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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. //#define DEBUG

  20. #include "avcodec.h"

  21. #include "dsputil.h"

  22. #include "mpegvideo.h"

  23. 

  24. #include "mpeg12data.h"

  25. 

  26. /* Start codes. */

  27. #define SEQ_END_CODE		0x000001b7

  28. #define SEQ_START_CODE		0x000001b3

  29. #define GOP_START_CODE		0x000001b8

  30. #define PICTURE_START_CODE	0x00000100

  31. #define SLICE_MIN_START_CODE	0x00000101

  32. #define SLICE_MAX_START_CODE	0x000001af

  33. #define EXT_START_CODE		0x000001b5

  34. #define USER_START_CODE		0x000001b2

  35. 

  36. static void mpeg1_encode_block(MpegEncContext *s, 

  37.                          DCTELEM *block, 

  38.                          int component);

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

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

  41. static int mpeg1_decode_block(MpegEncContext *s, 

  42.                               DCTELEM *block, 

  43.                               int n);

  44. static int mpeg2_decode_block_non_intra(MpegEncContext *s, 

  45.                                         DCTELEM *block, 

  46.                                         int n);

  47. static int mpeg2_decode_block_intra(MpegEncContext *s, 

  48.                                     DCTELEM *block, 

  49.                                     int n);

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

  51. 

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

  53. {

  54.     align_put_bits(&s->pb);

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

  56. }

  57. 

  58. /* put sequence header if needed */

  59. static void mpeg1_encode_sequence_header(MpegEncContext *s)

  60. {

  61.         unsigned int vbv_buffer_size;

  62.         unsigned int fps, v;

  63.         int n;

  64.         UINT64 time_code;

  65.         

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

  67.             /* mpeg1 header repeated every gop */

  68.             put_header(s, SEQ_START_CODE);

  69.             

  70.             /* search closest frame rate */

  71.             {

  72.                 int i, dmin, d;

  73.                 s->frame_rate_index = 0;

  74.                 dmin = 0x7fffffff;

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

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

  77.                     if (d < dmin) {

  78.                         dmin = d;

  79.                         s->frame_rate_index = i;

  80.                     }

  81.                 }

  82.             }

  83.  

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

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

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

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

  88.             v = s->bit_rate / 400;

  89.             if (v > 0x3ffff)

  90.                 v = 0x3ffff;

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

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

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

  94.                some margin just in case */

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

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

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

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

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

  100. 

  101.             put_header(s, GOP_START_CODE);

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

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

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

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

  106.             time_code = s->fake_picture_number * FRAME_RATE_BASE;

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

  108.             put_bits(&s->pb, 5, (UINT32)((time_code / (fps * 3600)) % 24));

  109.             put_bits(&s->pb, 6, (UINT32)((time_code / (fps * 60)) % 60));

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

  111.             put_bits(&s->pb, 6, (UINT32)((time_code / fps) % 60));

  112.             put_bits(&s->pb, 6, (UINT32)((time_code % fps) / FRAME_RATE_BASE));

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

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

  115.         }

  116. 

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

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

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

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

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

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

  123.                 mpeg1_skip_picture(s, s->fake_picture_number - 

  124.                                    s->gop_picture_number); 

  125.                 s->fake_picture_number++;

  126.             }

  127. 

  128.         }

  129.         s->fake_picture_number++;

  130. }

  131. 

  132. 

  133. /* insert a fake P picture */

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

  135. {

  136.     unsigned int mb_incr;

  137. 

  138.     /* mpeg1 picture header */

  139.     put_header(s, PICTURE_START_CODE);

  140.     /* temporal reference */

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

  142.     

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

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

  145.     

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

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

  148.     

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

  150.     

  151.     /* only one slice */

  152.     put_header(s, SLICE_MIN_START_CODE);

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

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

  155.     

  156.     mb_incr = 1;

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

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

  159.     

  160.     /* empty macroblock */

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

  162.     

  163.     /* zero motion x & y */

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

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

  166. 

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

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

  169.     while (mb_incr > 33) {

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

  171.         mb_incr -= 33;

  172.     }

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

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

  175.     

  176.     /* empty macroblock */

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

  178.     

  179.     /* zero motion x & y */

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

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

  182. }

  183. 

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

  185. {

  186.     static int done;

  187. 

  188.     if (!done) {

  189.         done = 1;

  190.         init_rl(&rl_mpeg1);

  191.     }

  192.     mpeg1_encode_sequence_header(s);

  193. 

  194.     /* mpeg1 picture header */

  195.     put_header(s, PICTURE_START_CODE);

  196.     /* temporal reference */

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

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

  199.     

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

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

  202.     

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

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

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

  206.     }

  207.     

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

  209.     

  210.     /* only one slice */

  211.     put_header(s, SLICE_MIN_START_CODE);

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

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

  214. }

  215. 

  216. void mpeg1_encode_mb(MpegEncContext *s,

  217.                      DCTELEM block[6][64],

  218.                      int motion_x, int motion_y)

  219. {

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

  221. 

