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/thread.h" 33 34#include "avcodec.h" 35#include "mpegvideo.h" 36#include "mpeg12.h" 37#include "mpeg12data.h" 38#include "mpeg12dec.h" 39#include "mpegvideodata.h" 40#include "startcode.h" 41 42static const uint8_t table_mb_ptype[7][2] = { 43 { 3, 5 }, // 0x01 MB_INTRA 44 { 1, 2 }, // 0x02 MB_PAT 45 { 1, 3 }, // 0x08 MB_FOR 46 { 1, 1 }, // 0x0A MB_FOR|MB_PAT 47 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA 48 { 1, 5 }, // 0x12 MB_QUANT|MB_PAT 49 { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT 50}; 51 52static const uint8_t table_mb_btype[11][2] = { 53 { 3, 5 }, // 0x01 MB_INTRA 54 { 2, 3 }, // 0x04 MB_BACK 55 { 3, 3 }, // 0x06 MB_BACK|MB_PAT 56 { 2, 4 }, // 0x08 MB_FOR 57 { 3, 4 }, // 0x0A MB_FOR|MB_PAT 58 { 2, 2 }, // 0x0C MB_FOR|MB_BACK 59 { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT 60 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA 61 { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT 62 { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT 63 { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT 64}; 65 66av_cold void ff_init_2d_vlc_rl(RLTable *rl, unsigned static_size, int flags) 67{ 68 int i; 69 VLCElem table[680] = { 0 }; 70 VLC vlc = { .table = table, .table_allocated = static_size }; 71 av_assert0(static_size <= FF_ARRAY_ELEMS(table)); 72 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 | flags); 73 74 for (i = 0; i < vlc.table_size; i++) { 75 int code = vlc.table[i].sym; 76 int len = vlc.table[i].len; 77 int level, run; 78 79 if (len == 0) { // illegal code 80 run = 65; 81 level = MAX_LEVEL; 82 } else if (len<0) { //more bits needed 83 run = 0; 84 level = code; 85 } else { 86 if (code == rl->n) { //esc 87 run = 65; 88 level = 0; 89 } else if (code == rl->n+1) { //eob 90 run = 0; 91 level = 127; 92 } else { 93 run = rl->table_run [code] + 1; 94 level = rl->table_level[code]; 95 } 96 } 97 rl->rl_vlc[0][i].len = len; 98 rl->rl_vlc[0][i].level = level; 99 rl->rl_vlc[0][i].run = run; 100 } 101} 102 103av_cold void ff_mpeg12_common_init(MpegEncContext *s) 104{ 105 106 s->y_dc_scale_table = 107 s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision]; 108 109} 110 111void ff_mpeg1_clean_buffers(MpegEncContext *s) 112{ 113 s->last_dc[0] = 1 << (7 + s->intra_dc_precision); 114 s->last_dc[1] = s->last_dc[0]; 115 s->last_dc[2] = s->last_dc[0]; 116 memset(s->last_mv, 0, sizeof(s->last_mv)); 117} 118 119 120/******************************************/ 121/* decoding */ 122 123VLC ff_mv_vlc; 124 125VLC ff_dc_lum_vlc; 126VLC ff_dc_chroma_vlc; 127 128VLC ff_mbincr_vlc; 129VLC ff_mb_ptype_vlc; 130VLC ff_mb_btype_vlc; 131VLC ff_mb_pat_vlc; 132 133static av_cold void mpeg12_init_vlcs(void) 134{ 135 INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12, 136 ff_mpeg12_vlc_dc_lum_bits, 1, 1, 137 ff_mpeg12_vlc_dc_lum_code, 2, 2, 512); 138 INIT_VLC_STATIC(&ff_dc_chroma_vlc, DC_VLC_BITS, 12, 139 ff_mpeg12_vlc_dc_chroma_bits, 1, 1, 140 ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514); 141 INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17, 142 &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1, 143 &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 266); 144 INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36, 145 &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1, 146 &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538); 147 INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64, 148 &ff_mpeg12_mbPatTable[0][1], 2, 1, 149 &ff_mpeg12_mbPatTable[0][0], 2, 1, 512); 150 151 INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7, 152 &table_mb_ptype[0][1], 2, 1, 153 &table_mb_ptype[0][0], 2, 1, 64); 154 INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11, 155 &table_mb_btype[0][1], 2, 1, 156 &table_mb_btype[0][0], 2, 1, 64); 157 158 INIT_2D_VLC_RL(ff_rl_mpeg1, 680, 0); 159 INIT_2D_VLC_RL(ff_rl_mpeg2, 674, 0); 160} 161 162av_cold void ff_mpeg12_init_vlcs(void) 163{ 164 static AVOnce init_static_once = AV_ONCE_INIT; 165 ff_thread_once(&init_static_once, mpeg12_init_vlcs); 166} 167 168#if FF_API_FLAG_TRUNCATED 169/** 170 * Find the end of the current frame in the bitstream. 