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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. #ifdef USE_FASTMEMCPY

  29. #include "fastmemcpy.h"

  30. #endif

  31. //#define DEBUG

  32. 

  33. #ifdef DEBUG

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

  35. #else

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

  37. #endif

  38. 

  39. /* Start codes. */

  40. #define SEQ_END_CODE		0x000001b7

  41. #define SEQ_START_CODE		0x000001b3

  42. #define GOP_START_CODE		0x000001b8

  43. #define PICTURE_START_CODE	0x00000100

  44. #define SLICE_MIN_START_CODE	0x00000101

  45. #define SLICE_MAX_START_CODE	0x000001af

  46. #define EXT_START_CODE		0x000001b5

  47. #define USER_START_CODE		0x000001b2

  48. 

  49. static void mpeg1_encode_block(MpegEncContext *s, 

  50.                          DCTELEM *block, 

  51.                          int component);

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

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

  54. static int mpeg1_decode_block(MpegEncContext *s, 

  55.                               DCTELEM *block, 

  56.                               int n);

  57. static int mpeg2_decode_block_non_intra(MpegEncContext *s, 

  58.                                         DCTELEM *block, 

  59.                                         int n);

  60. static int mpeg2_decode_block_intra(MpegEncContext *s, 

  61.                                     DCTELEM *block, 

  62.                                     int n);

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

  64. 

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

  66. {

  67.     align_put_bits(&s->pb);

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

  69. }

  70. 

  71. /* put sequence header if needed */

  72. static void mpeg1_encode_sequence_header(MpegEncContext *s)

  73. {

  74.         unsigned int vbv_buffer_size;

  75.         unsigned int fps, v;

  76.         int n;

  77.         UINT64 time_code;

  78.         

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

  80.             /* mpeg1 header repeated every gop */

  81.             put_header(s, SEQ_START_CODE);

  82.             

  83.             /* search closest frame rate */

  84.             {

  85.                 int i, dmin, d;

  86.                 s->frame_rate_index = 0;

  87.                 dmin = 0x7fffffff;

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

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

  90.                     if (d < dmin) {

  91.                         dmin = d;

  92.                         s->frame_rate_index = i;

  93.                     }

  94.                 }

  95.             }

  96.  

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

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

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

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

  101.             v = s->bit_rate / 400;

  102.             if (v > 0x3ffff)

  103.                 v = 0x3ffff;

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

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

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

  107.                some margin just in case */

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

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

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

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

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

  113. 

  114.             put_header(s, GOP_START_CODE);

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

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

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

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

  119.             time_code = s->fake_picture_number * FRAME_RATE_BASE;

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

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

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

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

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

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

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

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

  128.         }

  129. 

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

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

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

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

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

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

  136.                 mpeg1_skip_picture(s, s->fake_picture_number - 

  137.                                    s->gop_picture_number); 

  138.                 s->fake_picture_number++;

  139.             }

  140. 

  141.         }

  142.         s->fake_picture_number++;

  143. }

  144. 

  145. 

  146. /* insert a fake P picture */

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

  148. {

  149.     unsigned int mb_incr;

  150. 

  151.     /* mpeg1 picture header */

  152.     put_header(s, PICTURE_START_CODE);

  153.     /* temporal reference */

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

  155.     

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

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

  158.     

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

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

  161.     

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

  163.     

  164.     /* only one slice */

  165.     put_header(s, SLICE_MIN_START_CODE);

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

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

  168.     

  169.     mb_incr = 1;

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

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

  172.     

  173.     /* empty macroblock */

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

  175.     

  176.     /* zero motion x & y */

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

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

  179. 

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

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

  182.     while (mb_incr > 33) {

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

  184.         mb_incr -= 33;

  185.     }

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

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

  188.     

  189.     /* empty macroblock */

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

  191.     

  192.     /* zero motion x & y */

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

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

  195. }

  196. 

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

  198. {

  199.     static int done;

  200. 

  201.     if (!done) {

  202.         done = 1;

  203.         init_rl(&rl_mpeg1);

  204.     }

  205.     mpeg1_encode_sequence_header(s);

  206. 

  207.     /* mpeg1 picture header */

  208.     put_header(s, PICTURE_START_CODE);

  209.     /* temporal reference */

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

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

  212.     

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

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

  215.     

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

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

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

  219.     }

  220.     

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

  222.     

  223.     /* only one slice */

  224.     put_header(s, SLICE_MIN_START_CODE);

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

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

  227. }

  228. 

  229. void mpeg1_encode_mb(MpegEncContext *s,

  230.                      DCTELEM block[6][64],

  231.                      int motion_x, int motion_y)

  232. {

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

  234. 

  235.     mb_x = s->mb_x;

  236.     mb_y = s->mb_y;

  237. 

  238.     /* compute cbp */

  239.     cbp = 0;

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

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

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

  243.     }

  244. 

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

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

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

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

  249.         s->mb_incr++;

  250.     } else {

  251.         /* output mb incr */

  252.         mb_incr = s->mb_incr;

  253. 

  254.         while (mb_incr > 33) {

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

  256.             mb_incr -= 33;

  257.         }

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

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

  260.         

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

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

  263.         } else {

  264.             if (s->mb_intra) {

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

  266.             } else {

  267.                 if (cbp != 0) {

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

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

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

  271.                     } else {

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

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

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

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

  276.                     }

  277.                 } else {

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

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

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

  281.                 }

  282.             }

  283.         }

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

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

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

  287.             }

  288.         }

  289.         s->mb_incr = 1;

  290.     }

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

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

  293. }

  294. 

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

  296. {

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

  298. 

