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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 "dsputil.h"
  37. #include "mpegvideo.h"
  38. #include "error_resilience.h"
  39. #include "mpeg12.h"
  40. #include "mpeg12data.h"
  41. #include "bytestream.h"
  42. #include "vdpau_internal.h"
  43. #include "xvmc_internal.h"
  44. #include "thread.h"
  45.  
  46. uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];
  47.  
  48. static const uint8_t table_mb_ptype[7][2] = {
  49.     { 3, 5 }, // 0x01 MB_INTRA
  50.     { 1, 2 }, // 0x02 MB_PAT
  51.     { 1, 3 }, // 0x08 MB_FOR
  52.     { 1, 1 }, // 0x0A MB_FOR|MB_PAT
  53.     { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
  54.     { 1, 5 }, // 0x12 MB_QUANT|MB_PAT
  55.     { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
  56. };
  57.  
  58. static const uint8_t table_mb_btype[11][2] = {
  59.     { 3, 5 }, // 0x01 MB_INTRA
  60.     { 2, 3 }, // 0x04 MB_BACK
  61.     { 3, 3 }, // 0x06 MB_BACK|MB_PAT
  62.     { 2, 4 }, // 0x08 MB_FOR
  63.     { 3, 4 }, // 0x0A MB_FOR|MB_PAT
  64.     { 2, 2 }, // 0x0C MB_FOR|MB_BACK
  65.     { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
  66.     { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
  67.     { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
  68.     { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
  69.     { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
  70. };
  71.  
  72. #define INIT_2D_VLC_RL(rl, static_size)\
  73. {\
  74.     static RL_VLC_ELEM rl_vlc_table[static_size];\
  75.     INIT_VLC_STATIC(&rl.vlc, TEX_VLC_BITS, rl.n + 2,\
  76.                     &rl.table_vlc[0][1], 4, 2,\
  77.                     &rl.table_vlc[0][0], 4, 2, static_size);\
  78. \
  79.     rl.rl_vlc[0] = rl_vlc_table;\
  80.     init_2d_vlc_rl(&rl);\
  81. }
  82.  
  83. static av_cold void init_2d_vlc_rl(RLTable *rl)
  84. {
  85.     int i;
  86.  
  87.     for (i = 0; i < rl->vlc.table_size; i++) {
  88.         int code = rl->vlc.table[i][0];
  89.         int len  = rl->vlc.table[i][1];
  90.         int level, run;
  91.  
  92.         if (len == 0) { // illegal code
  93.             run   = 65;
  94.             level = MAX_LEVEL;
  95.         } else if (len<0) { //more bits needed
  96.             run   = 0;
  97.             level = code;
  98.         } else {
  99.             if (code == rl->n) { //esc
  100.                 run   = 65;
  101.                 level = 0;
  102.             } else if (code == rl->n+1) { //eob
  103.                 run   = 0;
  104.                 level = 127;
  105.             } else {
  106.                 run   = rl->table_run  [code] + 1;
  107.                 level = rl->table_level[code];
  108.             }
  109.         }
  110.         rl->rl_vlc[0][i].len   = len;
  111.         rl->rl_vlc[0][i].level = level;
  112.         rl->rl_vlc[0][i].run   = run;
  113.     }
  114. }
  115.  
  116. av_cold void ff_mpeg12_common_init(MpegEncContext *s)
  117. {
  118.  
  119.     s->y_dc_scale_table =
  120.     s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];
  121.  
  122. }
  123.  
  124. void ff_mpeg1_clean_buffers(MpegEncContext *s)
  125. {
  126.     s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
  127.     s->last_dc[1] = s->last_dc[0];
  128.     s->last_dc[2] = s->last_dc[0];
  129.     memset(s->last_mv, 0, sizeof(s->last_mv));
  130. }
  131.  
  132.  
  133. /******************************************/
  134. /* decoding */
  135.  
  136. VLC ff_mv_vlc;
  137.  
