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 / MPEG-4 part10 parser.
  25  * @author Michael Niedermayer <michaelni@gmx.at>
  26  */
  27
  28 #define UNCHECKED_BITSTREAM_READER 1
  29
  30 #include <assert.h>
  31 #include <stdint.h>
  32
  33 #include "libavutil/avutil.h"
  34 #include "libavutil/error.h"
  35 #include "libavutil/log.h"
  36 #include "libavutil/mem.h"
  37 #include "libavutil/pixfmt.h"
  38
  39 #include "avcodec.h"
  40 #include "get_bits.h"
  41 #include "golomb.h"
  42 #include "h264.h"
  43 #include "h264_sei.h"
  44 #include "h264_ps.h"
  45 #include "h264data.h"
  46 #include "internal.h"
  47 #include "mpegutils.h"
  48 #include "parser.h"
  49
  50 typedef struct H264ParseContext {
  51     ParseContext pc;
  52     H264ParamSets ps;
  53     H264DSPContext h264dsp;
  54     H264POCContext poc;
  55     H264SEIContext sei;
  56     int is_avc;
  57     int nal_length_size;
  58     int got_first;
  59     int picture_structure;
  60     uint8_t parse_history[6];
  61     int parse_history_count;
  62     int parse_last_mb;
  63     int64_t reference_dts;
  64     int last_frame_num, last_picture_structure;
  65 } H264ParseContext;
  66
  67
  68 static int h264_find_frame_end(H264ParseContext *p, const uint8_t *buf,
  69                                int buf_size, void *logctx)
  70 {
  71     int i, j;
  72     uint32_t state;
  73     ParseContext *pc = &p->pc;
  74
  75     int next_avc = p->is_avc ? 0 : buf_size;
  76 //    mb_addr= pc->mb_addr - 1;
  77     state = pc->state;
  78     if (state > 13)
  79         state = 7;
  80
  81     if (p->is_avc && !p->nal_length_size)
  82         av_log(logctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");
  83
  84     for (i = 0; i < buf_size; i++) {
  85         if (i >= next_avc) {
  86             int nalsize = 0;
  87             i = next_avc;
  88             for (j = 0; j < p->nal_length_size; j++)
  89                 nalsize = (nalsize << 8) | buf[i++];
  90             if (nalsize <= 0 || nalsize > buf_size - i) {
  91                 av_log(logctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);
  92                 return buf_size;
  93             }
  94             next_avc = i + nalsize;
  95             state    = 5;
  96         }
  97
  98         if (state == 7) {
  99             i += p->h264dsp.startcode_find_candidate(buf + i, next_avc - i);
 100             if (i < next_avc)
 101                 state = 2;
 102         } else if (state <= 2) {
 103             if (buf[i] == 1)
 104                 state ^= 5;            // 2->7, 1->4, 0->5
 105             else if (buf[i])
 106                 state = 7;
 107             else
 108                 state >>= 1;           // 2->1, 1->0, 0->0
 109         } else if (state <= 5) {
 110             int nalu_type = buf[i] & 0x1F;
 111             if (nalu_type == H264_NAL_SEI || nalu_type == H264_NAL_SPS ||
 112                 nalu_type == H264_NAL_PPS || nalu_type == H264_NAL_AUD) {
 113                 if (pc->frame_start_found) {
 114                     i++;
 115                     goto found;
 116                 }
 117             } else if (nalu_type == H264_NAL_SLICE || nalu_type == H264_NAL_DPA ||
 118                        nalu_type == H264_NAL_IDR_SLICE) {
 119                 state += 8;
 120                 continue;
 121             }
 122             state = 7;
 123         } else {
 124             p->parse_history[p->parse_history_count++] = buf[i];
 125             if (p->parse_history_count > 5) {
 126                 unsigned int mb, last_mb = p->parse_last_mb;
 127                 GetBitContext gb;
 128
 129                 init_get_bits(&gb, p->parse_history, 8*p->parse_history_count);
 130                 p->parse_history_count = 0;
 131                 mb= get_ue_golomb_long(&gb);
 132                 p->parse_last_mb = mb;
 133                 if (pc->frame_start_found) {
