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  1. /*
  2.  * MPEG-1/2 decoder
  3.  * Copyright (c) 2000, 2001 Fabrice Bellard
  4.  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. /**
  24.  * @file
  25.  * MPEG-1/2 decoder
  26.  */
  27.  
  28. #define UNCHECKED_BITSTREAM_READER 1
  29.  
  30. #include "libavutil/attributes.h"
  31. #include "libavutil/avassert.h"
  32. #include "libavutil/timecode.h"
  33.  
  34. #include "internal.h"
  35. #include "avcodec.h"
  36. #include "mpegvideo.h"
  37. #include "error_resilience.h"
  38. #include "mpeg12.h"
  39. #include "mpeg12data.h"
  40. #include "mpegvideodata.h"
  41. #include "bytestream.h"
  42. #include "vdpau_internal.h"
  43. #include "thread.h"
  44.  
  45. uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];
  46.  
  47. static const uint8_t table_mb_ptype[7][2] = {
  48.     { 3, 5 }, // 0x01 MB_INTRA
  49.     { 1, 2 }, // 0x02 MB_PAT
  50.     { 1, 3 }, // 0x08 MB_FOR
  51.     { 1, 1 }, // 0x0A MB_FOR|MB_PAT
  52.     { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
  53.     { 1, 5 }, // 0x12 MB_QUANT|MB_PAT
  54.     { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
  55. };
  56.  
  57. static const uint8_t table_mb_btype[11][2] = {
  58.     { 3, 5 }, // 0x01 MB_INTRA
  59.     { 2, 3 }, // 0x04 MB_BACK
  60.     { 3, 3 }, // 0x06 MB_BACK|MB_PAT
  61.     { 2, 4 }, // 0x08 MB_FOR
  62.     { 3, 4 }, // 0x0A MB_FOR|MB_PAT
  63.     { 2, 2 }, // 0x0C MB_FOR|MB_BACK
  64.     { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
  65.     { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
  66.     { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
  67.     { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
  68.     { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
  69. };
  70.  
  71. #define INIT_2D_VLC_RL(rl, static_size)\
  72. {\
  73.     static RL_VLC_ELEM rl_vlc_table[static_size];\
  74.     rl.rl_vlc[0] = rl_vlc_table;\
  75.     init_2d_vlc_rl(&rl, static_size);\
  76. }
  77.  
  78. static av_cold void init_2d_vlc_rl(RLTable *rl, unsigned static_size)
  79. {
  80.     int i;
  81.     VLC_TYPE table[680][2] = {{0}};
  82.     VLC vlc = { .table = table, .table_allocated = static_size };
  83.     av_assert0(static_size <= FF_ARRAY_ELEMS(table));
  84.     init_vlc(&vlc, TEX_VLC_BITS, rl->n + 2, &rl->table_vlc[0][1], 4, 2, &rl->table_vlc[0][0], 4, 2, INIT_VLC_USE_NEW_STATIC);
  85.  
  86.     for (i = 0; i < vlc.table_size; i++) {
  87.         int code = vlc.table[i][0];
  88.         int len  = vlc.table[i][1];
  89.         int level, run;
  90.  
  91.         if (len == 0) { // illegal code
  92.             run   = 65;
  93.             level = MAX_LEVEL;
  94.         } else if (len<0) { //more bits needed
  95.             run   = 0;
  96.             level = code;
  97.         } else {
  98.             if (code == rl->n) { //esc
  99.                 run   = 65;
  100.                 level = 0;
  101.             } else if (code == rl->n+1) { //eob
  102.                 run   = 0;
  103.                 level = 127;
  104.             } else {
  105.                 run   = rl->table_run  [code] + 1;
  106.                 level = rl->table_level[code];
  107.             }
  108.         }
  109.         rl->rl_vlc[0][i].len   = len;
  110.         rl->rl_vlc[0][i].level = level;
  111.         rl->rl_vlc[0][i].run   = run;
  112.     }
  113. }
  114.  
  115. av_cold void ff_mpeg12_common_init(MpegEncContext *s)
  116. {
  117.  
  118.     s->y_dc_scale_table =
  119.     s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];
  120.  
  121. }
  122.  
