libavcodec/mpeg12.c

   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 Libav.
   7  *
   8  * Libav 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  * Libav 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 Libav; 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 #include "libavutil/attributes.h"
  29 #include "internal.h"
  30 #include "avcodec.h"
  31 #include "mpegvideo.h"
  32 #include "error_resilience.h"
  33 #include "mpeg12.h"
  34 #include "mpeg12data.h"
  35 #include "mpegvideodata.h"
  36 #include "bytestream.h"
  37 #include "thread.h"
  38
  39 uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];
  40
  41 static const uint8_t table_mb_ptype[7][2] = {
  42     { 3, 5 }, // 0x01 MB_INTRA
  43     { 1, 2 }, // 0x02 MB_PAT
  44     { 1, 3 }, // 0x08 MB_FOR
  45     { 1, 1 }, // 0x0A MB_FOR|MB_PAT
  46     { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
  47     { 1, 5 }, // 0x12 MB_QUANT|MB_PAT
  48     { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
  49 };
  50
  51 static const uint8_t table_mb_btype[11][2] = {
  52     { 3, 5 }, // 0x01 MB_INTRA
  53     { 2, 3 }, // 0x04 MB_BACK
  54     { 3, 3 }, // 0x06 MB_BACK|MB_PAT
  55     { 2, 4 }, // 0x08 MB_FOR
  56     { 3, 4 }, // 0x0A MB_FOR|MB_PAT
  57     { 2, 2 }, // 0x0C MB_FOR|MB_BACK
  58     { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
  59     { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
  60     { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
  61     { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
  62     { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
  63 };
  64
  65 #define INIT_2D_VLC_RL(rl, static_size)\
  66 {\
  67     static RL_VLC_ELEM rl_vlc_table[static_size];\
  68     INIT_VLC_STATIC(&rl.vlc, TEX_VLC_BITS, rl.n + 2,\
  69                     &rl.table_vlc[0][1], 4, 2,\
  70                     &rl.table_vlc[0][0], 4, 2, static_size);\
  71 \
  72     rl.rl_vlc[0] = rl_vlc_table;\
  73     init_2d_vlc_rl(&rl);\
  74 }
  75
  76 static av_cold void init_2d_vlc_rl(RLTable *rl)
  77 {
  78     int i;
  79
  80     for (i = 0; i < rl->vlc.table_size; i++) {
  81         int code = rl->vlc.table[i][0];
  82         int len  = rl->vlc.table[i][1];
  83         int level, run;
  84
  85         if (len == 0) { // illegal code
  86             run   = 65;
  87             level = MAX_LEVEL;
  88         } else if (len<0) { //more bits needed
  89             run   = 0;
  90             level = code;
  91         } else {
  92             if (code == rl->n) { //esc
  93                 run   = 65;
  94                 level = 0;
  95             } else if (code == rl->n+1) { //eob
  96                 run   = 0;
  97                 level = 127;
  98             } else {
  99                 run   = rl->table_run  [code] + 1;
 100                 level = rl->table_level[code];
 101             }
 102         }
 103         rl->rl_vlc[0][i].len   = len;
 104         rl->rl_vlc[0][i].level = level;
 105         rl->rl_vlc[0][i].run   = run;
 106     }
 107 }
 108
 109 av_cold void ff_mpeg12_common_init(MpegEncContext *s)
 110 {
 111
 112     s->y_dc_scale_table =
 113     s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];
 114
 115 }
 116
 117 void ff_mpeg1_clean_buffers(MpegEncContext *s)
 118 {
 119     s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
 120     s->last_dc[1] = s->last_dc[0];
 121     s->last_dc[2] = s->last_dc[0];
 122     memset(s->last_mv, 0, sizeof(s->last_mv));
 123 }
 124
 125
 126 /******************************************/
 127 /* decoding */
 128
 129 VLC ff_mv_vlc;
 130
 131 VLC ff_dc_lum_vlc;
 132 VLC ff_dc_chroma_vlc;
 133
 134 VLC ff_mbincr_vlc;
 135 VLC ff_mb_ptype_vlc;
 136 VLC ff_mb_btype_vlc;
 137 VLC ff_mb_pat_vlc;
 138
 139 av_cold void ff_mpeg12_init_vlcs(void)
 140 {
 141     static int done = 0;
 142
 143     if (!done) {
 144         done = 1;
 145
 146         INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
 147                         ff_mpeg12_vlc_dc_lum_bits, 1, 1,
 148                         ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
 149         INIT_VLC_STATIC(&ff_dc_chroma_vlc,  DC_VLC_BITS, 12,
 150                         ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
 151                         ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
 152         INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
 153                         &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
 154                         &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);
 155         INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
 156                         &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
 157                         &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
 158         INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
 159                         &ff_mpeg12_mbPatTable[0][1], 2, 1,
 160                         &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);
 161
 162         INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
 163                         &table_mb_ptype[0][1], 2, 1,
 164                         &table_mb_ptype[0][0], 2, 1, 64);
 165         INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
 166                         &table_mb_btype[0][1], 2, 1,
 167                         &table_mb_btype[0][0], 2, 1, 64);
 168         ff_rl_init(&ff_rl_mpeg1, ff_mpeg12_static_rl_table_store[0]);
 169         ff_rl_init(&ff_rl_mpeg2, ff_mpeg12_static_rl_table_store[1]);
 170
 171         INIT_2D_VLC_RL(ff_rl_mpeg1, 680);
 172         INIT_2D_VLC_RL(ff_rl_mpeg2, 674);
 173     }
 174 }
 175
 176 /**
 177  * Find the end of the current frame in the bitstream.
