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libavcodec/h264_parser.c

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00001 /*
00002  * H.26L/H.264/AVC/JVT/14496-10/... parser
00003  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00028 #include "parser.h"
00029 #include "h264data.h"
00030 #include "golomb.h"
00031 
00032 #include <assert.h>
00033 
00034 
00035 static int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)
00036 {
00037     int i;
00038     uint32_t state;
00039     ParseContext *pc = &(h->s.parse_context);
00040 //printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
00041 //    mb_addr= pc->mb_addr - 1;
00042     state= pc->state;
00043     if(state>13)
00044         state= 7;
00045 
00046     for(i=0; i<buf_size; i++){
00047         if(state==7){
00048 #if HAVE_FAST_UNALIGNED
00049         /* we check i<buf_size instead of i+3/7 because its simpler
00050          * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
00051          */
00052 #    if HAVE_FAST_64BIT
00053             while(i<buf_size && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
00054                 i+=8;
00055 #    else
00056             while(i<buf_size && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
00057                 i+=4;
00058 #    endif
00059 #endif
00060             for(; i<buf_size; i++){
00061                 if(!buf[i]){
00062                     state=2;
00063                     break;
00064                 }
00065             }
00066         }else if(state<=2){
00067             if(buf[i]==1)   state^= 5; //2->7, 1->4, 0->5
00068             else if(buf[i]) state = 7;
00069             else            state>>=1; //2->1, 1->0, 0->0
00070         }else if(state<=5){
00071             int v= buf[i] & 0x1F;
00072             if(v==6 || v==7 || v==8 || v==9){
00073                 if(pc->frame_start_found){
00074                     i++;
00075                     goto found;
00076                 }
00077             }else if(v==1 || v==2 || v==5){
00078                 if(pc->frame_start_found){
00079                     state+=8;
00080                     continue;
00081                 }else
00082                     pc->frame_start_found = 1;
00083             }
00084             state= 7;
00085         }else{
00086             if(buf[i] & 0x80)
00087                 goto found;
00088             state= 7;
00089         }
00090     }
00091     pc->state= state;
00092     return END_NOT_FOUND;
00093 
00094 found:
00095     pc->state=7;
00096     pc->frame_start_found= 0;
00097     return i-(state&5);
00098 }
00099 
00108 static inline int parse_nal_units(AVCodecParserContext *s,
00109                                   AVCodecContext *avctx,
00110                                   const uint8_t *buf, int buf_size)
00111 {
00112     H264Context *h = s->priv_data;
00113     const uint8_t *buf_end = buf + buf_size;
00114     unsigned int pps_id;
00115     unsigned int slice_type;
00116     int state = -1;
00117     const uint8_t *ptr;
00118 
00119     /* set some sane default values */
00120     s->pict_type = AV_PICTURE_TYPE_I;
00121     s->key_frame = 0;
00122 
00123     h->s.avctx= avctx;
00124     h->sei_recovery_frame_cnt = -1;
00125     h->sei_dpb_output_delay         =  0;
00126     h->sei_cpb_removal_delay        = -1;
00127     h->sei_buffering_period_present =  0;
00128 
00129     if (!buf_size)
00130         return 0;
00131 
00132     for(;;) {
00133         int src_length, dst_length, consumed;
00134         buf = avpriv_mpv_find_start_code(buf, buf_end, &state);
00135         if(buf >= buf_end)
00136             break;
00137         --buf;
00138         src_length = buf_end - buf;
00139         switch (state & 0x1f) {
00140         case NAL_SLICE:
00141         case NAL_IDR_SLICE:
00142             // Do not walk the whole buffer just to decode slice header
00143             if (src_length > 20)
00144                 src_length = 20;
00145             break;
00146         }
00147         ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
00148         if (ptr==NULL || dst_length < 0)
00149             break;
00150 
00151         init_get_bits(&h->s.gb, ptr, 8*dst_length);
00152         switch(h->nal_unit_type) {
00153         case NAL_SPS:
00154             ff_h264_decode_seq_parameter_set(h);
00155             break;
00156         case NAL_PPS:
00157             ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
00158             break;
00159         case NAL_SEI:
00160             ff_h264_decode_sei(h);
00161             break;
00162         case NAL_IDR_SLICE:
00163             s->key_frame = 1;
00164             /* fall through */
00165         case NAL_SLICE:
00166             get_ue_golomb(&h->s.gb);  // skip first_mb_in_slice
00167             slice_type = get_ue_golomb_31(&h->s.gb);
00168             s->pict_type = golomb_to_pict_type[slice_type % 5];
00169             if (h->sei_recovery_frame_cnt >= 0) {
00170                 /* key frame, since recovery_frame_cnt is set */
00171                 s->key_frame = 1;
00172             }
00173             pps_id= get_ue_golomb(&h->s.gb);
00174             if(pps_id>=MAX_PPS_COUNT) {
00175                 av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
00176                 return -1;
00177             }
00178             if(!h->pps_buffers[pps_id]) {
00179                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
00180                 return -1;
00181             }
00182             h->pps= *h->pps_buffers[pps_id];
00183             if(!h->sps_buffers[h->pps.sps_id]) {
00184                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
00185                 return -1;
00186             }
00187             h->sps = *h->sps_buffers[h->pps.sps_id];
00188             h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);
00189 
00190             avctx->profile = ff_h264_get_profile(&h->sps);
00191             avctx->level   = h->sps.level_idc;
