_INTRA;

  556.         } else {

  557.             mb_type = MB_INTRA;

  558.         }

  559.         break;

  560.     case P_TYPE:

  561.         mb_type = get_vlc(&s->gb, &mb_ptype_vlc);

  562.         if (mb_type < 0)

  563.             return -1;

  564.         break;

  565.     case B_TYPE:

  566.         mb_type = get_vlc(&s->gb, &mb_btype_vlc);

  567.         if (mb_type < 0)

  568.             return -1;

  569.         break;

  570.     }

  571.     dprintf("mb_type=%x\n", mb_type);

  572.     motion_type = 0; /* avoid warning */

  573.     if (mb_type & (MB_FOR|MB_BACK)) {

  574.         /* get additionnal motion vector type */

  575.         if (s->picture_structure == PICT_FRAME && s->frame_pred_frame_dct) 

  576.             motion_type = MT_FRAME;

  577.         else

  578.             motion_type = get_bits(&s->gb, 2);

  579.     }

  580.     /* compute dct type */

  581.     if (s->picture_structure == PICT_FRAME && 

  582.         !s->frame_pred_frame_dct &&

  583.         (mb_type & (MB_PAT | MB_INTRA))) {

  584.         s->interlaced_dct = get_bits(&s->gb, 1);

  585. #ifdef DEBUG

  586.         if (s->interlaced_dct)

  587.             printf("interlaced_dct\n");

  588. #endif

  589.     } else {

  590.         s->interlaced_dct = 0; /* frame based */

  591.     }

  592. 

  593.     if (mb_type & MB_QUANT) {

  594.         if (s->mpeg2) {

  595.             if (s->q_scale_type) {

  596.                 s->qscale = non_linear_qscale[get_bits(&s->gb, 5)];

  597.             } else {

  598.                 s->qscale = get_bits(&s->gb, 5) << 1;

  599.             }

  600.         } else {

  601.             /* for mpeg1, we use the generic unquant code */

  602.             s->qscale = get_bits(&s->gb, 5);

  603.         }

  604.     }

  605.     if (mb_type & MB_INTRA) {

  606.         if (s->concealment_motion_vectors) {

  607.             /* just parse them */

  608.             if (s->picture_structure != PICT_FRAME) 

  609.                 get_bits(&s->gb, 1); /* field select */

  610.             mpeg_decode_motion(s, s->mpeg_f_code[0][0], 0);

  611.             mpeg_decode_motion(s, s->mpeg_f_code[0][1], 0);

  612.         }

  613.         s->mb_intra = 1;

  614.         cbp = 0x3f;

  615.         memset(s->last_mv, 0, sizeof(s->last_mv)); /* reset mv prediction */

  616.     } else {

  617.         s->mb_intra = 0;

  618.         cbp = 0;

  619.     }

  620.     /* special case of implicit zero motion vector */

  621.     if (s->pict_type == P_TYPE && !(mb_type & MB_FOR)) {

  622.         s->mv_dir = MV_DIR_FORWARD;

  623.         s->mv_type = MV_TYPE_16X16;

  624.         s->last_mv[0][0][0] = 0;

  625.         s->last_mv[0][0][1] = 0;

  626.         s->mv[0][0][0] = 0;

  627.         s->mv[0][0][1] = 0;

  628.     } else if (mb_type & (MB_FOR | MB_BACK)) {

  629.         /* motion vectors */

  630.         s->mv_dir = 0;

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

  632.             if (mb_type & (MB_FOR >> i)) {

  633.                 s->mv_dir |= (MV_DIR_FORWARD >> i);

  634.                 dprintf("mv_type=%d\n", motion_type);

  635.                 switch(motion_type) {

  636.                 case MT_FRAME: /* or MT_16X8 */

  637.                     if (s->picture_structure == PICT_FRAME) {

  638.                         /* MT_FRAME */

  639.                         s->mv_type = MV_TYPE_16X16;

  640.                         for(k=0;k<2;k++) {

  641.                             val = mpeg_decode_motion(s, s->mpeg_f_code[i][k], 

  642.                                                      s->last_mv[i][0][k]);

  643.                             s->last_mv[i][0][k] = val;

  644.                             s->last_mv[i][1][k] = val;

  645.                             /* full_pel: only for mpeg1 */

  646.                             if (s->full_pel[i])

  647.                                 val = val << 1;

  648.                             s->mv[i][0][k] = val;

  649.                             dprintf("mv%d: %d\n", k, val);

  650.                         }

  651.                     } else {

  652.                         /* MT_16X8 */

  653.                         s->mv_type = MV_TYPE_16X8;

  654.                         for(j=0;j<2;j++) {

  655.                             s->field_select[i][j] = get_bits(&s->gb, 1);

  656.                             for(k=0;k<2;k++) {

  657.                                 val = mpeg_decode_motion(s, s->mpeg_f_code[i][k],

  658.                                                          s->last_mv[i][j][k]);

  659.                                 s->last_mv[i][j][k] = val;

  660.                                 s->mv[i][j][k] = val;

  661.                             }

  662.                         }

  663.                     }

  664.                     break;

  665.                 case MT_FIELD:

  666.                     if (s->picture_structure == PICT_FRAME) {

  667.                         s->mv_type = MV_TYPE_FIELD;

  668.                         for(j=0;j<2;j++) {

  669.                             s->field_select[i][j] = get_bits(&s->gb, 1);

  670.                             val = mpeg_decode_motion(s, s->mpeg_f_code[i][0],

  671.                                                      s->last_mv[i][j][0]);

  672.                             s->last_mv[i][j][0] = val;

  673.                             s->mv[i][j][0] = val;

  674.                             dprintf("fmx=%d\n", val);

  675.                             val = mpeg_decode_motion(s, s->mpeg_f_code[i][1],

  676.                                                      s->last_mv[i][j][1] >> 1);

  677.                             s->last_mv[i][j][1] = val << 1;

  678.                             s->mv[i][j][1] = val;

  679.                             dprintf("fmy=%d\n", val);

  680.                         }

  681.                     } else {

  682.                         s->mv_type = MV_TYPE_16X16;

  683.                         s->field_select[i][0] = get_bits(&s->gb, 1);

  684.                         for(k=0;k<2;k++) {

  685.                             val = mpeg_decode_motion(s, s->mpeg_f_code[i][k],

  686.                                                      s->last_mv[i][0][k]);

  687.                             s->last_mv[i][0][k] = val;

  688.                             s->last_mv[i][1][k] = val;

  689.                             s->mv[i][0][k] = val;

  690.                         }

  691.                     }

  692.                     break;

  693.                 case MT_DMV:

  694.                     {

  695.                         int dmx, dmy, mx, my, m;

  696. 

  697.                         mx = mpeg_decode_motion(s, s->mpeg_f_code[i][0], 

  698.                                                 s->last_mv[i][0][0]);

  699.                         s->last_mv[i][0][0] = mx;

  700.                         s->last_mv[i][1][0] = mx;

  701.                         dmx = get_dmv(s);

  702.                         my = mpeg_decode_motion(s, s->mpeg_f_code[i][1], 

  703.                                                 s->last_mv[i][0][1] >> 1);

  704.                         dmy = get_dmv(s);

  705.                         s->mv_type = MV_TYPE_DMV;

  706.                         /* XXX: totally broken */

  707.                         if (s->picture_structure == PICT_FRAME) {

  708.                             s->last_mv[i][0][1] = my << 1;

  709.                             s->last_mv[i][1][1] = my << 1;

  710. 

  711.                             m = s->top_field_first ? 1 : 3;

  712.                             /* top -> top pred */

  713.                             s->mv[i][0][0] = mx; 

  714.                             s->mv[i][0][1] = my << 1;

  715.                             s->mv[i][1][0] = ((mx * m + (mx > 0)) >> 1) + dmx;

  716.                             s->mv[i][1][1] = ((my * m + (my > 0)) >> 1) + dmy - 1;

  717.                             m = 4 - m;

  718.                             s->mv[i][2][0] = mx;

  719.                             s->mv[i][2][1] = my << 1;

  720.                             s->mv[i][3][0] = ((mx * m + (mx > 0)) >> 1) + dmx;

  721.                             s->mv[i][3][1] = ((my * m + (my > 0)) >> 1) + dmy + 1;

  722.                         } else {

  723.                             s->last_mv[i][0][1] = my;

  724.                             s->last_mv[i][1][1] = my;

  725.                             s->mv[i][0][0] = mx;

  726.                             s->mv[i][0][1] = my;

  727.                             s->mv[i][1][0] = ((mx + (mx > 0)) >> 1) + dmx;

  728.                             s->mv[i][1][1] = ((my + (my > 0)) >> 1) + dmy - 1 

  729.                                 /* + 2 * cur_field */;

  730.                         }

  731.                     }

  732.                     break;

  733.                 }

  734.             }

  735.         }

  736.     }

  737. 

  738.     if ((mb_type & MB_INTRA) && s->concealment_motion_vectors) {

  739.         get_bits(&s->gb, 1); /* marker */

  740.     }

  741.     

  742.     if (mb_type & MB_PAT) {

  743.         cbp = get_vlc(&s->gb, &mb_pat_vlc);

  744.         if (cbp < 0)

  745.             return -1;

  746.         cbp++;

  747.     }

  748.     dprintf("cbp=%x\n", cbp);

  749. 

  750.     if (s->mpeg2) {

  751.         if (s->mb_intra) {

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

  753.                 if (cbp & (1 << (5 - i))) {

  754.                     if (mpeg2_decode_block_intra(s, block[i], i) < 0)

  755.                         return -1;

  756.                 }

  757.             }

  758.         } else {

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

  760.                 if (cbp & (1 << (5 - i))) {

  761.                     if (mpeg2_decode_block_non_intra(s, block[i], i) < 0)

  762.                         return -1;

  763.                 }

  764.             }

  765.         }

  766.     } else {

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

  768.             if (cbp & (1 << (5 - i))) {

  769.                 if (mpeg1_decode_block(s, block[i], i) < 0)

  770.                     return -1;

  771.             }

  772.         }

  773.     }

  774.     return 0;

  775. }

  776. 

  777. /* as h263, but only 17 codes */

  778. static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred)

  779. {

  780.     int code, sign, val, m, l, shift;

  781. 