 134                     if (mb <= last_mb)
 135                         goto found;
 136                 } else
 137                     pc->frame_start_found = 1;
 138                 state = 7;
 139             }
 140         }
 141     }
 142     pc->state = state;
 143     if (p->is_avc)
 144         return next_avc;
 145     return END_NOT_FOUND;
 146
 147 found:
 148     pc->state             = 7;
 149     pc->frame_start_found = 0;
 150     if (p->is_avc)
 151         return next_avc;
 152     return i - (state & 5) - 5 * (state > 7);
 153 }
 154
 155 static int scan_mmco_reset(AVCodecParserContext *s, GetBitContext *gb,
 156                            void *logctx)
 157 {
 158     H264PredWeightTable pwt;
 159     int slice_type_nos = s->pict_type & 3;
 160     H264ParseContext *p = s->priv_data;
 161     int list_count, ref_count[2];
 162
 163
 164     if (p->ps.pps->redundant_pic_cnt_present)
 165         get_ue_golomb(gb); // redundant_pic_count
 166
 167     if (slice_type_nos == AV_PICTURE_TYPE_B)
 168         get_bits1(gb); // direct_spatial_mv_pred
 169
 170     if (ff_h264_parse_ref_count(&list_count, ref_count, gb, p->ps.pps,
 171                                 slice_type_nos, p->picture_structure, logctx) < 0)
 172         return AVERROR_INVALIDDATA;
 173
 174     if (slice_type_nos != AV_PICTURE_TYPE_I) {
 175         int list;
 176         for (list = 0; list < list_count; list++) {
 177             if (get_bits1(gb)) {
 178                 int index;
 179                 for (index = 0; ; index++) {
 180                     unsigned int reordering_of_pic_nums_idc = get_ue_golomb_31(gb);
 181
 182                     if (reordering_of_pic_nums_idc < 3)
 183                         get_ue_golomb_long(gb);
 184                     else if (reordering_of_pic_nums_idc > 3) {
 185                         av_log(logctx, AV_LOG_ERROR,
 186                                "illegal reordering_of_pic_nums_idc %d\n",
 187                                reordering_of_pic_nums_idc);
 188                         return AVERROR_INVALIDDATA;
 189                     } else
 190                         break;
 191
 192                     if (index >= ref_count[list]) {
 193                         av_log(logctx, AV_LOG_ERROR,
 194                                "reference count %d overflow\n", index);
 195                         return AVERROR_INVALIDDATA;
 196                     }
 197                 }
 198             }
 199         }
 200     }
 201
 202     if ((p->ps.pps->weighted_pred && slice_type_nos == AV_PICTURE_TYPE_P) ||
 203         (p->ps.pps->weighted_bipred_idc == 1 && slice_type_nos == AV_PICTURE_TYPE_B))
 204         ff_h264_pred_weight_table(gb, p->ps.sps, ref_count, slice_type_nos,
 205                                   &pwt, logctx);
 206
 207     if (get_bits1(gb)) { // adaptive_ref_pic_marking_mode_flag
 208         int i;
 209         for (i = 0; i < MAX_MMCO_COUNT; i++) {
 210             MMCOOpcode opcode = get_ue_golomb_31(gb);
 211             if (opcode > (unsigned) MMCO_LONG) {
 212                 av_log(logctx, AV_LOG_ERROR,
 213                        "illegal memory management control operation %d\n",
 214                        opcode);
 215                 return AVERROR_INVALIDDATA;
 216             }
 217             if (opcode == MMCO_END)
 218                return 0;
 219             else if (opcode == MMCO_RESET)
 220                 return 1;
 221
 222             if (opcode == MMCO_SHORT2UNUSED || opcode == MMCO_SHORT2LONG)
 223                 get_ue_golomb_long(gb); // difference_of_pic_nums_minus1
 224             if (opcode == MMCO_SHORT2LONG || opcode == MMCO_LONG2UNUSED ||
 225                 opcode == MMCO_LONG || opcode == MMCO_SET_MAX_LONG)
 226                 get_ue_golomb_31(gb);
 227         }
 228     }
 229
 230     return 0;
 231 }
 232
 233 /**
 234  * Parse NAL units of found picture and decode some basic information.
