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 libavcodec/h264_parser.c
  24  * H.264 / AVC / MPEG4 part10 parser.
  25  * @author Michael Niedermayer <michaelni@gmx.at>
  26  */
  27
  28 #include "parser.h"
  29 #include "h264_parser.h"
  30 #include "h264data.h"
  31 #include "golomb.h"
  32
  33 #include <assert.h>
  34
  35
  36 int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)
  37 {
  38     int i;
  39     uint32_t state;
  40     ParseContext *pc = &(h->s.parse_context);
  41 //printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
  42 //    mb_addr= pc->mb_addr - 1;
  43     state= pc->state;
  44     if(state>13)
  45         state= 7;
  46
  47     for(i=0; i<buf_size; i++){
  48         if(state==7){
  49 #if HAVE_FAST_UNALIGNED
  50         /* we check i<buf_size instead of i+3/7 because its simpler
  51          * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
  52          */
  53 #    if HAVE_FAST_64BIT
  54             while(i<buf_size && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
  55                 i+=8;
  56 #    else
  57             while(i<buf_size && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
  58                 i+=4;
  59 #    endif
  60 #endif
  61             for(; i<buf_size; i++){
  62                 if(!buf[i]){
  63                     state=2;
  64                     break;
  65                 }
  66             }
  67         }else if(state<=2){
  68             if(buf[i]==1)   state^= 5; //2->7, 1->4, 0->5
  69             else if(buf[i]) state = 7;
  70             else            state>>=1; //2->1, 1->0, 0->0
  71         }else if(state<=5){
  72             int v= buf[i] & 0x1F;
  73             if(v==6 || v==7 || v==8 || v==9){
  74                 if(pc->frame_start_found){
  75                     i++;
  76                     goto found;
  77                 }
  78             }else if(v==1 || v==2 || v==5){
  79                 if(pc->frame_start_found){
  80                     state+=8;
  81                     continue;
  82                 }else
  83                     pc->frame_start_found = 1;
  84             }
  85             state= 7;
  86         }else{
  87             if(buf[i] & 0x80)
  88                 goto found;
  89             state= 7;
  90         }
  91     }
  92     pc->state= state;
  93     return END_NOT_FOUND;
  94
  95 found:
  96     pc->state=7;
  97     pc->frame_start_found= 0;
  98     return i-(state&5);
  99 }
 100
 101 /*!
 102  * Parse NAL units of found picture and decode some basic information.
 103  *
 104  * @param s parser context.
 105  * @param avctx codec context.
 106  * @param buf buffer with field/frame data.
 107  * @param buf_size size of the buffer.
 108  */
 109 static inline int parse_nal_units(AVCodecParserContext *s,
 110                                   AVCodecContext *avctx,
 111                                   const uint8_t *buf, int buf_size)
 112 {
 113     H264Context *h = s->priv_data;
 114     const uint8_t *buf_end = buf + buf_size;
 115     unsigned int pps_id;
 116     unsigned int slice_type;
 117     int state = -1;
 118     const uint8_t *ptr;
 119
 120     /* set some sane default values */
 121     s->pict_type = FF_I_TYPE;
 122     s->key_frame = 0;
 123
 124     h->s.avctx= avctx;
 125     h->sei_recovery_frame_cnt = -1;
 126     h->sei_dpb_output_delay         =  0;
 127     h->sei_cpb_removal_delay        = -1;
 128     h->sei_buffering_period_present =  0;
 129
 130     for(;;) {
 131         int src_length, dst_length, consumed;
 132         buf = ff_find_start_code(buf, buf_end, &state);
 133         if(buf >= buf_end)
 134             break;
 135         --buf;
 136         src_length = buf_end - buf;
 137         switch (state & 0x1f) {
 138         case NAL_SLICE:
 139         case NAL_IDR_SLICE:
 140             // Do not walk the whole buffer just to decode slice header
 141             if (src_length > 20)
 142                 src_length = 20;
 143             break;
 144         }
 145         ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
 146         if (ptr==NULL || dst_length < 0)
 147             break;
 148
 149         init_get_bits(&h->s.gb, ptr, 8*dst_length);
 150         switch(h->nal_unit_type) {
 151         case NAL_SPS:
 152             ff_h264_decode_seq_parameter_set(h);
 153             break;
 154         case NAL_PPS:
 155             ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
 156             break;
 157         case NAL_SEI:
 158             ff_h264_decode_sei(h);
 159             break;
 160         case NAL_IDR_SLICE:
 161             s->key_frame = 1;
 162             /* fall through */
 163         case NAL_SLICE:
 164             get_ue_golomb(&h->s.gb);  // skip first_mb_in_slice
 165             slice_type = get_ue_golomb_31(&h->s.gb);
 166             s->pict_type = golomb_to_pict_type[slice_type % 5];
 167             if (h->sei_recovery_frame_cnt >= 0) {
 168                 /* key frame, since recovery_frame_cnt is set */
 169                 s->key_frame = 1;
 170             }
 171             pps_id= get_ue_golomb(&h->s.gb);
 172             if(pps_id>=MAX_PPS_COUNT) {
 173                 av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