  782.     code = get_vlc(&s->gb, &mv_vlc);

  783.     if (code < 0) {

  784.         return 0xffff;

  785.     }

  786.     if (code == 0) {

  787.         return pred;

  788.     }

  789.     sign = get_bits(&s->gb, 1);

  790.     shift = fcode - 1;

  791.     val = (code - 1) << shift;

  792.     if (shift > 0)

  793.         val |= get_bits(&s->gb, shift);

  794.     val++;

  795.     if (sign)

  796.         val = -val;

  797.     val += pred;

  798.     

  799.     /* modulo decoding */

  800.     l = (1 << shift) * 16;

  801.     m = 2 * l;

  802.     if (val < -l) {

  803.         val += m;

  804.     } else if (val >= l) {

  805.         val -= m;

  806.     }

  807.     return val;

  808. }

  809. 

  810. static inline int decode_dc(MpegEncContext *s, int component)

  811. {

  812.     int code, diff;

  813. 

  814.     if (component == 0) {

  815.         code = get_vlc(&s->gb, &dc_lum_vlc);

  816.     } else {

  817.         code = get_vlc(&s->gb, &dc_chroma_vlc);

  818.     }

  819.     if (code < 0)

  820.         return 0xffff;

  821.     if (code == 0) {

  822.         diff = 0;

  823.     } else {

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

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

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

  827.     }

  828.     return diff;

  829. }

  830. 

  831. static int mpeg1_decode_block(MpegEncContext *s, 

  832.                                DCTELEM *block, 

  833.                                int n)

  834. {

  835.     int level, dc, diff, i, j, run;

  836.     int code, component;

  837.     RLTable *rl = &rl_mpeg1;

  838. 

  839.     if (s->mb_intra) {

  840.         /* DC coef */

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

  842.         diff = decode_dc(s, component);

  843.         if (diff >= 0xffff)

  844.             return -1;

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

  846.         dc += diff;

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

  848.         block[0] = dc;

  849.         dprintf("dc=%d diff=%d\n", dc, diff);

  850.         i = 1;

  851.     } else {

  852.         int bit_cnt, v;

  853.         UINT32 bit_buf;

  854.         UINT8 *buf_ptr;

  855.         i = 0;

  856.         /* special case for the first coef. no need to add a second vlc table */

  857.         SAVE_BITS(&s->gb);

  858.         SHOW_BITS(&s->gb, v, 2);

  859.         if (v & 2) {

  860.             run = 0;

  861.             level = 1 - ((v & 1) << 1);

  862.             FLUSH_BITS(2);

  863.             RESTORE_BITS(&s->gb);

  864.             goto add_coef;

  865.         }

  866.         RESTORE_BITS(&s->gb);

  867.     }

  868. 

  869.     /* now quantify & encode AC coefs */

  870.     for(;;) {

  871.         code = get_vlc(&s->gb, &rl->vlc);

  872.         if (code < 0) {

  873.             return -1;

  874.         }

  875.         if (code == 112) {

  876.             break;

  877.         } else if (code == 111) {

  878.             /* escape */

  879.             run = get_bits(&s->gb, 6);

  880.             level = get_bits(&s->gb, 8);

  881.             level = (level << 24) >> 24;

  882.             if (level == -128) {

  883.                 level = get_bits(&s->gb, 8) - 256;

  884.             } else if (level == 0) {

  885.                 level = get_bits(&s->gb, 8);

  886.             }

  887.         } else {

  888.             run = rl->table_run[code];

  889.             level = rl->table_level[code];

  890.             if (get_bits(&s->gb, 1))

  891.                 level = -level;

  892.         }

  893.         i += run;

  894.         if (i >= 64)

  895.             return -1;

  896.     add_coef:

  897.         dprintf("%d: run=%d level=%d\n", n, run, level);

  898. 	j = zigzag_direct[i];

  899.         block[j] = level;

  900.         i++;

  901.     }

  902.     s->block_last_index[n] = i;

  903.     return 0;

  904. }

  905. 

  906. /* Also does unquantization here, since I will never support mpeg2

  907.    encoding */

  908. static int mpeg2_decode_block_non_intra(MpegEncContext *s, 

  909.                                         DCTELEM *block, 

  910.                                         int n)

  911. {

  912.     int level, i, j, run;

  913.     int code;

  914.     RLTable *rl = &rl_mpeg1;

  915.     const UINT8 *scan_table;

  916.     const UINT16 *matrix;

  917.     int mismatch;

  918. 

  919.     if (s->alternate_scan)

  920.         scan_table = ff_alternate_vertical_scan;

  921.     else

  922.         scan_table = zigzag_direct;

  923.     mismatch = 1;

  924. 

  925.     {

  926.         int bit_cnt, v;

  927.         UINT32 bit_buf;

  928.         UINT8 *buf_ptr;

  929.         i = 0;

  930.         if (n < 4) 

  931.             matrix = s->non_intra_matrix;

  932.         else

  933.             matrix = s->chroma_non_intra_matrix;

  934.             