 235  *
 236  * @param s parser context.
 237  * @param avctx codec context.
 238  * @param buf buffer with field/frame data.
 239  * @param buf_size size of the buffer.
 240  */
 241 static inline int parse_nal_units(AVCodecParserContext *s,
 242                                   AVCodecContext *avctx,
 243                                   const uint8_t * const buf, int buf_size)
 244 {
 245     H264ParseContext *p = s->priv_data;
 246     H2645NAL nal = { NULL };
 247     int buf_index, next_avc;
 248     unsigned int pps_id;
 249     unsigned int slice_type;
 250     int state = -1, got_reset = 0;
 251     int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);
 252     int field_poc[2];
 253     int ret;
 254
 255     /* set some sane default values */
 256     s->pict_type         = AV_PICTURE_TYPE_I;
 257     s->key_frame         = 0;
 258     s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN;
 259
 260     ff_h264_sei_uninit(&p->sei);
 261     p->sei.frame_packing.frame_packing_arrangement_cancel_flag = -1;
 262
 263     if (!buf_size)
 264         return 0;
 265
 266     buf_index     = 0;
 267     next_avc      = p->is_avc ? 0 : buf_size;
 268     for (;;) {
 269         const SPS *sps;
 270         int src_length, consumed, nalsize = 0;
 271
 272         if (buf_index >= next_avc) {
 273             nalsize = get_nalsize(p->nal_length_size, buf, buf_size, &buf_index, avctx);
 274             if (nalsize < 0)
 275                 break;
 276             next_avc = buf_index + nalsize;
 277         } else {
 278             buf_index = find_start_code(buf, buf_size, buf_index, next_avc);
 279             if (buf_index >= buf_size)
 280                 break;
 281             if (buf_index >= next_avc)
 282                 continue;
 283         }
 284         src_length = next_avc - buf_index;
 285
 286         state = buf[buf_index];
 287         switch (state & 0x1f) {
 288         case H264_NAL_SLICE:
 289         case H264_NAL_IDR_SLICE:
 290             // Do not walk the whole buffer just to decode slice header
 291             if ((state & 0x1f) == H264_NAL_IDR_SLICE || ((state >> 5) & 0x3) == 0) {
 292                 /* IDR or disposable slice
 293                  * No need to decode many bytes because MMCOs shall not be present. */
 294                 if (src_length > 60)
 295                     src_length = 60;
 296             } else {
 297                 /* To decode up to MMCOs */
 298                 if (src_length > 1000)
 299                     src_length = 1000;
 300             }
 301             break;
 302         }
 303         consumed = ff_h2645_extract_rbsp(buf + buf_index, src_length, &nal, 1);
 304         if (consumed < 0)
 305             break;
 306
 307         buf_index += consumed;
 308
 309         ret = init_get_bits8(&nal.gb, nal.data, nal.size);
 310         if (ret < 0)
 311             goto fail;
 312         get_bits1(&nal.gb);
 313         nal.ref_idc = get_bits(&nal.gb, 2);
 314         nal.type    = get_bits(&nal.gb, 5);
 315
 316         switch (nal.type) {
 317         case H264_NAL_SPS:
 318             ff_h264_decode_seq_parameter_set(&nal.gb, avctx, &p->ps, 0);
 319             break;
 320         case H264_NAL_PPS:
 321             ff_h264_decode_picture_parameter_set(&nal.gb, avctx, &p->ps,
 322                                                  nal.size_bits);
 323             break;
 324         case H264_NAL_SEI:
 325             ff_h264_sei_decode(&p->sei, &nal.gb, &p->ps, avctx);
 326             break;
 327         case H264_NAL_IDR_SLICE:
 328             s->key_frame = 1;
 329
 330             p->poc.prev_frame_num        = 0;
 331             p->poc.prev_frame_num_offset = 0;
 332             p->poc.prev_poc_msb          =
 333             p->poc.prev_poc_lsb          = 0;
 334         /* fall through */
 335         case H264_NAL_SLICE:
 336             get_ue_golomb_long(&nal.gb);  // skip first_mb_in_slice
 337             slice_type   = get_ue_golomb_31(&nal.gb);
 338             s->pict_type = ff_h264_golomb_to_pict_type[slice_type % 5];
 339             if (p->sei.recovery_point.recovery_frame_cnt >= 0) {
 340                 /* key frame, since recovery_frame_cnt is set */
 341                 s->key_frame = 1;
 342             }
 343             pps_id = get_ue_golomb(&nal.gb);
 344             if (pps_id >= MAX_PPS_COUNT) {
 345                 av_log(avctx, AV_LOG_ERROR,
 346                        "pps_id %u out of range\n", pps_id);
 347                 goto fail;