  299.     if (val == 0) {

  300.         /* zero vector */

  301.         code = 0;

  302.         put_bits(&s->pb,

  303.                  mbMotionVectorTable[0][1], 

  304.                  mbMotionVectorTable[0][0]); 

  305.     } else {

  306.         bit_size = s->f_code - 1;

  307.         range = 1 << bit_size;

  308.         /* modulo encoding */

  309.         l = 16 * range;

  310.         m = 2 * l;

  311.         if (val < -l) {

  312.             val += m;

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

  314.             val -= m;

  315.         }

  316. 

  317.         if (val >= 0) {

  318.             val--;

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

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

  321.             sign = 0;

  322.         } else {

  323.             val = -val;

  324.             val--;

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

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

  327.             sign = 1;

  328.         }

  329.         put_bits(&s->pb,

  330.                  mbMotionVectorTable[code][1], 

  331.                  mbMotionVectorTable[code][0]); 

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

  333.         if (bit_size > 0) {

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

  335.         }

  336.     }

  337. }

  338. 

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

  340. {

  341.     int adiff, index;

  342. 

  343.     adiff = abs(diff);

  344.     index = vlc_dc_table[adiff];

  345.     if (component == 0) {

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

  347.     } else {

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

  349.     }

  350.     if (diff > 0) {

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

  352.     } else if (diff < 0) {

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

  354.     }

  355. }

  356. 

  357. static void mpeg1_encode_block(MpegEncContext *s, 

  358.                                DCTELEM *block, 

  359.                                int n)

  360. {

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

  362.     int code, component;

  363.     RLTable *rl = &rl_mpeg1;

  364. 

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

  366. 

  367.     /* DC coef */

  368.     if (s->mb_intra) {

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

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

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

  372.         encode_dc(s, diff, component);

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

  374.         i = 1;

  375.     } else {

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

  377.            it is handled slightly differently */

  378.         level = block[0];

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

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

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

  382.                 i = 1;

  383.         } else {

  384.             i = 0;

  385.             last_non_zero = -1;

  386.             goto next_coef;

  387.         }

  388.     }

  389. 

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

  391.     last_non_zero = i - 1;

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

  393.         j = zigzag_direct[i];

  394.         level = block[j];

  395.     next_coef:

  396. #if 0

  397.         if (level != 0)

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

  399. #endif            

  400.         /* encode using VLC */

  401.         if (level != 0) {

  402.             run = i - last_non_zero - 1;

  403.             sign = 0;

  404.             alevel = level;

  405.             if (alevel < 0) {

  406. 		sign = 1;

  407.                 alevel = -alevel;

  408. 	    }

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

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

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

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

  413.             } else {

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

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

  416.                 if (alevel < 128) {

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

  418.                 } else {

  419.                     if (level < 0) {

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

  421.                     } else {

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

  423.                     }

  424.                 }

  425.             }

  426.             last_non_zero = i;

  427.         }

  428.     }

  429.     /* end of block */

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

  431. }

  432. 

  433. /******************************************/

  434. /* decoding */

  435. 

  436. static VLC dc_lum_vlc;

  437. static VLC dc_chroma_vlc;

  438. static VLC mv_vlc;

  439. static VLC mbincr_vlc;

  440. static VLC mb_ptype_vlc;

  441. static VLC mb_btype_vlc;

  442. static VLC mb_pat_vlc;

  443. 

  444. void mpeg1_init_vlc(MpegEncContext *s)

  445. {

  446.     static int done = 0;

  447. 

  448.     if (!done) {

  449. 

  450.         init_vlc(&dc_lum_vlc, 9, 12, 

  451.                  vlc_dc_lum_bits, 1, 1,

  452.                  vlc_dc_lum_code, 2, 2);

  453.         init_vlc(&dc_chroma_vlc, 9, 12, 

  454.                  vlc_dc_chroma_bits, 1, 1,

  455.                  vlc_dc_chroma_code, 2, 2);

  456.         init_vlc(&mv_vlc, 9, 17, 

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

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

  459.         init_vlc(&mbincr_vlc, 9, 35, 

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

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

  462.         init_vlc(&mb_pat_vlc, 9, 63, 

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

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

  465.         

  466.         init_vlc(&mb_ptype_vlc, 6, 32, 

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

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

  469.         init_vlc(&mb_btype_vlc, 6, 32, 

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

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

  472.         init_rl(&rl_mpeg1);

  473.         init_rl(&rl_mpeg2);

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

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

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

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

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

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

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

  481.     }

  482. }

  483. 

  484. static inline int get_dmv(MpegEncContext *s)

  485. {

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

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

  488.     else

  489.         return 0;

  490. }

  491. 

  492. static inline int get_qscale(MpegEncContext *s)

  493. {

  494.     int qscale;

  495.     if (s->mpeg2) {

  496.         if (s->q_scale_type) {

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

  498.         } else {

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

  500.         }

  501.     } else {

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

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

  504.     }

  505.     return qscale;

  506. }

  507. 

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

  509. #define MT_FIELD 1

  510. #define MT_FRAME 2

  511. #define MT_16X8  2

  512. #define MT_DMV   3

  513. 

  514. static int mpeg_decode_mb(MpegEncContext *s,

  515.                           DCTELEM block[6][64])

  516. {

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

  518.     

  519.     /* skip mb handling */

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

  521.         /* read again increment */

  522.         s->mb_incr = 1;

  523.         for(;;) {

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

  525.             if (code < 0)

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

  527.             if (code >= 33) {

  528.                 if (code == 33) {

  529.                     s->mb_incr += 33;

  530.                 }

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

  532.             } else {

  533.                 s->mb_incr += code;

  534.                 break;

  535.             }

  536.         }

  537.     }

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

  539.         s->mb_x = 0;

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

  541.             return -1;

  542.         s->mb_y++;

  543.     }

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

  545. 