  222.     mb_x = s->mb_x;

  223.     mb_y = s->mb_y;

  224. 

  225.     /* compute cbp */

  226.     cbp = 0;

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

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

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

  230.     }

  231. 

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

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

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

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

  236.         s->mb_incr++;

  237.     } else {

  238.         /* output mb incr */

  239.         mb_incr = s->mb_incr;

  240. 

  241.         while (mb_incr > 33) {

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

  243.             mb_incr -= 33;

  244.         }

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

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

  247.         

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

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

  250.         } else {

  251.             if (s->mb_intra) {

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

  253.             } else {

  254.                 if (cbp != 0) {

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

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

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

  258.                     } else {

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

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

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

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

  263.                     }

  264.                 } else {

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

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

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

  268.                 }

  269.             }

  270.         }

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

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

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

  274.             }

  275.         }

  276.         s->mb_incr = 1;

  277.     }

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

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

  280. }

  281. 

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

  283. {

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

  285. 

  286.     if (val == 0) {

  287.         /* zero vector */

  288.         code = 0;

  289.         put_bits(&s->pb,

  290.                  mbMotionVectorTable[0][1], 

  291.                  mbMotionVectorTable[0][0]); 

  292.     } else {

  293.         bit_size = s->f_code - 1;

  294.         range = 1 << bit_size;

  295.         /* modulo encoding */

  296.         l = 16 * range;

  297.         m = 2 * l;

  298.         if (val < -l) {

  299.             val += m;

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

  301.             val -= m;

  302.         }

  303. 

  304.         if (val >= 0) {

  305.             val--;

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

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

  308.             sign = 0;

  309.         } else {

  310.             val = -val;

  311.             val--;

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

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

  314.             sign = 1;

  315.         }

  316.         put_bits(&s->pb,

  317.                  mbMotionVectorTable[code][1], 

  318.                  mbMotionVectorTable[code][0]); 

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

  320.         if (bit_size > 0) {

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

  322.         }

  323.     }

  324. }

  325. 

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

  327. {

  328.     int adiff, index;

  329. 

  330.     adiff = abs(diff);

  331.     index = vlc_dc_table[adiff];

  332.     if (component == 0) {

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

  334.     } else {

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

  336.     }

  337.     if (diff > 0) {

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

  339.     } else if (diff < 0) {

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

  341.     }

  342. }

  343. 

  344. static void mpeg1_encode_block(MpegEncContext *s, 

  345.                                DCTELEM *block, 

  346.                                int n)

  347. {

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

  349.     int code, component;

  350.     RLTable *rl = &rl_mpeg1;

  351. 

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

  353. 

  354.     /* DC coef */

  355.     if (s->mb_intra) {

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

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

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

  359.         encode_dc(s, diff, component);

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

  361.         i = 1;

  362.     } else {

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

  364.            it is handled slightly differently */

  365.         level = block[0];

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

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

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

  369.                 i = 1;

  370.         } else {

  371.             i = 0;

  372.             last_non_zero = -1;

  373.             goto next_coef;

  374.         }

  375.     }

  376. 

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

  378.     last_non_zero = i - 1;

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

  380.         j = zigzag_direct[i];

  381.         level = block[j];

  382.     next_coef:

  383. #if 0

  384.         if (level != 0)

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

  386. #endif            

  387.         /* encode using VLC */

  388.         if (level != 0) {

  389.             run = i - last_non_zero - 1;

  390.             sign = 0;

  391.             alevel = level;

  392.             if (alevel < 0) {

  393. 		sign = 1;

  394.                 alevel = -alevel;

  395. 	    }

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

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

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

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

  400.             } else {

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

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

  403.                 if (alevel < 128) {

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

  405.                 } else {

  406.                     if (level < 0) {

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

  408.                     } else {

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

  410.                     }

  411.                 }

  412.             }

  413.             last_non_zero = i;

  414.         }

  415.     }

  416.     /* end of block */

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

  418. }

  419. 

  420. /******************************************/

  421. /* decoding */

  422. 

  423. static VLC dc_lum_vlc;

  424. static VLC dc_chroma_vlc;

  425. static VLC mv_vlc;

  426. static VLC mbincr_vlc;

  427. static VLC mb_ptype_vlc;

  428. static VLC mb_btype_vlc;

  429. static VLC mb_pat_vlc;

  430. 

  431. void mpeg1_init_vlc(MpegEncContext *s)

  432. {

  433.     static int done = 0;

  434. 

  435.     if (!done) {

  436. 

  437.         init_vlc(&dc_lum_vlc, 9, 12, 

  438.                  vlc_dc_lum_bits, 1, 1,

  439.                  vlc_dc_lum_code, 2, 2);

  440.         init_vlc(&dc_chroma_vlc, 9, 12, 

  441.                  vlc_dc_chroma_bits, 1, 1,

  442.                  vlc_dc_chroma_code, 2, 2);

  443.         init_vlc(&mv_vlc, 9, 17, 

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

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

  446.         init_vlc(&mbincr_vlc, 9, 35, 

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

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

  449.         init_vlc(&mb_pat_vlc, 9, 63, 

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

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

  452.         

