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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 FFmpeg.
00006  *
00007  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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 "h264_parser.h"
00030 #include "h264data.h"
00031 #include "golomb.h"
00032 
00033 #include <assert.h>
00034 
00035 
00036 int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)
00037 {
00038     int i;
00039     uint32_t state;
00040     ParseContext *pc = &(h->s.parse_context);
00041 //printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
00042 //    mb_addr= pc->mb_addr - 1;
00043     state= pc->state;
00044     if(state>13)
00045         state= 7;
00046 
00047     for(i=0; i<buf_size; i++){
00048         if(state==7){
00049 #if HAVE_FAST_UNALIGNED
00050         /* we check i<buf_size instead of i+3/7 because its simpler
00051          * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
00052          */
00053 #    if HAVE_FAST_64BIT
00054             while(i<buf_size && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
00055                 i+=8;
00056 #    else
00057             while(i<buf_size && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
00058                 i+=4;
00059 #    endif
00060 #endif
00061             for(; i<buf_size; i++){
00062                 if(!buf[i]){
00063                     state=2;
00064                     break;
00065                 }
00066             }
00067         }else if(state<=2){
00068             if(buf[i]==1)   state^= 5; //2->7, 1->4, 0->5
00069             else if(buf[i]) state = 7;
00070             else            state>>=1; //2->1, 1->0, 0->0
00071         }else if(state<=5){
00072             int v= buf[i] & 0x1F;
00073             if(v==6 || v==7 || v==8 || v==9){
00074                 if(pc->frame_start_found){
00075                     i++;
00076                     goto found;
00077                 }
00078             }else if(v==1 || v==2 || v==5){
00079                 if(pc->frame_start_found){
00080                     state+=8;
00081                     continue;
00082                 }else
00083                     pc->frame_start_found = 1;
00084             }
00085             state= 7;
00086         }else{
00087             if(buf[i] & 0x80)
00088                 goto found;
00089             state= 7;
00090         }
00091     }
00092     pc->state= state;
00093     return END_NOT_FOUND;
00094 
00095 found:
00096     pc->state=7;
00097     pc->frame_start_found= 0;
00098     return i-(state&5);
00099 }
00100 
00109 static inline int parse_nal_units(AVCodecParserContext *s,
00110                                   AVCodecContext *avctx,
00111                                   const uint8_t *buf, int buf_size)
00112 {
00113     H264Context *h = s->priv_data;
00114     const uint8_t *buf_end = buf + buf_size;
00115     unsigned int pps_id;
00116     unsigned int slice_type;
00117     int state = -1;
00118     const uint8_t *ptr;
00119 
00120     /* set some sane default values */
00121     s->pict_type = FF_I_TYPE;
00122     s->key_frame = 0;
00123 
00124     h->s.avctx= avctx;
00125     h->sei_recovery_frame_cnt = -1;
00126     h->sei_dpb_output_delay         =  0;
00127     h->sei_cpb_removal_delay        = -1;
00128     h->sei_buffering_period_present =  0;
00129 
00130     for(;;) {
00131         int src_length, dst_length, consumed;
00132         buf = ff_find_start_code(buf, buf_end, &state);
00133         if(buf >= buf_end)
00134             break;
00135         --buf;
00136         src_length = buf_end - buf;
00137         switch (state & 0x1f) {
00138         case NAL_SLICE:
00139         case NAL_IDR_SLICE:
00140             // Do not walk the whole buffer just to decode slice header
00141             if (src_length > 20)
00142                 src_length = 20;
00143             break;
00144         }
00145         ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
00146         if (ptr==NULL || dst_length < 0)
00147             break;
00148 
00149         init_get_bits(&h->s.gb, ptr, 8*dst_length);
00150         switch(h->nal_unit_type) {
00151         case NAL_SPS:
00152             ff_h264_decode_seq_parameter_set(h);
00153             break;
00154         case NAL_PPS:
00155             ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
00156             break;
00157         case NAL_SEI:
00158             ff_h264_decode_sei(h);
00159             break;
00160         case NAL_IDR_SLICE:
00161             s->key_frame = 1;
00162             /* fall through */
00163         case NAL_SLICE:
00164             get_ue_golomb(&h->s.gb);  // skip first_mb_in_slice
00165             slice_type = get_ue_golomb_31(&h->s.gb);
00166             s->pict_type = golomb_to_pict_type[slice_type % 5];
00167             if (h->sei_recovery_frame_cnt >= 0) {
00168                 /* key frame, since recovery_frame_cnt is set */
00169                 s->key_frame = 1;
00170             }
00171             pps_id= get_ue_golomb(&h->s.gb);
00172             if(pps_id>=MAX_PPS_COUNT) {
00173                 av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
00174                 return -1;
00175             }
00176             if(!h->pps_buffers[pps_id]) {
00177                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
00178                 return -1;
00179             }
00180             h->pps= *h->pps_buffers[pps_id];
00181             if(!h->sps_buffers[h->pps.sps_id]) {
