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 "parser.h"
  31 #include "h264data.h"
  32 #include "golomb.h"
  33
  34 #include <assert.h>
  35
  36
  37 static int ff_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->s.parse_context);
  42     int next_avc= h->is_avc ? 0 : buf_size;
  43
  44 //printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
  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->s.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->s.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 its simpler
  70          * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
  71          */
  72 #    if HAVE_FAST_64BIT
  73             while(i<next_avc && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
  74                 i+=8;
  75 #    else
  76             while(i<next_avc && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
  77                 i+=4;
  78 #    endif
  79 #endif
  80             for(; i<next_avc; i++){
  81                 if(!buf[i]){
  82                     state=2;
  83                     break;
  84                 }
  85             }
  86         }else if(state<=2){
  87             if(buf[i]==1)   state^= 5; //2->7, 1->4, 0->5
  88             else if(buf[i]) state = 7;
  89             else            state>>=1; //2->1, 1->0, 0->0
  90         }else if(state<=5){
  91             int v= buf[i] & 0x1F;
  92             if(v==6 || v==7 || v==8 || v==9){
  93                 if(pc->frame_start_found){
  94                     i++;
  95                     goto found;
  96                 }
  97             }else if(v==1 || v==2 || v==5){
  98                 state+=8;
  99                 continue;
 100             }
 101             state= 7;
 102         }else{
 103             h->parse_history[h->parse_history_count++]= buf[i];
 104             if(h->parse_history_count>3){
 105                 unsigned int mb, last_mb= h->parse_last_mb;
 106                 GetBitContext gb;
 107
 108                 init_get_bits(&gb, h->parse_history, 8*h->parse_history_count);
 109                 h->parse_history_count=0;
 110                 mb= get_ue_golomb_long(&gb);
 111                 last_mb= h->parse_last_mb;
 112                 h->parse_last_mb= mb;
 113                 if(pc->frame_start_found){
 114                     if(mb <= last_mb)
 115                         goto found;
 116                 }else
 117                     pc->frame_start_found = 1;
 118                 state= 7;
 119             }
 120         }
 121     }
 122     pc->state= state;
 123     if(h->is_avc)
 124         return next_avc;
 125     return END_NOT_FOUND;
 126
 127 found:
 128     pc->state=7;
 129     pc->frame_start_found= 0;
 130     if(h->is_avc)
 131         return next_avc;
 132     return i-(state&5) - 3*(state>7);
 133 }
 134
 135 /**
 136  * Parse NAL units of found picture and decode some basic information.
 137  *
 138  * @param s parser context.
 139  * @param avctx codec context.
 140  * @param buf buffer with field/frame data.
 141  * @param buf_size size of the buffer.
 142  */
 143 static inline int parse_nal_units(AVCodecParserContext *s,
 144                                   AVCodecContext *avctx,
 145                                   const uint8_t *buf, int buf_size)
 146 {
 147     H264Context *h = s->priv_data;
 148     const uint8_t *buf_end = buf + buf_size;
 149     unsigned int pps_id;
 150     unsigned int slice_type;
 151     int state = -1;
 152     const uint8_t *ptr;
 153     int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);
 154
 155     /* set some sane default values */
 156     s->pict_type = AV_PICTURE_TYPE_I;
 157     s->key_frame = 0;
 158
 159     h->s.avctx= avctx;
 160     h->sei_recovery_frame_cnt = -1;
 161     h->sei_dpb_output_delay         =  0;
 162     h->sei_cpb_removal_delay        = -1;
 163     h->sei_buffering_period_present =  0;
 164
 165     if (!buf_size)
 166         return 0;
 167
 168     for(;;) {
 169         int src_length, dst_length, consumed, nalsize = 0;
 170         if (h->is_avc) {
 171             int i;
 172             if (h->nal_length_size >= buf_end - buf) break;
 173             nalsize = 0;
 174             for (i = 0; i < h->nal_length_size; i++)
 175                 nalsize = (nalsize << 8) | *buf++;
 176             if (nalsize <= 0 || nalsize > buf_end - buf) {
 177                 av_log(h->s.avctx, AV_LOG_ERROR, "AVC: nal size %d\n", nalsize);
 178                 break;
 179             }
 180             src_length = nalsize;
 181         } else {
 182         buf = avpriv_mpv_find_start_code(buf, buf_end, &state);
 183         if(buf >= buf_end)
 184             break;
 185         --buf;
 186         src_length = buf_end - buf;
 187         }
 188         switch (state & 0x1f) {
 189         case NAL_SLICE:
 190         case NAL_IDR_SLICE:
 191             // Do not walk the whole buffer just to decode slice header