 348             }
 349             if (!p->ps.pps_list[pps_id]) {
 350                 av_log(avctx, AV_LOG_ERROR,
 351                        "non-existing PPS %u referenced\n", pps_id);
 352                 goto fail;
 353             }
 354
 355             av_buffer_unref(&p->ps.pps_ref);
 356             av_buffer_unref(&p->ps.sps_ref);
 357             p->ps.pps = NULL;
 358             p->ps.sps = NULL;
 359             p->ps.pps_ref = av_buffer_ref(p->ps.pps_list[pps_id]);
 360             if (!p->ps.pps_ref)
 361                 goto fail;
 362             p->ps.pps = (const PPS*)p->ps.pps_ref->data;
 363
 364             if (!p->ps.sps_list[p->ps.pps->sps_id]) {
 365                 av_log(avctx, AV_LOG_ERROR,
 366                        "non-existing SPS %u referenced\n", p->ps.pps->sps_id);
 367                 goto fail;
 368             }
 369
 370             p->ps.sps_ref = av_buffer_ref(p->ps.sps_list[p->ps.pps->sps_id]);
 371             if (!p->ps.sps_ref)
 372                 goto fail;
 373             p->ps.sps = (const SPS*)p->ps.sps_ref->data;
 374
 375             sps = p->ps.sps;
 376
 377             // heuristic to detect non marked keyframes
 378             if (p->ps.sps->ref_frame_count <= 1 && p->ps.pps->ref_count[0] <= 1 && s->pict_type == AV_PICTURE_TYPE_I)
 379                 s->key_frame = 1;
 380
 381             p->poc.frame_num = get_bits(&nal.gb, sps->log2_max_frame_num);
 382
 383             s->coded_width  = 16 * sps->mb_width;
 384             s->coded_height = 16 * sps->mb_height;
 385             s->width        = s->coded_width  - (sps->crop_right + sps->crop_left);
 386             s->height       = s->coded_height - (sps->crop_top   + sps->crop_bottom);
 387             if (s->width <= 0 || s->height <= 0) {
 388                 s->width  = s->coded_width;
 389                 s->height = s->coded_height;
 390             }
 391
 392             switch (sps->bit_depth_luma) {
 393             case 9:
 394                 if (sps->chroma_format_idc == 3)      s->format = AV_PIX_FMT_YUV444P9;
 395                 else if (sps->chroma_format_idc == 2) s->format = AV_PIX_FMT_YUV422P9;
 396                 else                                  s->format = AV_PIX_FMT_YUV420P9;
 397                 break;
 398             case 10:
 399                 if (sps->chroma_format_idc == 3)      s->format = AV_PIX_FMT_YUV444P10;
 400                 else if (sps->chroma_format_idc == 2) s->format = AV_PIX_FMT_YUV422P10;
 401                 else                                  s->format = AV_PIX_FMT_YUV420P10;
 402                 break;
 403             case 8:
 404                 if (sps->chroma_format_idc == 3)      s->format = AV_PIX_FMT_YUV444P;
 405                 else if (sps->chroma_format_idc == 2) s->format = AV_PIX_FMT_YUV422P;
 406                 else                                  s->format = AV_PIX_FMT_YUV420P;
 407                 break;
 408             default:
 409                 s->format = AV_PIX_FMT_NONE;
 410             }
 411
 412             avctx->profile = ff_h264_get_profile(sps);
 413             avctx->level   = sps->level_idc;
 414
 415             if (sps->frame_mbs_only_flag) {
 416                 p->picture_structure = PICT_FRAME;
 417             } else {
 418                 if (get_bits1(&nal.gb)) { // field_pic_flag
 419                     p->picture_structure = PICT_TOP_FIELD + get_bits1(&nal.gb); // bottom_field_flag
 420                 } else {
 421                     p->picture_structure = PICT_FRAME;
 422                 }
 423             }
 424
 425             if (nal.type == H264_NAL_IDR_SLICE)
 426                 get_ue_golomb_long(&nal.gb); /* idr_pic_id */
 427             if (sps->poc_type == 0) {
 428                 p->poc.poc_lsb = get_bits(&nal.gb, sps->log2_max_poc_lsb);
 429
 430                 if (p->ps.pps->pic_order_present == 1 &&
 431                     p->picture_structure == PICT_FRAME)
 432                     p->poc.delta_poc_bottom = get_se_golomb(&nal.gb);
 433             }
 434
 435             if (sps->poc_type == 1 &&
 436                 !sps->delta_pic_order_always_zero_flag) {
 437                 p->poc.delta_poc[0] = get_se_golomb(&nal.gb);
 438
 439                 if (p->ps.pps->pic_order_present == 1 &&
 440                     p->picture_structure == PICT_FRAME)
 441                     p->poc.delta_poc[1] = get_se_golomb(&nal.gb);
 442             }
 443
 444             /* Decode POC of this picture.