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

  547.         /* skip mb */

  548.         s->mb_intra = 0;

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

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

  551.         s->mv_type = MV_TYPE_16X16;

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

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

  554.             s->mv_dir = MV_DIR_FORWARD;

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

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

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

  558.         } else {

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

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

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

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

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

  564.         }

  565.         s->mb_skiped = 1;

  566.         return 0;

  567.     }

  568. 

  569.     switch(s->pict_type) {

  570.     default:

  571.     case I_TYPE:

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

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

  574.                 return -1;

  575.             mb_type = MB_QUANT | MB_INTRA;

  576.         } else {

  577.             mb_type = MB_INTRA;

  578.         }

  579.         break;

  580.     case P_TYPE:

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

  582.         if (mb_type < 0)

  583.             return -1;

  584.         break;

  585.     case B_TYPE:

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

  587.         if (mb_type < 0)

  588.             return -1;

  589.         break;

  590.     }

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

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

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

  594.         /* get additionnal motion vector type */

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

  596.             motion_type = MT_FRAME;

  597.         else

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

  599.     }

  600.     /* compute dct type */

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

  602.         !s->frame_pred_frame_dct &&

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

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

  605. #ifdef DEBUG

  606.         if (s->interlaced_dct)

  607.             printf("interlaced_dct\n");

  608. #endif

  609.     } else {

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

  611.     }

  612. 

  613.     if (mb_type & MB_QUANT) {

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

  615.     }

  616.     if (mb_type & MB_INTRA) {

  617.         if (s->concealment_motion_vectors) {

  618.             /* just parse them */

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

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

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

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

  623.         }

  624.         s->mb_intra = 1;

  625.         cbp = 0x3f;

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

  627.     } else {

  628.         s->mb_intra = 0;

  629.         cbp = 0;

  630.     }

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

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

  633.         s->mv_dir = MV_DIR_FORWARD;

  634.         s->mv_type = MV_TYPE_16X16;

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

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

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

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

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

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

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

  642.         /* motion vectors */

  643.         s->mv_dir = 0;

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

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

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

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

  648.                 switch(motion_type) {

  649.                 case MT_FRAME: /* or MT_16X8 */

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

  651.                         /* MT_FRAME */

  652.                         s->mv_type = MV_TYPE_16X16;

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

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

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

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

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

  658.                             /* full_pel: only for mpeg1 */

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

  660.                                 val = val << 1;

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

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

  663.                         }

  664.                     } else {

  665.                         /* MT_16X8 */

  666.                         s->mv_type = MV_TYPE_16X8;

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

  668.                             s->field_select[i][j] = get_bits1(&s->gb);

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

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

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

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

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

  674.                             }

  675.                         }

  676.                     }

  677.                     break;

  678.                 case MT_FIELD:

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

  680.                         s->mv_type = MV_TYPE_FIELD;

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

  682.                             s->field_select[i][j] = get_bits1(&s->gb);

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

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

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

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

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

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

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

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

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

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

  693.                         }

  694.                     } else {

  695.                         s->mv_type = MV_TYPE_16X16;

  696.                         s->field_select[i][0] = get_bits1(&s->gb);

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

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

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

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

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

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

  703.                         }

  704.                     }

  705.                     break;

  706.                 case MT_DMV:

  707.                     {

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

  709. 

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

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

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

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

  714.                         dmx = get_dmv(s);

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

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

  717.                         dmy = get_dmv(s);

  718.                         s->mv_type = MV_TYPE_DMV;

  719.                         /* XXX: totally broken */

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

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

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

  723. 

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

  725.                             /* top -> top pred */

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

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

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

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

  730.                             m = 4 - m;

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

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

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

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

  735.                         } else {

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

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

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

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

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

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

  742.                                 /* + 2 * cur_field */;

  743.                         }

  744.                     }

  745.                     break;

  746.                 }

  747.             }

  748.         }

  749.     }

  750. 

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

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

  753.     }

  754.     

  755.     if (mb_type & MB_PAT) {

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

  757.         if (cbp < 0)

  758.             return -1;

  759.         cbp++;

  760.     }

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

  762. 

  763.     if (s->mpeg2) {

  764.         if (s->mb_intra) {

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

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

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

  768.                         return -1;

  769.                 }

  770.             }

  771.         } else {

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

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

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

  775.                         return -1;

  776.                 }

  777.             }

  778.         }

  779.     } else {

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

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

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

  783.                     return -1;

  784.             }

  785.         }

  786.     }

  787.     return 0;

  788. }

  789. 

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

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

  792. {

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

  794. 

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

  796.     if (code < 0) {

  797.         return 0xffff;

  798.     }

  799.     if (code == 0) {

  800.         return pred;

  801.     }

  802.     sign = get_bits1(&s->gb);

  803.     shift = fcode - 1;

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

  805.     if (shift > 0)

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

  807.     val++;

  808.     if (sign)

  809.         val = -val;

  810.     val += pred;

  811.     

  812.     /* modulo decoding */

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

  814.     m = 2 * l;

  815.     if (val < -l) {

  816.         val += m;

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

  818.         val -= m;

  819.     }

  820.     return val;

  821. }

  822. 

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

  824. {

  825.     int code, diff;

  826. 

  827.     if (component == 0) {

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

  829.     } else {

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

  831.     }

  832.     if (code < 0)

  833.         return 0xffff;

  834.     if (code == 0) {

  835.         diff = 0;

  836.     } else {

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

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

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

  840.     }

  841.     return diff;

  842. }

  843. 

  844. static int mpeg1_decode_block(MpegEncContext *s, 

  845.                                DCTELEM *block, 

  846.                                int n)

  847. {

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

  849.     int code, component;

  850.     RLTable *rl = &rl_mpeg1;

  851. 

