git.sesse.net Git - ffmpeg/blob - libavcodec/h264_sei.c

   1 /*
   2  * H.26L/H.264/AVC/JVT/14496-10/... sei decoding
   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 sei decoding.
  25  * @author Michael Niedermayer <michaelni@gmx.at>
  26  */
  27
  28 #include "internal.h"
  29 #include "avcodec.h"
  30 #include "h264.h"
  31 #include "golomb.h"
  32
  33 //#undef NDEBUG
  34 #include <assert.h>
  35
  36 static const uint8_t sei_num_clock_ts_table[9]={
  37     1,  1,  1,  2,  2,  3,  3,  2,  3
  38 };
  39
  40 void ff_h264_reset_sei(H264Context *h) {
  41     h->sei_recovery_frame_cnt       = -1;
  42     h->sei_dpb_output_delay         =  0;
  43     h->sei_cpb_removal_delay        = -1;
  44     h->sei_buffering_period_present =  0;
  45 }
  46
  47 static int decode_picture_timing(H264Context *h){
  48     MpegEncContext * const s = &h->s;
  49     if(h->sps.nal_hrd_parameters_present_flag || h->sps.vcl_hrd_parameters_present_flag){
  50         h->sei_cpb_removal_delay = get_bits(&s->gb, h->sps.cpb_removal_delay_length);
  51         h->sei_dpb_output_delay = get_bits(&s->gb, h->sps.dpb_output_delay_length);
  52     }
  53     if(h->sps.pic_struct_present_flag){
  54         unsigned int i, num_clock_ts;
  55         h->sei_pic_struct = get_bits(&s->gb, 4);
  56         h->sei_ct_type    = 0;
  57
  58         if (h->sei_pic_struct > SEI_PIC_STRUCT_FRAME_TRIPLING)
  59             return -1;
  60
  61         num_clock_ts = sei_num_clock_ts_table[h->sei_pic_struct];
  62
  63         for (i = 0 ; i < num_clock_ts ; i++){
  64             if(get_bits(&s->gb, 1)){                  /* clock_timestamp_flag */
  65                 unsigned int full_timestamp_flag;
  66                 h->sei_ct_type |= 1<<get_bits(&s->gb, 2);
  67                 skip_bits(&s->gb, 1);                 /* nuit_field_based_flag */
  68                 skip_bits(&s->gb, 5);                 /* counting_type */
  69                 full_timestamp_flag = get_bits(&s->gb, 1);
  70                 skip_bits(&s->gb, 1);                 /* discontinuity_flag */
  71                 skip_bits(&s->gb, 1);                 /* cnt_dropped_flag */
  72                 skip_bits(&s->gb, 8);                 /* n_frames */
  73                 if(full_timestamp_flag){
  74                     skip_bits(&s->gb, 6);             /* seconds_value 0..59 */
  75                     skip_bits(&s->gb, 6);             /* minutes_value 0..59 */
  76                     skip_bits(&s->gb, 5);             /* hours_value 0..23 */
  77                 }else{
  78                     if(get_bits(&s->gb, 1)){          /* seconds_flag */
  79                         skip_bits(&s->gb, 6);         /* seconds_value range 0..59 */
  80                         if(get_bits(&s->gb, 1)){      /* minutes_flag */
  81                             skip_bits(&s->gb, 6);     /* minutes_value 0..59 */
  82                             if(get_bits(&s->gb, 1))   /* hours_flag */
  83                                 skip_bits(&s->gb, 5); /* hours_value 0..23 */
  84                         }
  85                     }
  86                 }
  87                 if(h->sps.time_offset_length > 0)
  88                     skip_bits(&s->gb, h->sps.time_offset_length); /* time_offset */
  89             }
  90         }
  91
  92         if(s->avctx->debug & FF_DEBUG_PICT_INFO)
  93             av_log(s->avctx, AV_LOG_DEBUG, "ct_type:%X pic_struct:%d\n", h->sei_ct_type, h->sei_pic_struct);
  94     }
  95     return 0;
  96 }
  97
  98 static int decode_unregistered_user_data(H264Context *h, int size){
  99     MpegEncContext * const s = &h->s;
 100     uint8_t user_data[16+256];
 101     int e, build, i;