  123. void ff_mpeg1_clean_buffers(MpegEncContext *s)
  124. {
  125.     s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
  126.     s->last_dc[1] = s->last_dc[0];
  127.     s->last_dc[2] = s->last_dc[0];
  128.     memset(s->last_mv, 0, sizeof(s->last_mv));
  129. }
  130.  
  131.  
  132. /******************************************/
  133. /* decoding */
  134.  
  135. VLC ff_mv_vlc;
  136.  
  137. VLC ff_dc_lum_vlc;
  138. VLC ff_dc_chroma_vlc;
  139.  
  140. VLC ff_mbincr_vlc;
  141. VLC ff_mb_ptype_vlc;
  142. VLC ff_mb_btype_vlc;
  143. VLC ff_mb_pat_vlc;
  144.  
  145. av_cold void ff_mpeg12_init_vlcs(void)
  146. {
  147.     static int done = 0;
  148.  
  149.     if (!done) {
  150.         done = 1;
  151.  
  152.         INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
  153.                         ff_mpeg12_vlc_dc_lum_bits, 1, 1,
  154.                         ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
  155.         INIT_VLC_STATIC(&ff_dc_chroma_vlc,  DC_VLC_BITS, 12,
  156.                         ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
  157.                         ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
  158.         INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
  159.                         &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
  160.                         &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);
  161.         INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
  162.                         &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
  163.                         &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
  164.         INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
  165.                         &ff_mpeg12_mbPatTable[0][1], 2, 1,
  166.                         &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);
  167.  
  168.         INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
  169.                         &table_mb_ptype[0][1], 2, 1,
  170.                         &table_mb_ptype[0][0], 2, 1, 64);
  171.         INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
  172.                         &table_mb_btype[0][1], 2, 1,
  173.                         &table_mb_btype[0][0], 2, 1, 64);
  174.         ff_rl_init(&ff_rl_mpeg1, ff_mpeg12_static_rl_table_store[0]);
  175.         ff_rl_init(&ff_rl_mpeg2, ff_mpeg12_static_rl_table_store[1]);
  176.  
  177.         INIT_2D_VLC_RL(ff_rl_mpeg1, 680);
  178.         INIT_2D_VLC_RL(ff_rl_mpeg2, 674);
  179.     }
  180. }
  181.  
  182. /**
  183.  * Find the end of the current frame in the bitstream.
  184.  * @return the position of the first byte of the next frame, or -1
  185.  */
  186. int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
  187. {
  188.     int i;
  189.     uint32_t state = pc->state;
  190.  
  191.     /* EOF considered as end of frame */
  192.     if (buf_size == 0)
  193.         return 0;
  194.  
  195. /*
  196.  0  frame start         -> 1/4
  197.  1  first_SEQEXT        -> 0/2
  198.  2  first field start   -> 3/0
  199.  3  second_SEQEXT       -> 2/0
  200.  4  searching end
  201. */
  202.  
  203.     for (i = 0; i < buf_size; i++) {
  204.         av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
  205.         if (pc->frame_start_found & 1) {
  206.             if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
  207.                 pc->frame_start_found--;
  208.             else if (state == EXT_START_CODE + 2) {
  209.                 if ((buf[i] & 3) == 3)
  210.                     pc->frame_start_found = 0;
  211.                 else
  212.                     pc->frame_start_found = (pc->frame_start_found + 1) & 3;
  213.             }
  214.             state++;
  215.         } else {
  216.             i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
  217.             if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
  218.                 i++;
  219.                 pc->frame_start_found = 4;
  220.             }
  221.             if (state == SEQ_END_CODE) {
  222.                 pc->frame_start_found = 0;
  223.                 pc->state=-1;
  224.                 return i+1;
  225.             }
  226.             if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
  227.                 pc->frame_start_found = 0;
  228.             if (pc->frame_start_found  < 4 && state == EXT_START_CODE)
  229.                 pc->frame_start_found++;
  230.             if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
  231.                 if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
  232.                     pc->frame_start_found = 0;
  233.                     pc->state             = -1;
  234.                     return i - 3;
  235.                 }
  236.             }
  237.             if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
  238.                 ff_fetch_timestamp(s, i - 3, 1, i > 3);
  239.             }
  240.         }
  241.     }
  242.     pc->state = state;
  243.     return END_NOT_FOUND;
  244. }
  245.  
  246.