171 * @return the position of the first byte of the next frame, or -1 172 */ 173int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s) 174{ 175 int i; 176 uint32_t state = pc->state; 177 178 /* EOF considered as end of frame */ 179 if (buf_size == 0) 180 return 0; 181 182/* 183 0 frame start -> 1/4 184 1 first_SEQEXT -> 0/2 185 2 first field start -> 3/0 186 3 second_SEQEXT -> 2/0 187 4 searching end 188*/ 189 190 for (i = 0; i < buf_size; i++) { 191 av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4); 192 if (pc->frame_start_found & 1) { 193 if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80) 194 pc->frame_start_found--; 195 else if (state == EXT_START_CODE + 2) { 196 if ((buf[i] & 3) == 3) 197 pc->frame_start_found = 0; 198 else 199 pc->frame_start_found = (pc->frame_start_found + 1) & 3; 200 } 201 state++; 202 } else { 203 i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1; 204 if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) { 205 i++; 206 pc->frame_start_found = 4; 207 } 208 if (state == SEQ_END_CODE) { 209 pc->frame_start_found = 0; 210 pc->state=-1; 211 return i+1; 212 } 213 if (pc->frame_start_found == 2 && state == SEQ_START_CODE) 214 pc->frame_start_found = 0; 215 if (pc->frame_start_found < 4 && state == EXT_START_CODE) 216 pc->frame_start_found++; 217 if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) { 218 if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) { 219 pc->frame_start_found = 0; 220 pc->state = -1; 221 return i - 3; 222 } 223 } 224 if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) { 225 ff_fetch_timestamp(s, i - 3, 1, i > 3); 226 } 227 } 228 } 229 pc->state = state; 230 return END_NOT_FOUND; 231} 232#endif 233 234#define MAX_INDEX (64 - 1) 235 236int ff_mpeg1_decode_block_intra(GetBitContext *gb, 237 const uint16_t *quant_matrix, 238 const uint8_t *scantable, int last_dc[3], 239 int16_t *block, int index, int qscale) 240{ 241 int dc, diff, i = 0, component; 242 RLTable *rl = &ff_rl_mpeg1; 243 244 /* DC coefficient */ 245 component = index <= 3 ? 0 : index - 4 + 1; 246 247 diff = decode_dc(gb, component); 248 if (diff >= 0xffff) 249 return AVERROR_INVALIDDATA; 250 251 dc = last_dc[component]; 252 dc += diff; 253 last_dc[component] = dc; 254 255 block[0] = dc * quant_matrix[0]; 256 257 { 258 OPEN_READER(re, gb); 259 UPDATE_CACHE(re, gb); 260 if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF) 261 goto end; 262 263 /* now quantify & encode AC coefficients */ 264 while (1) { 265 int level, run, j; 266 267 GET_RL_VLC(level, run, re, gb, rl->rl_vlc[0], 268 TEX_VLC_BITS, 2, 0); 269 270 if (level != 0) { 271 i += run; 272 if (i > MAX_INDEX) 273 break; 274 275 j = scantable[i]; 276 level = (level * qscale * quant_matrix[j]) >> 4; 277 level = (level - 1) | 1; 278 level = (level ^ SHOW_SBITS(re, gb, 1)) - 279 SHOW_SBITS(re, gb, 1); 280 SKIP_BITS(re, gb, 1); 281 } else { 282 /* escape */ 283 run = SHOW_UBITS(re, gb, 6) + 1; 284 LAST_SKIP_BITS(re, gb, 6); 285 UPDATE_CACHE(re, gb); 286 level = SHOW_SBITS(re, gb, 8); 287 SKIP_BITS(re, gb, 8); 288 289 if (level == -128) { 290 level = SHOW_UBITS(re, gb, 8) - 256; 291 SKIP_BITS(re, gb, 8); 292 } else if (level == 0) { 293 level = SHOW_UBITS(re, gb, 8); 294 SKIP_BITS(re, gb, 8); 295 } 296 297 i += run; 298 if (i > MAX_INDEX) 299 break; 300 301 j = scantable[i]; 302 if (level < 0) { 303 level = -level; 304 level = (level * qscale * quant_matrix[j]) >> 4; 305 level = (level - 1) | 1; 306 level = -level; 307 } else { 308 level = (level * qscale * quant_matrix[j]) >> 4; 309 level = (level - 1) | 1; 310 } 311 } 312 313 block[j] = level; 314 if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF) 315 break; 316 317 UPDATE_CACHE(re, gb); 318 } 319end: 320 LAST_SKIP_BITS(re, gb, 2); 321 CLOSE_READER(re, gb); 322 } 323 324 if (i > MAX_INDEX) 325 i = AVERROR_INVALIDDATA; 326 327 return i; 328} 329