  935.         /* special case for the first coef. no need to add a second vlc table */

  936.         SAVE_BITS(&s->gb);

  937.         SHOW_BITS(&s->gb, v, 2);

  938.         if (v & 2) {

  939.             run = 0;

  940.             level = 1 - ((v & 1) << 1);

  941.             FLUSH_BITS(2);

  942.             RESTORE_BITS(&s->gb);

  943.             goto add_coef;

  944.         }

  945.         RESTORE_BITS(&s->gb);

  946.     }

  947. 

  948.     /* now quantify & encode AC coefs */

  949.     for(;;) {

  950.         code = get_vlc(&s->gb, &rl->vlc);

  951.         if (code < 0)

  952.             return -1;

  953.         if (code == 112) {

  954.             break;

  955.         } else if (code == 111) {

  956.             /* escape */

  957.             run = get_bits(&s->gb, 6);

  958.             level = get_bits(&s->gb, 12);

  959.             level = (level << 20) >> 20;

  960.         } else {

  961.             run = rl->table_run[code];

  962.             level = rl->table_level[code];

  963.             if (get_bits(&s->gb, 1))

  964.                 level = -level;

  965.         }

  966.         i += run;

  967.         if (i >= 64)

  968.             return -1;

  969.     add_coef:

  970. 	j = scan_table[i];

  971.         dprintf("%d: run=%d level=%d\n", n, run, level);

  972.         level = ((level * 2 + 1) * s->qscale * matrix[j]) / 32;

  973.         /* XXX: is it really necessary to saturate since the encoder

  974.            knows whats going on ? */

  975.         mismatch ^= level;

  976.         block[j] = level;

  977.         i++;

  978.     }

  979.     block[63] ^= (mismatch & 1);

  980.     s->block_last_index[n] = i;

  981.     return 0;

  982. }

  983. 

  984. static int mpeg2_decode_block_intra(MpegEncContext *s, 

  985.                                     DCTELEM *block, 

  986.                                     int n)

  987. {

  988.     int level, dc, diff, i, j, run;

  989.     int code, component;

  990.     RLTable *rl;

  991.     const UINT8 *scan_table;

  992.     const UINT16 *matrix;

  993.     int mismatch;

  994. 

  995.     if (s->alternate_scan)

  996.         scan_table = ff_alternate_vertical_scan;

  997.     else

  998.         scan_table = zigzag_direct;

  999.     mismatch = 1;

  1000. 

  1001.     /* DC coef */

  1002.     component = (n <= 3 ? 0 : n - 4 + 1);

  1003.     diff = decode_dc(s, component);

  1004.     if (diff >= 0xffff)

  1005.         return -1;

  1006.     dc = s->last_dc[component];

  1007.     dc += diff;

  1008.     s->last_dc[component] = dc;

  1009.     block[0] = dc << (3 - s->intra_dc_precision);

  1010.     dprintf("dc=%d\n", block[0]);

  1011.     i = 1;

  1012.     if (s->intra_vlc_format)

  1013.         rl = &rl_mpeg2;

  1014.     else

  1015.         rl = &rl_mpeg1;

  1016.     if (n < 4) 

  1017.         matrix = s->intra_matrix;

  1018.     else

  1019.         matrix = s->chroma_intra_matrix;

  1020.         

  1021.     /* now quantify & encode AC coefs */

  1022.     for(;;) {

  1023.         code = get_vlc(&s->gb, &rl->vlc);

  1024.         if (code < 0)

  1025.             return -1;

  1026.         if (code == 112) {

  1027.             break;

  1028.         } else if (code == 111) {

  1029.             /* escape */

  1030.             run = get_bits(&s->gb, 6);

  1031.             level = get_bits(&s->gb, 12);

  1032.             level = (level << 20) >> 20;

  1033.         } else {

  1034.             run = rl->table_run[code];

  1035.             level = rl->table_level[code];

  1036.             if (get_bits(&s->gb, 1))

  1037.                 level = -level;

  1038.         }

  1039.         i += run;

  1040.         if (i >= 64)

  1041.             return -1;

  1042. 	j = scan_table[i];

  1043.         dprintf("%d: run=%d level=%d\n", n, run, level);

  1044.         level = (level * s->qscale * matrix[j]) / 16;

  1045.         /* XXX: is it really necessary to saturate since the encoder

  1046.            knows whats going on ? */

  1047.         mismatch ^= level;

  1048.         block[j] = level;

  1049.         i++;

  1050.     }

  1051.     block[63] ^= (mismatch & 1);

  1052.     s->block_last_index[n] = i;

  1053.     return 0;

  1054. }

  1055. 

  1056. /* compressed picture size */

  1057. #define PICTURE_BUFFER_SIZE 100000

  1058. 

  1059. typedef struct Mpeg1Context {

  1060.     MpegEncContext mpeg_enc_ctx;

  1061.     UINT32 header_state;

  1062.     int start_code; /* current start code */

  1063.     UINT8 buffer[PICTURE_BUFFER_SIZE]; 

  1064.     UINT8 *buf_ptr;

  1065.     int buffer_size;

  1066.     int mpeg_enc_ctx_allocated; /* true if decoding context allocated */

  1067. } Mpeg1Context;

  1068. 

