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 #include <assert.h>
  34
  35 static const uint8_t sei_num_clock_ts_table[9] = {
  36     1, 1, 1, 2, 2, 3, 3, 2, 3
  37 };
  38
  39 void ff_h264_reset_sei(H264Context *h)
  40 {
  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 {
  49     if (h->sps.nal_hrd_parameters_present_flag ||
  50         h->sps.vcl_hrd_parameters_present_flag) {
  51         h->sei_cpb_removal_delay = get_bits(&h->gb,
  52                                             h->sps.cpb_removal_delay_length);
  53         h->sei_dpb_output_delay  = get_bits(&h->gb,
  54                                             h->sps.dpb_output_delay_length);
  55     }
  56     if (h->sps.pic_struct_present_flag) {
  57         unsigned int i, num_clock_ts;
  58
  59         h->sei_pic_struct = get_bits(&h->gb, 4);
  60         h->sei_ct_type    = 0;
  61
  62         if (h->sei_pic_struct > SEI_PIC_STRUCT_FRAME_TRIPLING)
  63             return AVERROR_INVALIDDATA;
  64
  65         num_clock_ts = sei_num_clock_ts_table[h->sei_pic_struct];
  66
  67         for (i = 0; i < num_clock_ts; i++) {
  68             if (get_bits(&h->gb, 1)) {                /* clock_timestamp_flag */
  69                 unsigned int full_timestamp_flag;
  70
  71                 h->sei_ct_type |= 1 << get_bits(&h->gb, 2);
  72                 skip_bits(&h->gb, 1);                 /* nuit_field_based_flag */
  73                 skip_bits(&h->gb, 5);                 /* counting_type */
  74                 full_timestamp_flag = get_bits(&h->gb, 1);
  75                 skip_bits(&h->gb, 1);                 /* discontinuity_flag */
  76                 skip_bits(&h->gb, 1);                 /* cnt_dropped_flag */
  77                 skip_bits(&h->gb, 8);                 /* n_frames */
  78                 if (full_timestamp_flag) {
  79                     skip_bits(&h->gb, 6);             /* seconds_value 0..59 */
  80                     skip_bits(&h->gb, 6);             /* minutes_value 0..59 */
  81                     skip_bits(&h->gb, 5);             /* hours_value 0..23 */
  82                 } else {
  83                     if (get_bits(&h->gb, 1)) {        /* seconds_flag */
  84                         skip_bits(&h->gb, 6);         /* seconds_value range 0..59 */
  85                         if (get_bits(&h->gb, 1)) {    /* minutes_flag */
  86                             skip_bits(&h->gb, 6);     /* minutes_value 0..59 */
  87                             if (get_bits(&h->gb, 1))  /* hours_flag */
  88                                 skip_bits(&h->gb, 5); /* hours_value 0..23 */
  89                         }
  90                     }
  91                 }
  92                 if (h->sps.time_offset_length > 0)
  93                     skip_bits(&h->gb,
  94                               h->sps.time_offset_length); /* time_offset */
  95             }
  96         }
  97
  98         if (h->avctx->debug & FF_DEBUG_PICT_INFO)
  99             av_log(h->avctx, AV_LOG_DEBUG, "ct_type:%X pic_struct:%d\n",
 100                    h->sei_ct_type, h->sei_pic_struct);
 101     }
 102     return 0;
 103 }
 104
 105 static int decode_unregistered_user_data(H264Context *h, int size)
 106 {
 107     uint8_t user_data[16 + 256];
 108     int e, build, i;
 109
 110     if (size < 16)
 111         return AVERROR_INVALIDDATA;
 112
 113     for (i = 0; i < sizeof(user_data) - 1 && i < size; i++)
 114         user_data[i] = get_bits(&h->gb, 8);
 115
 116     user_data[i] = 0;
 117     e = sscanf(user_data + 16, "x264 - core %d", &build);
