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