  852.     if (s->mb_intra) {

  853.         /* DC coef */

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

  855.         diff = decode_dc(s, component);

  856.         if (diff >= 0xffff)

  857.             return -1;

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

  859.         dc += diff;

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

  861.         block[0] = dc;

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

  863.         i = 1;

  864.     } else {

  865.         int bit_cnt, v;

  866.         UINT32 bit_buf;

  867.         UINT8 *buf_ptr;

  868.         i = 0;

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

  870.         SAVE_BITS(&s->gb);

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

  872.         if (v & 2) {

  873.             run = 0;

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

  875.             FLUSH_BITS(2);

  876.             RESTORE_BITS(&s->gb);

  877.             goto add_coef;

  878.         }

  879.         RESTORE_BITS(&s->gb);

  880.     }

  881. 

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

  883.     for(;;) {

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

  885.         if (code < 0) {

  886.             return -1;

  887.         }

  888.         if (code == 112) {

  889.             break;

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

  891.             /* escape */

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

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

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

  895.             if (level == -128) {

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

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

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

  899.             }

  900.         } else {

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

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

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

  904.                 level = -level;

  905.         }

  906.         i += run;

  907.         if (i >= 64)

  908.             return -1;

  909.     add_coef:

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

  911. 	j = zigzag_direct[i];

  912.         block[j] = level;

  913.         i++;

  914.     }

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

  916.     return 0;

  917. }

  918. 

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

  920.    encoding */

  921. static int mpeg2_decode_block_non_intra(MpegEncContext *s, 

  922.                                         DCTELEM *block, 

  923.                                         int n)

  924. {

  925.     int level, i, j, run;

  926.     int code;

  927.     RLTable *rl = &rl_mpeg1;

  928.     const UINT8 *scan_table;

  929.     const UINT16 *matrix;

  930.     int mismatch;

  931. 

  932.     if (s->alternate_scan)

  933.         scan_table = ff_alternate_vertical_scan;

  934.     else

  935.         scan_table = zigzag_direct;

  936.     mismatch = 1;

  937. 

  938.     {

  939.         int bit_cnt, v;

  940.         UINT32 bit_buf;

  941.         UINT8 *buf_ptr;

  942.         i = 0;

  943.         if (n < 4) 

  944.             matrix = s->non_intra_matrix;

  945.         else

  946.             matrix = s->chroma_non_intra_matrix;

  947.             

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

  949.         SAVE_BITS(&s->gb);

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

  951.         if (v & 2) {

  952.             run = 0;

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

  954.             FLUSH_BITS(2);

  955.             RESTORE_BITS(&s->gb);

  956.             goto add_coef;

  957.         }

  958.         RESTORE_BITS(&s->gb);

  959.     }

  960. 

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

  962.     for(;;) {

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

  964.         if (code < 0)

  965.             return -1;

  966.         if (code == 112) {

  967.             break;

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

  969.             /* escape */

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

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

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

  973.         } else {

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

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

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

  977.                 level = -level;

  978.         }

  979.         i += run;

  980.         if (i >= 64)

  981.             return -1;

  982.     add_coef:

  983. 	j = scan_table[i];

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

  985.         /* XXX: optimize */

  986.         if (level > 0) {

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

  988.         } else {

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

  990.             level = -level;

  991.         }

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

  993.            knows whats going on ? */

  994.         mismatch ^= level;

  995.         block[j] = level;

  996.         i++;

  997.     }

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

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

  1000.     return 0;

  1001. }

  1002. 

  1003. static int mpeg2_decode_block_intra(MpegEncContext *s, 

  1004.                                     DCTELEM *block, 

  1005.                                     int n)

  1006. {

  1007.     int level, dc, diff, i, j, run;

  1008.     int code, component;

  1009.     RLTable *rl;

  1010.     const UINT8 *scan_table;

  1011.     const UINT16 *matrix;

  1012.     int mismatch;

  1013. 

  1014.     if (s->alternate_scan)

  1015.         scan_table = ff_alternate_vertical_scan;

  1016.     else

  1017.         scan_table = zigzag_direct;

  1018. 

  1019.     /* DC coef */

  1020.     component = (n <= 3 ? 0 : n - 4 + 1);

  1021.     diff = decode_dc(s, component);

  1022.     if (diff >= 0xffff)

  1023.         return -1;

  1024.     dc = s->last_dc[component];

  1025.     dc += diff;

  1026.     s->last_dc[component] = dc;

  1027.     block[0] = dc << (3 - s->intra_dc_precision);

  1028.     dprintf("dc=%d\n", block[0]);

  1029.     mismatch = block[0] ^ 1;

  1030.     i = 1;

  1031.     if (s->intra_vlc_format)

  1032.         rl = &rl_mpeg2;

  1033.     else

  1034.         rl = &rl_mpeg1;

  1035.     if (n < 4) 

  1036.         matrix = s->intra_matrix;

  1037.     else

  1038.         matrix = s->chroma_intra_matrix;

  1039. 