00192 
00193             if(h->sps.frame_mbs_only_flag){
00194                 h->s.picture_structure= PICT_FRAME;
00195             }else{
00196                 if(get_bits1(&h->s.gb)) { //field_pic_flag
00197                     h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
00198                 } else {
00199                     h->s.picture_structure= PICT_FRAME;
00200                 }
00201             }
00202 
00203             if(h->sps.pic_struct_present_flag) {
00204                 switch (h->sei_pic_struct) {
00205                     case SEI_PIC_STRUCT_TOP_FIELD:
00206                     case SEI_PIC_STRUCT_BOTTOM_FIELD:
00207                         s->repeat_pict = 0;
00208                         break;
00209                     case SEI_PIC_STRUCT_FRAME:
00210                     case SEI_PIC_STRUCT_TOP_BOTTOM:
00211                     case SEI_PIC_STRUCT_BOTTOM_TOP:
00212                         s->repeat_pict = 1;
00213                         break;
00214                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
00215                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
00216                         s->repeat_pict = 2;
00217                         break;
00218                     case SEI_PIC_STRUCT_FRAME_DOUBLING:
00219                         s->repeat_pict = 3;
00220                         break;
00221                     case SEI_PIC_STRUCT_FRAME_TRIPLING:
00222                         s->repeat_pict = 5;
00223                         break;
00224                     default:
00225                         s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
00226                         break;
00227                 }
00228             } else {
00229                 s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
00230             }
00231 
00232             return 0; /* no need to evaluate the rest */
00233         }
00234         buf += consumed;
00235     }
00236     /* didn't find a picture! */
00237     av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit\n");
00238     return -1;
00239 }
00240 
00241 static int h264_parse(AVCodecParserContext *s,
00242                       AVCodecContext *avctx,
00243                       const uint8_t **poutbuf, int *poutbuf_size,
00244                       const uint8_t *buf, int buf_size)
00245 {
00246     H264Context *h = s->priv_data;
00247     ParseContext *pc = &h->s.parse_context;
00248     int next;
00249 
00250     if (!h->got_first) {
00251         h->got_first = 1;
00252         if (avctx->extradata_size) {
00253             h->s.avctx = avctx;
00254             // must be done like in the decoder.
00255             // otherwise opening the parser, creating extradata,
00256             // and then closing and opening again
00257             // will cause has_b_frames to be always set.
00258             // NB: estimate_timings_from_pts behaves exactly like this.
00259             if (!avctx->has_b_frames)
00260                 h->s.low_delay = 1;
00261             ff_h264_decode_extradata(h);
00262         }
00263     }
00264 
00265     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
00266         next= buf_size;
00267     }else{
00268         next= ff_h264_find_frame_end(h, buf, buf_size);
00269 
00270         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
00271             *poutbuf = NULL;
00272             *poutbuf_size = 0;
00273             return buf_size;
00274         }
00275 
00276         if(next<0 && next != END_NOT_FOUND){
00277             assert(pc->last_index + next >= 0 );
00278             ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
00279         }
00280     }
00281 
00282     parse_nal_units(s, avctx, buf, buf_size);
00283 
00284     if (h->sei_cpb_removal_delay >= 0) {
00285         s->dts_sync_point    = h->sei_buffering_period_present;
00286         s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
00287         s->pts_dts_delta     = h->sei_dpb_output_delay;
00288     } else {
00289         s->dts_sync_point    = INT_MIN;
00290         s->dts_ref_dts_delta = INT_MIN;
00291         s->pts_dts_delta     = INT_MIN;
00292     }
00293 
00294     if (s->flags & PARSER_FLAG_ONCE) {
00295         s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
00296     }
00297 
00298     *poutbuf = buf;
00299     *poutbuf_size = buf_size;
00300     return next;
00301 }
00302 
00303 static int h264_split(AVCodecContext *avctx,
00304                       const uint8_t *buf, int buf_size)
00305 {
00306     int i;
00307     uint32_t state = -1;
00308     int has_sps= 0;
00309 
00310     for(i=0; i<=buf_size; i++){
00311         if((state&0xFFFFFF1F) == 0x107)
00312             has_sps=1;
00313 /*        if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
00314         }*/
00315         if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
00316             if(has_sps){
00317                 while(i>4 && buf[i-5]==0) i--;
00318                 return i-4;
00319             }
00320         }
00321         if (i<buf_size)
00322             state= (state<<8) | buf[i];
00323     }
00324     return 0;
00325 }
00326 
00327 static void close(AVCodecParserContext *s)
00328 {
00329     H264Context *h = s->priv_data;
00330     ParseContext *pc = &h->s.parse_context;
00331 
00332     av_free(pc->buffer);
00333     ff_h264_free_context(h);
00334 }
00335 
00336 static int init(AVCodecParserContext *s)
00337 {
00338     H264Context *h = s->priv_data;
00339     h->thread_context[0] = h;
00340     h->s.slice_context_count = 1;
00341     return 0;
00342 }
00343 
00344 AVCodecParser ff_h264_parser = {
00345     .codec_ids      = { CODEC_ID_H264 },
00346     .priv_data_size = sizeof(H264Context),
00347     .parser_init    = init,
00348     .parser_parse   = h264_parse,
00349     .parser_close   = close,
00350     .split          = h264_split,
00351 };
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