  453.         init_vlc(&mb_ptype_vlc, 6, 32, 

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

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

  456.         init_vlc(&mb_btype_vlc, 6, 32, 

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

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

  459.         init_rl(&rl_mpeg1);

  460.         init_rl(&rl_mpeg2);

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

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

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

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

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

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

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

  468.     }

  469. }

  470. 

  471. static inline int get_dmv(MpegEncContext *s)

  472. {

  473.     if(get_bits1(&s->gb)) 

  474.         return 1 - (get_bits1(&s->gb) << 1);

  475.     else

  476.         return 0;

  477. }

  478. 

  479. static inline int get_qscale(MpegEncContext *s)

  480. {

  481.     int qscale;

  482.     if (s->mpeg2) {

  483.         if (s->q_scale_type) {

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

  485.         } else {

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

  487.         }

  488.     } else {

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

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

  491.     }

  492.     return qscale;

  493. }

  494. 

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

  496. #define MT_FIELD 1

  497. #define MT_FRAME 2

  498. #define MT_16X8  2

  499. #define MT_DMV   3

  500. 

  501. static int mpeg_decode_mb(MpegEncContext *s,

  502.                           DCTELEM block[6][64])

  503. {

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

  505.     

  506.     /* skip mb handling */

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

  508.         /* read again increment */

  509.         s->mb_incr = 1;

  510.         for(;;) {

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

  512.             if (code < 0)

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

  514.             if (code >= 33) {

  515.                 if (code == 33) {

  516.                     s->mb_incr += 33;

  517.                 }

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

  519.             } else {

  520.                 s->mb_incr += code;

  521.                 break;

  522.             }

  523.         }

  524.     }

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

  526.         s->mb_x = 0;

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

  528.             return -1;

  529.         s->mb_y++;

  530.     }

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

  532. 

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

  534.         /* skip mb */

  535.         s->mb_intra = 0;

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

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

  538.         s->mv_type = MV_TYPE_16X16;

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

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

  541.             s->mv_dir = MV_DIR_FORWARD;

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

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

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

  545.         } else {

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

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

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

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

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

  551.         }

  552.         s->mb_skiped = 1;

  553.         return 0;

  554.     }

  555. 

  556.     switch(s->pict_type) {

  557.     default:

  558.     case I_TYPE:

  559.         if (get_bits1(&s->gb) == 0) {

  560.             if (get_bits1(&s->gb) == 0)

  561.                 return -1;

  562.             mb_type = MB_QUANT | MB_INTRA;

  563.         } else {

  564.             mb_type = MB_INTRA;

  565.         }

  566.         break;

  567.     case P_TYPE:

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

  569.         if (mb_type < 0)

  570.             return -1;

  571.         break;

  572.     case B_TYPE:

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

  574.         if (mb_type < 0)

  575.             return -1;

  576.         break;

  577.     }

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

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

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

  581.         /* get additionnal motion vector type */

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

  583.             motion_type = MT_FRAME;

  584.         else

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

  586.     }

  587.     /* compute dct type */

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

  589.         !s->frame_pred_frame_dct &&

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

  591.         s->interlaced_dct = get_bits1(&s->gb);

  592. #ifdef DEBUG

  593.         if (s->interlaced_dct)

  594.             printf("interlaced_dct\n");

  595. #endif

  596.     } else {

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

  598.     }

  599. 

  600.     if (mb_type & MB_QUANT) {

  601.         s->qscale = get_qscale(s);

  602.     }

  603.     if (mb_type & MB_INTRA) {

  604.         if (s->concealment_motion_vectors) {

  605.             /* just parse them */

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

  607.                 skip_bits1(&s->gb); /* field select */

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

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

  610.         }

  611.         s->mb_intra = 1;

  612.         cbp = 0x3f;

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

  614.     } else {

  615.         s->mb_intra = 0;

  616.         cbp = 0;

  617.     }

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

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

  620.         s->mv_dir = MV_DIR_FORWARD;

  621.         s->mv_type = MV_TYPE_16X16;

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

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

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

  625.         s->last_mv[0][1][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("motion_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_bits1(&s->gb);

  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_bits1(&s->gb);

  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_bits1(&s->gb);

  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.         skip_bits1(&s->gb); /* 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_bits1(&s->gb);

  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_bits1(&s->gb))

  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_bits1(&s->gb))

  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.         /* XXX: optimize */

  973.         if (level > 0) {

  974.             level = ((level * 2 + 1) * s->qscale * matrix[j]) >> 5;

  975.         } else {

  976.             level = ((-level * 2 + 1) * s->qscale * matrix[j]) >> 5;

  977.             level = -level;

  978.         }

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

  980.            knows whats going on ? */

  981.         mismatch ^= level;

  982.         block[j] = level;

  983.         i++;

  984.     }

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

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

  987.     return 0;

  988. }

  989. 

