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 Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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 #include "libavutil/attributes.h"
  29 #include "parser.h"
  30 #include "h264data.h"
  31 #include "golomb.h"
  32 #include "internal.h"
  33 #include "mpegutils.h"
  34
  35 #include <assert.h>
  36
  37 typedef struct H264ParseContext {
  38     H264Context h;
  39     ParseContext pc;
  40     int got_first;
  41 } H264ParseContext;
  42
  43
  44 static int h264_find_frame_end(H264ParseContext *p, const uint8_t *buf,
  45                                int buf_size)
  46 {
  47     H264Context *h = &p->h;
  48     int i;
  49     uint32_t state;
  50     ParseContext *pc = &p->pc;
  51 //    mb_addr= pc->mb_addr - 1;
  52     state = pc->state;
  53     if (state > 13)
  54         state = 7;
  55
  56     for (i = 0; i < buf_size; i++) {
  57         if (state == 7) {
  58             i += h->h264dsp.startcode_find_candidate(buf + i, buf_size - i);
  59             if (i < buf_size)
  60                 state = 2;
  61         } else if (state <= 2) {
  62             if (buf[i] == 1)
  63                 state ^= 5;            // 2->7, 1->4, 0->5
  64             else if (buf[i])
  65                 state = 7;
  66             else
  67                 state >>= 1;           // 2->1, 1->0, 0->0
  68         } else if (state <= 5) {
  69             int nalu_type = buf[i] & 0x1F;
  70             if (nalu_type == NAL_SEI || nalu_type == NAL_SPS ||
  71                 nalu_type == NAL_PPS || nalu_type == NAL_AUD) {
  72                 if (pc->frame_start_found) {
  73                     i++;
  74                     goto found;
  75                 }
  76             } else if (nalu_type == NAL_SLICE || nalu_type == NAL_DPA ||
  77                        nalu_type == NAL_IDR_SLICE) {
  78                 if (pc->frame_start_found) {
  79                     state += 8;
  80                     continue;
  81                 } else
  82                     pc->frame_start_found = 1;
  83             }
  84             state = 7;
  85         } else {
  86             // first_mb_in_slice is 0, probably the first nal of a new slice
  87             if (buf[i] & 0x80)
  88                 goto found;
  89             state = 7;
  90         }
  91     }
  92     pc->state = state;
  93     return END_NOT_FOUND;
  94
  95 found:
  96     pc->state             = 7;
  97     pc->frame_start_found = 0;
  98     return i - (state & 5);
  99 }
 100
 101 static int scan_mmco_reset(AVCodecParserContext *s)
 102 {
 103     H264ParseContext *p = s->priv_data;
 104     H264Context      *h = &p->h;
 105     H264SliceContext *sl = &h->slice_ctx[0];
 106
 107     sl->slice_type_nos = s->pict_type & 3;
 108
 109     if (h->pps.redundant_pic_cnt_present)
 110         get_ue_golomb(&sl->gb); // redundant_pic_count
 111
 112     if (ff_set_ref_count(h, sl) < 0)
 113         return AVERROR_INVALIDDATA;
 114
 115     if (sl->slice_type_nos != AV_PICTURE_TYPE_I) {
 116         int list;
 117         for (list = 0; list < sl->list_count; list++) {
 118             if (get_bits1(&sl->gb)) {
 119                 int index;
 120                 for (index = 0; ; index++) {
 121                     unsigned int reordering_of_pic_nums_idc = get_ue_golomb_31(&sl->gb);
 122
 123                     if (reordering_of_pic_nums_idc < 3)
 124                         get_ue_golomb(&sl->gb);
 125                     else if (reordering_of_pic_nums_idc > 3) {
 126                         av_log(h->avctx, AV_LOG_ERROR,
 127                                "illegal reordering_of_pic_nums_idc %d\n",
 128                                reordering_of_pic_nums_idc);
 129                         return AVERROR_INVALIDDATA;
 130                     } else
 131                         break;
 132
 133                     if (index >= sl->ref_count[list]) {
 134                         av_log(h->avctx, AV_LOG_ERROR,
 135                                "reference count %d overflow\n", index);
 136                         return AVERROR_INVALIDDATA;
 137                     }
 138                 }
 139             }
 140         }
 141     }
 142