  1040.     /* now quantify & encode AC coefs */

  1041.     for(;;) {

  1042.         code = get_vlc(&s->gb, &rl->vlc);

  1043.         if (code < 0)

  1044.             return -1;

  1045.         if (code == 112) {

  1046.             break;

  1047.         } else if (code == 111) {

  1048.             /* escape */

  1049.             run = get_bits(&s->gb, 6);

  1050.             level = get_bits(&s->gb, 12);

  1051.             level = (level << 20) >> 20;

  1052.         } else {

  1053.             run = rl->table_run[code];

  1054.             level = rl->table_level[code];

  1055.             if (get_bits1(&s->gb))

  1056.                 level = -level;

  1057.         }

  1058.         i += run;

  1059.         if (i >= 64)

  1060.             return -1;

  1061. 	j = scan_table[i];

  1062.         dprintf("%d: run=%d level=%d\n", n, run, level);

  1063.         level = (level * s->qscale * matrix[j]) / 16;

  1064.         /* XXX: is it really necessary to saturate since the encoder

  1065.            knows whats going on ? */

  1066.         mismatch ^= level;

  1067.         block[j] = level;

  1068.         i++;

  1069.     }

  1070.     block[63] ^= (mismatch & 1);

  1071.     s->block_last_index[n] = i;

  1072.     return 0;

  1073. }

  1074. 

  1075. /* compressed picture size */

  1076. #define PICTURE_BUFFER_SIZE 100000

  1077. 

  1078. typedef struct Mpeg1Context {

  1079.     MpegEncContext mpeg_enc_ctx;

  1080.     UINT32 header_state;

  1081.     int start_code; /* current start code */

  1082.     UINT8 buffer[PICTURE_BUFFER_SIZE]; 

  1083.     UINT8 *buf_ptr;

  1084.     int buffer_size;

  1085.     int mpeg_enc_ctx_allocated; /* true if decoding context allocated */

  1086. } Mpeg1Context;

  1087. 

  1088. static int mpeg_decode_init(AVCodecContext *avctx)

  1089. {

  1090.     Mpeg1Context *s = avctx->priv_data;

  1091. 

  1092.     s->header_state = 0xff;

  1093.     s->mpeg_enc_ctx_allocated = 0;

  1094.     s->buffer_size = PICTURE_BUFFER_SIZE;

  1095.     s->start_code = -1;

  1096.     s->buf_ptr = s->buffer;

  1097.     s->mpeg_enc_ctx.picture_number = 0;

  1098.     return 0;

  1099. }

  1100. 

  1101. /* return the 8 bit start code value and update the search

  1102.    state. Return -1 if no start code found */

  1103. static int find_start_code(UINT8 **pbuf_ptr, UINT8 *buf_end, 

  1104.                            UINT32 *header_state)

  1105. {

  1106.     UINT8 *buf_ptr;

  1107.     unsigned int state, v;

  1108.     int val;

  1109. 

  1110.     state = *header_state;

  1111.     buf_ptr = *pbuf_ptr;

  1112.     while (buf_ptr < buf_end) {

  1113.         v = *buf_ptr++;

  1114.         if (state == 0x000001) {

  1115.             state = ((state << 8) | v) & 0xffffff;

  1116.             val = state;

  1117.             goto found;

  1118.         }

  1119.         state = ((state << 8) | v) & 0xffffff;

  1120.     }

  1121.     val = -1;

  1122.  found:

  1123.     *pbuf_ptr = buf_ptr;

  1124.     *header_state = state;

  1125.     return val;

  1126. }

  1127. 

  1128. static int mpeg1_decode_picture(AVCodecContext *avctx, 

  1129.                                 UINT8 *buf, int buf_size)

  1130. {

  1131.     Mpeg1Context *s1 = avctx->priv_data;

  1132.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1133.     int ref, f_code;

  1134. 

  1135.     init_get_bits(&s->gb, buf, buf_size);

  1136. 

  1137.     ref = get_bits(&s->gb, 10); /* temporal ref */

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

  1139.     dprintf("pict_type=%d number=%d\n", s->pict_type, s->picture_number);

  1140.     skip_bits(&s->gb, 16);

  1141.     if (s->pict_type == P_TYPE || s->pict_type == B_TYPE) {

  1142.         s->full_pel[0] = get_bits1(&s->gb);

  1143.         f_code = get_bits(&s->gb, 3);

  1144.         if (f_code == 0)

  1145.             return -1;

  1146.         s->mpeg_f_code[0][0] = f_code;

  1147.         s->mpeg_f_code[0][1] = f_code;

  1148.     }

  1149.     if (s->pict_type == B_TYPE) {

  1150.         s->full_pel[1] = get_bits1(&s->gb);

  1151.         f_code = get_bits(&s->gb, 3);

  1152.         if (f_code == 0)

  1153.             return -1;

  1154.         s->mpeg_f_code[1][0] = f_code;

  1155.         s->mpeg_f_code[1][1] = f_code;

  1156.     }

  1157.     s->y_dc_scale = 8;

  1158.     s->c_dc_scale = 8;

  1159.     s->first_slice = 1;

  1160.     return 0;

  1161. }

  1162. 

  1163. static void mpeg_decode_sequence_extension(MpegEncContext *s)

  1164. {

  1165.     int horiz_size_ext, vert_size_ext;

  1166.     int bit_rate_ext, vbv_buf_ext, low_delay;

  1167.     int frame_rate_ext_n, frame_rate_ext_d;

  1168. 

  1169.     skip_bits(&s->gb, 8); /* profil and level */

  1170.     skip_bits(&s->gb, 1); /* progressive_sequence */

  1171.     skip_bits(&s->gb, 2); /* chroma_format */

  1172.     horiz_size_ext = get_bits(&s->gb, 2);

  1173.     vert_size_ext = get_bits(&s->gb, 2);

  1174.     s->width |= (horiz_size_ext << 12);

  1175.     s->height |= (vert_size_ext << 12);

  1176.     bit_rate_ext = get_bits(&s->gb, 12);  /* XXX: handle it */

  1177.     s->bit_rate = ((s->bit_rate / 400) | (bit_rate_ext << 12)) * 400;

  1178.     skip_bits1(&s->gb); /* marker */

  1179.     vbv_buf_ext = get_bits(&s->gb, 8);

  1180.     low_delay = get_bits1(&s->gb);

  1181.     frame_rate_ext_n = get_bits(&s->gb, 2);

  1182.     frame_rate_ext_d = get_bits(&s->gb, 5);

  1183.     if (frame_rate_ext_d >= 1)

  1184.         s->frame_rate = (s->frame_rate * frame_rate_ext_n) / frame_rate_ext_d;

  1185.     dprintf("sequence extension\n");

  1186.     s->mpeg2 = 1;

  1187. }

  1188. 