  990. static int mpeg2_decode_block_intra(MpegEncContext *s, 

  991.                                     DCTELEM *block, 

  992.                                     int n)

  993. {

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

  995.     int code, component;

  996.     RLTable *rl;

  997.     const UINT8 *scan_table;

  998.     const UINT16 *matrix;

  999.     int mismatch;

  1000. 

  1001.     if (s->alternate_scan)

  1002.         scan_table = ff_alternate_vertical_scan;

  1003.     else

  1004.         scan_table = zigzag_direct;

  1005. 

  1006.     /* DC coef */

  1007.     component = (n <= 3 ? 0 : n - 4 + 1);

  1008.     diff = decode_dc(s, component);

  1009.     if (diff >= 0xffff)

  1010.         return -1;

  1011.     dc = s->last_dc[component];

  1012.     dc += diff;

  1013.     s->last_dc[component] = dc;

  1014.     block[0] = dc << (3 - s->intra_dc_precision);

  1015.     dprintf("dc=%d\n", block[0]);

  1016.     mismatch = block[0] ^ 1;

  1017.     i = 1;

  1018.     if (s->intra_vlc_format)

  1019.         rl = &rl_mpeg2;

  1020.     else

  1021.         rl = &rl_mpeg1;

  1022.     if (n < 4) 

  1023.         matrix = s->intra_matrix;

  1024.     else

  1025.         matrix = s->chroma_intra_matrix;

  1026. 

  1027.     /* now quantify & encode AC coefs */

  1028.     for(;;) {

  1029.         code = get_vlc(&s->gb, &rl->vlc);

  1030.         if (code < 0)

  1031.             return -1;

  1032.         if (code == 112) {

  1033.             break;

  1034.         } else if (code == 111) {

  1035.             /* escape */

  1036.             run = get_bits(&s->gb, 6);

  1037.             level = get_bits(&s->gb, 12);

  1038.             level = (level << 20) >> 20;

  1039.         } else {

  1040.             run = rl->table_run[code];

  1041.             level = rl->table_level[code];

  1042.             if (get_bits1(&s->gb))

  1043.                 level = -level;

  1044.         }

  1045.         i += run;

  1046.         if (i >= 64)

  1047.             return -1;

  1048. 	j = scan_table[i];

  1049.         dprintf("%d: run=%d level=%d\n", n, run, level);

  1050.         level = (level * s->qscale * matrix[j]) / 16;

  1051.         /* XXX: is it really necessary to saturate since the encoder

  1052.            knows whats going on ? */

  1053.         mismatch ^= level;

  1054.         block[j] = level;

  1055.         i++;

  1056.     }

  1057.     block[63] ^= (mismatch & 1);

  1058.     s->block_last_index[n] = i;

  1059.     return 0;

  1060. }

  1061. 

  1062. /* compressed picture size */

  1063. #define PICTURE_BUFFER_SIZE 100000

  1064. 

  1065. typedef struct Mpeg1Context {

  1066.     MpegEncContext mpeg_enc_ctx;

  1067.     UINT32 header_state;

  1068.     int start_code; /* current start code */

  1069.     UINT8 buffer[PICTURE_BUFFER_SIZE]; 

  1070.     UINT8 *buf_ptr;

  1071.     int buffer_size;

  1072.     int mpeg_enc_ctx_allocated; /* true if decoding context allocated */

  1073. } Mpeg1Context;

  1074. 

  1075. static int mpeg_decode_init(AVCodecContext *avctx)

  1076. {

  1077.     Mpeg1Context *s = avctx->priv_data;

  1078. 

  1079.     s->header_state = 0xff;

  1080.     s->mpeg_enc_ctx_allocated = 0;

  1081.     s->buffer_size = PICTURE_BUFFER_SIZE;

  1082.     s->start_code = -1;

  1083.     s->buf_ptr = s->buffer;

  1084.     s->mpeg_enc_ctx.picture_number = 0;

  1085.     return 0;

  1086. }

  1087. 

  1088. /* return the 8 bit start code value and update the search

  1089.    state. Return -1 if no start code found */

  1090. static int find_start_code(UINT8 **pbuf_ptr, UINT8 *buf_end, 

  1091.                            UINT32 *header_state)

  1092. {

  1093.     UINT8 *buf_ptr;

  1094.     unsigned int state, v;

  1095.     int val;

  1096. 

  1097.     state = *header_state;

  1098.     buf_ptr = *pbuf_ptr;

  1099.     while (buf_ptr < buf_end) {

  1100.         v = *buf_ptr++;

  1101.         if (state == 0x000001) {

  1102.             state = ((state << 8) | v) & 0xffffff;

  1103.             val = state;

  1104.             goto found;

  1105.         }

  1106.         state = ((state << 8) | v) & 0xffffff;

  1107.     }

  1108.     val = -1;

  1109.  found:

  1110.     *pbuf_ptr = buf_ptr;

  1111.     *header_state = state;

  1112.     return val;

  1113. }

  1114. 

