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