 192             if (src_length > 20)
 193                 src_length = 20;
 194             break;
 195         }
 196         ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
 197         if (ptr==NULL || dst_length < 0)
 198             break;
 199
 200         init_get_bits(&h->s.gb, ptr, 8*dst_length);
 201         switch(h->nal_unit_type) {
 202         case NAL_SPS:
 203             ff_h264_decode_seq_parameter_set(h);
 204             break;
 205         case NAL_PPS:
 206             ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
 207             break;
 208         case NAL_SEI:
 209             ff_h264_decode_sei(h);
 210             break;
 211         case NAL_IDR_SLICE:
 212             s->key_frame = 1;
 213             /* fall through */
 214         case NAL_SLICE:
 215             get_ue_golomb_long(&h->s.gb);  // skip first_mb_in_slice
 216             slice_type = get_ue_golomb_31(&h->s.gb);
 217             s->pict_type = golomb_to_pict_type[slice_type % 5];
 218             if (h->sei_recovery_frame_cnt >= 0) {
 219                 /* key frame, since recovery_frame_cnt is set */
 220                 s->key_frame = 1;
 221             }
 222             pps_id= get_ue_golomb(&h->s.gb);
 223             if(pps_id>=MAX_PPS_COUNT) {
 224                 av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
 225                 return -1;
 226             }
 227             if(!h->pps_buffers[pps_id]) {
 228                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
 229                 return -1;
 230             }
 231             h->pps= *h->pps_buffers[pps_id];
 232             if(!h->sps_buffers[h->pps.sps_id]) {
 233                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
 234                 return -1;
 235             }
 236             h->sps = *h->sps_buffers[h->pps.sps_id];
 237             h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);
 238
 239             avctx->profile = ff_h264_get_profile(&h->sps);
 240             avctx->level   = h->sps.level_idc;
 241
 242             if(h->sps.frame_mbs_only_flag){
 243                 h->s.picture_structure= PICT_FRAME;
 244             }else{
 245                 if(get_bits1(&h->s.gb)) { //field_pic_flag
 246                     h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
 247                 } else {
 248                     h->s.picture_structure= PICT_FRAME;
 249                 }
 250             }
 251
 252             if(h->sps.pic_struct_present_flag) {
 253                 switch (h->sei_pic_struct) {
 254                     case SEI_PIC_STRUCT_TOP_FIELD:
 255                     case SEI_PIC_STRUCT_BOTTOM_FIELD:
 256                         s->repeat_pict = 0;
 257                         break;
 258                     case SEI_PIC_STRUCT_FRAME:
 259                     case SEI_PIC_STRUCT_TOP_BOTTOM:
 260                     case SEI_PIC_STRUCT_BOTTOM_TOP:
 261                         s->repeat_pict = 1;
 262                         break;
 263                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
 264                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
 265                         s->repeat_pict = 2;
 266                         break;
 267                     case SEI_PIC_STRUCT_FRAME_DOUBLING:
 268                         s->repeat_pict = 3;
 269                         break;
 270                     case SEI_PIC_STRUCT_FRAME_TRIPLING:
 271                         s->repeat_pict = 5;
 272                         break;
 273                     default:
 274                         s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
 275                         break;
 276                 }
 277             } else {
 278                 s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
 279             }
 280
 281             return 0; /* no need to evaluate the rest */
 282         }
 283         buf += h->is_avc ? nalsize : consumed;
 284     }
 285     if (q264)
 286         return 0;
 287     /* didn't find a picture! */
 288     av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);
 289     return -1;
 290 }
 291
 292 static int h264_parse(AVCodecParserContext *s,
 293                       AVCodecContext *avctx,
 294                       const uint8_t **poutbuf, int *poutbuf_size,
 295                       const uint8_t *buf, int buf_size)
 296 {
 297     H264Context *h = s->priv_data;
 298     ParseContext *pc = &h->s.parse_context;
 299     int next;
 300
 301     if (!h->got_first) {
 302         h->got_first = 1;
 303         if (avctx->extradata_size) {
 304             h->s.avctx = avctx;
 305             // must be done like in decoder, otherwise opening the parser,
 306             // letting it create extradata and then closing and opening again
 307             // will cause has_b_frames to be always set.
