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 "parser.h"
  29 #include "h264data.h"
  30 #include "golomb.h"
  31
  32 #include <assert.h>
  33
  34
  35 static int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)
  36 {
  37     int i;
  38     uint32_t state;
  39     ParseContext *pc = &(h->s.parse_context);
  40 //    mb_addr= pc->mb_addr - 1;
  41     state= pc->state;
  42     if(state>13)
  43         state= 7;
  44
  45     for(i=0; i<buf_size; i++){
  46         if(state==7){
  47 #if HAVE_FAST_UNALIGNED
  48         /* we check i<buf_size instead of i+3/7 because its simpler
  49          * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
  50          */
  51 #    if HAVE_FAST_64BIT
  52             while(i<buf_size && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
  53                 i+=8;
  54 #    else
  55             while(i<buf_size && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
  56                 i+=4;
  57 #    endif
  58 #endif
  59             for(; i<buf_size; i++){
  60                 if(!buf[i]){
  61                     state=2;
  62                     break;
  63                 }
  64             }
  65         }else if(state<=2){
  66             if(buf[i]==1)   state^= 5; //2->7, 1->4, 0->5
  67             else if(buf[i]) state = 7;
  68             else            state>>=1; //2->1, 1->0, 0->0
  69         }else if(state<=5){
  70             int v= buf[i] & 0x1F;
  71             if(v==6 || v==7 || v==8 || v==9){
  72                 if(pc->frame_start_found){
  73                     i++;
  74                     goto found;
  75                 }
  76             }else if(v==1 || v==2 || v==5){
  77                 if(pc->frame_start_found){
  78                     state+=8;
  79                     continue;
  80                 }else
  81                     pc->frame_start_found = 1;
  82             }
  83             state= 7;
  84         }else{
  85             if(buf[i] & 0x80)
  86                 goto found;
  87             state= 7;
  88         }
  89     }
  90     pc->state= state;
  91     return END_NOT_FOUND;
  92
  93 found:
  94     pc->state=7;
  95     pc->frame_start_found= 0;
  96     return i-(state&5);
  97 }
  98
  99 /**
 100  * Parse NAL units of found picture and decode some basic information.
 101  *
 102  * @param s parser context.
 103  * @param avctx codec context.
 104  * @param buf buffer with field/frame data.
 105  * @param buf_size size of the buffer.
 106  */
 107 static inline int parse_nal_units(AVCodecParserContext *s,
 108                                   AVCodecContext *avctx,
 109                                   const uint8_t *buf, int buf_size)
 110 {
 111     H264Context *h = s->priv_data;
 112     const uint8_t *buf_end = buf + buf_size;
 113     unsigned int pps_id;
 114     unsigned int slice_type;
 115     int state = -1;
 116     const uint8_t *ptr;
 117
 118     /* set some sane default values */
 119     s->pict_type = AV_PICTURE_TYPE_I;
 120     s->key_frame = 0;
 121
 122     h->s.avctx= avctx;
 123     h->sei_recovery_frame_cnt = -1;
 124     h->sei_dpb_output_delay         =  0;
 125     h->sei_cpb_removal_delay        = -1;
 126     h->sei_buffering_period_present =  0;
 127
 128     if (!buf_size)
 129         return 0;
 130
 131     for(;;) {
 132         int src_length, dst_length, consumed;
 133         buf = avpriv_mpv_find_start_code(buf, buf_end, &state);
 134         if(buf >= buf_end)
 135             break;
 136         --buf;
 137         src_length = buf_end - buf;
 138         switch (state & 0x1f) {
 139         case NAL_SLICE:
 140         case NAL_IDR_SLICE:
 141             // Do not walk the whole buffer just to decode slice header
 142             if (src_length > 20)
 143                 src_length = 20;
 144             break;
 145         }
 146         ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
 147         if (ptr==NULL || dst_length < 0)
 148             break;
 149
 150         init_get_bits(&h->s.gb, ptr, 8*dst_length);
 151         switch(h->nal_unit_type) {
 152         case NAL_SPS:
 153             ff_h264_decode_seq_parameter_set(h);
 154             break;
 155         case NAL_PPS:
 156             ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
 157             break;
 158         case NAL_SEI:
 159             ff_h264_decode_sei(h);
 160             break;
 161         case NAL_IDR_SLICE:
 162             s->key_frame = 1;
 163             /* fall through */
 164         case NAL_SLICE:
 165             get_ue_golomb(&h->s.gb);  // skip first_mb_in_slice
 166             slice_type = get_ue_golomb_31(&h->s.gb);
 167             s->pict_type = golomb_to_pict_type[slice_type % 5];
 168             if (h->sei_recovery_frame_cnt >= 0) {
 169                 /* key frame, since recovery_frame_cnt is set */
 170                 s->key_frame = 1;
 171             }
 172             pps_id= get_ue_golomb(&h->s.gb);
 173             if(pps_id>=MAX_PPS_COUNT) {
 174                 av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
 175                 return -1;
 176             }
 177             if(!h->pps_buffers[pps_id]) {
 178                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
 179                 return -1;
 180             }
 181             h->pps= *h->pps_buffers[pps_id];
 182             if(!h->sps_buffers[h->pps.sps_id]) {
 183                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
 184                 return -1;
 185             }
 186             h->sps = *h->sps_buffers[h->pps.sps_id];
 187             h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);
 188
 189             avctx->profile = ff_h264_get_profile(&h->sps);