  1189. static void mpeg_decode_quant_matrix_extension(MpegEncContext *s)

  1190. {

  1191.     int i, v, j;

  1192. 

  1193.     dprintf("matrix extension\n");

  1194. 

  1195.     if (get_bits1(&s->gb)) {

  1196.         for(i=0;i<64;i++) {

  1197.             v = get_bits(&s->gb, 8);

  1198.             j = zigzag_direct[i];

  1199.             s->intra_matrix[j] = v;

  1200.             s->chroma_intra_matrix[j] = v;

  1201.         }

  1202.     }

  1203.     if (get_bits1(&s->gb)) {

  1204.         for(i=0;i<64;i++) {

  1205.             v = get_bits(&s->gb, 8);

  1206.             j = zigzag_direct[i];

  1207.             s->non_intra_matrix[j] = v;

  1208.             s->chroma_non_intra_matrix[j] = v;

  1209.         }

  1210.     }

  1211.     if (get_bits1(&s->gb)) {

  1212.         for(i=0;i<64;i++) {

  1213.             v = get_bits(&s->gb, 8);

  1214.             j = zigzag_direct[i];

  1215.             s->chroma_intra_matrix[j] = v;

  1216.         }

  1217.     }

  1218.     if (get_bits1(&s->gb)) {

  1219.         for(i=0;i<64;i++) {

  1220.             v = get_bits(&s->gb, 8);

  1221.             j = zigzag_direct[i];

  1222.             s->chroma_non_intra_matrix[j] = v;

  1223.         }

  1224.     }

  1225. }

  1226. 

  1227. static void mpeg_decode_picture_coding_extension(MpegEncContext *s)

  1228. {

  1229.     s->full_pel[0] = s->full_pel[1] = 0;

  1230.     s->mpeg_f_code[0][0] = get_bits(&s->gb, 4);

  1231.     s->mpeg_f_code[0][1] = get_bits(&s->gb, 4);

  1232.     s->mpeg_f_code[1][0] = get_bits(&s->gb, 4);

  1233.     s->mpeg_f_code[1][1] = get_bits(&s->gb, 4);

  1234.     s->intra_dc_precision = get_bits(&s->gb, 2);

  1235.     s->picture_structure = get_bits(&s->gb, 2);

  1236.     s->top_field_first = get_bits1(&s->gb);

  1237.     s->frame_pred_frame_dct = get_bits1(&s->gb);

  1238.     s->concealment_motion_vectors = get_bits1(&s->gb);

  1239.     s->q_scale_type = get_bits1(&s->gb);

  1240.     s->intra_vlc_format = get_bits1(&s->gb);

  1241.     s->alternate_scan = get_bits1(&s->gb);

  1242.     s->repeat_first_field = get_bits1(&s->gb);

  1243.     s->chroma_420_type = get_bits1(&s->gb);

  1244.     s->progressive_frame = get_bits1(&s->gb);

  1245.     /* composite display not parsed */

  1246.     dprintf("intra_dc_precion=%d\n", s->intra_dc_precision);

  1247.     dprintf("picture_structure=%d\n", s->picture_structure);

  1248.     dprintf("conceal=%d\n", s->concealment_motion_vectors);

  1249.     dprintf("intra_vlc_format=%d\n", s->intra_vlc_format);

  1250.     dprintf("alternate_scan=%d\n", s->alternate_scan);

  1251.     dprintf("frame_pred_frame_dct=%d\n", s->frame_pred_frame_dct);

  1252. }

  1253. 

  1254. static void mpeg_decode_extension(AVCodecContext *avctx, 

  1255.                                   UINT8 *buf, int buf_size)

  1256. {

  1257.     Mpeg1Context *s1 = avctx->priv_data;

  1258.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1259.     int ext_type;

  1260. 

  1261.     init_get_bits(&s->gb, buf, buf_size);

  1262.     

  1263.     ext_type = get_bits(&s->gb, 4);

  1264.     switch(ext_type) {

  1265.     case 0x1:

  1266.         /* sequence ext */

  1267.         mpeg_decode_sequence_extension(s);

  1268.         break;

  1269.     case 0x3:

  1270.         /* quant matrix extension */

  1271.         mpeg_decode_quant_matrix_extension(s);

  1272.         break;

  1273.     case 0x8:

  1274.         /* picture extension */

  1275.         mpeg_decode_picture_coding_extension(s);

  1276.         break;

  1277.     }

  1278. }

  1279. 

  1280. /* return 1 if end of frame */

  1281. static int mpeg_decode_slice(AVCodecContext *avctx, 

  1282.                               AVPicture *pict,

  1283.                               int start_code,

  1284.                               UINT8 *buf, int buf_size)

  1285. {

  1286.     Mpeg1Context *s1 = avctx->priv_data;

  1287.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1288.     int ret;

  1289. 

  1290.     start_code = (start_code - 1) & 0xff;

  1291.     if (start_code >= s->mb_height)

  1292.         return -1;

  1293.     s->last_dc[0] = 1 << (7 + s->intra_dc_precision);

  1294.     s->last_dc[1] = s->last_dc[0];

  1295.     s->last_dc[2] = s->last_dc[0];

  1296.     memset(s->last_mv, 0, sizeof(s->last_mv));

  1297.     s->mb_x = -1;

  1298.     s->mb_y = start_code;

  1299.     s->mb_incr = 0;

  1300. 