00182                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
00183                 return -1;
00184             }
00185             h->sps = *h->sps_buffers[h->pps.sps_id];
00186             h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);
00187 
00188             avctx->profile = h->sps.profile_idc;
00189             avctx->level   = h->sps.level_idc;
00190 
00191             if(h->sps.frame_mbs_only_flag){
00192                 h->s.picture_structure= PICT_FRAME;
00193             }else{
00194                 if(get_bits1(&h->s.gb)) { //field_pic_flag
00195                     h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
00196                 } else {
00197                     h->s.picture_structure= PICT_FRAME;
00198                 }
00199             }
00200 
00201             if(h->sps.pic_struct_present_flag) {
00202                 switch (h->sei_pic_struct) {
00203                     case SEI_PIC_STRUCT_TOP_FIELD:
00204                     case SEI_PIC_STRUCT_BOTTOM_FIELD:
00205                         s->repeat_pict = 0;
00206                         break;
00207                     case SEI_PIC_STRUCT_FRAME:
00208                     case SEI_PIC_STRUCT_TOP_BOTTOM:
00209                     case SEI_PIC_STRUCT_BOTTOM_TOP:
00210                         s->repeat_pict = 1;
00211                         break;
00212                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
00213                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
00214                         s->repeat_pict = 2;
00215                         break;
00216                     case SEI_PIC_STRUCT_FRAME_DOUBLING:
00217                         s->repeat_pict = 3;
00218                         break;
00219                     case SEI_PIC_STRUCT_FRAME_TRIPLING:
00220                         s->repeat_pict = 5;
00221                         break;
00222                     default:
00223                         s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
00224                         break;
00225                 }
00226             } else {
00227                 s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
00228             }
00229 
00230             return 0; /* no need to evaluate the rest */
00231         }
00232         buf += consumed;
00233     }
00234     /* didn't find a picture! */
00235     av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit\n");
00236     return -1;
00237 }
00238 
00239 static int h264_parse(AVCodecParserContext *s,
00240                       AVCodecContext *avctx,
00241                       const uint8_t **poutbuf, int *poutbuf_size,
00242                       const uint8_t *buf, int buf_size)
00243 {
00244     H264Context *h = s->priv_data;
00245     ParseContext *pc = &h->s.parse_context;
00246     int next;
00247 
00248     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
00249         next= buf_size;
00250     }else{
00251         next= ff_h264_find_frame_end(h, buf, buf_size);
00252 
00253         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
00254             *poutbuf = NULL;
00255             *poutbuf_size = 0;
00256             return buf_size;
00257         }
00258 
00259         if(next<0 && next != END_NOT_FOUND){
00260             assert(pc->last_index + next >= 0 );
00261             ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
00262         }
00263 
00264         parse_nal_units(s, avctx, buf, buf_size);
00265 
00266         if (h->sei_cpb_removal_delay >= 0) {
00267             s->dts_sync_point    = h->sei_buffering_period_present;
00268             s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
00269             s->pts_dts_delta     = h->sei_dpb_output_delay;
00270         } else {
00271             s->dts_sync_point    = INT_MIN;
00272             s->dts_ref_dts_delta = INT_MIN;
00273             s->pts_dts_delta     = INT_MIN;
00274         }
00275     }
00276 
00277     *poutbuf = buf;
00278     *poutbuf_size = buf_size;
00279     return next;
00280 }
00281 
00282 static int h264_split(AVCodecContext *avctx,
00283                       const uint8_t *buf, int buf_size)
00284 {
00285     int i;
00286     uint32_t state = -1;
00287     int has_sps= 0;
00288 
00289     for(i=0; i<=buf_size; i++){
00290         if((state&0xFFFFFF1F) == 0x107)
00291             has_sps=1;
00292 /*        if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
00293         }*/
00294         if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
00295             if(has_sps){
00296                 while(i>4 && buf[i-5]==0) i--;
00297                 return i-4;
00298             }
00299         }
00300         if (i<buf_size)
00301             state= (state<<8) | buf[i];
00302     }
00303     return 0;
00304 }
00305 
00306 static void close(AVCodecParserContext *s)
00307 {
00308     H264Context *h = s->priv_data;
00309     ParseContext *pc = &h->s.parse_context;
00310 
00311     av_free(pc->buffer);
00312     ff_h264_free_context(h);
00313 }
00314 
00315 static int init(AVCodecParserContext *s)
00316 {
00317     H264Context *h = s->priv_data;
00318     h->thread_context[0] = h;
00319     return 0;
00320 }
00321 
00322 AVCodecParser h264_parser = {
00323     { CODEC_ID_H264 },
00324     sizeof(H264Context),
00325     init,
00326     h264_parse,
00327     close,
00328     h264_split,
00329 };

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