  1069. static int mpeg_decode_init(AVCodecContext *avctx)

  1070. {

  1071.     Mpeg1Context *s = avctx->priv_data;

  1072. 

  1073.     s->header_state = 0xff;

  1074.     s->mpeg_enc_ctx_allocated = 0;

  1075.     s->buffer_size = PICTURE_BUFFER_SIZE;

  1076.     s->start_code = -1;

  1077.     s->buf_ptr = s->buffer;

  1078.     s->mpeg_enc_ctx.picture_number = 0;

  1079.     return 0;

  1080. }

  1081. 

  1082. /* return the 8 bit start code value and update the search

  1083.    state. Return -1 if no start code found */

  1084. static int find_start_code(UINT8 **pbuf_ptr, UINT8 *buf_end, 

  1085.                            UINT32 *header_state)

  1086. {

  1087.     UINT8 *buf_ptr;

  1088.     unsigned int state, v;

  1089.     int val;

  1090. 

  1091.     state = *header_state;

  1092.     buf_ptr = *pbuf_ptr;

  1093.     while (buf_ptr < buf_end) {

  1094.         v = *buf_ptr++;

  1095.         if (state == 0x000001) {

  1096.             state = ((state << 8) | v) & 0xffffff;

  1097.             val = state;

  1098.             goto found;

  1099.         }

  1100.         state = ((state << 8) | v) & 0xffffff;

  1101.     }

  1102.     val = -1;

  1103.  found:

  1104.     *pbuf_ptr = buf_ptr;

  1105.     *header_state = state;

  1106.     return val;

  1107. }

  1108. 

  1109. static int mpeg1_decode_picture(AVCodecContext *avctx, 

  1110.                                 UINT8 *buf, int buf_size)

  1111. {

  1112.     Mpeg1Context *s1 = avctx->priv_data;

  1113.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1114.     int ref, f_code;

  1115. 

  1116.     init_get_bits(&s->gb, buf, buf_size);

  1117. 

  1118.     ref = get_bits(&s->gb, 10); /* temporal ref */

  1119.     s->pict_type = get_bits(&s->gb, 3);

  1120.     dprintf("pict_type=%d\n", s->pict_type);

  1121.     get_bits(&s->gb, 16);

  1122.     if (s->pict_type == P_TYPE || s->pict_type == B_TYPE) {

  1123.         s->full_pel[0] = get_bits(&s->gb, 1);

  1124.         f_code = get_bits(&s->gb, 3);

  1125.         if (f_code == 0)

  1126.             return -1;

  1127.         s->mpeg_f_code[0][0] = f_code;

  1128.         s->mpeg_f_code[0][1] = f_code;

  1129.     }

  1130.     if (s->pict_type == B_TYPE) {

  1131.         s->full_pel[1] = get_bits(&s->gb, 1);

  1132.         f_code = get_bits(&s->gb, 3);

  1133.         if (f_code == 0)

  1134.             return -1;

  1135.         s->mpeg_f_code[1][0] = f_code;

  1136.         s->mpeg_f_code[1][1] = f_code;

  1137.     }

  1138.     s->y_dc_scale = 8;

  1139.     s->c_dc_scale = 8;

  1140.     s->first_slice = 1;

  1141.     return 0;

  1142. }

  1143. 

  1144. static void mpeg_decode_sequence_extension(MpegEncContext *s)

  1145. {

  1146.     int horiz_size_ext, vert_size_ext;

  1147.     int bit_rate_ext, vbv_buf_ext, low_delay;

  1148.     int frame_rate_ext_n, frame_rate_ext_d;

  1149. 

  1150.     get_bits(&s->gb, 8); /* profil and level */

  1151.     get_bits(&s->gb, 1); /* progressive_sequence */

  1152.     get_bits(&s->gb, 2); /* chroma_format */

  1153.     horiz_size_ext = get_bits(&s->gb, 2);

  1154.     vert_size_ext = get_bits(&s->gb, 2);

  1155.     s->width |= (horiz_size_ext << 12);

  1156.     s->height |= (vert_size_ext << 12);

  1157.     bit_rate_ext = get_bits(&s->gb, 12);  /* XXX: handle it */

  1158.     s->bit_rate = ((s->bit_rate / 400) | (bit_rate_ext << 12)) * 400;

  1159.     get_bits(&s->gb, 1); /* marker */

  1160.     vbv_buf_ext = get_bits(&s->gb, 8);

  1161.     low_delay = get_bits(&s->gb, 1);

  1162.     frame_rate_ext_n = get_bits(&s->gb, 2);

  1163.     frame_rate_ext_d = get_bits(&s->gb, 5);

  1164.     if (frame_rate_ext_d >= 1)

  1165.         s->frame_rate = (s->frame_rate * frame_rate_ext_n) / frame_rate_ext_d;

  1166.     dprintf("sequence extension\n");

  1167.     s->mpeg2 = 1;

  1168. }

  1169. 

  1170. static void mpeg_decode_quant_matrix_extension(MpegEncContext *s)

  1171. {

  1172.     int i, v;

  1173. 

