git.sesse.net Git - ffmpeg/blob - libavcodec/h264_parser.c

   1 /*
   2  * H.26L/H.264/AVC/JVT/14496-10/... parser
   3  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * H.264 / AVC / MPEG4 part10 parser.
  25  * @author Michael Niedermayer <michaelni@gmx.at>
  26  */
  27
  28 #define UNCHECKED_BITSTREAM_READER 1
  29
  30 #include "libavutil/attributes.h"
  31 #include "parser.h"
  32 #include "h264data.h"
  33 #include "golomb.h"
  34 #include "internal.h"
  35
  36
  37 static int h264_find_frame_end(H264Context *h, const uint8_t *buf,
  38                                int buf_size)
  39 {
  40     int i, j;
  41     uint32_t state;
  42     ParseContext *pc = &h->parse_context;
  43     int next_avc= h->is_avc ? 0 : buf_size;
  44
  45 //    mb_addr= pc->mb_addr - 1;
  46     state = pc->state;
  47     if (state > 13)
  48         state = 7;
  49
  50     if (h->is_avc && !h->nal_length_size)
  51         av_log(h->avctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");
  52
  53     for (i = 0; i < buf_size; i++) {
  54         if (i >= next_avc) {
  55             int nalsize = 0;
  56             i = next_avc;
  57             for (j = 0; j < h->nal_length_size; j++)
  58                 nalsize = (nalsize << 8) | buf[i++];
  59             if (nalsize <= 0 || nalsize > buf_size - i) {
  60                 av_log(h->avctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);
  61                 return buf_size;
  62             }
  63             next_avc = i + nalsize;
  64             state    = 5;
  65         }
  66
  67         if (state == 7) {
  68 #if HAVE_FAST_UNALIGNED
  69             /* we check i < buf_size instead of i + 3 / 7 because it is
  70              * simpler and there must be FF_INPUT_BUFFER_PADDING_SIZE
  71              * bytes at the end.
  72              */
  73 #    if HAVE_FAST_64BIT
  74             while (i < next_avc &&
  75                    !((~*(const uint64_t *)(buf + i) &
  76                       (*(const uint64_t *)(buf + i) - 0x0101010101010101ULL)) &
  77                       0x8080808080808080ULL))
  78                 i += 8;
  79 #    else
  80             while (i < next_avc &&
  81                    !((~*(const uint32_t *)(buf + i) &
  82                       (*(const uint32_t *)(buf + i) - 0x01010101U)) &
  83                       0x80808080U))
  84                 i += 4;
  85 #    endif
  86 #endif
  87             for (; i < next_avc; i++)
  88                 if (!buf[i]) {
  89                     state = 2;
  90                     break;
  91                 }
  92         } else if (state <= 2) {
  93             if (buf[i] == 1)
  94                 state ^= 5;            // 2->7, 1->4, 0->5
  95             else if (buf[i])
  96                 state = 7;
  97             else
  98                 state >>= 1;           // 2->1, 1->0, 0->0
  99         } else if (state <= 5) {
 100             int v = buf[i] & 0x1F;
 101             if (v == 6 || v == 7 || v == 8 || v == 9) {
 102                 if (pc->frame_start_found) {
 103                     i++;
 104                     goto found;
 105                 }
 106             } else if (v == 1 || v == 2 || v == 5) {
 107                 state += 8;
 108                 continue;
 109             }
 110             state = 7;
 111         } else {
 112             h->parse_history[h->parse_history_count++]= buf[i];
 113             if (h->parse_history_count>3) {
 114                 unsigned int mb, last_mb= h->parse_last_mb;
 115                 GetBitContext gb;
 116
 117                 init_get_bits(&gb, h->parse_history, 8*h->parse_history_count);
 118                 h->parse_history_count=0;
 119                 mb= get_ue_golomb_long(&gb);
 120                 last_mb= h->parse_last_mb;
 121                 h->parse_last_mb= mb;
 122                 if (pc->frame_start_found) {
 123                     if (mb <= last_mb)
 124                         goto found;
 125                 } else
 126                     pc->frame_start_found = 1;
 127                 state = 7;
 128             }
 129         }
 130     }
 131     pc->state = state;
 132     if (h->is_avc)
 133         return next_avc;
 134     return END_NOT_FOUND;
 135
 136 found:
 137     pc->state             = 7;
 138     pc->frame_start_found = 0;
 139     if (h->is_avc)
 140         return next_avc;
 141     return i - (state & 5) - 3 * (state > 7);
 142 }
 143
 144 /**
 145  * Parse NAL units of found picture and decode some basic information.