 143     if ((h->pps.weighted_pred && sl->slice_type_nos == AV_PICTURE_TYPE_P) ||
 144         (h->pps.weighted_bipred_idc == 1 && sl->slice_type_nos == AV_PICTURE_TYPE_B))
 145         ff_pred_weight_table(h, sl);
 146
 147     if (get_bits1(&sl->gb)) { // adaptive_ref_pic_marking_mode_flag
 148         int i;
 149         for (i = 0; i < MAX_MMCO_COUNT; i++) {
 150             MMCOOpcode opcode = get_ue_golomb_31(&sl->gb);
 151             if (opcode > (unsigned) MMCO_LONG) {
 152                 av_log(h->avctx, AV_LOG_ERROR,
 153                        "illegal memory management control operation %d\n",
 154                        opcode);
 155                 return AVERROR_INVALIDDATA;
 156             }
 157             if (opcode == MMCO_END)
 158                return 0;
 159             else if (opcode == MMCO_RESET)
 160                 return 1;
 161
 162             if (opcode == MMCO_SHORT2UNUSED || opcode == MMCO_SHORT2LONG)
 163                 get_ue_golomb(&sl->gb);
 164             if (opcode == MMCO_SHORT2LONG || opcode == MMCO_LONG2UNUSED ||
 165                 opcode == MMCO_LONG || opcode == MMCO_SET_MAX_LONG)
 166                 get_ue_golomb_31(&sl->gb);
 167         }
 168     }
 169
 170     return 0;
 171 }
 172
 173 /**
 174  * Parse NAL units of found picture and decode some basic information.
 175  *
 176  * @param s parser context.
 177  * @param avctx codec context.
 178  * @param buf buffer with field/frame data.
 179  * @param buf_size size of the buffer.
 180  */
 181 static inline int parse_nal_units(AVCodecParserContext *s,
 182                                   AVCodecContext *avctx,
 183                                   const uint8_t *buf, int buf_size)
 184 {
 185     H264ParseContext *p = s->priv_data;
 186     H264Context      *h = &p->h;
 187     H264SliceContext *sl = &h->slice_ctx[0];
 188     const uint8_t *buf_end = buf + buf_size;
 189     unsigned int pps_id;
 190     unsigned int slice_type;
 191     int state = -1, got_reset = 0;
 192     const uint8_t *ptr;
 193     int field_poc[2];
 194
 195     /* set some sane default values */
 196     s->pict_type         = AV_PICTURE_TYPE_I;
 197     s->key_frame         = 0;
 198     s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN;
 199
 200     h->avctx = avctx;
 201     ff_h264_reset_sei(h);
 202
 203     if (!buf_size)
 204         return 0;
 205
 206     for (;;) {
 207         int src_length, dst_length, consumed;
 208         buf = avpriv_find_start_code(buf, buf_end, &state);
 209         if (buf >= buf_end)
 210             break;
 211         --buf;
 212         src_length = buf_end - buf;
 213         switch (state & 0x1f) {
 214         case NAL_SLICE:
 215         case NAL_IDR_SLICE:
 216             // Do not walk the whole buffer just to decode slice header
 217             if ((state & 0x1f) == NAL_IDR_SLICE || ((state >> 5) & 0x3) == 0) {
 218                 /* IDR or disposable slice
 219                  * No need to decode many bytes because MMCOs shall not be present. */
 220                 if (src_length > 60)
 221                     src_length = 60;
 222             } else {
 223                 /* To decode up to MMCOs */
 224                 if (src_length > 1000)
 225                     src_length = 1000;
 226             }
 227             break;
 228         }
 229         ptr = ff_h264_decode_nal(h, sl, buf, &dst_length, &consumed, src_length);
 230         if (!ptr || dst_length < 0)
 231             break;
 232
 233         init_get_bits(&h->gb, ptr, 8 * dst_length);
 234         switch (h->nal_unit_type) {
 235         case NAL_SPS:
 236             ff_h264_decode_seq_parameter_set(h);
 237             break;
 238         case NAL_PPS:
 239             ff_h264_decode_picture_parameter_set(h, h->gb.size_in_bits);
 240             break;
 241         case NAL_SEI:
 242             ff_h264_decode_sei(h);
 243             break;
 244         case NAL_IDR_SLICE:
 245             s->key_frame = 1;
 246
 247             h->prev_frame_num        = 0;
 248             h->prev_frame_num_offset = 0;
 249             h->prev_poc_msb          =
 250             h->prev_poc_lsb          = 0;
 251         /* fall through */
 252         case NAL_SLICE:
 253             init_get_bits(&sl->gb, ptr, 8 * dst_length);