  1174.     if (get_bits(&s->gb, 1)) {

  1175.         for(i=0;i<64;i++) {

  1176.             v = get_bits(&s->gb, 8);

  1177.             s->intra_matrix[i] = v;

  1178.             s->chroma_intra_matrix[i] = v;

  1179.         }

  1180.     }

  1181.     if (get_bits(&s->gb, 1)) {

  1182.         for(i=0;i<64;i++) {

  1183.             v = get_bits(&s->gb, 8);

  1184.             s->non_intra_matrix[i] = v;

  1185.             s->chroma_non_intra_matrix[i] = v;

  1186.         }

  1187.     }

  1188.     if (get_bits(&s->gb, 1)) {

  1189.         for(i=0;i<64;i++) {

  1190.             v = get_bits(&s->gb, 8);

  1191.             s->chroma_intra_matrix[i] = v;

  1192.         }

  1193.     }

  1194.     if (get_bits(&s->gb, 1)) {

  1195.         for(i=0;i<64;i++) {

  1196.             v = get_bits(&s->gb, 8);

  1197.             s->chroma_non_intra_matrix[i] = v;

  1198.         }

  1199.     }

  1200. }

  1201. 

  1202. static void mpeg_decode_picture_coding_extension(MpegEncContext *s)

  1203. {

  1204.     s->full_pel[0] = s->full_pel[1] = 0;

  1205.     s->mpeg_f_code[0][0] = get_bits(&s->gb, 4);

  1206.     s->mpeg_f_code[0][1] = get_bits(&s->gb, 4);

  1207.     s->mpeg_f_code[1][0] = get_bits(&s->gb, 4);

  1208.     s->mpeg_f_code[1][1] = get_bits(&s->gb, 4);

  1209.     s->intra_dc_precision = get_bits(&s->gb, 2);

  1210.     s->picture_structure = get_bits(&s->gb, 2);

  1211.     s->top_field_first = get_bits(&s->gb, 1);

  1212.     s->frame_pred_frame_dct = get_bits(&s->gb, 1);

  1213.     s->concealment_motion_vectors = get_bits(&s->gb, 1);

  1214.     s->q_scale_type = get_bits(&s->gb, 1);

  1215.     s->intra_vlc_format = get_bits(&s->gb, 1);

  1216.     s->alternate_scan = get_bits(&s->gb, 1);

  1217.     s->repeat_first_field = get_bits(&s->gb, 1);

  1218.     s->chroma_420_type = get_bits(&s->gb, 1);

  1219.     s->progressive_frame = get_bits(&s->gb, 1);

  1220.     /* composite display not parsed */

  1221.     dprintf("dc_preci=%d\n", s->intra_dc_precision);

  1222.     dprintf("pict_structure=%d\n", s->picture_structure);

  1223.     dprintf("conceal=%d\n", s->concealment_motion_vectors);

  1224.     dprintf("intrafmt=%d\n", s->intra_vlc_format);

  1225.     dprintf("frame_pred_frame_dct=%d\n", s->frame_pred_frame_dct);

  1226. }

  1227. 

  1228. static void mpeg_decode_extension(AVCodecContext *avctx, 

  1229.                                   UINT8 *buf, int buf_size)

  1230. {

  1231.     Mpeg1Context *s1 = avctx->priv_data;

  1232.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1233.     int ext_type;

  1234. 

  1235.     init_get_bits(&s->gb, buf, buf_size);

  1236.     

  1237.     ext_type = get_bits(&s->gb, 4);

  1238.     switch(ext_type) {

  1239.     case 0x1:

  1240.         /* sequence ext */

  1241.         mpeg_decode_sequence_extension(s);

  1242.         break;

  1243.     case 0x3:

  1244.         /* quant matrix extension */

  1245.         mpeg_decode_quant_matrix_extension(s);

  1246.         break;

  1247.     case 0x8:

  1248.         /* picture extension */

  1249.         mpeg_decode_picture_coding_extension(s);

  1250.         break;

  1251.     }

  1252. }

  1253. 

  1254. /* return 1 if end of frame */

  1255. static int mpeg_decode_slice(AVCodecContext *avctx, 

  1256.                               AVPicture *pict,

  1257.                               int start_code,

  1258.                               UINT8 *buf, int buf_size)

  1259. {

  1260.     Mpeg1Context *s1 = avctx->priv_data;

  1261.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1262.     int ret;

  1263.     DCTELEM block[6][64];

  1264. 

  1265.     start_code = (start_code - 1) & 0xff;

  1266.     if (start_code >= s->mb_height)

  1267.         return -1;

  1268.     s->last_dc[0] = 1 << (7 + s->intra_dc_precision);

  1269.     s->last_dc[1] = s->last_dc[0];

  1270.     s->last_dc[2] = s->last_dc[0];

  1271.     memset(s->last_mv, 0, sizeof(s->last_mv));

  1272.     s->mb_x = -1;

  1273.     s->mb_y = start_code;

  1274.     s->mb_incr = 0;

  1275. 

  1276.     /* start frame decoding */

  1277.     if (s->first_slice) {

  1278.         s->first_slice = 0;

  1279.         MPV_frame_start(s);

  1280.     }

  1281. 

  1282.     init_get_bits(&s->gb, buf, buf_size);

  1283. 