  1115. static int mpeg1_decode_picture(AVCodecContext *avctx, 

  1116.                                 UINT8 *buf, int buf_size)

  1117. {

  1118.     Mpeg1Context *s1 = avctx->priv_data;

  1119.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1120.     int ref, f_code;

  1121. 

  1122.     init_get_bits(&s->gb, buf, buf_size);

  1123. 

  1124.     ref = get_bits(&s->gb, 10); /* temporal ref */

  1125.     s->pict_type = get_bits(&s->gb, 3);

  1126.     dprintf("pict_type=%d number=%d\n", s->pict_type, s->picture_number);

  1127.     skip_bits(&s->gb, 16);

  1128.     if (s->pict_type == P_TYPE || s->pict_type == B_TYPE) {

  1129.         s->full_pel[0] = get_bits1(&s->gb);

  1130.         f_code = get_bits(&s->gb, 3);

  1131.         if (f_code == 0)

  1132.             return -1;

  1133.         s->mpeg_f_code[0][0] = f_code;

  1134.         s->mpeg_f_code[0][1] = f_code;

  1135.     }

  1136.     if (s->pict_type == B_TYPE) {

  1137.         s->full_pel[1] = get_bits1(&s->gb);

  1138.         f_code = get_bits(&s->gb, 3);

  1139.         if (f_code == 0)

  1140.             return -1;

  1141.         s->mpeg_f_code[1][0] = f_code;

  1142.         s->mpeg_f_code[1][1] = f_code;

  1143.     }

  1144.     s->y_dc_scale = 8;

  1145.     s->c_dc_scale = 8;

  1146.     s->first_slice = 1;

  1147.     return 0;

  1148. }

  1149. 

  1150. static void mpeg_decode_sequence_extension(MpegEncContext *s)

  1151. {

  1152.     int horiz_size_ext, vert_size_ext;

  1153.     int bit_rate_ext, vbv_buf_ext, low_delay;

  1154.     int frame_rate_ext_n, frame_rate_ext_d;

  1155. 

  1156.     skip_bits(&s->gb, 8); /* profil and level */

  1157.     skip_bits(&s->gb, 1); /* progressive_sequence */

  1158.     skip_bits(&s->gb, 2); /* chroma_format */

  1159.     horiz_size_ext = get_bits(&s->gb, 2);

  1160.     vert_size_ext = get_bits(&s->gb, 2);

  1161.     s->width |= (horiz_size_ext << 12);

  1162.     s->height |= (vert_size_ext << 12);

  1163.     bit_rate_ext = get_bits(&s->gb, 12);  /* XXX: handle it */

  1164.     s->bit_rate = ((s->bit_rate / 400) | (bit_rate_ext << 12)) * 400;

  1165.     skip_bits1(&s->gb); /* marker */

  1166.     vbv_buf_ext = get_bits(&s->gb, 8);

  1167.     low_delay = get_bits1(&s->gb);

  1168.     frame_rate_ext_n = get_bits(&s->gb, 2);

  1169.     frame_rate_ext_d = get_bits(&s->gb, 5);

  1170.     if (frame_rate_ext_d >= 1)

  1171.         s->frame_rate = (s->frame_rate * frame_rate_ext_n) / frame_rate_ext_d;

  1172.     dprintf("sequence extension\n");

  1173.     s->mpeg2 = 1;

  1174. }

  1175. 

  1176. static void mpeg_decode_quant_matrix_extension(MpegEncContext *s)

  1177. {

  1178.     int i, v, j;

  1179. 

  1180.     dprintf("matrix extension\n");

  1181. 

  1182.     if (get_bits1(&s->gb)) {

  1183.         for(i=0;i<64;i++) {

  1184.             v = get_bits(&s->gb, 8);

  1185.             j = zigzag_direct[i];

  1186.             s->intra_matrix[j] = v;

  1187.             s->chroma_intra_matrix[j] = v;

  1188.         }

  1189.     }

  1190.     if (get_bits1(&s->gb)) {

  1191.         for(i=0;i<64;i++) {

  1192.             v = get_bits(&s->gb, 8);

  1193.             j = zigzag_direct[i];

  1194.             s->non_intra_matrix[j] = v;

  1195.             s->chroma_non_intra_matrix[j] = v;

  1196.         }

  1197.     }

  1198.     if (get_bits1(&s->gb)) {

  1199.         for(i=0;i<64;i++) {

  1200.             v = get_bits(&s->gb, 8);

  1201.             j = zigzag_direct[i];

  1202.             s->chroma_intra_matrix[j] = v;

  1203.         }

  1204.     }

  1205.     if (get_bits1(&s->gb)) {

  1206.         for(i=0;i<64;i++) {

  1207.             v = get_bits(&s->gb, 8);

  1208.             j = zigzag_direct[i];

  1209.             s->chroma_non_intra_matrix[j] = v;

  1210.         }

  1211.     }

  1212. }

  1213. 