 190             avctx->level   = h->sps.level_idc;
 191
 192             if(h->sps.frame_mbs_only_flag){
 193                 h->s.picture_structure= PICT_FRAME;
 194             }else{
 195                 if(get_bits1(&h->s.gb)) { //field_pic_flag
 196                     h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
 197                 } else {
 198                     h->s.picture_structure= PICT_FRAME;
 199                 }
 200             }
 201
 202             if(h->sps.pic_struct_present_flag) {
 203                 switch (h->sei_pic_struct) {
 204                     case SEI_PIC_STRUCT_TOP_FIELD:
 205                     case SEI_PIC_STRUCT_BOTTOM_FIELD:
 206                         s->repeat_pict = 0;
 207                         break;
 208                     case SEI_PIC_STRUCT_FRAME:
 209                     case SEI_PIC_STRUCT_TOP_BOTTOM:
 210                     case SEI_PIC_STRUCT_BOTTOM_TOP:
 211                         s->repeat_pict = 1;
 212                         break;
 213                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
 214                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
 215                         s->repeat_pict = 2;
 216                         break;
 217                     case SEI_PIC_STRUCT_FRAME_DOUBLING:
 218                         s->repeat_pict = 3;
 219                         break;
 220                     case SEI_PIC_STRUCT_FRAME_TRIPLING:
 221                         s->repeat_pict = 5;
 222                         break;
 223                     default:
 224                         s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
 225                         break;
 226                 }
 227             } else {
 228                 s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
 229             }
 230
 231             return 0; /* no need to evaluate the rest */
 232         }
 233         buf += consumed;
 234     }
 235     /* didn't find a picture! */
 236     av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit\n");
 237     return -1;
 238 }
 239
 240 static int h264_parse(AVCodecParserContext *s,
 241                       AVCodecContext *avctx,
 242                       const uint8_t **poutbuf, int *poutbuf_size,
 243                       const uint8_t *buf, int buf_size)
 244 {
 245     H264Context *h = s->priv_data;
 246     ParseContext *pc = &h->s.parse_context;
 247     int next;
 248
 249     if (!h->got_first) {
 250         h->got_first = 1;
 251         if (avctx->extradata_size) {
 252             h->s.avctx = avctx;
 253             // must be done like in the decoder.
 254             // otherwise opening the parser, creating extradata,
 255             // and then closing and opening again
 256             // will cause has_b_frames to be always set.
 257             // NB: estimate_timings_from_pts behaves exactly like this.
 258             if (!avctx->has_b_frames)
 259                 h->s.low_delay = 1;
 260             ff_h264_decode_extradata(h);
 261         }
 262     }
 263
 264     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
 265         next= buf_size;
 266     }else{
 267         next= ff_h264_find_frame_end(h, buf, buf_size);
 268
 269         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 270             *poutbuf = NULL;
 271             *poutbuf_size = 0;
 272             return buf_size;
 273         }
 274
 275         if(next<0 && next != END_NOT_FOUND){
 276             assert(pc->last_index + next >= 0 );
 277             ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
 278         }
 279     }
 280
 281     parse_nal_units(s, avctx, buf, buf_size);
 282
 283     if (h->sei_cpb_removal_delay >= 0) {
 284         s->dts_sync_point    = h->sei_buffering_period_present;
 285         s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
 286         s->pts_dts_delta     = h->sei_dpb_output_delay;
 287     } else {
 288         s->dts_sync_point    = INT_MIN;
 289         s->dts_ref_dts_delta = INT_MIN;
 290         s->pts_dts_delta     = INT_MIN;
 291     }
 292
 293     if (s->flags & PARSER_FLAG_ONCE) {
 294         s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
 295     }
 296
 297     *poutbuf = buf;
 298     *poutbuf_size = buf_size;
 299     return next;
 300 }
 301
 302 static int h264_split(AVCodecContext *avctx,
 303                       const uint8_t *buf, int buf_size)
 304 {
 305     int i;
 306     uint32_t state = -1;
 307     int has_sps= 0;
 308
 309     for(i=0; i<=buf_size; i++){
 310         if((state&0xFFFFFF1F) == 0x107)
 311             has_sps=1;
 312 /*        if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
 313         }*/
 314         if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
 315             if(has_sps){
 316                 while(i>4 && buf[i-5]==0) i--;
 317                 return i-4;
 318             }
 319         }
 320         if (i<buf_size)
 321             state= (state<<8) | buf[i];
 322     }
 323     return 0;
 324 }
 325
 326 static void close(AVCodecParserContext *s)
 327 {
 328     H264Context *h = s->priv_data;
 329     ParseContext *pc = &h->s.parse_context;
 330
 331     av_free(pc->buffer);
 332     ff_h264_free_context(h);
 333 }
 334
 335 static int init(AVCodecParserContext *s)
 336 {
 337     H264Context *h = s->priv_data;
 338     h->thread_context[0] = h;
 339     h->s.slice_context_count = 1;
 340     return 0;
 341 }
 342
 343 AVCodecParser ff_h264_parser = {
 344     .codec_ids      = { AV_CODEC_ID_H264 },
 345     .priv_data_size = sizeof(H264Context),
 346     .parser_init    = init,
 347     .parser_parse   = h264_parse,
 348     .parser_close   = close,
 349     .split          = h264_split,
 350 };