 118     if (e == 1 && build > 0)
 119         h->x264_build = build;
 120
 121     if (h->avctx->debug & FF_DEBUG_BUGS)
 122         av_log(h->avctx, AV_LOG_DEBUG, "user data:\"%s\"\n", user_data + 16);
 123
 124     for (; i < size; i++)
 125         skip_bits(&h->gb, 8);
 126
 127     return 0;
 128 }
 129
 130 static int decode_recovery_point(H264Context *h)
 131 {
 132     h->sei_recovery_frame_cnt = get_ue_golomb(&h->gb);
 133
 134     /* 1b exact_match_flag,
 135      * 1b broken_link_flag,
 136      * 2b changing_slice_group_idc */
 137     skip_bits(&h->gb, 4);
 138
 139     return 0;
 140 }
 141
 142 static int decode_buffering_period(H264Context *h)
 143 {
 144     unsigned int sps_id;
 145     int sched_sel_idx;
 146     SPS *sps;
 147
 148     sps_id = get_ue_golomb_31(&h->gb);
 149     if (sps_id > 31 || !h->sps_buffers[sps_id]) {
 150         av_log(h->avctx, AV_LOG_ERROR,
 151                "non-existing SPS %d referenced in buffering period\n", sps_id);
 152         return AVERROR_INVALIDDATA;
 153     }
 154     sps = h->sps_buffers[sps_id];
 155
 156     // NOTE: This is really so duplicated in the standard... See H.264, D.1.1
 157     if (sps->nal_hrd_parameters_present_flag) {
 158         for (sched_sel_idx = 0; sched_sel_idx < sps->cpb_cnt; sched_sel_idx++) {
 159             h->initial_cpb_removal_delay[sched_sel_idx] =
 160                 get_bits(&h->gb, sps->initial_cpb_removal_delay_length);
 161             // initial_cpb_removal_delay_offset
 162             skip_bits(&h->gb, sps->initial_cpb_removal_delay_length);
 163         }
 164     }
 165     if (sps->vcl_hrd_parameters_present_flag) {
 166         for (sched_sel_idx = 0; sched_sel_idx < sps->cpb_cnt; sched_sel_idx++) {
 167             h->initial_cpb_removal_delay[sched_sel_idx] =
 168                 get_bits(&h->gb, sps->initial_cpb_removal_delay_length);
 169             // initial_cpb_removal_delay_offset
 170             skip_bits(&h->gb, sps->initial_cpb_removal_delay_length);
 171         }
 172     }
 173
 174     h->sei_buffering_period_present = 1;
 175     return 0;
 176 }
 177
 178 int ff_h264_decode_sei(H264Context *h)
 179 {
 180     while (get_bits_left(&h->gb) > 16) {
 181         int size = 0;
 182         int type = 0;
 183         int ret  = 0;
 184
 185         do
 186             type += show_bits(&h->gb, 8);
 187         while (get_bits(&h->gb, 8) == 255);
 188
 189         do
 190             size += show_bits(&h->gb, 8);
 191         while (get_bits(&h->gb, 8) == 255);
 192
 193         switch (type) {
 194         case SEI_TYPE_PIC_TIMING: // Picture timing SEI
 195             ret = decode_picture_timing(h);
 196             if (ret < 0)
 197                 return ret;
 198             break;
 199         case SEI_TYPE_USER_DATA_UNREGISTERED:
 200             ret = decode_unregistered_user_data(h, size);
 201             if (ret < 0)
 202                 return ret;
 203             break;
 204         case SEI_TYPE_RECOVERY_POINT:
 205             ret = decode_recovery_point(h);
 206             if (ret < 0)
 207                 return ret;
 208             break;
 209         case SEI_BUFFERING_PERIOD:
 210             ret = decode_buffering_period(h);
 211             if (ret < 0)
 212                 return ret;
 213             break;
 214         default:
 215             av_log(h->avctx, AV_LOG_DEBUG, "unknown SEI type %d\n", type);
 216             skip_bits(&h->gb, 8 * size);
 217         }
 218
 219         // FIXME check bits here
 220         align_get_bits(&h->gb);
 221     }
 222
 223     return 0;
 224 }