  1214. static void mpeg_decode_picture_coding_extension(MpegEncContext *s)

  1215. {

  1216.     s->full_pel[0] = s->full_pel[1] = 0;

  1217.     s->mpeg_f_code[0][0] = get_bits(&s->gb, 4);

  1218.     s->mpeg_f_code[0][1] = get_bits(&s->gb, 4);

  1219.     s->mpeg_f_code[1][0] = get_bits(&s->gb, 4);

  1220.     s->mpeg_f_code[1][1] = get_bits(&s->gb, 4);

  1221.     s->intra_dc_precision = get_bits(&s->gb, 2);

  1222.     s->picture_structure = get_bits(&s->gb, 2);

  1223.     s->top_field_first = get_bits1(&s->gb);

  1224.     s->frame_pred_frame_dct = get_bits1(&s->gb);

  1225.     s->concealment_motion_vectors = get_bits1(&s->gb);

  1226.     s->q_scale_type = get_bits1(&s->gb);

  1227.     s->intra_vlc_format = get_bits1(&s->gb);

  1228.     s->alternate_scan = get_bits1(&s->gb);

  1229.     s->repeat_first_field = get_bits1(&s->gb);

  1230.     s->chroma_420_type = get_bits1(&s->gb);

  1231.     s->progressive_frame = get_bits1(&s->gb);

  1232.     /* composite display not parsed */

  1233.     dprintf("intra_dc_precion=%d\n", s->intra_dc_precision);

  1234.     dprintf("picture_structure=%d\n", s->picture_structure);

  1235.     dprintf("conceal=%d\n", s->concealment_motion_vectors);

  1236.     dprintf("intra_vlc_format=%d\n", s->intra_vlc_format);

  1237.     dprintf("alternate_scan=%d\n", s->alternate_scan);

  1238.     dprintf("frame_pred_frame_dct=%d\n", s->frame_pred_frame_dct);

  1239. }

  1240. 

  1241. static void mpeg_decode_extension(AVCodecContext *avctx, 

  1242.                                   UINT8 *buf, int buf_size)

  1243. {

  1244.     Mpeg1Context *s1 = avctx->priv_data;

  1245.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1246.     int ext_type;

  1247. 

  1248.     init_get_bits(&s->gb, buf, buf_size);

  1249.     

  1250.     ext_type = get_bits(&s->gb, 4);

  1251.     switch(ext_type) {

  1252.     case 0x1:

  1253.         /* sequence ext */

  1254.         mpeg_decode_sequence_extension(s);

  1255.         break;

  1256.     case 0x3:

  1257.         /* quant matrix extension */

  1258.         mpeg_decode_quant_matrix_extension(s);

  1259.         break;

  1260.     case 0x8:

  1261.         /* picture extension */

  1262.         mpeg_decode_picture_coding_extension(s);

  1263.         break;

  1264.     }

  1265. }

  1266. 

  1267. /* return 1 if end of frame */

  1268. static int mpeg_decode_slice(AVCodecContext *avctx, 

  1269.                               AVPicture *pict,

  1270.                               int start_code,

  1271.                               UINT8 *buf, int buf_size)

  1272. {

  1273.     Mpeg1Context *s1 = avctx->priv_data;

  1274.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1275.     int ret;

  1276. 

  1277.     start_code = (start_code - 1) & 0xff;

  1278.     if (start_code >= s->mb_height)

  1279.         return -1;

  1280.     s->last_dc[0] = 1 << (7 + s->intra_dc_precision);

  1281.     s->last_dc[1] = s->last_dc[0];

  1282.     s->last_dc[2] = s->last_dc[0];

  1283.     memset(s->last_mv, 0, sizeof(s->last_mv));

  1284.     s->mb_x = -1;

  1285.     s->mb_y = start_code;

  1286.     s->mb_incr = 0;

  1287. 

  1288.     /* start frame decoding */

  1289.     if (s->first_slice) {

  1290.         s->first_slice = 0;

  1291.         MPV_frame_start(s);

  1292.     }

  1293. 

  1294.     init_get_bits(&s->gb, buf, buf_size);

  1295. 

  1296.     s->qscale = get_qscale(s);

  1297.     /* extra slice info */

  1298.     while (get_bits1(&s->gb) != 0) {

  1299.         skip_bits(&s->gb, 8);

  1300.     }

  1301. 

  1302.     for(;;) {

  1303.         memset(s->block, 0, sizeof(s->block));

  1304.         ret = mpeg_decode_mb(s, s->block);

  1305.         dprintf("ret=%d\n", ret);

  1306.         if (ret < 0)

  1307.             return -1;

  1308.         if (ret == 1)

  1309.             break;

  1310.         MPV_decode_mb(s, s->block);

  1311.     }

  1312.     

  1313.     /* end of slice reached */

  1314.     if (s->mb_x == (s->mb_width - 1) &&

  1315.         s->mb_y == (s->mb_height - 1)) {

  1316.         /* end of image */

  1317.         UINT8 **picture;

  1318. 

  1319.         MPV_frame_end(s);

  1320. 