 254             get_ue_golomb(&sl->gb);  // skip first_mb_in_slice
 255             slice_type   = get_ue_golomb_31(&sl->gb);
 256             s->pict_type = golomb_to_pict_type[slice_type % 5];
 257             if (h->sei_recovery_frame_cnt >= 0) {
 258                 /* key frame, since recovery_frame_cnt is set */
 259                 s->key_frame = 1;
 260             }
 261             pps_id = get_ue_golomb(&sl->gb);
 262             if (pps_id >= MAX_PPS_COUNT) {
 263                 av_log(h->avctx, AV_LOG_ERROR,
 264                        "pps_id %u out of range\n", pps_id);
 265                 return -1;
 266             }
 267             if (!h->pps_buffers[pps_id]) {
 268                 av_log(h->avctx, AV_LOG_ERROR,
 269                        "non-existing PPS %u referenced\n", pps_id);
 270                 return -1;
 271             }
 272             h->pps = *h->pps_buffers[pps_id];
 273             if (!h->sps_buffers[h->pps.sps_id]) {
 274                 av_log(h->avctx, AV_LOG_ERROR,
 275                        "non-existing SPS %u referenced\n", h->pps.sps_id);
 276                 return -1;
 277             }
 278             h->sps       = *h->sps_buffers[h->pps.sps_id];
 279             h->frame_num = get_bits(&sl->gb, h->sps.log2_max_frame_num);
 280
 281             s->coded_width  = 16 * h->sps.mb_width;
 282             s->coded_height = 16 * h->sps.mb_height;
 283             s->width        = s->coded_width  - (h->sps.crop_right + h->sps.crop_left);
 284             s->height       = s->coded_height - (h->sps.crop_top   + h->sps.crop_bottom);
 285             if (s->width <= 0 || s->height <= 0) {
 286                 s->width  = s->coded_width;
 287                 s->height = s->coded_height;
 288             }
 289
 290             switch (h->sps.bit_depth_luma) {
 291             case 9:
 292                 if (CHROMA444(h))      s->format = AV_PIX_FMT_YUV444P9;
 293                 else if (CHROMA422(h)) s->format = AV_PIX_FMT_YUV422P9;
 294                 else                   s->format = AV_PIX_FMT_YUV420P9;
 295                 break;
 296             case 10:
 297                 if (CHROMA444(h))      s->format = AV_PIX_FMT_YUV444P10;
 298                 else if (CHROMA422(h)) s->format = AV_PIX_FMT_YUV422P10;
 299                 else                   s->format = AV_PIX_FMT_YUV420P10;
 300                 break;
 301             case 8:
 302                 if (CHROMA444(h))      s->format = AV_PIX_FMT_YUV444P;
 303                 else if (CHROMA422(h)) s->format = AV_PIX_FMT_YUV422P;
 304                 else                   s->format = AV_PIX_FMT_YUV420P;
 305                 break;
 306             default:
 307                 s->format = AV_PIX_FMT_NONE;
 308             }
 309
 310             avctx->profile = ff_h264_get_profile(&h->sps);
 311             avctx->level   = h->sps.level_idc;
 312
 313             if (h->sps.frame_mbs_only_flag) {
 314                 h->picture_structure = PICT_FRAME;
 315             } else {
 316                 if (get_bits1(&sl->gb)) { // field_pic_flag
 317                     h->picture_structure = PICT_TOP_FIELD + get_bits1(&sl->gb); // bottom_field_flag
 318                 } else {
 319                     h->picture_structure = PICT_FRAME;
 320                 }
 321             }
 322
 323             if (h->nal_unit_type == NAL_IDR_SLICE)
 324                 get_ue_golomb(&sl->gb); /* idr_pic_id */
 325             if (h->sps.poc_type == 0) {
 326                 h->poc_lsb = get_bits(&sl->gb, h->sps.log2_max_poc_lsb);
 327
 328                 if (h->pps.pic_order_present == 1 &&
 329                     h->picture_structure == PICT_FRAME)
 330                     h->delta_poc_bottom = get_se_golomb(&sl->gb);
 331             }
 332
 333             if (h->sps.poc_type == 1 &&
 334                 !h->sps.delta_pic_order_always_zero_flag) {
 335                 h->delta_poc[0] = get_se_golomb(&sl->gb);
 336
 337                 if (h->pps.pic_order_present == 1 &&
 338                     h->picture_structure == PICT_FRAME)
 339                     h->delta_poc[1] = get_se_golomb(&sl->gb);
 340             }
 341
 342             /* Decode POC of this picture.