 146  *
 147  * @param s parser context.
 148  * @param avctx codec context.
 149  * @param buf buffer with field/frame data.
 150  * @param buf_size size of the buffer.
 151  */
 152 static inline int parse_nal_units(AVCodecParserContext *s,
 153                                   AVCodecContext *avctx,
 154                                   const uint8_t *buf, int buf_size)
 155 {
 156     H264Context *h         = s->priv_data;
 157     const uint8_t *buf_end = buf + buf_size;
 158     unsigned int pps_id;
 159     unsigned int slice_type;
 160     int state = -1;
 161     const uint8_t *ptr;
 162     int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);
 163     int field_poc[2];
 164
 165     /* set some sane default values */
 166     s->pict_type         = AV_PICTURE_TYPE_I;
 167     s->key_frame         = 0;
 168     s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN;
 169
 170     h->avctx                        = avctx;
 171     h->sei_recovery_frame_cnt       = -1;
 172     h->sei_dpb_output_delay         = 0;
 173     h->sei_cpb_removal_delay        = -1;
 174     h->sei_buffering_period_present = 0;
 175     h->sei_fpa.frame_packing_arrangement_cancel_flag = -1;
 176
 177     if (!buf_size)
 178         return 0;
 179
 180     for (;;) {
 181         int src_length, dst_length, consumed, nalsize = 0;
 182         if (h->is_avc) {
 183             int i;
 184             if (h->nal_length_size >= buf_end - buf) break;
 185             nalsize = 0;
 186             for (i = 0; i < h->nal_length_size; i++)
 187                 nalsize = (nalsize << 8) | *buf++;
 188             if (nalsize <= 0 || nalsize > buf_end - buf) {
 189                 av_log(h->avctx, AV_LOG_ERROR, "AVC: nal size %d\n", nalsize);
 190                 break;
 191             }
 192             src_length = nalsize;
 193         } else {
 194         buf = avpriv_find_start_code(buf, buf_end, &state);
 195         if (buf >= buf_end)
 196             break;
 197         --buf;
 198         src_length = buf_end - buf;
 199         }
 200         switch (state & 0x1f) {
 201         case NAL_SLICE:
 202         case NAL_IDR_SLICE:
 203             // Do not walk the whole buffer just to decode slice header
 204             if (src_length > 20)
 205                 src_length = 20;
 206             break;
 207         }
 208         ptr = ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
 209         if (ptr == NULL || dst_length < 0)
 210             break;
 211
 212         init_get_bits(&h->gb, ptr, 8 * dst_length);
 213         switch (h->nal_unit_type) {
 214         case NAL_SPS:
 215             ff_h264_decode_seq_parameter_set(h);
 216             break;
 217         case NAL_PPS:
 218             ff_h264_decode_picture_parameter_set(h, h->gb.size_in_bits);
 219             break;
 220         case NAL_SEI:
 221             ff_h264_decode_sei(h);
 222             break;
 223         case NAL_IDR_SLICE:
 224             s->key_frame = 1;
 225
 226             h->prev_frame_num        = 0;
 227             h->prev_frame_num_offset = 0;
 228             h->prev_poc_msb          =
 229             h->prev_poc_lsb          = 0;
 230         /* fall through */
 231         case NAL_SLICE:
 232             get_ue_golomb_long(&h->gb);  // skip first_mb_in_slice
 233             slice_type   = get_ue_golomb_31(&h->gb);
 234             s->pict_type = golomb_to_pict_type[slice_type % 5];
 235             if (h->sei_recovery_frame_cnt >= 0) {
 236                 /* key frame, since recovery_frame_cnt is set */
 237                 s->key_frame = 1;
 238             }
 239             pps_id = get_ue_golomb(&h->gb);
 240             if (pps_id >= MAX_PPS_COUNT) {
 241                 av_log(h->avctx, AV_LOG_ERROR,
 242                        "pps_id out of range\n");
 243                 return -1;
 244             }
 245             if (!h->pps_buffers[pps_id]) {
 246                 av_log(h->avctx, AV_LOG_ERROR,
 247                        "non-existing PPS referenced\n");
 248                 return -1;
 249             }
 250             h->pps = *h->pps_buffers[pps_id];
 251             if (!h->sps_buffers[h->pps.sps_id]) {
 252                 av_log(h->avctx, AV_LOG_ERROR,
 253                        "non-existing SPS referenced\n");
 254                 return -1;
 255             }
 256             h->sps       = *h->sps_buffers[h->pps.sps_id];
 257             h->frame_num = get_bits(&h->gb, h->sps.log2_max_frame_num);
 258
 259             avctx->profile = ff_h264_get_profile(&h->sps);
 260             avctx->level   = h->sps.level_idc;
 261
 262             if (h->sps.frame_mbs_only_flag) {
 263                 h->picture_structure = PICT_FRAME;
 264             } else {
 265                 if (get_bits1(&h->gb)) { // field_pic_flag
 266                     h->picture_structure = PICT_TOP_FIELD + get_bits1(&h->gb); // bottom_field_flag
 267                 } else {