  1321.         /* XXX: incorrect reported qscale for mpeg2 */

  1322.         if (s->pict_type == B_TYPE) {

  1323.             picture = s->current_picture;

  1324.             avctx->quality = s->qscale;

  1325.         } else {

  1326.             /* latency of 1 frame for I and P frames */

  1327.             /* XXX: use another variable than picture_number */

  1328.             if (s->picture_number == 0) {

  1329.                 picture = NULL;

  1330.             } else {

  1331.                 picture = s->last_picture;

  1332.                 avctx->quality = s->last_qscale;

  1333.             }

  1334.             s->last_qscale = s->qscale;

  1335.             s->picture_number++;

  1336.         }

  1337.         if (picture) {

  1338.             pict->data[0] = picture[0];

  1339.             pict->data[1] = picture[1];

  1340.             pict->data[2] = picture[2];

  1341.             pict->linesize[0] = s->linesize;

  1342.             pict->linesize[1] = s->linesize / 2;

  1343.             pict->linesize[2] = s->linesize / 2;

  1344.             return 1;

  1345.         } else {

  1346.             return 0;

  1347.         }

  1348.     } else {

  1349.         return 0;

  1350.     }

  1351. }

  1352. 

  1353. static int mpeg1_decode_sequence(AVCodecContext *avctx, 

  1354.                                  UINT8 *buf, int buf_size)

  1355. {

  1356.     Mpeg1Context *s1 = avctx->priv_data;

  1357.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1358.     int width, height, i, v, j;

  1359.     

  1360.     init_get_bits(&s->gb, buf, buf_size);

  1361. 

  1362.     width = get_bits(&s->gb, 12);

  1363.     height = get_bits(&s->gb, 12);

  1364.     skip_bits(&s->gb, 4);

  1365.     s->frame_rate_index = get_bits(&s->gb, 4);

  1366.     if (s->frame_rate_index == 0)

  1367.         return -1;

  1368.     s->bit_rate = get_bits(&s->gb, 18) * 400;

  1369.     if (get_bits1(&s->gb) == 0) /* marker */

  1370.         return -1;

  1371.     if (width <= 0 || height <= 0 ||

  1372.         (width % 2) != 0 || (height % 2) != 0)

  1373.         return -1;

  1374.     if (width != s->width ||

  1375.         height != s->height) {

  1376.         /* start new mpeg1 context decoding */

  1377.         s->out_format = FMT_MPEG1;

  1378.         if (s1->mpeg_enc_ctx_allocated) {

  1379.             MPV_common_end(s);

  1380.         }

  1381.         s->width = width;

  1382.         s->height = height;

  1383.         s->has_b_frames = 1;

  1384.         s->avctx = avctx;

  1385.         avctx->width = width;

  1386.         avctx->height = height;

  1387.         avctx->frame_rate = frame_rate_tab[s->frame_rate_index];

  1388.         avctx->bit_rate = s->bit_rate;

  1389.         

  1390.         if (MPV_common_init(s) < 0)

  1391.             return -1;

  1392.         mpeg1_init_vlc(s);

  1393.         s1->mpeg_enc_ctx_allocated = 1;

  1394.     }

  1395. 

  1396.     skip_bits(&s->gb, 10); /* vbv_buffer_size */

  1397.     skip_bits(&s->gb, 1);

  1398. 

  1399.     /* get matrix */

  1400.     if (get_bits1(&s->gb)) {

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

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

  1403.             j = zigzag_direct[i];

  1404.             s->intra_matrix[j] = v;

  1405.             s->chroma_intra_matrix[j] = v;

  1406.         }

  1407. #ifdef DEBUG

  1408.         dprintf("intra matrix present\n");

  1409.         for(i=0;i<64;i++)

  1410.             dprintf(" %d", s->intra_matrix[zigzag_direct[i]]);

  1411.         printf("\n");

  1412. #endif

  1413.     } else {

  1414.         for(i=0;i<64;i++) {

  1415.             v = default_intra_matrix[i];

  1416.             s->intra_matrix[i] = v;

  1417.             s->chroma_intra_matrix[i] = v;

  1418.         }

  1419.     }

  1420.     if (get_bits1(&s->gb)) {

  1421.         for(i=0;i<64;i++) {

  1422.             v = get_bits(&s->gb, 8);

  1423.             j = zigzag_direct[i];

  1424.             s->non_intra_matrix[j] = v;

  1425.             s->chroma_non_intra_matrix[j] = v;

  1426.         }

  1427. #ifdef DEBUG

  1428.         dprintf("non intra matrix present\n");

  1429.         for(i=0;i<64;i++)

  1430.             dprintf(" %d", s->non_intra_matrix[zigzag_direct[i]]);

  1431.         printf("\n");

  1432. #endif

  1433.     } else {

  1434.         for(i=0;i<64;i++) {

  1435.             v = default_non_intra_matrix[i];

  1436.             s->non_intra_matrix[i] = v;

  1437.             s->chroma_non_intra_matrix[i] = v;

  1438.         }

  1439.     }

  1440. 

