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 #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, j;
  38     uint32_t state;
  39     ParseContext *pc = &(h->s.parse_context);
  40     int next_avc= h->is_avc ? 0 : buf_size;
  41
  42 //printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
  43 //    mb_addr= pc->mb_addr - 1;
  44     state= pc->state;
  45     if(state>13)
  46         state= 7;
  47
  48     if(h->is_avc && !h->nal_length_size)
  49         av_log(h->s.avctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");
  50
  51     for(i=0; i<buf_size; i++){
  52         if(i >= next_avc) {
  53             int nalsize = 0;
  54             i = next_avc;
  55             for(j = 0; j < h->nal_length_size; j++)
  56                 nalsize = (nalsize << 8) | buf[i++];
  57             if(nalsize <= 0 || nalsize > buf_size - i){
  58                 av_log(h->s.avctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);
  59                 return buf_size;
  60             }
  61             next_avc= i + nalsize;
  62             state= 5;
  63         }
  64
  65         if(state==7){
  66 #if HAVE_FAST_UNALIGNED
  67         /* we check i<buf_size instead of i+3/7 because its simpler
  68          * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
  69          */
  70 #    if HAVE_FAST_64BIT
  71             while(i<next_avc && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
  72                 i+=8;
  73 #    else
  74             while(i<next_avc && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
  75                 i+=4;
  76 #    endif
  77 #endif
  78             for(; i<next_avc; i++){
  79                 if(!buf[i]){
  80                     state=2;
  81                     break;
  82                 }
  83             }
  84         }else if(state<=2){
  85             if(buf[i]==1)   state^= 5; //2->7, 1->4, 0->5
  86             else if(buf[i]) state = 7;
  87             else            state>>=1; //2->1, 1->0, 0->0
  88         }else if(state<=5){
  89             int v= buf[i] & 0x1F;
  90             if(v==6 || v==7 || v==8 || v==9){
  91                 if(pc->frame_start_found){
  92                     i++;
  93                     goto found;
  94                 }
  95             }else if(v==1 || v==2 || v==5){
  96                 if(pc->frame_start_found){
  97                     state+=8;
  98                     continue;
  99                 }else
 100                     pc->frame_start_found = 1;
 101             }
 102             state= 7;
 103         }else{
 104             if(buf[i] & 0x80)
 105                 goto found;
 106             state= 7;
 107         }
 108     }
 109     pc->state= state;
 110     if(h->is_avc)
 111         return next_avc;
 112     return END_NOT_FOUND;
 113
 114 found:
 115     pc->state=7;
 116     pc->frame_start_found= 0;
 117     if(h->is_avc)
 118         return next_avc;
 119     return i-(state&5);
 120 }
 121
 122 /**
 123  * Parse NAL units of found picture and decode some basic information.
 124  *
 125  * @param s parser context.
 126  * @param avctx codec context.
 127  * @param buf buffer with field/frame data.
 128  * @param buf_size size of the buffer.
 129  */
 130 static inline int parse_nal_units(AVCodecParserContext *s,
 131                                   AVCodecContext *avctx,
 132                                   const uint8_t *buf, int buf_size)
 133 {
 134     H264Context *h = s->priv_data;
 135     const uint8_t *buf_end = buf + buf_size;
 136     unsigned int pps_id;
 137     unsigned int slice_type;
 138     int state = -1;
 139     const uint8_t *ptr;
 140
 141     /* set some sane default values */
 142     s->pict_type = AV_PICTURE_TYPE_I;
 143     s->key_frame = 0;
 144
 145     h->s.avctx= avctx;
 146     h->sei_recovery_frame_cnt = -1;
 147     h->sei_dpb_output_delay         =  0;
 148     h->sei_cpb_removal_delay        = -1;
 149     h->sei_buffering_period_present =  0;
 150
 151     if (!buf_size)
 152         return 0;
 153
 154     for(;;) {
 155         int src_length, dst_length, consumed;
 156         buf = ff_find_start_code(buf, buf_end, &state);
 157         if(buf >= buf_end)
 158             break;
 159         --buf;
 160         src_length = buf_end - buf;
 161         switch (state & 0x1f) {
 162         case NAL_SLICE:
 163         case NAL_IDR_SLICE:
 164             // Do not walk the whole buffer just to decode slice header
 165             if (src_length > 20)
 166                 src_length = 20;
 167             break;
 168         }
 169         ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
 170         if (ptr==NULL || dst_length < 0)
 171             break;
 172
 173         init_get_bits(&h->s.gb, ptr, 8*dst_length);
 174         switch(h->nal_unit_type) {
 175         case NAL_SPS:
 176             ff_h264_decode_seq_parameter_set(h);
 177             break;
 178         case NAL_PPS:
 179             ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
 180             break;
 181         case NAL_SEI:
 182             ff_h264_decode_sei(h);
 183             break;
 184         case NAL_IDR_SLICE:
 185             s->key_frame = 1;
 186             /* fall through */
 187         case NAL_SLICE:
 188             get_ue_golomb(&h->s.gb);  // skip first_mb_in_slice
 189             slice_type = get_ue_golomb_31(&h->s.gb);
 190             s->pict_type = golomb_to_pict_type[slice_type % 5];
 191             if (h->sei_recovery_frame_cnt >= 0) {
 192                 /* key frame, since recovery_frame_cnt is set */
 193                 s->key_frame = 1;
 194             }
 195             pps_id= get_ue_golomb(&h->s.gb);
 196             if(pps_id>=MAX_PPS_COUNT) {
 197                 av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
 198                 return -1;
 199             }
 200             if(!h->pps_buffers[pps_id]) {
 201                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
 202                 return -1;
 203             }
 204             h->pps= *h->pps_buffers[pps_id];