 445              * The prev_ values needed for decoding POC of the next picture are not set here. */
 446             field_poc[0] = field_poc[1] = INT_MAX;
 447             ff_h264_init_poc(field_poc, &s->output_picture_number, sps,
 448                              &p->poc, p->picture_structure, nal.ref_idc);
 449
 450             /* Continue parsing to check if MMCO_RESET is present.
 451              * FIXME: MMCO_RESET could appear in non-first slice.
 452              *        Maybe, we should parse all undisposable non-IDR slice of this
 453              *        picture until encountering MMCO_RESET in a slice of it. */
 454             if (nal.ref_idc && nal.type != H264_NAL_IDR_SLICE) {
 455                 got_reset = scan_mmco_reset(s, &nal.gb, avctx);
 456                 if (got_reset < 0)
 457                     goto fail;
 458             }
 459
 460             /* Set up the prev_ values for decoding POC of the next picture. */
 461             p->poc.prev_frame_num        = got_reset ? 0 : p->poc.frame_num;
 462             p->poc.prev_frame_num_offset = got_reset ? 0 : p->poc.frame_num_offset;
 463             if (nal.ref_idc != 0) {
 464                 if (!got_reset) {
 465                     p->poc.prev_poc_msb = p->poc.poc_msb;
 466                     p->poc.prev_poc_lsb = p->poc.poc_lsb;
 467                 } else {
 468                     p->poc.prev_poc_msb = 0;
 469                     p->poc.prev_poc_lsb =
 470                         p->picture_structure == PICT_BOTTOM_FIELD ? 0 : field_poc[0];
 471                 }
 472             }
 473
 474             if (sps->pic_struct_present_flag && p->sei.picture_timing.present) {
 475                 switch (p->sei.picture_timing.pic_struct) {
 476                 case SEI_PIC_STRUCT_TOP_FIELD:
 477                 case SEI_PIC_STRUCT_BOTTOM_FIELD:
 478                     s->repeat_pict = 0;
 479                     break;
 480                 case SEI_PIC_STRUCT_FRAME:
 481                 case SEI_PIC_STRUCT_TOP_BOTTOM:
 482                 case SEI_PIC_STRUCT_BOTTOM_TOP:
 483                     s->repeat_pict = 1;
 484                     break;
 485                 case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
 486                 case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
 487                     s->repeat_pict = 2;
 488                     break;
 489                 case SEI_PIC_STRUCT_FRAME_DOUBLING:
 490                     s->repeat_pict = 3;
 491                     break;
 492                 case SEI_PIC_STRUCT_FRAME_TRIPLING:
 493                     s->repeat_pict = 5;
 494                     break;
 495                 default:
 496                     s->repeat_pict = p->picture_structure == PICT_FRAME ? 1 : 0;
 497                     break;
 498                 }
 499             } else {
 500                 s->repeat_pict = p->picture_structure == PICT_FRAME ? 1 : 0;
 501             }
 502
 503             if (p->picture_structure == PICT_FRAME) {
 504                 s->picture_structure = AV_PICTURE_STRUCTURE_FRAME;
 505                 if (sps->pic_struct_present_flag && p->sei.picture_timing.present) {
 506                     switch (p->sei.picture_timing.pic_struct) {
 507                     case SEI_PIC_STRUCT_TOP_BOTTOM:
 508                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
 509                         s->field_order = AV_FIELD_TT;
 510                         break;
 511                     case SEI_PIC_STRUCT_BOTTOM_TOP:
 512                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
 513                         s->field_order = AV_FIELD_BB;
 514                         break;