 178  * @return the position of the first byte of the next frame, or -1
 179  */
 180 int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
 181 {
 182     int i;
 183     uint32_t state = pc->state;
 184
 185     /* EOF considered as end of frame */
 186     if (buf_size == 0)
 187         return 0;
 188
 189 /*
 190  0  frame start         -> 1/4
 191  1  first_SEQEXT        -> 0/2
 192  2  first field start   -> 3/0
 193  3  second_SEQEXT       -> 2/0
 194  4  searching end
 195 */
 196
 197     for (i = 0; i < buf_size; i++) {
 198         assert(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
 199         if (pc->frame_start_found & 1) {
 200             if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
 201                 pc->frame_start_found--;
 202             else if (state == EXT_START_CODE + 2) {
 203                 if ((buf[i] & 3) == 3)
 204                     pc->frame_start_found = 0;
 205                 else
 206                     pc->frame_start_found = (pc->frame_start_found + 1) & 3;
 207             }
 208             state++;
 209         } else {
 210             i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
 211             if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
 212                 i++;
 213                 pc->frame_start_found = 4;
 214             }
 215             if (state == SEQ_END_CODE) {
 216                 pc->frame_start_found = 0;
 217                 pc->state=-1;
 218                 return i+1;
 219             }
 220             if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
 221                 pc->frame_start_found = 0;
 222             if (pc->frame_start_found  < 4 && state == EXT_START_CODE)
 223                 pc->frame_start_found++;
 224             if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
 225                 if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
 226                     pc->frame_start_found = 0;
 227                     pc->state             = -1;
 228                     return i - 3;
 229                 }
 230             }
 231             if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
 232                 ff_fetch_timestamp(s, i - 3, 1);
 233             }
 234         }
 235     }
 236     pc->state = state;
 237     return END_NOT_FOUND;
 238 }
 239
 240 #define MAX_INDEX (64 - 1)
 241
 242 int ff_mpeg1_decode_block_intra(GetBitContext *gb,
 243                                 const uint16_t *quant_matrix,
 244                                 uint8_t *const scantable, int last_dc[3],
 245                                 int16_t *block, int index, int qscale)
 246 {
 247     int dc, diff, i = 0, component;
 248     RLTable *rl = &ff_rl_mpeg1;
 249
 250     /* DC coefficient */
 251     component = index <= 3 ? 0 : index - 4 + 1;
 252
 253     diff = decode_dc(gb, component);
 254     if (diff >= 0xffff)
 255         return AVERROR_INVALIDDATA;
 256
 257     dc  = last_dc[component];
 258     dc += diff;
 259     last_dc[component] = dc;
 260
 261     block[0] = dc * quant_matrix[0];
 262
 263     {
 264         OPEN_READER(re, gb);
 265         /* now quantify & encode AC coefficients */
 266         while (1) {
 267             int level, run, j;
 268
 269             UPDATE_CACHE(re, gb);
 270             GET_RL_VLC(level, run, re, gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
 271
 272             if (level == 127) {
 273                 break;
 274             } else if (level != 0) {
 275                 i += run;
 276                 if (i > MAX_INDEX)
 277                     break;
 278
 279                 j = scantable[i];
 280                 level = (level * qscale * quant_matrix[j]) >> 4;
 281                 level = (level - 1) | 1;
 282                 level = (level ^ SHOW_SBITS(re, gb, 1)) -
 283                         SHOW_SBITS(re, gb, 1);
 284                 LAST_SKIP_BITS(re, gb, 1);
 285             } else {
 286                 /* escape */
 287                 run = SHOW_UBITS(re, gb, 6) + 1;
 288                 LAST_SKIP_BITS(re, gb, 6);
 289                 UPDATE_CACHE(re, gb);
 290                 level = SHOW_SBITS(re, gb, 8);
 291                 SKIP_BITS(re, gb, 8);
 292
 293                 if (level == -128) {
 294                     level = SHOW_UBITS(re, gb, 8) - 256;
 295                     LAST_SKIP_BITS(re, gb, 8);
 296                 } else if (level == 0) {
 297                     level = SHOW_UBITS(re, gb, 8);
 298                     LAST_SKIP_BITS(re, gb, 8);
 299                 }
 300
 301                 i += run;
 302                 if (i > MAX_INDEX)
 303                     break;
 304
 305                 j = scantable[i];
 306                 if (level < 0) {
 307                     level = -level;
 308                     level = (level * qscale * quant_matrix[j]) >> 4;
 309                     level = (level - 1) | 1;
 310                     level = -level;
 311                 } else {
 312                     level = (level * qscale * quant_matrix[j]) >> 4;
 313                     level = (level - 1) | 1;
 314                 }
 315             }
 316
 317             block[j] = level;
 318         }
 319         CLOSE_READER(re, gb);
 320     }
 321
 322     if (i > MAX_INDEX)
 323         i = AVERROR_INVALIDDATA;
 324
 325     return i;
 326 }