 205             if(!h->sps_buffers[h->pps.sps_id]) {
 206                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
 207                 return -1;
 208             }
 209             h->sps = *h->sps_buffers[h->pps.sps_id];
 210             h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);
 211
 212             avctx->profile = ff_h264_get_profile(&h->sps);
 213             avctx->level   = h->sps.level_idc;
 214
 215             if(h->sps.frame_mbs_only_flag){
 216                 h->s.picture_structure= PICT_FRAME;
 217             }else{
 218                 if(get_bits1(&h->s.gb)) { //field_pic_flag
 219                     h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
 220                 } else {
 221                     h->s.picture_structure= PICT_FRAME;
 222                 }
 223             }
 224
 225             if(h->sps.pic_struct_present_flag) {
 226                 switch (h->sei_pic_struct) {
 227                     case SEI_PIC_STRUCT_TOP_FIELD:
 228                     case SEI_PIC_STRUCT_BOTTOM_FIELD:
 229                         s->repeat_pict = 0;
 230                         break;
 231                     case SEI_PIC_STRUCT_FRAME:
 232                     case SEI_PIC_STRUCT_TOP_BOTTOM:
 233                     case SEI_PIC_STRUCT_BOTTOM_TOP:
 234                         s->repeat_pict = 1;
 235                         break;
 236                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
 237                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
 238                         s->repeat_pict = 2;
 239                         break;
 240                     case SEI_PIC_STRUCT_FRAME_DOUBLING:
 241                         s->repeat_pict = 3;
 242                         break;
 243                     case SEI_PIC_STRUCT_FRAME_TRIPLING:
 244                         s->repeat_pict = 5;
 245                         break;
 246                     default:
 247                         s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
 248                         break;
 249                 }
 250             } else {
 251                 s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
 252             }
 253
 254             return 0; /* no need to evaluate the rest */
 255         }
 256         buf += consumed;
 257     }
 258     /* didn't find a picture! */
 259     av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);
 260     return -1;
 261 }
 262
 263 static int h264_parse(AVCodecParserContext *s,
 264                       AVCodecContext *avctx,
 265                       const uint8_t **poutbuf, int *poutbuf_size,
 266                       const uint8_t *buf, int buf_size)
 267 {
 268     H264Context *h = s->priv_data;
 269     ParseContext *pc = &h->s.parse_context;
 270     int next;
 271
 272     if (!h->got_first) {
 273         h->got_first = 1;
 274         if (avctx->extradata_size) {
 275             h->s.avctx = avctx;
 276             // must be done like in decoder, otherwise opening the parser,
 277             // letting it create extradata and then closing and opening again
 278             // will cause has_b_frames to be always set.
 279             // Note that estimate_timings_from_pts does exactly this.
 280             if (!avctx->has_b_frames)
 281                 h->s.low_delay = 1;
 282             ff_h264_decode_extradata(h, avctx->extradata, avctx->extradata_size);
 283         }
 284     }
 285
 286     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
 287         next= buf_size;
 288     }else{
 289         next= ff_h264_find_frame_end(h, buf, buf_size);
 290
 291         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 292             *poutbuf = NULL;
 293             *poutbuf_size = 0;
 294             return buf_size;
 295         }
 296
 297         if(next<0 && next != END_NOT_FOUND){
 298             assert(pc->last_index + next >= 0 );
 299             ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
 300         }
 301     }
 302
 303     if(!h->is_avc){
 304     parse_nal_units(s, avctx, buf, buf_size);
 305
 306     if (h->sei_cpb_removal_delay >= 0) {
 307         s->dts_sync_point    = h->sei_buffering_period_present;
 308         s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
 309         s->pts_dts_delta     = h->sei_dpb_output_delay;
 310     } else {
 311         s->dts_sync_point    = INT_MIN;
 312         s->dts_ref_dts_delta = INT_MIN;
 313         s->pts_dts_delta     = INT_MIN;
 314     }
 315
 316     if (s->flags & PARSER_FLAG_ONCE) {
 317         s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
 318     }
 319     }
 320
 321     *poutbuf = buf;
 322     *poutbuf_size = buf_size;
 323     return next;
 324 }
 325
 326 static int h264_split(AVCodecContext *avctx,
 327                       const uint8_t *buf, int buf_size)
 328 {
 329     int i;
 330     uint32_t state = -1;
 331     int has_sps= 0;
 332
 333     for(i=0; i<=buf_size; i++){
 334         if((state&0xFFFFFF1F) == 0x107)
 335             has_sps=1;
 336 /*        if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
 337         }*/
 338         if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
 339             if(has_sps){
 340                 while(i>4 && buf[i-5]==0) i--;
 341                 return i-4;
 342             }
 343         }
 344         if (i<buf_size)
 345             state= (state<<8) | buf[i];
 346     }
 347     return 0;
 348 }
 349
 350 static void close(AVCodecParserContext *s)
 351 {
 352     H264Context *h = s->priv_data;
 353     ParseContext *pc = &h->s.parse_context;
 354
 355     av_free(pc->buffer);
 356     ff_h264_free_context(h);
 357 }
 358
 359 static int init(AVCodecParserContext *s)
 360 {
 361     H264Context *h = s->priv_data;
 362     h->thread_context[0] = h;
 363     return 0;
 364 }
 365
 366 AVCodecParser ff_h264_parser = {
 367     { CODEC_ID_H264 },
 368     sizeof(H264Context),
 369     init,
 370     h264_parse,
 371     close,
 372     h264_split,
 373 };