 515                     default:
 516                         s->field_order = AV_FIELD_PROGRESSIVE;
 517                         break;
 518                     }
 519                 } else {
 520                     if (field_poc[0] < field_poc[1])
 521                         s->field_order = AV_FIELD_TT;
 522                     else if (field_poc[0] > field_poc[1])
 523                         s->field_order = AV_FIELD_BB;
 524                     else
 525                         s->field_order = AV_FIELD_PROGRESSIVE;
 526                 }
 527             } else {
 528                 if (p->picture_structure == PICT_TOP_FIELD)
 529                     s->picture_structure = AV_PICTURE_STRUCTURE_TOP_FIELD;
 530                 else
 531                     s->picture_structure = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;
 532                 if (p->poc.frame_num == p->last_frame_num &&
 533                     p->last_picture_structure != AV_PICTURE_STRUCTURE_UNKNOWN &&
 534                     p->last_picture_structure != AV_PICTURE_STRUCTURE_FRAME &&
 535                     p->last_picture_structure != s->picture_structure) {
 536                     if (p->last_picture_structure == AV_PICTURE_STRUCTURE_TOP_FIELD)
 537                         s->field_order = AV_FIELD_TT;
 538                     else
 539                         s->field_order = AV_FIELD_BB;
 540                 } else {
 541                     s->field_order = AV_FIELD_UNKNOWN;
 542                 }
 543                 p->last_picture_structure = s->picture_structure;
 544                 p->last_frame_num = p->poc.frame_num;
 545             }
 546
 547             av_freep(&nal.rbsp_buffer);
 548             return 0; /* no need to evaluate the rest */
 549         }
 550     }
 551     if (q264) {
 552         av_freep(&nal.rbsp_buffer);
 553         return 0;
 554     }
 555     /* didn't find a picture! */
 556     av_log(avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);
 557 fail:
 558     av_freep(&nal.rbsp_buffer);
 559     return -1;
 560 }
 561
 562 static int h264_parse(AVCodecParserContext *s,
 563                       AVCodecContext *avctx,
 564                       const uint8_t **poutbuf, int *poutbuf_size,
 565                       const uint8_t *buf, int buf_size)
 566 {
 567     H264ParseContext *p = s->priv_data;
 568     ParseContext *pc = &p->pc;
 569     int next;
 570
 571     if (!p->got_first) {
 572         p->got_first = 1;
 573         if (avctx->extradata_size) {
 574             ff_h264_decode_extradata(avctx->extradata, avctx->extradata_size,
 575                                      &p->ps, &p->is_avc, &p->nal_length_size,
 576                                      avctx->err_recognition, avctx);
 577         }
 578     }
 579
 580     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
 581         next = buf_size;
 582     } else {
 583         next = h264_find_frame_end(p, buf, buf_size, avctx);
 584
 585         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 586             *poutbuf      = NULL;
 587             *poutbuf_size = 0;
 588             return buf_size;
 589         }
 590
 591         if (next < 0 && next != END_NOT_FOUND) {
 592             av_assert1(pc->last_index + next >= 0);
 593             h264_find_frame_end(p, &pc->buffer[pc->last_index + next], -next, avctx); // update state
 594         }
 595     }
 596
 597     parse_nal_units(s, avctx, buf, buf_size);
 598
 599     if (avctx->framerate.num)
 600         avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1}));
 601     if (p->sei.picture_timing.cpb_removal_delay >= 0) {