  1441.     /* we set mpeg2 parameters so that it emulates mpeg1 */

  1442.     s->progressive_sequence = 1;

  1443.     s->progressive_frame = 1;

  1444.     s->picture_structure = PICT_FRAME;

  1445.     s->frame_pred_frame_dct = 1;

  1446.     s->mpeg2 = 0;

  1447.     return 0;

  1448. }

  1449. 

  1450. /* handle buffering and image synchronisation */

  1451. static int mpeg_decode_frame(AVCodecContext *avctx, 

  1452.                              void *data, int *data_size,

  1453.                              UINT8 *buf, int buf_size)

  1454. {

  1455.     Mpeg1Context *s = avctx->priv_data;

  1456.     UINT8 *buf_end, *buf_ptr, *buf_start;

  1457.     int len, start_code_found, ret, code, start_code, input_size;

  1458.     AVPicture *picture = data;

  1459. 

  1460.     dprintf("fill_buffer\n");

  1461. 

  1462.     *data_size = 0;

  1463.     /* special case for last picture */

  1464.     if (buf_size == 0) {

  1465.         MpegEncContext *s2 = &s->mpeg_enc_ctx;

  1466.         if (s2->picture_number > 0) {

  1467.             picture->data[0] = s2->next_picture[0];

  1468.             picture->data[1] = s2->next_picture[1];

  1469.             picture->data[2] = s2->next_picture[2];

  1470.             picture->linesize[0] = s2->linesize;

  1471.             picture->linesize[1] = s2->linesize / 2;

  1472.             picture->linesize[2] = s2->linesize / 2;

  1473.             *data_size = sizeof(AVPicture);

  1474.         }

  1475.         return 0;

  1476.     }

  1477. 

  1478.     buf_ptr = buf;

  1479.     buf_end = buf + buf_size;

  1480.     while (buf_ptr < buf_end) {

  1481.         buf_start = buf_ptr;

  1482.         /* find start next code */

  1483.         code = find_start_code(&buf_ptr, buf_end, &s->header_state);

  1484.         if (code >= 0) {

  1485.             start_code_found = 1;

  1486.         } else {

  1487.             start_code_found = 0;

  1488.         }

  1489.         /* copy to buffer */

  1490.         len = buf_ptr - buf_start;

  1491.         if (len + (s->buf_ptr - s->buffer) > s->buffer_size) {

  1492.             /* data too big : flush */

  1493.             s->buf_ptr = s->buffer;

  1494.             if (start_code_found)

  1495.                 s->start_code = code;

  1496.         } else {

  1497.             memcpy(s->buf_ptr, buf_start, len);

  1498.             s->buf_ptr += len;

  1499.             

  1500.             if (start_code_found) {

  1501.                 /* prepare data for next start code */

  1502.                 input_size = s->buf_ptr - s->buffer;

  1503.                 start_code = s->start_code;

  1504.                 s->buf_ptr = s->buffer;

  1505.                 s->start_code = code;

  1506.                 switch(start_code) {

  1507.                 case SEQ_START_CODE:

  1508.                     mpeg1_decode_sequence(avctx, s->buffer, 

  1509.                                           input_size);

  1510.                     break;

  1511.                             

  1512.                 case PICTURE_START_CODE:

  1513.                     /* we have a complete image : we try to decompress it */

  1514.                     mpeg1_decode_picture(avctx, 

  1515.                                          s->buffer, input_size);

  1516.                     break;

  1517.                 case EXT_START_CODE:

  1518.                     mpeg_decode_extension(avctx,

  1519.                                           s->buffer, input_size);

  1520.                     break;

  1521.                 default:

  1522.                     if (start_code >= SLICE_MIN_START_CODE &&

  1523.                         start_code <= SLICE_MAX_START_CODE) {

  1524.                         ret = mpeg_decode_slice(avctx, picture,

  1525.                                                 start_code, s->buffer, input_size);

  1526.                         if (ret == 1) {

  1527.                             /* got a picture: exit */

  1528.                             *data_size = sizeof(AVPicture);

  1529.                             goto the_end;

  1530.                         }

  1531.                     }

  1532.                     break;

  1533.                 }

  1534.             }

  1535.         }

  1536.     }

  1537.  the_end:

  1538.     return buf_ptr - buf;

  1539. }

  1540. 

  1541. static int mpeg_decode_end(AVCodecContext *avctx)

  1542. {

  1543.     Mpeg1Context *s = avctx->priv_data;

  1544. 

  1545.     if (s->mpeg_enc_ctx_allocated)

  1546.         MPV_common_end(&s->mpeg_enc_ctx);

  1547.     return 0;

  1548. }

  1549. 

  1550. AVCodec mpeg_decoder = {

  1551.     "mpegvideo",

  1552.     CODEC_TYPE_VIDEO,

  1553.     CODEC_ID_MPEG1VIDEO,

  1554.     sizeof(Mpeg1Context),

  1555.     mpeg_decode_init,

  1556.     NULL,

  1557.     mpeg_decode_end,

  1558.     mpeg_decode_frame,

  1559. };