 174                 return -1;
 175             }
 176             if(!h->pps_buffers[pps_id]) {
 177                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
 178                 return -1;
 179             }
 180             h->pps= *h->pps_buffers[pps_id];
 181             if(!h->sps_buffers[h->pps.sps_id]) {
 182                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
 183                 return -1;
 184             }
 185             h->sps = *h->sps_buffers[h->pps.sps_id];
 186             h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);
 187
 188             if(h->sps.frame_mbs_only_flag){
 189                 h->s.picture_structure= PICT_FRAME;
 190             }else{
 191                 if(get_bits1(&h->s.gb)) { //field_pic_flag
 192                     h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
 193                 } else {
 194                     h->s.picture_structure= PICT_FRAME;
 195                 }
 196             }
 197
 198             if(h->sps.pic_struct_present_flag) {
 199                 switch (h->sei_pic_struct) {
 200                     case SEI_PIC_STRUCT_TOP_FIELD:
 201                     case SEI_PIC_STRUCT_BOTTOM_FIELD:
 202                         s->repeat_pict = 0;
 203                         break;
 204                     case SEI_PIC_STRUCT_FRAME:
 205                     case SEI_PIC_STRUCT_TOP_BOTTOM:
 206                     case SEI_PIC_STRUCT_BOTTOM_TOP:
 207                         s->repeat_pict = 1;
 208                         break;
 209                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
 210                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
 211                         s->repeat_pict = 2;
 212                         break;
 213                     case SEI_PIC_STRUCT_FRAME_DOUBLING:
 214                         s->repeat_pict = 3;
 215                         break;
 216                     case SEI_PIC_STRUCT_FRAME_TRIPLING:
 217                         s->repeat_pict = 5;
 218                         break;
 219                     default:
 220                         s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
 221                         break;
 222                 }
 223             } else {
 224                 s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
 225             }
 226
 227             return 0; /* no need to evaluate the rest */
 228         }
 229         buf += consumed;
 230     }
 231     /* didn't find a picture! */
 232     av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit\n");
 233     return -1;
 234 }
 235
 236 static int h264_parse(AVCodecParserContext *s,
 237                       AVCodecContext *avctx,
 238                       const uint8_t **poutbuf, int *poutbuf_size,
 239                       const uint8_t *buf, int buf_size)
 240 {
 241     H264Context *h = s->priv_data;
 242     ParseContext *pc = &h->s.parse_context;
 243     int next;
 244
 245     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
 246         next= buf_size;
 247     }else{
 248         next= ff_h264_find_frame_end(h, buf, buf_size);
 249
 250         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 251             *poutbuf = NULL;
 252             *poutbuf_size = 0;
 253             return buf_size;
 254         }
 255
 256         if(next<0 && next != END_NOT_FOUND){
 257             assert(pc->last_index + next >= 0 );
 258             ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
 259         }
 260
 261         parse_nal_units(s, avctx, buf, buf_size);
 262
 263         if (h->sei_cpb_removal_delay >= 0) {
 264             s->dts_sync_point    = h->sei_buffering_period_present;
 265             s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
 266             s->pts_dts_delta     = h->sei_dpb_output_delay;
 267         } else {
 268             s->dts_sync_point    = INT_MIN;
 269             s->dts_ref_dts_delta = INT_MIN;
 270             s->pts_dts_delta     = INT_MIN;
 271         }
 272     }
 273
 274     *poutbuf = buf;
 275     *poutbuf_size = buf_size;
 276     return next;
 277 }
 278
 279 static int h264_split(AVCodecContext *avctx,
 280                       const uint8_t *buf, int buf_size)
 281 {
 282     int i;
 283     uint32_t state = -1;
 284     int has_sps= 0;
 285
 286     for(i=0; i<=buf_size; i++){
 287         if((state&0xFFFFFF1F) == 0x107)
 288             has_sps=1;
 289 /*        if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
 290         }*/
 291         if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
 292             if(has_sps){
 293                 while(i>4 && buf[i-5]==0) i--;
 294                 return i-4;
 295             }
 296         }
 297         if (i<buf_size)
 298             state= (state<<8) | buf[i];
 299     }
 300     return 0;
 301 }
 302
 303 static void close(AVCodecParserContext *s)
 304 {
 305     H264Context *h = s->priv_data;
 306     ParseContext *pc = &h->s.parse_context;
 307
 308     av_free(pc->buffer);
 309     ff_h264_free_context(h);
 310 }
 311
 312
 313 AVCodecParser h264_parser = {
 314     { CODEC_ID_H264 },
 315     sizeof(H264Context),
 316     NULL,
 317     h264_parse,
 318     close,
 319     h264_split,
 320 };