 602         s->dts_sync_point    = p->sei.buffering_period.present;
 603         s->dts_ref_dts_delta = p->sei.picture_timing.cpb_removal_delay;
 604         s->pts_dts_delta     = p->sei.picture_timing.dpb_output_delay;
 605     } else {
 606         s->dts_sync_point    = INT_MIN;
 607         s->dts_ref_dts_delta = INT_MIN;
 608         s->pts_dts_delta     = INT_MIN;
 609     }
 610
 611     if (s->flags & PARSER_FLAG_ONCE) {
 612         s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
 613     }
 614
 615     if (s->dts_sync_point >= 0) {
 616         int64_t den = avctx->time_base.den * (int64_t)avctx->pkt_timebase.num;
 617         if (den > 0) {
 618             int64_t num = avctx->time_base.num * (int64_t)avctx->pkt_timebase.den;
 619             if (s->dts != AV_NOPTS_VALUE) {
 620                 // got DTS from the stream, update reference timestamp
 621                 p->reference_dts = s->dts - av_rescale(s->dts_ref_dts_delta, num, den);
 622             } else if (p->reference_dts != AV_NOPTS_VALUE) {
 623                 // compute DTS based on reference timestamp
 624                 s->dts = p->reference_dts + av_rescale(s->dts_ref_dts_delta, num, den);
 625             }
 626
 627             if (p->reference_dts != AV_NOPTS_VALUE && s->pts == AV_NOPTS_VALUE)
 628                 s->pts = s->dts + av_rescale(s->pts_dts_delta, num, den);
 629
 630             if (s->dts_sync_point > 0)
 631                 p->reference_dts = s->dts; // new reference
 632         }
 633     }
 634
 635     *poutbuf      = buf;
 636     *poutbuf_size = buf_size;
 637     return next;
 638 }
 639
 640 static int h264_split(AVCodecContext *avctx,
 641                       const uint8_t *buf, int buf_size)
 642 {
 643     uint32_t state = -1;
 644     int has_sps    = 0;
 645     int has_pps    = 0;
 646     const uint8_t *ptr = buf, *end = buf + buf_size;
 647     int nalu_type;
 648
 649     while (ptr < end) {
 650         ptr = avpriv_find_start_code(ptr, end, &state);
 651         if ((state & 0xFFFFFF00) != 0x100)
 652             break;
 653         nalu_type = state & 0x1F;
 654         if (nalu_type == H264_NAL_SPS) {
 655             has_sps = 1;
 656         } else if (nalu_type == H264_NAL_PPS)
 657             has_pps = 1;
 658         /* else if (nalu_type == 0x01 ||
 659          *     nalu_type == 0x02 ||
 660          *     nalu_type == 0x05) {
 661          *  }
 662          */
 663         else if ((nalu_type != H264_NAL_SEI || has_pps) &&
 664                   nalu_type != H264_NAL_AUD && nalu_type != H264_NAL_SPS_EXT &&
 665                   nalu_type != 0x0f) {
 666             if (has_sps) {
 667                 while (ptr - 4 > buf && ptr[-5] == 0)
 668                     ptr--;
 669                 return ptr - 4 - buf;
 670             }
 671         }
 672     }
 673
 674     return 0;
 675 }
 676
 677 static void h264_close(AVCodecParserContext *s)
 678 {
 679     H264ParseContext *p = s->priv_data;
 680     ParseContext *pc = &p->pc;
 681
 682     av_freep(&pc->buffer);
 683
 684     ff_h264_sei_uninit(&p->sei);
 685     ff_h264_ps_uninit(&p->ps);
 686 }
 687
 688 static av_cold int init(AVCodecParserContext *s)
 689 {
 690     H264ParseContext *p = s->priv_data;
 691
 692     p->reference_dts = AV_NOPTS_VALUE;
 693     p->last_frame_num = INT_MAX;
 694     ff_h264dsp_init(&p->h264dsp, 8, 1);
 695     return 0;
 696 }
 697
 698 AVCodecParser ff_h264_parser = {
 699     .codec_ids      = { AV_CODEC_ID_H264 },
 700     .priv_data_size = sizeof(H264ParseContext),
 701     .parser_init    = init,
 702     .parser_parse   = h264_parse,
 703     .parser_close   = h264_close,
 704     .split          = h264_split,
 705 };