 308             // Note that estimate_timings_from_pts does exactly this.
 309             if (!avctx->has_b_frames)
 310                 h->s.low_delay = 1;
 311             ff_h264_decode_extradata(h, avctx->extradata, avctx->extradata_size);
 312         }
 313     }
 314
 315     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
 316         next= buf_size;
 317     }else{
 318         next= ff_h264_find_frame_end(h, buf, buf_size);
 319
 320         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 321             *poutbuf = NULL;
 322             *poutbuf_size = 0;
 323             return buf_size;
 324         }
 325
 326         if(next<0 && next != END_NOT_FOUND){
 327             assert(pc->last_index + next >= 0 );
 328             ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
 329         }
 330     }
 331
 332     parse_nal_units(s, avctx, buf, buf_size);
 333
 334     if (h->sei_cpb_removal_delay >= 0) {
 335         s->dts_sync_point    = h->sei_buffering_period_present;
 336         s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
 337         s->pts_dts_delta     = h->sei_dpb_output_delay;
 338     } else {
 339         s->dts_sync_point    = INT_MIN;
 340         s->dts_ref_dts_delta = INT_MIN;
 341         s->pts_dts_delta     = INT_MIN;
 342     }
 343
 344     if (s->flags & PARSER_FLAG_ONCE) {
 345         s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
 346     }
 347
 348     *poutbuf = buf;
 349     *poutbuf_size = buf_size;
 350     return next;
 351 }
 352
 353 static int h264_split(AVCodecContext *avctx,
 354                       const uint8_t *buf, int buf_size)
 355 {
 356     int i;
 357     uint32_t state = -1;
 358     int has_sps= 0;
 359
 360     for(i=0; i<=buf_size; i++){
 361         if((state&0xFFFFFF1F) == 0x107)
 362             has_sps=1;
 363 /*        if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
 364         }*/
 365         if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
 366             if(has_sps){
 367                 while(i>4 && buf[i-5]==0) i--;
 368                 return i-4;
 369             }
 370         }
 371         if (i<buf_size)
 372             state= (state<<8) | buf[i];
 373     }
 374     return 0;
 375 }
 376
 377 static void close(AVCodecParserContext *s)
 378 {
 379     H264Context *h = s->priv_data;
 380     ParseContext *pc = &h->s.parse_context;
 381
 382     av_free(pc->buffer);
 383     ff_h264_free_context(h);
 384 }
 385
 386 static int init(AVCodecParserContext *s)
 387 {
 388     H264Context *h = s->priv_data;
 389     h->thread_context[0] = h;
 390     h->s.slice_context_count = 1;
 391     return 0;
 392 }
 393
 394 AVCodecParser ff_h264_parser = {
 395     .codec_ids      = { CODEC_ID_H264 },
 396     .priv_data_size = sizeof(H264Context),
 397     .parser_init    = init,
 398     .parser_parse   = h264_parse,
 399     .parser_close   = close,
 400     .split          = h264_split,
 401 };