 343              * The prev_ values needed for decoding POC of the next picture are not set here. */
 344             field_poc[0] = field_poc[1] = INT_MAX;
 345             ff_init_poc(h, field_poc, &s->output_picture_number);
 346
 347             /* Continue parsing to check if MMCO_RESET is present.
 348              * FIXME: MMCO_RESET could appear in non-first slice.
 349              *        Maybe, we should parse all undisposable non-IDR slice of this
 350              *        picture until encountering MMCO_RESET in a slice of it. */
 351             if (h->nal_ref_idc && h->nal_unit_type != NAL_IDR_SLICE) {
 352                 got_reset = scan_mmco_reset(s);
 353                 if (got_reset < 0)
 354                     return got_reset;
 355             }
 356
 357             /* Set up the prev_ values for decoding POC of the next picture. */
 358             h->prev_frame_num        = got_reset ? 0 : h->frame_num;
 359             h->prev_frame_num_offset = got_reset ? 0 : h->frame_num_offset;
 360             if (h->nal_ref_idc != 0) {
 361                 if (!got_reset) {
 362                     h->prev_poc_msb = h->poc_msb;
 363                     h->prev_poc_lsb = h->poc_lsb;
 364                 } else {
 365                     h->prev_poc_msb = 0;
 366                     h->prev_poc_lsb =
 367                         h->picture_structure == PICT_BOTTOM_FIELD ? 0 : field_poc[0];
 368                 }
 369             }
 370
 371             if (h->sps.pic_struct_present_flag) {
 372                 switch (h->sei_pic_struct) {
 373                 case SEI_PIC_STRUCT_TOP_FIELD:
 374                 case SEI_PIC_STRUCT_BOTTOM_FIELD:
 375                     s->repeat_pict = 0;
 376                     break;
 377                 case SEI_PIC_STRUCT_FRAME:
 378                 case SEI_PIC_STRUCT_TOP_BOTTOM:
 379                 case SEI_PIC_STRUCT_BOTTOM_TOP:
 380                     s->repeat_pict = 1;
 381                     break;
 382                 case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
 383                 case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
 384                     s->repeat_pict = 2;
 385                     break;
 386                 case SEI_PIC_STRUCT_FRAME_DOUBLING:
 387                     s->repeat_pict = 3;
 388                     break;
 389                 case SEI_PIC_STRUCT_FRAME_TRIPLING:
 390                     s->repeat_pict = 5;
 391                     break;
 392                 default:
 393                     s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;
 394                     break;
 395                 }
 396             } else {
 397                 s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;
 398             }
 399
 400             if (h->picture_structure == PICT_FRAME) {
 401                 s->picture_structure = AV_PICTURE_STRUCTURE_FRAME;
 402                 if (h->sps.pic_struct_present_flag) {
 403                     switch (h->sei_pic_struct) {
 404                     case SEI_PIC_STRUCT_TOP_BOTTOM:
 405                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
 406                         s->field_order = AV_FIELD_TT;
 407                         break;
 408                     case SEI_PIC_STRUCT_BOTTOM_TOP:
 409                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
 410                         s->field_order = AV_FIELD_BB;
 411                         break;
 412                     default:
 413                         s->field_order = AV_FIELD_PROGRESSIVE;
 414                         break;
 415                     }
 416                 } else {
 417                     if (field_poc[0] < field_poc[1])
 418                         s->field_order = AV_FIELD_TT;
 419                     else if (field_poc[0] > field_poc[1])
 420                         s->field_order = AV_FIELD_BB;
 421                     else
 422                         s->field_order = AV_FIELD_PROGRESSIVE;
 423                 }
 424             } else {
 425                 if (h->picture_structure == PICT_TOP_FIELD)
 426                     s->picture_structure = AV_PICTURE_STRUCTURE_TOP_FIELD;
 427                 else
 428                     s->picture_structure = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;
 429                 s->field_order = AV_FIELD_UNKNOWN;
 430             }
 431
 432             return 0; /* no need to evaluate the rest */
 433         }
 434         buf += consumed;
 435     }
 436     /* didn't find a picture! */
 437     av_log(h->avctx, AV_LOG_ERROR, "missing picture in access unit\n");
 438     return -1;
 439 }
 440
 441 static int h264_parse(AVCodecParserContext *s,
 442                       AVCodecContext *avctx,
 443                       const uint8_t **poutbuf, int *poutbuf_size,
 444                       const uint8_t *buf, int buf_size)
 445 {
 446     H264ParseContext *p = s->priv_data;
 447     H264Context      *h = &p->h;
 448     ParseContext *pc = &p->pc;
 449     int next;
 450
 451     if (!p->got_first) {
 452         p->got_first = 1;
 453         if (avctx->extradata_size) {
 454             h->avctx = avctx;
 455             // must be done like in the decoder.