  1284.     s->qscale = get_bits(&s->gb, 5);

  1285.     /* extra slice info */

  1286.     while (get_bits(&s->gb, 1) != 0) {

  1287.         get_bits(&s->gb, 8);

  1288.     }

  1289. 

  1290.     for(;;) {

  1291.         memset(block, 0, sizeof(block));

  1292.         ret = mpeg_decode_mb(s, block);

  1293.         dprintf("ret=%d\n", ret);

  1294.         if (ret < 0)

  1295.             return -1;

  1296.         if (ret == 1)

  1297.             break;

  1298.         MPV_decode_mb(s, block);

  1299.     }

  1300.     

  1301.     /* end of slice reached */

  1302.     if (s->mb_x == (s->mb_width - 1) &&

  1303.         s->mb_y == (s->mb_height - 1)) {

  1304.         /* end of image */

  1305.         UINT8 **picture;

  1306. 

  1307.         MPV_frame_end(s);

  1308. 

  1309.         /* XXX: incorrect reported qscale for mpeg2 */

  1310.         if (s->pict_type == B_TYPE) {

  1311.             picture = s->current_picture;

  1312.             avctx->quality = s->qscale;

  1313.         } else {

  1314.             /* latency of 1 frame for I and P frames */

  1315.             /* XXX: use another variable than picture_number */

  1316.             if (s->picture_number == 0) {

  1317.                 picture = NULL;

  1318.             } else {

  1319.                 picture = s->last_picture;

  1320.                 avctx->quality = s->last_qscale;

  1321.             }

  1322.             s->last_qscale = s->qscale;

  1323.             s->picture_number++;

  1324.         }

  1325.         if (picture) {

  1326.             pict->data[0] = picture[0];

  1327.             pict->data[1] = picture[1];

  1328.             pict->data[2] = picture[2];

  1329.             pict->linesize[0] = s->linesize;

  1330.             pict->linesize[1] = s->linesize / 2;

  1331.             pict->linesize[2] = s->linesize / 2;

  1332.             return 1;

  1333.         } else {

  1334.             return 0;

  1335.         }

  1336.     } else {

  1337.         return 0;

  1338.     }

  1339. }

  1340. 

  1341. static int mpeg1_decode_sequence(AVCodecContext *avctx, 

  1342.                                  UINT8 *buf, int buf_size)

  1343. {

  1344.     Mpeg1Context *s1 = avctx->priv_data;

  1345.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1346.     int width, height, i, v;

  1347.     

  1348.     init_get_bits(&s->gb, buf, buf_size);

  1349. 

  1350.     width = get_bits(&s->gb, 12);

  1351.     height = get_bits(&s->gb, 12);

  1352.     get_bits(&s->gb, 4);

  1353.     s->frame_rate_index = get_bits(&s->gb, 4);

  1354.     if (s->frame_rate_index == 0)

  1355.         return -1;

  1356.     s->bit_rate = get_bits(&s->gb, 18) * 400;

  1357.     if (get_bits(&s->gb, 1) == 0) /* marker */

  1358.         return -1;

  1359.     if (width <= 0 || height <= 0 ||

  1360.         (width % 2) != 0 || (height % 2) != 0)

  1361.         return -1;

  1362.     if (width != s->width ||

  1363.         height != s->height) {

  1364.         /* start new mpeg1 context decoding */

  1365.         s->out_format = FMT_MPEG1;

  1366.         if (s1->mpeg_enc_ctx_allocated) {

  1367.             MPV_common_end(s);

  1368.         }

  1369.         s->width = width;

  1370.         s->height = height;

  1371.         s->has_b_frames = 1;

  1372.         avctx->width = width;

  1373.         avctx->height = height;

  1374.         avctx->frame_rate = frame_rate_tab[s->frame_rate_index];

  1375.         avctx->bit_rate = s->bit_rate;

  1376.         

  1377.         if (MPV_common_init(s) < 0)

  1378.             return -1;

  1379.         mpeg1_init_vlc(s);

  1380.         s1->mpeg_enc_ctx_allocated = 1;

  1381.     }

  1382. 

  1383.     get_bits(&s->gb, 10); /* vbv_buffer_size */

  1384.     get_bits(&s->gb, 1);

  1385. 

  1386.     /* get matrix */

  1387.     if (get_bits(&s->gb, 1)) {

  1388.         for(i=0;i<64;i++) {

  1389.             v = get_bits(&s->gb, 8);

  1390.             s->intra_matrix[i] = v;

  1391.             s->chroma_intra_matrix[i] = v;

  1392.         }

  1393.     } else {

  1394.         for(i=0;i<64;i++) {

  1395.             v = default_intra_matrix[i];

  1396.             s->intra_matrix[i] = v;

  1397.             s->chroma_intra_matrix[i] = v;

  1398.         }

  1399.     }

  1400.     if (get_bits(&s->gb, 1)) {

  1401.         for(i=0;i<64;i++) {

  1402.             v = get_bits(&s->gb, 8);

  1403.             s->non_intra_matrix[i] = v;

  1404.             s->chroma_non_intra_matrix[i] = v;

  1405.         }

  1406.     } else {

  1407.         for(i=0;i<64;i++) {

  1408.             v = default_non_intra_matrix[i];

  1409.             s->non_intra_matrix[i] = v;

  1410.             s->chroma_non_intra_matrix[i] = v;

  1411.         }

  1412.     }

  1413. 