 102
 103     if(size<16)
 104         return -1;
 105
 106     for(i=0; i<sizeof(user_data)-1 && i<size; i++){
 107         user_data[i]= get_bits(&s->gb, 8);
 108     }
 109
 110     user_data[i]= 0;
 111     e= sscanf(user_data+16, "x264 - core %d"/*%s - H.264/MPEG-4 AVC codec - Copyleft 2005 - http://www.videolan.org/x264.html*/, &build);
 112     if(e==1 && build>0)
 113         h->x264_build= build;
 114
 115     if(s->avctx->debug & FF_DEBUG_BUGS)
 116         av_log(s->avctx, AV_LOG_DEBUG, "user data:\"%s\"\n", user_data+16);
 117
 118     for(; i<size; i++)
 119         skip_bits(&s->gb, 8);
 120
 121     return 0;
 122 }
 123
 124 static int decode_recovery_point(H264Context *h){
 125     MpegEncContext * const s = &h->s;
 126
 127     h->sei_recovery_frame_cnt = get_ue_golomb(&s->gb);
 128     skip_bits(&s->gb, 4);       /* 1b exact_match_flag, 1b broken_link_flag, 2b changing_slice_group_idc */
 129
 130     return 0;
 131 }
 132
 133 static int decode_buffering_period(H264Context *h){
 134     MpegEncContext * const s = &h->s;
 135     unsigned int sps_id;
 136     int sched_sel_idx;
 137     SPS *sps;
 138
 139     sps_id = get_ue_golomb_31(&s->gb);
 140     if(sps_id > 31 || !h->sps_buffers[sps_id]) {
 141         av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS %d referenced in buffering period\n", sps_id);
 142         return -1;
 143     }
 144     sps = h->sps_buffers[sps_id];
 145
 146     // NOTE: This is really so duplicated in the standard... See H.264, D.1.1
 147     if (sps->nal_hrd_parameters_present_flag) {
 148         for (sched_sel_idx = 0; sched_sel_idx < sps->cpb_cnt; sched_sel_idx++) {
 149             h->initial_cpb_removal_delay[sched_sel_idx] = get_bits(&s->gb, sps->initial_cpb_removal_delay_length);
 150             skip_bits(&s->gb, sps->initial_cpb_removal_delay_length); // initial_cpb_removal_delay_offset
 151         }
 152     }
 153     if (sps->vcl_hrd_parameters_present_flag) {
 154         for (sched_sel_idx = 0; sched_sel_idx < sps->cpb_cnt; sched_sel_idx++) {
 155             h->initial_cpb_removal_delay[sched_sel_idx] = get_bits(&s->gb, sps->initial_cpb_removal_delay_length);
 156             skip_bits(&s->gb, sps->initial_cpb_removal_delay_length); // initial_cpb_removal_delay_offset
 157         }
 158     }
 159
 160     h->sei_buffering_period_present = 1;
 161     return 0;
 162 }
 163
 164 int ff_h264_decode_sei(H264Context *h){
 165     MpegEncContext * const s = &h->s;
 166
 167     while (get_bits_left(&s->gb) > 16) {
 168         int size, type;
 169
 170         type=0;
 171         do{
 172             type+= show_bits(&s->gb, 8);
 173         }while(get_bits(&s->gb, 8) == 255);
 174
 175         size=0;
 176         do{
 177             size+= show_bits(&s->gb, 8);
 178         }while(get_bits(&s->gb, 8) == 255);
 179
 180         switch(type){
 181         case SEI_TYPE_PIC_TIMING: // Picture timing SEI
 182             if(decode_picture_timing(h) < 0)
 183                 return -1;
 184             break;
 185         case SEI_TYPE_USER_DATA_UNREGISTERED:
 186             if(decode_unregistered_user_data(h, size) < 0)
 187                 return -1;
 188             break;
 189         case SEI_TYPE_RECOVERY_POINT:
 190             if(decode_recovery_point(h) < 0)
 191                 return -1;
 192             break;
 193         case SEI_BUFFERING_PERIOD:
 194             if(decode_buffering_period(h) < 0)
 195                 return -1;
 196             break;
 197         default:
 198             skip_bits(&s->gb, 8*size);
 199         }
 200
 201         //FIXME check bits here
 202         align_get_bits(&s->gb);
 203     }
 204
 205     return 0;
 206 }