  1301.     /* start frame decoding */

  1302.     if (s->first_slice) {

  1303.         s->first_slice = 0;

  1304.         MPV_frame_start(s);

  1305.     }

  1306. 

  1307.     init_get_bits(&s->gb, buf, buf_size);

  1308. 

  1309.     s->qscale = get_qscale(s);

  1310.     /* extra slice info */

  1311.     while (get_bits1(&s->gb) != 0) {

  1312.         skip_bits(&s->gb, 8);

  1313.     }

  1314. 

  1315.     for(;;) {

  1316.         memset(s->block, 0, sizeof(s->block));

  1317.         ret = mpeg_decode_mb(s, s->block);

  1318.         dprintf("ret=%d\n", ret);

  1319.         if (ret < 0)

  1320.             return -1;

  1321.         if (ret == 1)

  1322.             break;

  1323.         MPV_decode_mb(s, s->block);

  1324.     }

  1325.     

  1326.     /* end of slice reached */

  1327.     if (s->mb_x == (s->mb_width - 1) &&

  1328.         s->mb_y == (s->mb_height - 1)) {

  1329.         /* end of image */

  1330.         UINT8 **picture;

  1331. 

  1332.         MPV_frame_end(s);

  1333. 

  1334.         /* XXX: incorrect reported qscale for mpeg2 */

  1335.         if (s->pict_type == B_TYPE) {

  1336.             picture = s->current_picture;

  1337.             avctx->quality = s->qscale;

  1338.         } else {

  1339.             /* latency of 1 frame for I and P frames */

  1340.             /* XXX: use another variable than picture_number */

  1341.             if (s->picture_number == 0) {

  1342.                 picture = NULL;

  1343.             } else {

  1344.                 picture = s->last_picture;

  1345.                 avctx->quality = s->last_qscale;

  1346.             }

  1347.             s->last_qscale = s->qscale;

  1348.             s->picture_number++;

  1349.         }

  1350.         if (picture) {

  1351.             pict->data[0] = picture[0];

  1352.             pict->data[1] = picture[1];

  1353.             pict->data[2] = picture[2];

  1354.             pict->linesize[0] = s->linesize;

  1355.             pict->linesize[1] = s->linesize / 2;

  1356.             pict->linesize[2] = s->linesize / 2;

  1357.             return 1;

  1358.         } else {

  1359.             return 0;

  1360.         }

  1361.     } else {

  1362.         return 0;

  1363.     }

  1364. }

  1365. 

  1366. static int mpeg1_decode_sequence(AVCodecContext *avctx, 

  1367.                                  UINT8 *buf, int buf_size)

  1368. {

  1369.     Mpeg1Context *s1 = avctx->priv_data;

  1370.     MpegEncContext *s = &s1->mpeg_enc_ctx;

  1371.     int width, height, i, v, j;

  1372.     

  1373.     init_get_bits(&s->gb, buf, buf_size);

  1374. 

  1375.     width = get_bits(&s->gb, 12);

  1376.     height = get_bits(&s->gb, 12);

  1377.     skip_bits(&s->gb, 4);

  1378.     s->frame_rate_index = get_bits(&s->gb, 4);

  1379.     if (s->frame_rate_index == 0)

  1380.         return -1;

  1381.     s->bit_rate = get_bits(&s->gb, 18) * 400;

  1382.     if (get_bits1(&s->gb) == 0) /* marker */

  1383.         return -1;

  1384.     if (width <= 0 || height <= 0 ||

  1385.         (width % 2) != 0 || (height % 2) != 0)

  1386.         return -1;

  1387.     if (width != s->width ||

  1388.         height != s->height) {

  1389.         /* start new mpeg1 context decoding */

  1390.         s->out_format = FMT_MPEG1;

  1391.         if (s1->mpeg_enc_ctx_allocated) {

  1392.             MPV_common_end(s);

  1393.         }

  1394.         s->width = width;

  1395.         s->height = height;

  1396.         s->has_b_frames = 1;

  1397.         avctx->width = width;

  1398.         avctx->height = height;

  1399.         avctx->frame_rate = frame_rate_tab[s->frame_rate_index];

  1400.         avctx->bit_rate = s->bit_rate;

  1401.         

  1402.         if (MPV_common_init(s) < 0)

  1403.             return -1;

  1404.         mpeg1_init_vlc(s);

  1405.         s1->mpeg_enc_ctx_allocated = 1;

  1406.     }

  1407. 

  1408.     skip_bits(&s->gb, 10); /* vbv_buffer_size */

  1409.     skip_bits(&s->gb, 1);

  1410. 

  1411.     /* get matrix */

  1412.     if (get_bits1(&s->gb)) {

  1413.         for(i=0;i<64;i++) {

  1414.             v = get_bits(&s->gb, 8);

  1415.             j = zigzag_direct[i];

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

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

  1418.         }

  1419. #ifdef DEBUG

  1420.         dprintf("intra matrix present\n");

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

  1422.             dprintf(" %d", s->intra_matrix[zigzag_direct[i]]);

  1423.         printf("\n");

  1424. #endif

  1425.     } else {

  1426.         for(i=0;i<64;i++) {

  1427.             v = default_intra_matrix[i];

  1428.             s->intra_matrix[i] = v;

  1429.             s->chroma_intra_matrix[i] = v;

  1430.         }

  1431.     }

  1432.     if (get_bits1(&s->gb)) {

  1433.         for(i=0;i<64;i++) {

  1434.             v = get_bits(&s->gb, 8);

  1435.             j = zigzag_direct[i];

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

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

  1438.         }

  1439. #ifdef DEBUG

  1440.         dprintf("non intra matrix present\n");

  1441.         for(i=0;i<64;i++)

  1442.             dprintf(" %d", s->non_intra_matrix[zigzag_direct[i]]);

  1443.         printf("\n");

  1444. #endif

  1445.     } else {

  1446.         for(i=0;i<64;i++) {

  1447.             v = default_non_intra_matrix[i];

  1448.             s->non_intra_matrix[i] = v;

  1449.             s->chroma_non_intra_matrix[i] = v;

  1450.         }

  1451.     }

  1452. 