  138. VLC ff_dc_lum_vlc;
  139. VLC ff_dc_chroma_vlc;
  140.  
  141. VLC ff_mbincr_vlc;
  142. VLC ff_mb_ptype_vlc;
  143. VLC ff_mb_btype_vlc;
  144. VLC ff_mb_pat_vlc;
  145.  
  146. av_cold void ff_mpeg12_init_vlcs(void)
  147. {
  148.     static int done = 0;
  149.  
  150.     if (!done) {
  151.         done = 1;
  152.  
  153.         INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
  154.                         ff_mpeg12_vlc_dc_lum_bits, 1, 1,
  155.                         ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
  156.         INIT_VLC_STATIC(&ff_dc_chroma_vlc,  DC_VLC_BITS, 12,
  157.                         ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
  158.                         ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
  159.         INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
  160.                         &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
  161.                         &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);
  162.         INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
  163.                         &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
  164.                         &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
  165.         INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
  166.                         &ff_mpeg12_mbPatTable[0][1], 2, 1,
  167.                         &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);
  168.  
  169.         INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
  170.                         &table_mb_ptype[0][1], 2, 1,
  171.                         &table_mb_ptype[0][0], 2, 1, 64);
  172.         INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
  173.                         &table_mb_btype[0][1], 2, 1,
  174.                         &table_mb_btype[0][0], 2, 1, 64);
  175.         ff_init_rl(&ff_rl_mpeg1, ff_mpeg12_static_rl_table_store[0]);
  176.         ff_init_rl(&ff_rl_mpeg2, ff_mpeg12_static_rl_table_store[1]);
  177.  
  178.         INIT_2D_VLC_RL(ff_rl_mpeg1, 680);
  179.         INIT_2D_VLC_RL(ff_rl_mpeg2, 674);
  180.     }
  181. }
  182.  
  183. /**
  184.  * Find the end of the current frame in the bitstream.
  185.  * @return the position of the first byte of the next frame, or -1
  186.  */
  187. int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
  188. {
  189.     int i;
  190.     uint32_t state = pc->state;
  191.  
  192.     /* EOF considered as end of frame */
  193.     if (buf_size == 0)
  194.         return 0;
  195.  
  196. /*
  197.  0  frame start         -> 1/4
  198.  1  first_SEQEXT        -> 0/2
  199.  2  first field start   -> 3/0
  200.  3  second_SEQEXT       -> 2/0
  201.  4  searching end
  202. */
  203.  
  204.     for (i = 0; i < buf_size; i++) {
  205.         av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
  206.         if (pc->frame_start_found & 1) {
  207.             if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
  208.                 pc->frame_start_found--;
  209.             else if (state == EXT_START_CODE + 2) {
  210.                 if ((buf[i] & 3) == 3)
  211.                     pc->frame_start_found = 0;
  212.                 else
  213.                     pc->frame_start_found = (pc->frame_start_found + 1) & 3;
  214.             }
  215.             state++;
  216.         } else {
  217.             i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
  218.             if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
  219.                 i++;
  220.                 pc->frame_start_found = 4;
  221.             }
  222.             if (state == SEQ_END_CODE) {
  223.                 pc->frame_start_found = 0;
  224.                 pc->state=-1;
  225.                 return i+1;
  226.             }
  227.             if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
  228.                 pc->frame_start_found = 0;
  229.             if (pc->frame_start_found  < 4 && state == EXT_START_CODE)
  230.                 pc->frame_start_found++;
  231.             if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
  232.                 if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
  233.                     pc->frame_start_found = 0;
  234.                     pc->state             = -1;
  235.                     return i - 3;
  236.                 }
  237.             }
  238.             if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
  239.                 ff_fetch_timestamp(s, i - 3, 1);
  240.             }
  241.         }
  242.     }
  243.     pc->state = state;
  244.     return END_NOT_FOUND;
  245. }
  246.  
  247.