 268                     h->picture_structure = PICT_FRAME;
 269                 }
 270             }
 271
 272             if (h->nal_unit_type == NAL_IDR_SLICE)
 273                 get_ue_golomb(&h->gb); /* idr_pic_id */
 274             if (h->sps.poc_type == 0) {
 275                 h->poc_lsb = get_bits(&h->gb, h->sps.log2_max_poc_lsb);
 276
 277                 if (h->pps.pic_order_present == 1 &&
 278                     h->picture_structure == PICT_FRAME)
 279                     h->delta_poc_bottom = get_se_golomb(&h->gb);
 280             }
 281
 282             if (h->sps.poc_type == 1 &&
 283                 !h->sps.delta_pic_order_always_zero_flag) {
 284                 h->delta_poc[0] = get_se_golomb(&h->gb);
 285
 286                 if (h->pps.pic_order_present == 1 &&
 287                     h->picture_structure == PICT_FRAME)
 288                     h->delta_poc[1] = get_se_golomb(&h->gb);
 289             }
 290
 291             ff_init_poc(h, field_poc, NULL);
 292
 293             if (h->sps.pic_struct_present_flag) {
 294                 switch (h->sei_pic_struct) {
 295                 case SEI_PIC_STRUCT_TOP_FIELD:
 296                 case SEI_PIC_STRUCT_BOTTOM_FIELD:
 297                     s->repeat_pict = 0;
 298                     break;
 299                 case SEI_PIC_STRUCT_FRAME:
 300                 case SEI_PIC_STRUCT_TOP_BOTTOM:
 301                 case SEI_PIC_STRUCT_BOTTOM_TOP:
 302                     s->repeat_pict = 1;
 303                     break;
 304                 case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
 305                 case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
 306                     s->repeat_pict = 2;
 307                     break;
 308                 case SEI_PIC_STRUCT_FRAME_DOUBLING:
 309                     s->repeat_pict = 3;
 310                     break;
 311                 case SEI_PIC_STRUCT_FRAME_TRIPLING:
 312                     s->repeat_pict = 5;
 313                     break;
 314                 default:
 315                     s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;
 316                     break;
 317                 }
 318             } else {
 319                 s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;
 320             }
 321
 322             if (h->picture_structure == PICT_FRAME) {
 323                 s->picture_structure = AV_PICTURE_STRUCTURE_FRAME;
 324                 if (h->sps.pic_struct_present_flag) {
 325                     switch (h->sei_pic_struct) {
 326                     case SEI_PIC_STRUCT_TOP_BOTTOM:
 327                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
 328                         s->field_order = AV_FIELD_TT;
 329                         break;
 330                     case SEI_PIC_STRUCT_BOTTOM_TOP:
 331                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
 332                         s->field_order = AV_FIELD_BB;
 333                         break;
 334                     default:
 335                         s->field_order = AV_FIELD_PROGRESSIVE;
 336                         break;
 337                     }
 338                 } else {
 339                     if (field_poc[0] < field_poc[1])
 340                         s->field_order = AV_FIELD_TT;
 341                     else if (field_poc[0] > field_poc[1])
 342                         s->field_order = AV_FIELD_BB;
 343                     else
 344                         s->field_order = AV_FIELD_PROGRESSIVE;
 345                 }
 346             } else {
 347                 if (h->picture_structure == PICT_TOP_FIELD)
 348                     s->picture_structure = AV_PICTURE_STRUCTURE_TOP_FIELD;
 349                 else
 350                     s->picture_structure = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;
 351                 s->field_order = AV_FIELD_UNKNOWN;
 352             }
 353
 354             return 0; /* no need to evaluate the rest */
 355         }
 356         buf += h->is_avc ? nalsize : consumed;
 357     }
 358     if (q264)
 359         return 0;
 360     /* didn't find a picture! */
 361     av_log(h->avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);
 362     return -1;
 363 }
 364
 365 static int h264_parse(AVCodecParserContext *s,
 366                       AVCodecContext *avctx,
 367                       const uint8_t **poutbuf, int *poutbuf_size,
 368                       const uint8_t *buf, int buf_size)
 369 {
 370     H264Context *h   = s->priv_data;
 371     ParseContext *pc = &h->parse_context;
 372     int next;
 373
 374     if (!h->got_first) {
 375         h->got_first = 1;
 376         if (avctx->extradata_size) {
 377             h->avctx = avctx;
 378             // must be done like in decoder, otherwise opening the parser,
 379             // letting it create extradata and then closing and opening again
 380             // will cause has_b_frames to be always set.