  1453.     /* we set mpeg2 parameters so that it emulates mpeg1 */

  1454.     s->progressive_sequence = 1;

  1455.     s->progressive_frame = 1;

  1456.     s->picture_structure = PICT_FRAME;

  1457.     s->frame_pred_frame_dct = 1;

  1458.     s->mpeg2 = 0;

  1459.     return 0;

  1460. }

  1461. 

  1462. /* handle buffering and image synchronisation */

  1463. static int mpeg_decode_frame(AVCodecContext *avctx, 

  1464.                              void *data, int *data_size,

  1465.                              UINT8 *buf, int buf_size)

  1466. {

  1467.     Mpeg1Context *s = avctx->priv_data;

  1468.     UINT8 *buf_end, *buf_ptr, *buf_start;

  1469.     int len, start_code_found, ret, code, start_code, input_size;

  1470.     AVPicture *picture = data;

  1471. 

  1472.     dprintf("fill_buffer\n");

  1473. 

  1474.     *data_size = 0;

  1475.     /* special case for last picture */

  1476.     if (buf_size == 0) {

  1477.         MpegEncContext *s2 = &s->mpeg_enc_ctx;

  1478.         if (s2->picture_number > 0) {

  1479.             picture->data[0] = s2->next_picture[0];

  1480.             picture->data[1] = s2->next_picture[1];

  1481.             picture->data[2] = s2->next_picture[2];

  1482.             picture->linesize[0] = s2->linesize;

  1483.             picture->linesize[1] = s2->linesize / 2;

  1484.             picture->linesize[2] = s2->linesize / 2;

  1485.             *data_size = sizeof(AVPicture);

  1486.         }

  1487.         return 0;

  1488.     }

  1489. 

  1490.     buf_ptr = buf;

  1491.     buf_end = buf + buf_size;

  1492.     while (buf_ptr < buf_end) {

  1493.         buf_start = buf_ptr;

  1494.         /* find start next code */

  1495.         code = find_start_code(&buf_ptr, buf_end, &s->header_state);

  1496.         if (code >= 0) {

  1497.             start_code_found = 1;

  1498.         } else {

  1499.             start_code_found = 0;

  1500.         }

  1501.         /* copy to buffer */

  1502.         len = buf_ptr - buf_start;

  1503.         if (len + (s->buf_ptr - s->buffer) > s->buffer_size) {

  1504.             /* data too big : flush */

  1505.             s->buf_ptr = s->buffer;

  1506.             if (start_code_found)

  1507.                 s->start_code = code;

  1508.         } else {

  1509.             memcpy(s->buf_ptr, buf_start, len);

  1510.             s->buf_ptr += len;

  1511.             

  1512.             if (start_code_found) {

  1513.                 /* prepare data for next start code */

  1514.                 input_size = s->buf_ptr - s->buffer;

  1515.                 start_code = s->start_code;

  1516.                 s->buf_ptr = s->buffer;

  1517.                 s->start_code = code;

  1518.                 switch(start_code) {

  1519.                 case SEQ_START_CODE:

  1520.                     mpeg1_decode_sequence(avctx, s->buffer, 

  1521.                                           input_size);

  1522.                     break;

  1523.                             

  1524.                 case PICTURE_START_CODE:

  1525.                     /* we have a complete image : we try to decompress it */

  1526.                     mpeg1_decode_picture(avctx, 

  1527.                                          s->buffer, input_size);

  1528.                     break;

  1529.                 case EXT_START_CODE:

  1530.                     mpeg_decode_extension(avctx,

  1531.                                           s->buffer, input_size);

  1532.                     break;

  1533.                 default:

  1534.                     if (start_code >= SLICE_MIN_START_CODE &&

  1535.                         start_code <= SLICE_MAX_START_CODE) {

  1536.                         ret = mpeg_decode_slice(avctx, picture,

  1537.                                                 start_code, s->buffer, input_size);

  1538.                         if (ret == 1) {

  1539.                             /* got a picture: exit */

  1540.                             *data_size = sizeof(AVPicture);

  1541.                             goto the_end;

  1542.                         }

  1543.                     }

  1544.                     break;

  1545.                 }

  1546.             }

  1547.         }

  1548.     }

  1549.  the_end:

  1550.     return buf_ptr - buf;

  1551. }

  1552. 

  1553. static int mpeg_decode_end(AVCodecContext *avctx)

  1554. {

  1555.     Mpeg1Context *s = avctx->priv_data;

  1556. 

  1557.     if (s->mpeg_enc_ctx_allocated)

  1558.         MPV_common_end(&s->mpeg_enc_ctx);

  1559.     return 0;

  1560. }

  1561. 

  1562. AVCodec mpeg_decoder = {

  1563.     "mpegvideo",

  1564.     CODEC_TYPE_VIDEO,

  1565.     CODEC_ID_MPEG1VIDEO,

  1566.     sizeof(Mpeg1Context),

  1567.     mpeg_decode_init,

  1568.     NULL,

  1569.     mpeg_decode_end,

  1570.     mpeg_decode_frame,

  1571. };