  1414.     /* we set mpeg2 parameters so that it emulates mpeg1 */

  1415.     s->progressive_sequence = 1;

  1416.     s->progressive_frame = 1;

  1417.     s->picture_structure = PICT_FRAME;

  1418.     s->frame_pred_frame_dct = 1;

  1419.     s->mpeg2 = 0;

  1420.     return 0;

  1421. }

  1422. 

  1423. /* handle buffering and image synchronisation */

  1424. static int mpeg_decode_frame(AVCodecContext *avctx, 

  1425.                              void *data, int *data_size,

  1426.                              UINT8 *buf, int buf_size)

  1427. {

  1428.     Mpeg1Context *s = avctx->priv_data;

  1429.     UINT8 *buf_end, *buf_ptr, *buf_start;

  1430.     int len, start_code_found, ret, code, start_code, input_size;

  1431.     AVPicture *picture = data;

  1432. 

  1433.     dprintf("fill_buffer\n");

  1434. 

  1435.     *data_size = 0;

  1436.     /* special case for last picture */

  1437.     if (buf_size == 0) {

  1438.         MpegEncContext *s2 = &s->mpeg_enc_ctx;

  1439.         if (s2->picture_number > 0) {

  1440.             picture->data[0] = s2->next_picture[0];

  1441.             picture->data[1] = s2->next_picture[1];

  1442.             picture->data[2] = s2->next_picture[2];

  1443.             picture->linesize[0] = s2->linesize;

  1444.             picture->linesize[1] = s2->linesize / 2;

  1445.             picture->linesize[2] = s2->linesize / 2;

  1446.             *data_size = sizeof(AVPicture);

  1447.         }

  1448.         return 0;

  1449.     }

  1450. 

  1451.     buf_ptr = buf;

  1452.     buf_end = buf + buf_size;

  1453.     while (buf_ptr < buf_end) {

  1454.         buf_start = buf_ptr;

  1455.         /* find start next code */

  1456.         code = find_start_code(&buf_ptr, buf_end, &s->header_state);

  1457.         if (code >= 0) {

  1458.             start_code_found = 1;

  1459.         } else {

  1460.             start_code_found = 0;

  1461.         }

  1462.         /* copy to buffer */

  1463.         len = buf_ptr - buf_start;

  1464.         if (len + (s->buf_ptr - s->buffer) > s->buffer_size) {

  1465.             /* data too big : flush */

  1466.             s->buf_ptr = s->buffer;

  1467.             if (start_code_found)

  1468.                 s->start_code = code;

  1469.         } else {

  1470.             memcpy(s->buf_ptr, buf_start, len);

  1471.             s->buf_ptr += len;

  1472.             

  1473.             if (start_code_found) {

  1474.                 /* prepare data for next start code */

  1475.                 input_size = s->buf_ptr - s->buffer;

  1476.                 start_code = s->start_code;

  1477.                 s->buf_ptr = s->buffer;

  1478.                 s->start_code = code;

  1479.                 switch(start_code) {

  1480.                 case SEQ_START_CODE:

  1481.                     mpeg1_decode_sequence(avctx, s->buffer, 

  1482.                                           input_size);

  1483.                     break;

  1484.                             

  1485.                 case PICTURE_START_CODE:

  1486.                     /* we have a complete image : we try to decompress it */

  1487.                     mpeg1_decode_picture(avctx, 

  1488.                                          s->buffer, input_size);

  1489.                     break;

  1490.                 case EXT_START_CODE:

  1491.                     mpeg_decode_extension(avctx,

  1492.                                           s->buffer, input_size);

  1493.                     break;

  1494.                 default:

  1495.                     if (start_code >= SLICE_MIN_START_CODE &&

  1496.                         start_code <= SLICE_MAX_START_CODE) {

  1497.                         ret = mpeg_decode_slice(avctx, picture,

  1498.                                                 start_code, s->buffer, input_size);

  1499.                         if (ret == 1) {

  1500.                             /* got a picture: exit */

  1501.                             *data_size = sizeof(AVPicture);

  1502.                             goto the_end;

  1503.                         }

  1504.                     }

  1505.                     break;

  1506.                 }

  1507.             }

  1508.         }

  1509.     }

  1510.  the_end:

  1511.     return buf_ptr - buf;

  1512. }

  1513. 

  1514. static int mpeg_decode_end(AVCodecContext *avctx)

  1515. {

  1516.     Mpeg1Context *s = avctx->priv_data;

  1517. 

  1518.     if (s->mpeg_enc_ctx_allocated)

  1519.         MPV_common_end(&s->mpeg_enc_ctx);

  1520.     return 0;

  1521. }

  1522. 

  1523. AVCodec mpeg_decoder = {

  1524.     "mpegvideo",

  1525.     CODEC_TYPE_VIDEO,

  1526.     CODEC_ID_MPEG1VIDEO,

  1527.     sizeof(Mpeg1Context),

  1528.     mpeg_decode_init,

  1529.     NULL,

  1530.     mpeg_decode_end,

  1531.     mpeg_decode_frame,

  1532. };