 381             // Note that estimate_timings_from_pts does exactly this.
 382             if (!avctx->has_b_frames)
 383                 h->low_delay = 1;
 384             ff_h264_decode_extradata(h, avctx->extradata, avctx->extradata_size);
 385         }
 386     }
 387
 388     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
 389         next = buf_size;
 390     } else {
 391         next = h264_find_frame_end(h, buf, buf_size);
 392
 393         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 394             *poutbuf      = NULL;
 395             *poutbuf_size = 0;
 396             return buf_size;
 397         }
 398
 399         if (next < 0 && next != END_NOT_FOUND) {
 400             av_assert1(pc->last_index + next >= 0);
 401             h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); // update state
 402         }
 403     }
 404
 405     parse_nal_units(s, avctx, buf, buf_size);
 406
 407     if (h->sei_cpb_removal_delay >= 0) {
 408         s->dts_sync_point    = h->sei_buffering_period_present;
 409         s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
 410         s->pts_dts_delta     = h->sei_dpb_output_delay;
 411     } else {
 412         s->dts_sync_point    = INT_MIN;
 413         s->dts_ref_dts_delta = INT_MIN;
 414         s->pts_dts_delta     = INT_MIN;
 415     }
 416
 417     if (s->flags & PARSER_FLAG_ONCE) {
 418         s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
 419     }
 420
 421     *poutbuf      = buf;
 422     *poutbuf_size = buf_size;
 423     return next;
 424 }
 425
 426 static int h264_split(AVCodecContext *avctx,
 427                       const uint8_t *buf, int buf_size)
 428 {
 429     int i;
 430     uint32_t state = -1;
 431     int has_sps    = 0;
 432
 433     for (i = 0; i <= buf_size; i++) {
 434         if ((state & 0xFFFFFF1F) == 0x107)
 435             has_sps = 1;
 436         /*  if ((state&0xFFFFFF1F) == 0x101 ||
 437          *     (state&0xFFFFFF1F) == 0x102 ||
 438          *     (state&0xFFFFFF1F) == 0x105) {
 439          *  }
 440          */
 441         if ((state & 0xFFFFFF00) == 0x100 && (state & 0xFFFFFF1F) != 0x107 &&
 442             (state & 0xFFFFFF1F) != 0x108 && (state & 0xFFFFFF1F) != 0x109) {
 443             if (has_sps) {
 444                 while (i > 4 && buf[i - 5] == 0)
 445                     i--;
 446                 return i - 4;
 447             }
 448         }
 449         if (i < buf_size)
 450             state = (state << 8) | buf[i];
 451     }
 452     return 0;
 453 }
 454
 455 static void close(AVCodecParserContext *s)
 456 {
 457     H264Context *h   = s->priv_data;
 458     ParseContext *pc = &h->parse_context;
 459
 460     av_free(pc->buffer);
 461     ff_h264_free_context(h);
 462 }
 463
 464 static av_cold int init(AVCodecParserContext *s)
 465 {
 466     H264Context *h = s->priv_data;
 467     h->thread_context[0]   = h;
 468     h->slice_context_count = 1;
 469     return 0;
 470 }
 471
 472 AVCodecParser ff_h264_parser = {
 473     .codec_ids      = { AV_CODEC_ID_H264 },
 474     .priv_data_size = sizeof(H264Context),
 475     .parser_init    = init,
 476     .parser_parse   = h264_parse,
 477     .parser_close   = close,
 478     .split          = h264_split,
 479 };