 456             // otherwise opening the parser, creating extradata,
 457             // and then closing and opening again
 458             // will cause has_b_frames to be always set.
 459             // NB: estimate_timings_from_pts behaves exactly like this.
 460             if (!avctx->has_b_frames)
 461                 h->low_delay = 1;
 462             ff_h264_decode_extradata(h);
 463         }
 464     }
 465
 466     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
 467         next = buf_size;
 468     } else {
 469         next = h264_find_frame_end(p, buf, buf_size);
 470
 471         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 472             *poutbuf      = NULL;
 473             *poutbuf_size = 0;
 474             return buf_size;
 475         }
 476
 477         if (next < 0 && next != END_NOT_FOUND) {
 478             assert(pc->last_index + next >= 0);
 479             h264_find_frame_end(p, &pc->buffer[pc->last_index + next], -next); // update state
 480         }
 481     }
 482
 483     parse_nal_units(s, avctx, buf, buf_size);
 484
 485     if (h->sei_cpb_removal_delay >= 0) {
 486         s->dts_sync_point    = h->sei_buffering_period_present;
 487         s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
 488         s->pts_dts_delta     = h->sei_dpb_output_delay;
 489     } else {
 490         s->dts_sync_point    = INT_MIN;
 491         s->dts_ref_dts_delta = INT_MIN;
 492         s->pts_dts_delta     = INT_MIN;
 493     }
 494
 495     if (s->flags & PARSER_FLAG_ONCE) {
 496         s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
 497     }
 498
 499     *poutbuf      = buf;
 500     *poutbuf_size = buf_size;
 501     return next;
 502 }
 503
 504 static int h264_split(AVCodecContext *avctx,
 505                       const uint8_t *buf, int buf_size)
 506 {
 507     int i;
 508     uint32_t state = -1;
 509     int has_sps    = 0;
 510
 511     for (i = 0; i <= buf_size; i++) {
 512         if ((state & 0xFFFFFF1F) == 0x107)
 513             has_sps = 1;
 514         /*  if((state&0xFFFFFF1F) == 0x101 ||
 515          *     (state&0xFFFFFF1F) == 0x102 ||
 516          *     (state&0xFFFFFF1F) == 0x105) {
 517          *  }
 518          */
 519         if ((state & 0xFFFFFF00) == 0x100 && (state & 0xFFFFFF1F) != 0x106 &&
 520             (state & 0xFFFFFF1F) != 0x107 && (state & 0xFFFFFF1F) != 0x108 &&
 521             (state & 0xFFFFFF1F) != 0x109 && (state & 0xFFFFFF1F) != 0x10d &&
 522             (state & 0xFFFFFF1F) != 0x10f) {
 523             if (has_sps) {
 524                 while (i > 4 && buf[i - 5] == 0)
 525                     i--;
 526                 return i - 4;
 527             }
 528         }
 529         if (i < buf_size)
 530             state = (state << 8) | buf[i];
 531     }
 532     return 0;
 533 }
 534
 535 static void close(AVCodecParserContext *s)
 536 {
 537     H264ParseContext *p = s->priv_data;
 538     H264Context      *h = &p->h;
 539     ParseContext *pc = &p->pc;
 540
 541     av_free(pc->buffer);
 542     ff_h264_free_context(h);
 543 }
 544
 545 static av_cold int init(AVCodecParserContext *s)
 546 {
 547     H264ParseContext *p = s->priv_data;
 548     H264Context      *h = &p->h;
 549
 550     h->slice_ctx = av_mallocz(sizeof(*h->slice_ctx));
 551     if (!h->slice_ctx)
 552         return 0;
 553     h->nb_slice_ctx = 1;
 554
 555     h->slice_context_count = 1;
 556     ff_h264dsp_init(&h->h264dsp, 8, 1);
 557     return 0;
 558 }
 559
 560 AVCodecParser ff_h264_parser = {
 561     .codec_ids      = { AV_CODEC_ID_H264 },
 562     .priv_data_size = sizeof(H264ParseContext),
 563     .parser_init    = init,
 564     .parser_parse   = h264_parse,
 565     .parser_close   = close,
 566     .split          = h264_split,
 567 };